Cb - Truck/Tractor Air Brake System Components - Part B Flashcards

1
Q

Spring brake chambers apply and hold a parking brake application:

A

Without air pressure.

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2
Q

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

A

Spring brakes contain large, powerful springs.

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3
Q

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

A

Not apply if either service reservoir air pressure is lost.

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4
Q

The function of the park control valve is to provide manual:

A

And automatic control of all parking/emergency brakes on unit.

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5
Q

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

A

Application of the spring brakes.

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6
Q

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

A

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

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7
Q

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

A

Allows the spring brakes to modulate application if primary service reservoir air pressure is lost.

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8
Q

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

A

Apply and release quickly.

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9
Q

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

A

To charge the trailer reservoirs.

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10
Q

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

A

To apply and release trailer service brakes.

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11
Q

The trailer supply valve supplies air pressure to the trailer from:

A

Both primary and secondary reservoirs.

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12
Q

In the event that pressure in both primary and secondary reservoirs falls below 50 psi (354 kPa) the:

A

Trailer supply valve will close off supply air pressure to the trailer, trailer emergency brakes will apply, and tractor protection valve will close the trailer service line.

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13
Q

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

A

Independently control trailer service brakes.

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14
Q

If the operator makes a 20 psi (138 kPa) application with the trailer brake control valve while making a 10 psi (69 kPa) application with the dual-circuit brake valve:

A

Tractor brakes will be applied with 10 psi (69 kPa) and trailer brakes are applied with 20 psi (138 kPa).

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15
Q

Tractors equipped with a bobtail proportioning relay valve will reduce:

A

Primary application pressure when the tractor is not towing a trailer.

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16
Q

The brake light switch is normally:

A

Open switch that is closed by primary or secondary service pressure.