New York CDL Permit Test - Double

The trailer hand valve works the trailer brakes but should only be used when testing them. Using it while driving could create a skid. Never use the trailer hand valve while parking because doing so may release the air pressure from the braking system, releasing the brakes that are holding the vehicle in place.

Retarders are mechanisms in some vehicles that help slow a vehicle and reduce the need for braking. However, using a retarder may cause wheels to skid when they have poor traction. Turn off retarders when traveling under wet, snowy, or icy conditions.

If confronted by an aggressive driver, the most important thing to do is try to get out of their way. Avoid making eye contact with the driver and do not let yourself be provoked by gestures. Do not try to challenge aggressive drivers by speeding up.

The easiest way to spot a trailer skid is to use your mirrors. Any time you brake hard, check your mirrors to ensure that your trailer is still in its proper position.

To avoid becoming an aggressive driver, begin a trip with realistic expectations of how long the trip will take, allowing extra time for traffic delays. Do not tailgate other vehicles. To avoid upsetting other drivers, do not drive slowly in the left lane and do not gesture at the drivers (even in seemingly minor ways, like shaking your head).

The service air line carries air and is controlled by either the foot brake or trailer hand brake. The service air line is attached to relay valves, which allow the trailer brakes to be applied quickly.

You can tell that your vehicle is equipped with an Anti-Lock Braking System (ABS) if it has a yellow ABS malfunction lamp on the instrument panel.