Cdl "combination"

A driver crosses the air lines when hooking up an old trailer, what will happen?

(A) the hand valve will apply the tractor brakes instead of the trailer brakes.

(B) the brake pedal will work the trailer spring brakes instead of the air brakes.

(C) if the trailer has no spring brakes, he or she could drive away but wouldn't have trailer brakes.

You have coupled with a semi trailer. Where should you put the front trailer supports before driving away?

(A) raised 3/4 way with the crank handle removed.

(B) raised 1/2 way with the crank handle secured in its bracket.

(C) fully raised with the crank handle secured in its bracket.

If the spring brakes don't release when you push the trailer air supply control, you should _____.

(A) cross the air lines

(B) check the air line connections

(C) check the electrical service cable

When backing a tractor under a trailer you should ____.

(A) always use the lowest gear

(B) always approach the trailer at a slight angle.

(C) do it quickly to ensure that the kingpin is locked into the fifth wheel.

How much space should be between the upper and lower fifth wheel after coupling?

(A) just enough to see light through it.

(B) none

(C) about 1/4 inch

A trailer is most likely to Jack knife when it is _____.

(A) empty (b) loaded to full capacity

(C) over loaded

When coupling the proper position of the fifth wheel is ____.

(A) tilted up towards the end of the tractor.

(B) level with the ground.

(C) tilted down towards the end of the tractor.

You are coupling a tractor and semi trailer and have backed up but not under it. What should you hook up before backing under?

(A) electrical service cable

(B) emergency and service air lines

(C) nothing, back up and lock fifth wheel.

How should you test the tractor - semi trailer connection for security?

(A) rock the trailer back and forth with the trailer brakes locked.

(B) pull gently forward in low gear against the locked trailer brakes then look at it carefully.

(C) put the tractor in gear and pull ahead with a sharp jerk.

The best way to tell if your trailer has started to skid is to ____.

(A) hear the wheels skidding

(B) feel for "pulling" in the cab

(C) see it in your mirrors

Semi trailers made before 1975 that are equipped with air brakes ___.

(A) often do not have spring brakes

(B) have only a service air line

(C) usually need a gland hand converter

Why should you be sure that the fifth wheel plate is greased as required?

(A) to ensure good electrical connections

(B) to reduce heat and noise

(C) to prevent steering problems

The trailer air supply control should automatically close when the air pressure falls between ____.

(A) 20-45 psi (b) 60-85 psi

(c) 100-125psi

Your emergency air line breaks or gets pulled apart while you are driving. The loss of air pressure will cause the ___.

(A) air compressor to unload instead of pumping air.

(B) emergency trailer brakes to come on.

(C) trailer supply valve to open.