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Pierceopedia is an alphabetic universe of fire truck terminology. Whether you're a fire service veteran or a rookie on the squad, this interactive fire truck glossary will elevate your knowledge of fire truck features, components and parts. 



A fire truck accelerator, typically in the form of a foot pedal, is used to control the speed of a vehicle.

Access Ladder

An access ladder is designed for climbing with one or more rungs (of any shape) with an inclination between 60 and 90 degrees.

Aerial Device

There are three (3) aerial devices defined by NFPA standards: aerial ladders, elevating platforms and water towers. Aerial devices can be designed with one or multiple functions, from appropriately positioning fire responders on scene to managing material handling, providing continuous egress or discharging water.

Learn more about the types of aerial devices in our informative blog: 3 Types of Aerial Devices: A Comprehensive Overview

Aerial Fire Apparatus

An aerial fire apparatus is a vehicle equipped with an aerial device (aerial ladder, elevating device or water tower) that is designed to perform fireground operations at positions elevated from the ground, including discharging water, providing continuous egress, supporting firefighting and rescue operations.

There are several types of aerial fire apparatus:

- Pumper fire apparatus with an aerial device
- Non Quint or Quint fire apparatus
- Mobile foam fire apparatus with an aerial device

The capabilities of aerial fire apparatus can vary greatly from department to department and from mission to mission. Aerial fire apparatus should be uniquely designed to meet the mission requirements of a fire department.

Based on these requirements, aerial fire apparatus can be custom built in three configurations:

- Rear mount aerial device
- Mid-mount aerial device
- Tractor-drawn aerial device

Access more information on types of aerial apparatus and aerial configurations in this informative blog post: Types of Aerial Fire Trucks: NFPA Classification Overview

Aerial Ladder

An aerial ladder is an aerial device that can be mounted on a fire truck with either a mid-mount, rear-mount or tractor-drawn configuration.

An aerial ladder is designed to maximize vertical reach for rapid response, ventilation, extinguishment and rescue operations. An aerial ladder can include a waterway, which supplies water to the end of the device via the apparatus water pump. If an aerial ladder apparatus does not include a water pump, the waterway must be supplied via a separate pumping apparatus.

Aerial Placement

Aerial placement refers to how an aerial device is positioned at an emergency scene and can significantly impact the effectiveness of fire ground operations. The placement type depends on the type of fire and the structure that requires protection.

There are two aerial placement strategies:
  • Horizontal placement focuses on the reach of the aerial device and is useful in residential areas. With horizontal placement, a fire truck can be parked on the road and the aerial device can be extended to reach the roofline to execute firefighting operations.
  • Vertical placement focuses on the height of the aerial or ladder device and is often required in cities with multi-level buildings. Vertical placement positions apparatus to allow for optimal aerial ascent upwards to perform firefighting operations.
Continue to this blog to learn more about aerial placement and operation: Aerial Placement and Operation: 6 Benefits of Pierce Ascendant Aerials

Aerial Platform

An aerial platform is an aerial device with a basket attached to the tip of the device, also known as a tower. The platform or basket is enclosed and allows for the safe transportation of personnel and equipment. An aerial platform typically includes a waterway, which supplies water to the end of the device via the apparatus water pump. If an aerial platform apparatus does not include a water pump, the waterway must be supplied via a separate pumping apparatus.

Air Control Panel

An air control panel is an arrangement of gauges, regulators, valves and air system piping at a centralized location that enables operators to monitor and adjust airflow and pressure within the system.

Air Pack

A self-contained breathing apparatus (SCBA) is the breathing apparatus that firefighters wear which provides clean breathing air during fire suppression and rescue operations.


An airbag is an inflatable cushion built into vehicles designed to protect occupants and reduce injury in the event of a crash.

Aircraft Rescue and Firefighting (ARFF)

Aircraft rescue and firefighting (ARFF) is a specialized type of firefighting that includes emergency response, mitigation, evacuation, and rescue following aviation accidents or incidents.

Aircraft rescue and firefighting vehicles are designed specifically to support these fireground operations.

Angle of Approach

The angle of approach is the maximum ramp angle onto which a vehicle can climb from a horizontal plane without interference. To measure the angle of approach, draw a line from where the front tire meets the ground to the lowest-hanging part of the vehicle at the front overhang and measure the angle to the ground.

Angle of Departure

The angle of departure is the maximum ramp angle from which a vehicle can descend without interference. To measure the angle of departure, draw a line from where the rear tire meets the ground to the lowest-hanging part of the vehicle at the rear overhang and measure the angle to the ground.

Anti-Lock Braking System

An anti-lock braking system (ABS) is an anti-skid safety feature on vehicles designed to automate brake pumping—wheels are unable to lock up, maintaining traction on the road and allowing operators to focus on safely steering the vehicle.


A vehicle designed to be used under emergency conditions to transport personnel and equipment or to support the suppression of fires or mitigation of other hazardous situations.

Articulating Boom

An articulating boom is an aerial device consisting of two or more folding boom sections that extend and retract by adjusting the angle of the knuckle joints.

Attack Hose / Attack Line

An attack hose or an attack line is a hose that advances towards and extinguishes fire. Attack lines are typically pre-connected to the fire truck's pump to be ready for immediate use in firefighting operations. Attack lines are designed to withstand high water pressure and abrasion to give firefighters the flexibility and power needed to extinguish fires.

If you’re interested in learning more about fire hose deployment and operations, reference our blog: Fire Truck Hose Deployment: Tips to Optimize Operational Tactics

Auxiliary Braking System

An auxiliary braking system is a device used on heavy-duty vehicles to augment the functions of the primary friction-based braking system. An auxiliary braking system is an additional system used to slow vehicles, with the final braking done by the main service braking system. Examples include a driveline retarder, engine retarder, exhaust retarder or transmission retarder.

Auxiliary Hydraulic Power

An auxiliary hydraulic power system can be a small gasoline engine, diesel engine or electric motor-driven hydraulic pump used to operate auxiliary equipment or attachments. The addition of an auxiliary hydraulic power system increases the versatility of a vehicle by allowing it to perform additional functions in lieu of the main hydraulic system.

Auxiliary Water Pump

An auxiliary water pump is mounted on a fire apparatus in addition to the main fire pump and used in firefighting in conjunction with or independently of the main fire pump.


Back-up Alarm

A fire truck back-up alarm is an audible device designed to warn passers-by that a fire apparatus is moving in reserve. A back-up alarm is automatically triggered to sound when an apparatus is engaged in reserve and is standard on every Pierce fire truck.


A backdraft is a deflagration that occurs when oxygen is introduced into a ventilation-limited space containing unburned fuel and gases. When the air combines with the unburned fuel, rapid ignition may occur with devastating force.

Base Rail

A base rail is the lower rail of an aerial ladder, to which rungs and reinforcements are attached.

See the three types of aerial devices in more detail here.

Base Section

The base section of an aerial device is the first or bottom section of an aerial device.

Find out more about types of aerial devices now.

Blacked Out Fire Truck

A blacked-out fire truck is a fire truck that has parts and/or components coated in black material or ordered with a black finish. Traditionally, many of these fire truck parts and components were a chrome finish, but now come in several color options, including black, red or custom requests.


A fire truck boom is an assembled component of an aerial device that allows for elevated fire fighting operations, reaching up, down, out and potentially over obstructions with articulation.

There are three types of aerial devices as defined by the NFPA, learn more here: 3 Types of Aerial Devices: A Comprehensive Overview


Booster Line

A booster line is a type of fire hose that is usually one inch in diameter and rubber jacketed. Booster lines are often stored on reels and are used to combat small fires. They are usually supplied by the water carried in the apparatus' booster tank.

Booster Tank

A booster tank is a built-in water tank on a fire apparatus that supplies booster lines and hand lines at a fire until a new connection with a water source, like a fire hydrant or dry hydrant, can be made.

Breathing Air System

A breathing air system includes all the necessary components, lines and devices required to deliver breathing air. This includes specialty equipment such as compressors, a purification system, pressure regulators, safety devices, manifolds, air tanks or receivers, and interconnecting piping.

Find out more about clean cab storage initiatives for breathing apparatus now.

Broom Compartment

A broom compartment is a type of body compartment found on fire apparatus that is typically short and wide with a drop down door for easy access.

Access additional information about smart compartmentation and storage FAQs here.

Brush Truck

A brush truck is a type of firefighting vehicle typically used to fight wildland or grass fires. In many cases, a brush truck is a 4-wheel drive pick-up truck-based vehicle designed for optimal off-road driving with a mounted pump and tank.

Learn more about the different types of fire truck classifications now.

Bulk Tank

A bulk tank is a portable tank generally mounted to the side of the apparatus to support rural or non-hydrant water supplies. Bulk tanks can range from 1000 to 3500 gallons of water capacity.

Bunker Gear

Bunker gear, also known as turnout gear, is the type of personal protective equipment or fire protective apparel that firefighters wear on duty.


Cab / Crew Cab

The enclosed area at the front of a fire truck where the driver and other crew members sit. The rear portion of a cab is often referred to as the crew cab.

Cargo Area

Also referred to as the dunnage area, the cargo area is the storage space directly above the pump house or under the aerial device.

Cascade Filling System

A cascade filling system is a high-pressure cylinder storage system which is used for the supply of air to the SCBA fill station.

Center of Gravity

A fire truck’s center of gravity is the point at which the entire weight of the fire apparatus is considered to be concentrated so that, if supported at this point, the apparatus would remain in equilibrium in any position.

Charged Line

A charged line, also called a charged hose, is a pressurized, water-filled hose that is ready for use.


A chassis is the basic load bearing framework of the fire apparatus. The term rolling chassis means the frame plus the “running gear” (including the engine, transmission, drive shaft, and suspension).

The ideal chassis type will depend on the apparatus required. And the type of chassis impacts the gross vehicle weight rating, which in turn, affects powertrain and horsepower. These items help determine payload capacity and the amount of equipment and number of personnel that the truck can carry.

Class A Foam

Class A foam is formulated to be used on Class A fires which involve combustibles such as wood, paper, and other natural materials. This type of foam breaks down the surface tension of water and allows the water to impregnate the combustible materials faster than water alone.

Class B Foam

Class B foam is formulated to be used on Class B fires which involve flammable liquids such as gasoline or other fuels. This type of foam floats, creating a surface vapor barrier on top of a flammable liquid to stop the flammable liquid and vapors from burning. This foam is typically used at 1%, 3%, and 6% mixing ratios.

Clean Cab

Clean cab refers to a cab that contains options to reduce the exposure of fire fighters to carcinogens. There are multiple options to consider when designing a fire apparatus, including the interior and exterior. Through the CARE (Carcinogen Awareness & Reduction to Exposure) program, Pierce Manufacturing, in partnership with the Firefighter Cancer Support Network, raises awareness about the dangers of carcinogens to fire fighters.

The main objectives of clean cab environments are selecting easy-to-clean surfaces and maintaining clean air within the cab which reduces the opportunity for exposure to carcinogens.

Read more about clean cab advancements in this blog.

CO2 Extinguisher

A CO2 extinguisher is an extinguisher designed for Class B and C (flammable liquid and electrical) fires. The carbon dioxide displaces oxygen while simultaneously cooling the fuel.

Collapse Zone

A collapse zone is an area identified around a structure (usually on fire) that may contain debris should the structure collapse.

Collision Avoidance

Collision avoidance systems, or collision mitigation systems activate and alert drivers in real-time as their vehicles approach first responders. HAAS Alert collision mitigation systems is an example of this.

Combination Nozzle

A combination nozzle is a type of hose nozzle that combines the pressure of a straight tip nozzle and the pattern of a fog tip nozzle. There are several different variations of combination nozzles, including single gallonage, adjustable gallonage, automatic, and multi-purpose.

Command and Communications Apparatus

Command and communications apparatus, or mobile command vehicles, are apparatus used to manage, organize, and monitor incidents for long durations. Command and communications apparatus can include many features, like radio and video equipment, computer networks, weather monitoring equipment, room for personnel, food storage, showers, bathrooms, kitchens, canteen areas, closet storage and conference rooms. Police, fire departments, and government agencies often rely on this vehicle type.


A compartment is an area within the fire truck in which equipment or gear may be stored. Compartmentation is an important component of fire apparatus design.

Compressed Air Foam System (CAFS)

A compressed air foam system (CAFS) combines air under pressure with a foam solution to create foam. CAFS makes a fire hose approximately 50% lighter than water/foam alone, resulting in less firefighter fatigue. CAFS allows the water/foam mixture to adhere to the burning material longer giving the water/foam mixture a longer time to impregnate the burning material.

The Hercules CAFS adds compressed air to Husky foam systems and comes with controls that fit easily on any pump panel for straightforward and organized operation.

Compressed Breathing Air

Compressed breathing air is the same air that is breathed in and out by firefighters but has been compressed and maintained under pressure.

Cooperative Purchasing / Consortium

A fire apparatus consortium is a group purchasing organization that offers procurement on behalf of public organizations or other entities. The procurement process for fire apparatus can become complex as a result of needs assessments, public bids, reviews, and additional steps. A consortium helps save time and money by streamlining the process.

Crash Testing

Crash testing is the process by which fire apparatus undergo multiple independent third party tests to ensure the vehicle meets (or exceeds) the requirements set out by the Society of Automotive Engineers (SAE) and other industry standards. 

Crash testing is necessary to improve protection of the vehicle's occupants. Tests focus on the cab’s structural integrity, including determining what would happen to the cab’s structure and its occupants during an accident.

Read more about crash testing in this blog.


A type of hose storage method, in which the hose can be quickly unloaded from either side of the apparatus. The hose lays across the pump, and is pre-connected to a pump outlet and is equipped with a nozzle. Crosslays extend the width of the fire truck and allow access to hose lines from either side.

Curb Weight

Defined by NFPA 1901 as “the total weight of the complete vehicle less the payload,” the curb weight refers to the overall total weight of the vehicle, without any personnel or equipment on board.


Dead Lay

A dead lay is a load of hose that is not connected to a pump outlet. This is often used for larger supply lines.


A fire apparatus dealer plays an instrumental role in helping fire departments find, design and purchase fire apparatus. Pierce’s experienced dealers collaborate with fire department representatives to develop a custom, innovative apparatus design, and provide extensive aftermarket support capabilities throughout the life of a fire apparatus.

Our blog, Benefits of a Strong Fire Apparatus Dealer Network, explains more about dealers.

Deck Gun or Deluge Gun

A deck gun, or deluge gun is a large water nozzle usually attached to the top of a fire truck. Many can be removed from the truck and mounted to a portable stand. They can rotate and elevate and can deliver more water than a hand-held hose.


Decontamination is the process of thoroughly rinsing equipment and gear while on-site and transporting any contaminated gear to the station while maintaining separation from personnel. Fire scenes expose personnel, equipment, and apparatus to a range of biological and chemical contaminants that pose carcinogenic risks. As such, decontamination is key to improving firefighter safety.

Department of Transportation (DOT)

The Department of Transportation (DOT) is the federal body developing and enforcing regulations, standards and resources related to firefighting, emergency response, transportation systems and the handling of hazardous materials.

Diesel Exhaust Fluid (DEF)

Diesel Exhaust Fluid (DEF) is a solution of urea and water used to reduce pollutants from and increase longevity of selective catalytic reduction (SCR) systems in diesel engines.


A dispatch message is a message sent by the dispatcher and received by the fire hall. Dispatch can also refer to the process of the fire department’s initial response to an emergency.


Drafting is a process used to pull water from a source other than a hydrant or other specific fire apparatus. For example, water might be drafted from lakes, ponds, pools, or cisterns. Drafting is particularly common in rural areas where access to hydrants is limited.

Drop Tank

A drop tank is a portable tank used at fire scenes to store water.

Dry Chemical Agent

A dry chemical agent is an agent used on certain types of fires. There are different types of dry chemical agents available.

Dunnage Area

Also referred to as the cargo area, a dunnage area is used to store equipment and miscellaneous cargo.



Electrodeposition coating (e-coat) is a primer that is applied to apparatus parts and components to provide resistance to corrosion, abrasion, and chemicals. Paint is then applied on top of the e-coat. Even if the paint is scratched, the protective e-coat layer ensures that the paint will not peel and the scratch doesn’t become a localized area of corrosion. E-coat is typically applied to the chassis, frame rails, and parts of the apparatus undercarriage. Read more about e-coat in this blog.

Electric Fire Truck

An electric fire truck is a fire truck that operates on an electric drivetrain or battery power instead of or in combination with an internal combustion engine.

Electric fire trucks such as the Pierce® Volterra™ offer a range of benefits, including zero emissions and reduced noise.

There are different types of electric fire trucks available, including parallel-electric drivetrain fire trucks, which operate with an internal combustion engine as backup, and range-extended electric vehicles, which run on battery power with a generator or engine for backup power.

Electric Fire Truck Charging Infrastructure

Electric fire truck charging infrastructure is the infrastructure necessary to charge electric fire trucks. Stations utilizing electric vehicles such as a Pierce® Volterra™ fire truck need to have the correct charging infrastructure in place. The infrastructure typically requires 480-volt power, although if this is not available, a step-up transformer may be used.

Electrical Fire

An electrical fire is a fire caused by electricity or faulty electrical equipment.

Electrical Load Management

Electric load management, which is often simply called load management, refers to the system in place that matches electricity supply with demand. This consists of a device that continuously monitors the electrical system voltage and automatically sheds predetermined loads in a defined order to prevent over-discharging of the vehicle’s batteries.

Elevating Platform

An elevating platform is a type of aerial apparatus that has an aerial ladder with a basket or platform at the tip. The platform is enclosed and allows for safe transportation of passengers up and down. This apparatus is a common addition to fire trucks that operate within communities in which many people work or live in elevated locations such as mid-rise or high-rise buildings. (See also Aerial Apparatus)

Elliptical Tanker

An elliptical tanker is a type of pumper tanker truck that has an elliptical-shaped water tank.

Emergency Medical Services (EMS)

Emergency Medical Services (EMS) is the system and team that provides coordinated response and care for medical emergencies. These emergency services provide pre-hospital treatment to people with serious injuries or illness and transport to hospitals or other healthcare institutions.

Emergency Power Unit (EPU)

Emergency power unit (EPU) is the backup power source that allows controlled aerial operation in case of hydraulic system failure.

Emergency Warning Lights

Emergency warning lights are a fire truck’s flashing lights which are designed to catch the attention of pedestrians and drivers so that they are aware of the fire truck and can move out of its path if needed. Newer lighting systems typically use LED technology. The NFPA 1901 Standard identifies required zones on fire apparatus in which warning light systems must be positioned.


Also known as a pumper, an engine is a fire suppression vehicle that has a water pump and typically carries hoses, other equipment, and a limited supply of water. (See also Pumper)

Engine Company

Engine company refers to the combination of a fire truck and those staffing it.

Equipment Allowance

Equipment Allowance is part of the calculated in-service weight for all types of apparatus. It is the amount of additional miscellaneous equipment weight that can be carried on the completed vehicle as it leaves the factory. For example, on a pumper fire apparatus with more than 250 cubic feet of compartment space the equipment allowance is 2500 lbs.

Equipment allowance is the also additional amount of weight above the NFPA rated dry tip load that can be added to an aerial ladder or platform without compromising the stability of the apparatus. The equipment allowance must be known and accounted for at the time of aerial stability testing carried out by the vehicle manufacturer.

Exposure Protection

Exposures are structures or buildings that are at risk due to a fire. Exposure protection is the process firefighters use to protect these structures to minimize the risk of the fire spreading and causing additional damage.

Extension Ladder

An extension ladder is a type of portable ground ladder, manufactured in various lengths, that provides access and egress for firefighting operations. They can have two or more sections which allow for lengthening or extending a ladder.


Extrication is the act of removing an entangled or trapped person or thing.



The Fire Apparatus Manufacturers’ Association (FAMA) is a non-profit organization engaged in enhancing fire apparatus industry quality and improving the emergency services community.

Federal Motor Vehicle Safety Standards (FMVSS)

Federal Motor Vehicle Safety Standards, or FMVSS for short, are regulations set by the National Highway Transportation Safety Administration (NHTSA). These are mandatory and must be adhered to by all motor vehicle or motor vehicle equipment manufacturers. For example, fire trucks must undergo cab crash tests to comply with these and other standards.

Final Inspection

A final inspection is an extensive inspection that a fire truck goes through before it is released from the manufacturing facility. The robust Pierce fire truck final inspection process includes three steps—a final product evaluation, a thorough inspection with the customer and any final adjustments.

See the entire step-by-step process in our blog post here.


Fire Apparatus

Fire apparatus refers to emergency vehicles designed to transport equipment and personnel to the scene of a fire or other hazardous situation. There are many different types of fire apparatus, including aerials, pumpers, rescues, tankers, command units and electric fire trucks. These can be completed as build to order or already produced stock trucks.

Fire Flow

Fire flow refers to the flow rate of a water supply that is available for firefighting by the responding fire department.

Fire Pump

A fire pump is a water pump that is mounted on a fire apparatus and intended for use in firefighting. The fire pump is sometimes referred to as the “heart” of the fire truck.

Fire Truck Global Positioning System (GPS)

A fire truck global positioning system (GPS) is a satellite-based positioning and navigation system that is built into or added to the cab of a fire truck. It enables quick navigation to the scene of an emergency and tracking of emergency vehicle locations.

Fire Truck Graphics

Fire truck graphics refer to the text, designs and logos that are painted on or adhered to firefighting vehicles.

Fire truck graphics provide a critical safety feature in accordance with the National Fire Protection Association (NFPA)1901 Section 4.21 and present fire departments with opportunities for both differentiation and customization.

There are many considerations your fire department should keep in mind during the graphics selection process. Our blog covers everything you need to know.

Fire Truck Manufacturer

A fire truck manufacturer is a company that constructs firefighting vehicles or parts. Pierce Manufacturing is the industry’s leading fire truck manufacturer.

Fire Wall

A fire wall is a fire-resistant barrier designed to prevent the spread of a fire. It might be built between or through structures, buildings, or electrical transformers, or in vehicles or aircraft.


A firehose is a high-pressure hose used for carrying water or another fire retardant used to extinguish a fire.

Fixed Power Source

A fixed power source is a line voltage source of power. A portable generator is not considered a fixed power source.


Flashover refers to the sudden ignition of all flammable materials in a structure or room. This occurs when the flammable gases from the contents of the room reach their ignition point.


A fleet refers to a group of fire trucks, either from a single fire station or from multiple stations in a particular geographical area.

Fleet Management

Fleet management refers to the management of a fleet of fire trucks and can include a variety of functions, including daily operations, maintenance, training, safety, procurement, access to parts and more.

You can learn more about fleet management in our blog.

Fly Section

The fly section is the section of an aerial device furthest from the base section with an extendable ladder or aerial device.


Foam is an extinguishing agent formed by mixing foam concentrate with water and aerating the solution for expansion. Foam creates a barrier between the fuel sources and heat, preventing ignition.

There are different types of foam systems, designed for use in suppressing different types of fires.
  • Class ‘A’ foam is used for Class ‘A’ fires, which include solid combustibles such as paper, wood, cloth and some plastics.
  • Class ‘B’ foam is used for Class ‘B’ fires, which are fires that involve flammable liquids such as alcohol, ether, oil, gasoline or grease.

Learn more in our blog: Fire-Fighting Foam: What It Is and Why Fire Departments Need It

Foam Concentrate

Foam concentrate is raw foam liquid as it rests in its storage container before the introduction of water and air.

Foam Proportioner

A foam proportioner is a method or device that combines water with foam concentrate to form the foam solution in a foam system.

Foam Solution

Foam solution refers to the mixture of the foam concentrate with water.

Foam System

A foam system refers to the equipment that creates the foam. It allows a certain amount of foam concentrate to be combined with water through fire apparatus pumps.

Fog Nozzle

A fog nozzle is a hose nozzle that breaks up the water stream creating droplets and dispersing the water outwards.

Learn more about the different types of nozzles in our blog: Fog Tip Nozzle vs. Straight Tip Nozzle (A Highly Contentious Topic)

Fog Stream

The fog stream refers to the type of stream that comes from a fog nozzle. A fog nozzle creates a wide cast of water, in contrast to a straight-tip nozzle which creates a solid, steady stream.

Forestry Line

A forestry line is a small-diameter hose used in fighting forest and brush fires. Its light-weight construction is designed to help reduce firefighter fatigue.

Forward Lay

A forward lay is the laying of a water supply line from the water source to the scene of the fire. It is the opposite of a reverse lay.


Gallons Per Minute (GPM)

Gallons per minute (GPM) is the unit used to describe the rate of flow of water or foam. This is used to measure output of fire engines, pumps, hydrants and other sources.

Gauge Pressure

The gauge pressure refers to the pressure relative to atmospheric pressure as measured by a gauge.


A generator is a device that converts mechanical energy into electrical power for use in an external circuit.

Global Positioning System (GPS)

A Global Positioning System (GPS) is a network of satellites that enable users to pinpoint the location of something on the earth.


Also called slope, grade is the measurement of the angle used in road design and expressed as a percentage of elevation over distance. A 45-degree slope is equal to a 100-percent grade.

Gravity Tank

A gravity tank is a vessel that stores water at atmospheric pressure and relies on gravity to distribute it using a downward distribution system. These tanks are usually elevated above building roofs to fully take advantage of gravity.

Gross Axle Weight Rating (GAWR)

The gross axle weight rating, or GAWR for short, is the maximum distributed weight that may be supported by an axle of a vehicle, as specified by the final stage manufacturer.

Gross Vehicle Weight Rating (GVWR)

The gross vehicle weight rating, or GVWR for short, is the maximum operating weight of a vehicle as specified by the manufacturer. It includes the vehicle’s chassis, body, engine, engine fluids, fuel, pump, aerial, accessories, driver, passengers and cargo.

Ground Clearance

The ground clearance refers to the vertical distance from the vehicle component to the ground.

Ground Ladder

A ground ladder is a ladder that is designed for its base to be placed on the ground. It can provide a means of safe access (or egress) and may also be used as bridging.

Ground Penetration

Ground penetration is a dimension that represents how far an aerial stabilizer can vertically extend after it reaches the ground. The higher the number, the greater side slope the aerial can be set up and operated on.


H-Style Aerial Stabilizers

Aerial stabilizers are devices that stabilize the fire apparatus while the aerial ladder is in operation. When extended, the H-style aerial stabilizers form an “H” shape with the rig.

There are many inherent benefits of H-style aerial stabilizers, from a higher stabilizer strength-to-weight ratio to improved leveling capabilities on uneven ground. Learn all of the benefits of H-style aerial stabilizers in this blog post.

Hand Line

A hand line is a hose that has a small diameter (usually 1.5–2.5 inches) and is typically used inside a structure to apply water directly onto the fire.

Hand Rail

The hand rail is the top structural member of an aerial ladder section to which reinforcement and lacings are attached.

Hard Suction Hose

A hard suction hose is a non-collapsible suction hose that is attached to a pump and used to draft water from a source. This type of hose is used when the water source is lower than the pump.

Hazardous Materials (HAZMAT) Response Fire Apparatus

Hazardous materials (HAZMAT) response fire apparatus refers to an emergency vehicle designed to respond to the scene of a hazardous material incident. The apparatus often features a command center with vast storage for specialized suits, over-pack drums and decontamination equipment. It can include computer and weather gear, radio/video monitoring and small labs for analyzing material.

Heating, Ventilation and Air Conditioning (HVAC)

The heating, ventilation and air conditioning (HVAC) system on a fire truck refers to the combination of multiple components, including the heater, air conditioner, air filter, blower motor, evaporator coil, ducting and housing.

Heavy-Duty Rescue Apparatus

Heavy-duty rescue apparatus (HDR) refers to vehicles that are built with spacious, heavy-duty construction. They are designed to have large capacity and high durability.

Learn more about this topic in our blog: Advancements in Rescue Pumper Storage.

Heavy-Duty Steel Ladder

A heavy-duty steel ladder is a ladder constructed of steel and designed for strength, stability and durability.

Hercules System

The Hercules™ system is a special compressed air foam system (CAFS) from Pierce. The water, air, and foam mixture that it produces has low surface tension which allows it to spread quickly, cover a large surface area and adhere to the fuel source for longer than water. The foam has the ability to penetrate and cool the fuel source materials much faster than water alone.

High Idle Speed Control

High idle speed control is a switch or control system that offers the means to increase the engine speed to a higher preset speed.

High Voltage

High voltage electricity describes an electrical potential that is high enough to cause damage or injury.

High-Rise Pack

A high-rise pack is a length of hose, bundled in such a way that it can be carried to a scene for deployment. These packs are typically used in high-rise structures where the hose must be transported to a water source within the building.

Hinged Door

A hinged door refers to a type of fire truck door that includes a flat double panel and is attached to the vehicle by hinges. Hinged doors may also be called double pan doors or lap doors.

We cover this topic in depth in our blog post: Fire Truck Doors: Hinged Vs. Roll-Up Doors


A hose is the length of tubing used to draw water from a source and deliver it to the fire. Different types of hoses are used in firefighting, including hand lines, large diameter hoses and booster lines.

Hose Coupling

A hose coupling is a fitting at the end of a hose used for connection to a water source or another hose.

Hose Roller

A hose roller is a spindle used to reel and store a fire hose. It is also a device to remove air and water from a hose prior to packing the hose back on the pumper or engine.

Hose Strap

A hose strap is a length of rope of webbed nylon, either sewn into a loop or with a metal hook at one end and an eye loop at the other. It has several uses including carrying hoses and other items and opening and closing doors.

Hose Tower

A hose tower is a structure in the fire station where hoses are hung to dry.

Hose Wagon

A hose wagon refers to a section of fire apparatus designed for transporting a reeled hose. These can be used today for transporting large diameter hose especially for industrial applications. Traditional fire apparatus included a steamer and a hose wagon, although these types of apparatus are no longer manufactured.

Hose Wrench

A hose wrench is a durable wrench that is used to loosen or tighten fire hose couplings.


The hosebed is the area of the apparatus that carries a fire department's hose. Hosebeds are available in many sizes and are placed strategically on apparatus to support the requested hose sizes, types and lengths.

Hosebeds can be high or low on apparatus, and can be placed in several locations, including the rear of the apparatus, crosslays, speedlays and the front bumper.

You can learn more about pump house configurations here or dive into more strategic hose bed considerations in our blog post: Fire Truck Hose Deployment: Tips to Optimize Operational Tactics.

Husky System

The HuskyTM system is a Pierce foam system that delivers high capacity without straining electrical systems. Husky systems handle foam for viscosities for class A and B fires. There are several types of Husky systems to choose from, including Husky 3, Husky 12 and Husky Industrial.


A hydrant is a metal casing that is connected to a water supply system and has one or more valved outlets which can be connected to a hose or pumper. A hydrant is often used as the primary water source at the scene of a fire.

Hydraulic Ladder Rack

A hydraulic ladder rack is a ladder rack that enables repositioning of the ladder to enable easy unloading of the ladder or access to otherwise inaccessible areas of the vehicle.

Hydraulic Spreader

A hydraulic spreader is a tool used to push things apart, for example, prying a vehicle door open. It has two metal arms that come together at a narrow point. The spreader is powered by hydraulic fluid supplied by hoses and a power unit or through an internal pump that is run by a battery pack.


Idle Reduction Technology

Idle reduction technology (IRT) is a system designed to lower the amount of wasted energy during truck idling. This technology can shut off the engine entirely when the vehicle is not in use, while also maintaining power to carry out other functions such as powering accessories and lighting. You can read more about idle reduction technology in this blog post.

In-service Weight

The in-service weight, sometimes referred to as gross vehicle weight, is the maximum actual vehicle weight under any conditions of operation.

Independent Suspension

Independent suspension is a type of vehicle suspension system in which wheels on the same axle can move vertically independently of each other.

Learn all about this topic by reviewing the Fire Truck Suspension Comparison Guide.

Industrial Fire Truck

An industrial fire truck refers to a heavy-duty apparatus designed to operate at high-risk fire scenes that require extensive capabilities in terms of water and foam suppression systems. An industrial fire truck offers a much higher flow rate (3,000–10,000 GPM) than a traditional pumper truck (1,500–2,000 GPM).

Learn more about this fire truck in our blog post: Industrial Fire Truck Design, Selection and Use (With Examples).

Industrial Fire Truck

An industrial fire truck refers to a heavy-duty apparatus designed to operate at high-risk fire scenes that require extensive capabilities in terms of water and foam suppression systems. An industrial fire truck offers a much higher flow rate (3,000–10,000 GPM) than a traditional pumper truck (1,500–2,000 GPM).

Learn more about this fire truck in our blog post: [Industrial Fire Truck Design, Selection and Use (With Examples)](

Initial Attack Apparatus

Initial attack apparatus is the fire apparatus used to initiate fire suppression attack. It includes a fire pump that has at least 250 GPM capacity, a water tank and a hose body.


Instability is a term used pertaining to an aerial fire apparatus. The apparatus is considered to be stable when there is no sign of rollover. The lifting of a tire or stabilizer on the opposite side of the vehicle from the load does not necessarily indicate a condition of instability. Instability occurs when an aerial device can no longer support a given load and overturning is imminent.


The intake is a part of a fire pump that’s connected to the water source.


Interlock refers to a device or arrangement in which one part’s function is controlled by that of another.

ISO Rating

The ISO rating is a score issued by the Insurance Services Office (ISO). This independent organization scores fire departments against its standards to decide property insurance costs. The ISO rating reflects preparedness for fighting fires and considers multiple factors, including staffing capacities, water supply, firefighting training and standard operating procedures.


Jaws of Life

Jaws of life is a general term for a hydraulic rescue tool that can be used to push, pull, or cut material, usually parts of a vehicle. “Jaws of Life” is a product name copyrighted by Hurst.

Jump Line

A jump line is a hose kept in an extended bumper (the jump bumper). It is preconnected to the engine, allowing for speedy attack.


Knuckle for Articulating Booms

A knuckle for articulating booms is a connector hinge between lower and upper booms of an articulating device.


Ladder Company

A ladder company is the name of a firefighting unit and apparatus that is primarily responsible for ventilation, forcible entry into a structure, ladder placement, search and rescue and overhaul.

Ladder Section

A ladder section comprises an open “U” design with rungs to make up the base section of an aerial ladder.

Large Diameter Hose

A large diameter hose, or LDH for short, is the largest hose used by firefighters. It is usually 4–5 inches in diameter and may be used to transport large volumes of water from a hydrant to the pumper truck under relatively low pressure.

Leader Line

A leader line is a hose that has a gated wye at the end. These lines are typically 2.5 inches or 3 inches in diameter and feed two or three narrower attack lines through the wye.


Leasing refers to renting a piece of property. It involves a legally-binding contract where the lessor (owner) rents to the lessee.

Pierce Manufacturing offers a lease purchase plan, where fire departments can purchase the apparatus gradually over time, or turn-in lease plan, with a “balloon payment” for the estimated resale value of the apparatus at the end of the lease.

Live Load

Live load refers to the forces acting on the aerial device as a result of its load, including personnel, water, equipment and nozzle reaction.

Low Voltage

Low voltage refers to a voltage not exceeding 60 V (dc), 30 V rms (ac) or 42.4 V peak (ac). In fire apparatus, it is usually 12 V.


Master Stream

A master stream is a large nozzle, either portable or fixed to a fire apparatus, capable of throwing large volumes of water over relatively long distances.

Miscellaneous Equipment

Miscellaneous equipment refers to firefighting equipment that may need to be stored in the fire truck, such as firefighting tools, extrication equipment, protective gear and other resources.


Mobile refers to equipment that can be transported from one place to another, for example, from the fire station to the scene of a fire.

Mobile Water Supply

A mobile water supply involves using a vehicle to transport water to a fire and emergency scene when other means such as a fixed water or hydrant system are not readily available.

Mobile Water Supply Apparatus

Mobile water supply apparatus is a wheeled fire apparatus equipped to carry large volumes of water to a fire. It is often used in areas without an adequate or universal water supply system, such as rural areas without hydrants.

A tanker fire truck can be classified as a pumper fire apparatus or a mobile water supply apparatus, according to National Fire Protection Association guidelines. Tankers or tenders in the mobile water supply classification have a primary mission to carry water.

Based on NFPA guidelines, a mobile water supply apparatus must include, but is not limited to:
  • A water tank with a minimum certified capacity of 1,000 gallons
  • A minimum of 10 cu. ft of weather-resistant compartmentation
  • A minimum hose storage area of 6 cu. ft for 2​1⁄2" or larger fire hose
  • A water pump and ladders are not required
To learn more about tankers, visit our blog. [LINK once published]

Momentary Switch

A momentary switch is a switch that returns to the off position when released.

Motor Vehicle Accident

Also called a major vehicle accident or motor vehicle collision, a motor vehicle accident describes an event in which a motor vehicle has collided with another vehicle or a pedestrian, animal, object, or structure.

Fire departments are often called to the scene of motor vehicle accidents to provide immediate patient care, auto extrication, scene safety, support, equipment and firefighting capabilities.

Multiplexing / Multiplexing Vehicle

Multiplexing (MUX) or vehicle multiplexing (V-MUX) is a complete electrical control system in which power distribution units (nodes) reduce wire harness bundles and electrical control hardware. MUX is a means of simplifying an electrical system to transmit multiple electrical signals over one line. Pierce accomplishes multiplexing a vehicle utilizing our Command ZoneTM System.

Learn more about Command Zone now.

Mutual Aid

In emergency services, mutual aid refers to an agreement among emergency responders to provide assistance in communities or facilities outside their usual jurisdictional boundaries.

Mutual aid is often required in situations where the scale of an emergency response exceeds local resources, during a multiple-alarm fire or major disaster, or when those resources are the closest available resource.


National Fire Protection Association

The National Fire Protection Association (NFPA) is an international nonprofit organization devoted to eliminating death, injury and property and economic loss due to fire, electrical and related hazards.

Pierce Manufacturing builds fire apparatus to meet the NFPA 1901 Standard for Automotive Fire Apparatus and NFPA 1906 Standard for Wildland Fire Apparatus.

NH Thread

A NH thread (national hose thread) is the standard thread found on the end of a fire hose which will match devices, inlets and outlets on your pump panel as well.

Non-Walk In

A non-walk in Rescue fire truck provides storage for the equipment used in many types of incidents including motor vehicle accidents, hazardous material spills, and fires. There is no space in the body area for firefighters.

Read our comparative blog post to learn more: Walk-In Vs Non-Walk-In Rescue Fire Trucks



A nozzle is an end attachment for a fire hose and determines how water will be applied to a fire. Nozzles are used on handlines and master stream devices.

Fire truck mounted or portable nozzles are part of the master stream devices that are mounted to the truck or the aerial device to provide water support in firefighting operations.

Nozzles are intended to support fireground operations and match the mission of the truck. Nozzles can be used based on the application required and to manage different types of call scenarios.

Nozzle Reaction

The nozzle reaction is the force that occurs when a water stream is discharged from the nozzle.

Nozzle Tip

The nozzle tip is the end part of the nozzle. Different types of tips include fog tips and straight tips.
  • A straight tip nozzle provides firefighters with a stream of solid water that is not altered during flow.
  • A fog nozzle tip breaks up the stream of flowing water to disperse the water outward. Instead of a solid, steady stream of water, a fog nozzle creates a wider cast of water.
To learn more about nozzles, read out blog: Fog Tip Nozzle vs. Straight Tip Nozzle



The operator is the person who is responsible for operating the control system of a fire apparatus.

Operator’s Panel

The operator’s panel houses controls for the fire truck.

Order Lifecycle

The order lifecycle of a fire truck includes several steps:
  • Bidding and awarding
  • Reviewing the contract and placing an order
  • Approving the package and attending a pre-construction visit
  • Engineering review
  • Manufacturing
  • Final inspection
The fire truck order process involves a lot of collaboration between fire departments, dealer sales representatives and Pierce professionals, but the final result brings both improved safety and pride to a community.

Overall Height

Overall height (OAH) is a critical vehicular parameter. It impacts a vehicle’s capability to enter a fire station and navigate streets and roads within a fire district.

The OAH is the dimension from the ground to the highest point on the top of the apparatus. The overall height can be driven by the cab, body or mounted items that extend above the apparatus.

For aerial products, the aerial device will typically drive the overall height of the apparatus. Depending on the wheel, tire and suspension combination, the frame height will vary, and in turn, will impact the overall height as well.

Overall Length

Overall length (OAL) is a critical vehicular parameter. It impacts a vehicle’s capability to enter a fire station and navigate streets and roads within a fire district.

The OAL is the dimension from the front-most point on the apparatus to the rear-most point. The OAL is typically driven by the combination of five key components: the front bumper, cab, pumphouse, body and rear bumper.

For aerial products, the aerial device can potentially influence the overall length as well.

Overall Weight

Overall weight is a vehicular parameter that defines the weight of the fire truck.

Overrides (Aerial Device)

Overrides are manual controls used to take over all aerial device movement functions by an operator. Overrides ignore all safety features built into the aerial control system and must be used with extreme caution.


Platform Fire Truck

A platform fire truck has an aerial ladder with a platform attached to the tip. The platform includes an enclosed space for transporting crew and other passengers up and down.

Platforms can be elevated for long periods and have the ability to flow water and fire suppression agents, like firefighting foam, at high rates.

Learn more about the differences between ladder and platform fire trucks.

Portable Generator

A portable generator is a generator that can be easily transported to different locations, for example, to the scene of a fire in a vehicle.

Portable Water Tank

A portable water tank provides a portable water source to provide necessary water supply in non-hydrant areas.

Pounds Per Square Inch (PSI)

Pounds per square inch is a measurement used to indicate pressure.

Power Takeoff (PTO)

A power takeoff is a rotary device used to provide power directly from an engine or through a transmission to power secondary functions. On a fire apparatus PTOs are used to drive water and hydraulic pumps, generators, and winches.

Powered Equipment Rack

A powered equipment rack is a storage rack that can be moved up and down without manual effort, usually using hydraulics or electric power.

Preconnected Hose Line

A preconnected hose line is a basic fire fighting hose line that is already connected directly to a pumper’s discharge outlet.


The Pierce PUC™ (Pierce Ultimate Configuration) is an innovative apparatus solution designed to simplify firefighters’ actions and reduce unnecessary risk. The PUC pump eliminates the pump house, moving the pump forward below the cab to reduce overall vehicular space used for fire suppression, maximize space for equipment and offer enhanced flow capabilities up to 2,000 GPM.

Learn more in this blog: Pierce Ultimate Configuration: 9 Key Benefits for Fire Departments

Pump Discharge Pressure Classification

Fire pumps are rated per NFPA standards with a pump discharge pressure classification.
  • Normal Pressure: Pump discharge pressure less than 500 psi (3500 kPa).
  • High Pressure: Pump discharge pressure from 500 psi (3500 kPa) to less than 1100 psi (7600 kPa).
  • Ultra-High Pressure: Pump discharge pressure of 1100 psi (7600 kPa) or greater

Pump Operator

A pump operator is the person responsible for operating the pump on a pumper fire truck.

Pump Operator Panel

The pump operator panel is the area on a fire apparatus that contains the gauges, controls, and other instruments for operating the pump.

Pump Operator Position

The pump operator position is the location from which the pump operator operates the pump.


Pumper is another term for an engine. It describes a fire apparatus with a permanently mounted fire pump, water tank, and hose body whose primary purpose is to combat fires.

NFPA requires that pumper fire trucks have a “minimum of 40 cubic feet of enclosed weather-resistant compartmentation” to store firefighting equipment. As long as trucks are built to follow the NFPA specifications detailed in Chapter 5 of The Standard for Automotive Fire Apparatus, pumpers can vary in length, width, height and added features.

Learn everything you need to know about pumper fire apparatus now.


In the fire truck ordering process, the purchaser is the authority with responsibility for the specification and acceptance of the apparatus.

Purchasing Authority

In the fire truck ordering process, the purchasing authority is the agency that has the sole responsibility and authority for negotiating, placing, and where necessary, modifying each and every solicitation, purchase order or other award issued by a governing body.

Push In Ceremony

A push-in ceremony is an event to celebrate introducing a new truck into a fire station.


Quick Lock Waterway

Also called a pinnable waterway, a quick lock waterway is a locking bracket that enables the aerial waterway monitor and nozzle to move from the tip of the fly section (the standard location, considered “water tower” mode) to the upper mid section (considered “rescue” mode).


A quintuple combination pumper, or quint for short, is a fire service apparatus that serves the dual purpose of a pumper (engine) and an aerial ladder truck.

The name “quint” is derived from the Latin quinque, meaning five, and refers to the five functions that a quint provides: pump, water tank, fire hose, aerial device and ground ladders.

Looking for more information on quints? Read our informative blog detailing NFPA requirements, benefits and highlighting several quint fire truck examples.


Ramp Breakover Angle

Also called the rampover angle, the ramp breakover angle describes the maximum angle that a vehicle can drive over without the apex of the angle touching the underside of the vehicle.

Rated Capacity (Aerial Device)

The aerial device rated capacity is the total amount of weight of all personnel and equipment that can be supported at the outermost rung of an aerial ladder or on the platform of an elevating platform with the aerial device placed in its maximum horizontal position when the stabilizers are fully deployed. This capacity will be defined wet (when flowing water) or dry (no water flowing), wind speed and amount of ice coverage.

Rated Capacity (Water Pump)

The water pump rated capacity is the flow rate to which the pump manufacturer certifies the compliance of the pump when it is new.

Rear Engine Power Takeoff (REPTO) Water Pump

A rear engine power takeoff (REPTO) driven water pump is only available from Pierce with the PUC pump. The PUC pump receives its power directly from the engine. In this drive application, the PUC pump is located in the middle of the truck.

Red Line

A red line is a rubber-jacketed hose with a 1-inch diameter. It is usually stored on a reel and used on small fires.


Refurbishment is the process of repairing and improving equipment to “like new” condition.

Rescue Apparatus

The rescue apparatus is a highly specialized and customized vehicle for technical rescue using a wide array of the latest tools and technologies coupled with highly trained operators for a mission to save lives and property under extraordinary circumstances.

A rescue pumper fire truck offers both rescue and pumper capabilities. These come in different designs, including heavy-duty rescue pumper trucks.

Rescue Company

Also called a squad, a rescue company refers to a rescue truck and the fire fighters who staff it.

Rescue Engine

A rescue engine is a fire truck designed for deployment to the scene of a rescue situation and can function as a pumper/engine on an incident.

Residual Pressure

Residual pressure is the amount of pressure (per the pump’s intake manifold gauge) once water is flowing from the discharge manifold.

Reverse Lay

Reverse lay is a type of hose lay where the pump is placed at the source of the water and the hose is laid from the fire to the water source.


Also called flameover, rollover refers to a stage in a structure fire during which the fire becomes hot enough for one or more gasses to reach their ignition point and the cloud of fuel ignites. This manifests as a flame “rolling” across the ceiling, hence the term rollover.

Rollup Door

A rollup door is constructed of aluminum extrusions that are joined together to create a solid, yet flexible protective door. Each door rolls up on a spring-loaded roller take-up spool and disappears into the header at the top of the compartment opening.

These types of doors offer safety and operator benefits, for example, the avoidance of an open door causing a visual or physical obstruction and the ability to leave doors open in parking bays.

To learn more, read our comparative blog post: Fire Truck Doors: Hinged Vs. Roll-Up Doors

Roof Ladder

A roof ladder is a ladder that has two hooks attached to the end so that the ladder can be easily and securely attached to a roof peak.


Scene Safety

 Scene safety refers to a condition of securing and controlling an emergency scene that facilitates the protection of emergency personnel (firefighters, paramedics, police other emergency responders, etc.), victims and property. 

Self-Contained Breathing Apparatus (SCBA)

A Self-Contained Breathing Apparatus (SCBA) is an independent respiration device worn by rescue workers, firefighters and others to provide breathable air in an atmosphere that is toxic or otherwise immediately dangerous to life or health.

Self-Contained Foam System / CAFS

A self-contained foam system is a modular firefighting tool mounted on the truck but completely independent, which uses breathing air, nitrogen or argon for propelling a firefighting agent out of a pressurized vessel.

Learn more about CAFS (compressed air foam systems).

Short Jacking

Short jacking is the process of stabilizing a ladder truck by extending aerial stabilizers on one side of the truck while deploying opposite-side stabilizers straight down. When obstacles like parked cars or curbs prevent stabilizers from being deployed on both sides of an apparatus, short jacking is a safe and necessary alternative.

Learn more about aerial stabilizers.


 A siren is an audible warning designed to alert pedestrians and motorists about the approach of an emergency vehicle. Regulations regarding sounds and usage vary by jurisdiction. 

Skirt Height

Skirt height is an apparatus measurement of the distance from the top of the frame rail to the bottom of the body. It is used to set the height of the compartment floors off the ground.


A sky-boom is a hydraulic arm which can be extended, raised and lowered to facilitate aerial firefighting. Sky-boom is equipped with a ladder and water and/or foam delivery system.

Learn more about sky-boom aerials.

Small Diameter Hose

 A small diameter hose is one measuring less than 2.5 inches in diameter and offers lighter weight and greater maneuverability than larger diameter hoses, making them ideal for attack lines or booster lines. 

Solid Stream

A solid stream is an unbroken, uninterrupted, undivided flow of water typically generated using a straight-tip nozzle. A solid stream provides greater accuracy and distance, making it ideal for attacking the seat of a fire.

Learn more about water stream patterns and nozzles.

Split-Shaft PTO

A split-shaft PTO (power-takeoff) pump drive uses a pump transmission to redirect power from the main drive line to the water pump when needed. The pump and gearbox are most commonly mounted together as a single unit and the pump is driven directly from the gearbox by means of a chain, gears or belt. In this drive application, the water pump is typically mounted in the middle of the truck or midship.


Stability, in the context of aerial fire apparatus, indicates the apparatus shows no sign of rollover. Conversely, instability occurs when an aerial device can no longer support a given load and overturning is imminent. Note: the lifting of a tire or stabilizer on the opposite side of the vehicle does not necessarily indicate a condition of instability. 


A stabilizer, also referred to as an outrigger, is a device attached to a firefighting vehicle to help prevent the overturning of the vehicle during aerial operations.

Learn more about the types of aerial stabilizers and the additional functional features which allow for fast, reliable aerial operations on the fire ground.

Stabilizer Beam

A stabilizer beam is the horizontally extending portion of an H-style stabilizer structure.

For a more detailed look at H-style stabilizers and the benefits they bring to the fire scene, read our blog: 4 Benefits of H-Style Aerial Stabilizers

Stabilizer Foot

A stabilizer foot is a permanently attached pad at the bottom of the stabilizer jack.

To learn more about aerial device features, take a look at our additional resources:

Stabilizer Jack

A stabilizer jack is the vertically extending portion of a stabilizer system that contacts the ground.

Stabilizer Pad

 A stabilizer pad, also known as an “auxiliary ground pad” or “ground pad,” is a plate inserted beneath a stabilizer to give a greater surface bearing area. 

Stabilizer Spread

 The stabilizer spread refers to the distance between the centerlines of the side supporting stabilizers when they are fully extended. 


 Steamer is the term used for referencing the pump main/large inlet(s). 

Straight Stream

Straight stream refers to a steady level delivery of water typically generated with a straight tip nozzle.

Learn more about stream patterns in our blog.

Straight Tip Nozzle

A straight tip nozzle delivers a solid stream of water that does not change during flow. Advantages of straight tip nozzles include precision, adjustability with stacking tips and simplicity of design.

Read our nozzle comparison now: Fog Tip Nozzle vs. Straight Tip Nozzle

Structure Fire

A structure fire is an event involving a building (residential, commercial, industrial, rural or other) in which a fire has started and spread and can pose a threat to the building itself or nearby structures. Guidelines for structural firefighting are outlined in NFPA 1851: Standard on Selection, Car and Maintenance of Protective Ensembles for Structural Fire Fighting and Proximity Fire Fighting. 

Suction Hose

 A suction hose is a large-diameter hose used to draw water from an unpressurized source such as a tank, pond or creek. They are sometimes referred to as “hard suction hoses” as they are made with higher rigidity to resist collapse due to vacuum pressure. Suction hoses are essential in rural areas where fire hydrants are sparse or at events where water demand exceeds local hydrant capacity. 

Supply Hose / Supply Line

A supply line is a flexible large-diameter hose with fittings on both ends designed to carry water from a fire hydrant or other pressurized source to a pump supplying attack lines.

Learn more about hose types, storage and deployment here: Fire Truck Hose Deployment: Tips to Optimize Operational Tactics

Suspension Systems

Fire truck suspension systems are the cushions which carry the truck’s weight to ensure an optimal balance of stability, control and ride quality. There are several types of suspension systems available on fire apparatus, including: multi or stacked leaf spring, parabolic leaf spring, walking beam or bogie, air ride, independent suspension, or suspension combinations

Learn more about choosing the right fire truck suspension system here.


Tank Fill

 A tank fill is a valve used to supply water from a water pump to a water tank. 

Tank to Pump Valve

 A tank to pump valve is the valve used to supply water from a water tank to a water pump. 


A tanker, also referred to as a “tender,” is a truck designed to transport a large quantity of water to a fire emergency scene. A tanker fire truck can be classified as a pumper fire apparatus or a mobile water supply, according to NFPA guidelines.

If your fire department is considering adding a tanker fire truck to its fleet, here are some simple guidelines which may be helpful.


Telematics refers to the collection and analysis of real-time data regarding the status, location and activity of a fire truck. The use of telematics allows fire departments to improve operation, trafficking and maintenance programs and reduce the total cost of truck ownership.

Learn more about the benefits of telematics.


Tender is an alternate term for a tanker, a truck designed to transport a large quantity of water to a fire emergency scene. There are many different types of tender trucks available to fire departments. See all of the options here

Texas Chute Out

A Texas Chute Out (TCO), also referred to as a “side stacked hose bed,” is an aerial body style in which the hose bed is full width (and typically full length) on one side of the body. Using a long narrow water tank, the TCO allows for low side-only compartments on the TCO side and full height and depth compartments on the opposite side. 


A tiller fire truck is designed to have two operators. Also referred to as “tractor drawn aerial” or “hook-and-ladder,” these specialized trucks maximize maneuverability as the “tillerman” can steer the rear portion of the truck independently of the front portion.

A fire department may consider a tiller fire truck when they are looking for improved maneuverability, increased compartment space, fast set-up time, improved visibility and condensed fleet size.

See all of the benefits of tiller fire trucks.

Trash Line

A trash line, often referred to as a “bumper line,” is a hose used for discharging water from the front (bumper) of a truck. The term “trash line” comes from their frequent use for small fire events, such as dumpster fires, trash can fires and small brush fires which do not require larger lines. 

Truck Company

A Truck company includes firefighters are responsible for a range of tasks: search and rescue, forcible entry, ventilation, securing utilities and overhaul. Also referred to as “ladder companies,” they are typically equipped to address emergencies such as vehicle extractions and technical rescues.

Turning Radius

The turning radius, or turning circle, of a vehicle is the smallest circular turn a vehicle is capable of making. 

Turnout Gear

Turnout gear, or bunker gear, refers to the personal protective equipment (protective gear) worn by firefighters. 


A turntable is a structural component which connects an aerial device to a vehicle’s chassis and stabilization system through a rotating bearing permitting 360-degree continuous rotation of the aerial device. 


Underwriters Laboratories

Underwriters Laboratories (UL) is a third-party certification company which tests products against established standards. UL testing is used in fire truck manufacturing to challenge fire apparatus to meet specified NFPA 1901 or ULC-S515 standards.

A UL-certified engineer performs this testing toward the end of the manufacturing process. Fire departments often ask for certification to confirm safety requirements have been satisfied.

Learn more about the third-party testing process and how Pierce goes above and beyond industry testing standards with our Vehicle Inspection Program.

Underwriters Laboratories Canada

Underwriters Laboratories of Canada (UL Canada or ULC) is an independent product safety testing, certification and inspection organization which supports governmental product safety regulations and it complements federal, provincial and municipal public safety initiatives while working with other governments and international safety systems to help further international trade with adherence to local and international safety requirements.

Learn more about ULC here.

Urban Firefighting

Urban firefighting refers to firefighting activities in densely populated areas with a variety of commercial and residential structures. In addition to fires, Urban firefighters respond to a range of calls, including medical emergencies, hazardous materials incidents, search and rescue and more.

What are some apparatus design and configuration considerations for urban firefighting? Take a look at our blog to learn more.



A valve is a device used to control the flow of water or other firefighting material. There are many types and configurations of valves for different firefighting needs. 

Vehicle Fire

A vehicle fire is the undesirable and/or uncontrolled burning of a motor vehicle, such as a car, truck, motorcycle, bus, train, plane, boat or construction or agricultural machinery. 


Ventilation is the active attempt to release smoke, heat and gasses from a burning structure without introducing so much fresh oxygen as to cause the fire to grow. Ventilation can be vertical, creating openings in a roof, or horizontal, using existing windows and doors. 


VLH is a Pierce-specific term referring to the threads used on every inlet and discharge of the plumbing system. These threads provide adapter/cap/plug pressure relief allowing end users to safely remove the items while pressurized without being harmed. 



A walk-in rescue fire truck features enclosed open space in the body of the apparatus devoted to personnel. Modern walk-in rescues come in all shapes and sizes. Simpler models feature an aisle down the center of the body, providing space for firefighters to sit and recharge at the scene of an emergency, more complex versions can include compartments, laboratories, command centers, specialized equipment and more onboard.

Learn more about walk-in rescue vehicles or read a comparison of walk-in to non-walk in rescues.

War Wagon

A war wagon is a firefighting apparatus designed as a structural, short-body pumper with low hose bed.

Warning Lights

Fire truck warning lights are highly visible, bright and often flashing or strobing lights designed to alert motorists and pedestrians of the oncoming presence of an emergency vehicle.

Learn more about industry standards and trends in apparatus lighting systems so you can make the right lighting choice for your department.

Water Curtain

A water curtain is a vapor barrier formed by spraying water through a specialized nozzle. Properly deployed, a water curtain can absorb heat and protect nearby structures from hot gasses, smoke and embers which could cause a fire to spread. 

Water Tender

Also referred to as a “tanker” or a “tender,” a water tender is a truck designed to transport a large quantity of water to a fire emergency scene. 

See examples of tankers and find specifications here.

Water Tower

A water tower is an aerial device consisting of a power-operated boom which articulates, telescopes or both and a waterway designed to supply a large-capacity mobile elevated water stream. Water towers are commonly found in industrial fire service or within departments looking for elevated master stream capabilities.

Read a comprehensive overview of aerial device types or learn more about NFPA classification’s now.

Wet Down Ceremony

A wet down ceremony is a way of anointing new firefighting equipment with water from a retiring vehicle or a neighboring department’s vehicle. The wet-down often precedes a push-in ceremony. 


The wheelbase of an apparatus is defined as the distance between the center of the front and rear wheels. For vehicles with more than two axles (e.g., tandem rear axle), the wheelbase is the distance between the steering (front) axle and the center point of the driving (rear) tandem axle group.

Wildland Urban Interface

The Wildland Urban Interface (WUI) fire truck combines the attributes of a Type 1 and Type 3 fire truck to manage areas defined by the U.S. Fire Administration as those “where human-made structures and infrastructure (e.g., cell towers, schools, water supply facilities, etc.) are in, or adjacent to, areas prone to wildfire.”

Learn more about the unique features and benefits of Wildland Urban Interface (WUI) fire trucks.