Hooking Up/Unhooking. Midland Belly/Bottom Dump Trailer 4.6MB, Belly/Bottom Dump Trailer

4.6 HOOKING UP/UNHOOKING

Special care should be taken when hooking up or unhooking trailer to be sure the equipment is in good condition and all systems are functioning as required.

4.6.1 HOOKING UP

Follow this procedure when hooking up the trailer to towing vehicle (tractor or lead trailer):

1. Back the towing vehicle up in a straight line to the trailer and align the fifth wheel opening with the trailer king pin.

2. Stop before the fifth wheel makes contact with the trailer and apply the towing vehicle parking brake.

3. Inspect all the coupling components before hooking up: a. Inspect trailer coupling components.

Check that king pin is not broken, bent or chipped. Check that the oscillating plate is not bent or cracked. Check that the pivot bushings are in good condition and that the mounting fasteners are tightened to their specified torque.

King Pin

If problems found, correct before proceeding.

b. Inspect fifth wheel coupling components. Check that the fifth wheel assembly is securely anchored to the B train or tractor frame. Check that the structure of the frame, pivot and fifth wheel is not bent, broken or cracked. Check that the jaws of the lock are open.

If problems found, correct before proceeding.

c. Be sure that the fifth wheel plate is cleaned and greased.

a. Use the crank on the landing gear to raise or lower the trailer as required.

b. On drop leg landing gear, care must be taken if the trailer is too low to climb up on the 5th

8. Connect brake lines. Route the lines so they do not get pinched when the trailer is attached to the tow unit.

Fifth Wheel

Fig. 11 COUPLING COMPONENTS

4. Open the coupler lock.

5. Tilt the fifth wheel plate back.

6. Check that the trailer is at the required height to slide onto the fifth wheel.

7. Block the trailer wheels.

wheel. It may be necessary to raise the trailer and repin the drop legs.

The trailer oscillating plate should contact the fifth wheel just behind the pivot point as the towing unit backs under the trailer.

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9. Check brake application by applying and releasing brakes. If brakes do not release, air lines may be crossed. Do not continue unless brakes are functioning properly.

10. Re-apply trailer brakes using trailer hand valve.

11. Back slowly under trailer keeping the king pin centered in the fifth wheel jaws.

12. Back up until the fifth wheel coupler locks on the trailer king pin.

13. Gently move the towing vehicle back and forth while the trailer brakes are engaged to check that the jaws have locked around the king pin.

14. Set parking brake, stop engine and dismount.

15. Visually check that the coupler jaws are securely locked around the king pin and the coupler release lever is in the locked position. Release and hook up again if the jaws are not securely locked around the king pin.

16. Check that the trailer oscillating plate is resting on the fifth wheel.

Fig. 12 COUPLER LOCKS

17. Connect and secure the electrical terminal. Check that all electrical circuits are completed and that all lights are working.

18. Route the electrical and air lines to prevent snagging, dragging and pinching.

19. Raise the landing gear.

a. Remove the anchor pins, raise leg and repin on the drop leg style.

b. Use the crank to raise the legs if equipped with the crank style. Stow crank.

20. Remove blocks or chocks from the wheels.

21. Perform Pre-Trip Inspection before starting.

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