Tactor/trailer Air Brake System

Front 1

Spring brake chambers apply and hold a parking brake application

Back 1

Without air pressure

Front 2

Caution must be exercised when working around spring brake equipped vehicles because

Back 2

Spring brakes contain large powerful springs

Front 3

Air supply for parking/emergency brake operation flows through a double check valve so that the emergency brakes will

Back 3

Not apply if either service reservoir air pressure is lost

Front 4

The function of the park control valve is to provide manual

Back 4

And automatic control of all the parking/emergency brake on the unit

Front 5

A quick release valve is often used in parking/emergency brake circuits to provide quick

Back 5

Application of the spring brakes

Front 6

An anti-compounding double check valve is often used in parking/emergency brake circuits to

Back 6

Release the parking/emergency brakes when the service brakes are applied

Front 7

Some truck/tractor units are equipped with a spring brake valve that

Back 7

Allows modulated application of the spring brakes if primary derive reservoir air pressure is lost

Front 8

A relay valve is used in parking/emergency brake circuits that use spring brake valves to ensure that the spring brakes

Back 8

Apply and release quickly

Front 9

The purpose of the trailer supply line is to transmit air pressure

Back 9

To charge the trailer reservoirs

Front 10

The purpose of the trailer service line is to transmit air pressure

Back 10

To apply and release trailer service brakes

Front 11

The trailer supply valve supplies air pressure to the trailer from

Back 11

Both the primary and secondary reservoirs

Front 12

In the event that pressure in both primary and secondary reservoirs falls below 50psi the

Back 12

Trailer supply valve will close off supply air pressure to the trailer

Trailer emergency brakes will apply

Tractor protection valve will close the trailer service line

Front 13

The purpose of the trailer brake control valve is to allow the operator to

Back 13

Independently control trailer service brakes

Front 14

If the operator makes a 20psi application with the trailer brake control valve while making a 10psi application with the dual-circuit brake valve

Back 14

Tractor brakes will be applied with 10psi and trailer brakes are applied with 20psi

Front 15

Tractors equipped with a bobtail proportioning relay valve will reduce

Back 15

Primary application pressure when the tractor is not towing a trailer

Front 16

The brake light switch is normally

Back 16

Open switch that is closed by primary or secondary service pressure

Front 17

The purpose of the primary service circuit is to allow the operator to control the application and release of the ____ axle brakes

Back 17

Drive

Front 18

The ______ valve in an air brake system gives the operator control of all the service brakes on the vehicle

Back 18

Dual-circuit brake

Front 19

The dual circuit brake valve in the apply position will be applying the secondary brakes. Air pressure from the primary delivery port also flows through the ____ onto the top of the secondary piston

Back 19

Orifice

Front 20

The relay valve is installed in the brake system to control ____

Back 20

Brake lag

Front 21

The relay valve, located near the primary brake chambers in the primary brake circuit, speeds up ____ and _____ time of drive axle brakes

Back 21

Application and release

Front 22

When the operator depresses the treadle of the dual circuit brake valve, air pressure is sent to the ______ port of the relay valve and applies force to the upper surface of the ______

Back 22

Control

Relay piston

Front 23

The amount of air that is required to get the relay valve piston to move downwards, close the exhaust valve and open the inlet valve is called

Back 23

Cracking pressure

Front 24

A type 30 brake chamber indicates that the chamber has a diaphragm are of

Back 24

30in squared

Front 25

The purpose of the secondary service circuit is to allow the operator to control the application and release of ____ axle brakes

Back 25

Steer

Front 26

The function of a ______ valve is to provide a faster brake release by allowing the air in the brake chambers to exhaust at a location closer to the steer axle than the dual circuit brake valve

Back 26

Quick release