DMV PA - CDL Doubles and Triples Endorsement Text Book Questions (And Answers)

  1. 1. What is a converter dolly?
    • A converter gear or dolly is a coupling device of one or two axles and a fifth wheel by which a semitrailer
    • can be coupled to the rear of a tractor-trailer combination forming a double bottom rig.

    (Page 7-2)
  2. 2. Do converter dollies have spring brakes?
    Yes, as explained below:

    POSITION CONVERTER DOLLY IN FRONT OF SECOND (REAR) TRAILER

    • • Release dolly brakes by opening the air tank petcock. (Or, if the dolly has spring brakes, use
    • the dolly parking brake control.)

    (Page 7-2)
  3. 3. What three methods can you use to secure a second trailer before coupling?
    • COUPLING TWIN TRAILERS
    • SECURE SECOND (REAR) TRAILER

    • • If the second trailer doesn't have spring brakes, drive the tractor close to the trailer, connect the
    • emergency line, charge the trailer air tank, and disconnect the emergency line. This will set the
    • trailer emergency brakes (if the slack adjusters are correctly adjusted). Chock the wheels if you
    • have any doubt about the brakes.

    • COUPLE TRACTOR AND FIRST SEMI-TRAILER AS DESCRIBED EARLIER
    • ***Caution:For the safest handling on the road, the more heavily loaded semi-trailer should
    • be in first position behind the tractor. The lighter trailer should be in the rear.***
    • A converter gear or dolly is a coupling device of one or two axles and a fifth wheel by which a semitrailer
    • can be coupled to the rear of a tractor-trailer combination forming a double bottom rig.

    • 1.) POSITION CONVERTER DOLLY IN FRONT OF SECOND (REAR) TRAILER
    • • Release dolly brakes by opening the air tank petcock. (Or, if the dolly has spring brakes, use
    • the dolly parking brake control.)

    • If the distance is not too great, wheel dolly into position by hand so it is in line with the kingpin.

    • Or, use the tractor and first semi-trailer to pick up the converter dolly:

    - Position combination as close as possible to converter dolly.

    - Move dolly to rear of first semi-trailer and couple it to the trailer.

    - Lock pintle hook.

    - Secure dolly support in raised position.

    - Pull dolly into position as close as possible to nose of the second semi-trailer.

    - Lower dolly support.

    - Unhook dolly from first trailer.

    - Wheel dolly into position in front of second trailer in line with the kingpin.

    2.) CONNECT CONVERTER DOLLY TO FRONT TRAILER

    • Back first semi-trailer into position in front of dolly tongue.

    • Hook dolly to front trailer.

    - Lock pintle hook.

    - Secure converter gear support in raised position.

    3.) CONNECT CONVERTER DOLLY TO REAR TRAILER

    • Make sure trailer brakes are locked and/or wheels chocked.

    • • Make sure trailer height is correct. (It must be slightly lower than the center of the fifth wheel, so
    • trailer is raised slightly when dolly is pushed under.)

    • Back converter dolly under rear trailer.

    • Raise landing gear slightly off ground to prevent damage if trailer moves.

    • Test coupling by pulling against pin of number two semi-trailer.

    • • Make visual check of coupling. (No space between upper and lower fifth wheel. Locking jaws
    • closed on kingpin.)

    • Connect safety chains, air hoses, and light cords.

    • • Close converter dolly air tank petcock and shut-off valves at rear of second trailer (service and
    • emergency shut-offs).

    • Open shut-off valves at rear of first trailer (and on dolly if so equipped).

    • Raise landing gear completely.

    • • Charge trailers (push "air supply" knob in) and check for air at rear of second trailer by opening
    • the emergency line shut-off. If air pressure isn't there, something is wrong and the brakes won't
    • work.

    (Page 7-2/7-3)
  4. 4. What do you check when making a visual check of coupling?
    • COUPLING SYSTEM AREAS
    • • Check fifth wheel (lower):
    • - Securely mounted to frame.

    - No missing, damaged parts.

    - Enough grease.

    - No visible space between upper and lower fifth wheel.

    - Locking jaws around the shank, not the head of kingpin.

    - Release arm properly seated and safety latch/lock engaged.

    • Fifth wheel (upper):

    - Glide plate securely mounted to trailer frame.

    - Kingpin not damaged.

    • Air and electric lines to trailer:

    - Electrical cord firmly plugged in and secured.

    • - Air lines properly connected to glad hands, no air leaks, properly secured with enough slack
    • for turns.

    - All lines free from damage.

    • Sliding fifth wheel:

    - Slide not damaged or parts missing.

    - Properly greased.

    - All locking pins present and locked in place.

    - If air powered–no air leaks.

    • - Check that fifth wheel is not so far forward that tractor frame will hit landing gear, or cab hit
    • the trailer, during turns.

    (Page 7-4/7-5)
  5. 5. Why should you pull a dolly out from under a trailer before you disconnect it
    from the trailer in front?
    • UNCOUPLING TWIN TRAILERS
    • UNCOUPLE REAR TRAILER

    • Park rig in a straight line on firm level ground.

    • Apply parking brakes so rig won't move.

    • Chock wheels of second trailer if it doesn't have spring brakes.

    • Lower landing gear of second semi-trailer enough to remove some weight from dolly.

    • Close air shut-offs at rear of first semi-trailer (and on dolly if so equipped).

    • Disconnect all dolly air and electric lines and secure them.

    • Release dolly brakes.

    • Release converter dolly fifth wheel latch.

    • Slowly pull tractor, first semi-trailer and dolly forward to pull dolly out from under rear semitrailer.

    UNCOUPLE CONVERTER DOLLY

    • Lower dolly landing gear.

    • Disconnect safety chains.

    • Apply converter gear spring brakes or chock wheels.

    • Release pintle hook on first semi-trailer.

    • Slowly pull clear of dolly.

    • ***Caution:Never unlock the pintle hook with the dolly still under the rear trailer. The
    • dolly tow bar may fly up, possibly causing injury and making it very difficult to
    • re-couple.***
    • (Page 7-3)
  6. 6. A. What should you check for when inspecting the converter dolly?

    B. The pintle hook?
    A. Converter dolly air tank drain valve: CLOSED.

    B. Make sure pintle hook is latched.


    • DOUBLE AND TRIPLE TRAILERS
    • • Shut-off valves (at rear of trailers, in service and emergency lines):

    - Rear of front trailers: OPEN.

    - Rear of last trailer: CLOSED.

    - Converter dolly air tank drain valve: CLOSED.

    • Be sure air lines are supported and glad hands are properly connected.

    • If spare tire is carried on converter gear (dolly), make sure it's secured.

    • Be sure pintle-eye of dolly is in place in pintle hook of trailer(s).

    • • Make sure pintle hook is latched.
    • • Safety chains should be secured to trailer(s).

    • Be sure light cords are firmly in sockets on trailers.

    (Page 7-5)
  7. 7. A. Should the shut-off valves on the rear of the last trailer be open or closed?

    B. On the first trailer in a set of doubles?

    C. On the middle trailer in a set of triples?
    A. Closed

    B. Open

    C. Closed

    Read below for full explanation:

    • DOUBLE AND TRIPLE TRAILERS
    • • Shut-off valves (at rear of trailers, in service and emergency lines):

    - Rear of front trailers:OPEN.

    - Rear of last trailer:CLOSED.

    • - Converter dolly air tank drain valve:CLOSED.
    • • Be sure air lines are supported and glad hands are properly connected.

    • If spare tire is carried on converter gear (dolly), make sure it's secured.

    • Be sure pintle-eye of dolly is in place in pintle hook of trailer(s).

    • Make sure pintle hook is latched.

    • Safety chains should be secured to trailer(s).

    • Be sure light cords are firmly in sockets on trailers.

    Do these checks in addition to Section 5.3, "Inspecting Air Brake Systems."

    (Page 7-5)
  8. 8. How can you test that air flows to all trailers?
    CHECK THAT AIR FLOWS TO ALL TRAILERS (Double and Triple Trailers)

    • Use the tractor parking brake and/or chock the wheels to hold the vehicle. Wait for air pressure to
    • reach normal, then push in the red "trailer air supply" knob. This will supply air to the emergency
    • (supply) lines. Use the trailer handbrake to provide air to the service line. Go to the rear of the rig.
    • Open the emergency line shut-off valve at the rear of the last trailer. You should hear air escaping,
    • showing the entire system is charged. Close the emergency line valve. Open the service line valve
    • to check that service pressure goes through all the trailers (this test assumes that the trailer
    • handbrake or the service brake pedal is on), then close the valve. If you do NOT hear air escaping
    • from both lines, check that the shut-off valves on the trailer(s) and dolly(s) are in the OPEN position.
    • You MUST have air all the way to the back for all the brakes to work.
    • TEST TRACTOR PROTECTION VALVE
    • Charge the trailer air brake system. (That is, build up normal air pressure and push the "air supply"
    • knob in.) Shut the engine off.
    • Step on and off the brake pedal several times to reduce the air pressure in the tanks. The trailer air
    • supply control (also called the tractor protection valve control) should pop out (or go from "normal"
    • to "emergency" position) when the air pressure falls into the pressure range specified by the
    • manufacturer. (Usually within the range of 20 to 45 psi.)
    • If the tractor protection valve doesn't work right, an air hose or trailer brake leak could drain all the
    • air from the tractor. This would cause the emergency brakes to come on, with possible loss of
    • control.

    • TEST TRAILER EMERGENCY BRAKES
    • Charge the trailer air brake system and check that the trailer rolls freely. Then, stop and pull out the
    • trailer air supply control (also called tractor protection valve control or trailer emergency valve) or
    • place it in the "emergency" position. Pull gently on the trailer with the tractor to check that the trailer
    • emergency brakes are on.

    TEST TRAILER SERVICE BRAKES

    • Check for normal air pressure, release the parking brakes, move the vehicle forward slowly, and
    • apply trailer brakes with the hand control (trolley valve), if so equipped. You should feel the brakes
    • come on. This tells you the trailer brakes are connected and working. (The trailer brakes should be
    • tested with the hand valve, but controlled in normal operation with the foot pedal, which applies air
    • to the service brakes at all wheels.)

    (Page 7-5/7-6)
Author
Tibrious
ID
2283
Card Set
DMV PA - CDL Doubles and Triples Endorsement Text Book Questions (And Answers)
Description
Test Questions (and answers,) for the Doubles and Triples Endorsement portion of the Commercial Drivers License Exam of Pennsylvania, but taken directly from the Commercial Drivers Manual.
Updated