Axle Alignment. Midland Belly/Bottom Dump Trailer 4.6MB, Belly/Bottom Dump Trailer

5.2.4 AXLE ALIGNMENT

A standard axle is used as the main transverse structural member to transmit loads between the trailer frame and the surface contacting components.

All running gear components are attached to or part of the axle assembly.

Although there is very little that can go wrong with the axle itself, loose, bent or damaged attaching components can cause the axle to go out of alignment. This misalignment will be found during the regularly scheduled 25,000 mile inspection. However, axle misalignment shows itself most commonly by accelerated tire wear and dogtracking by the trailer. Visually check the tire wear when checking air pressure. The driver should identify these handling characteristics to service personnel or correction.

To check axle alignment, follow this procedure:

1. Select a working area that is level, with a compacted surface and is large enough to provide access from all sides.

2. Move the trailer forward and backward several times to remove any binding from the components.

3. Stop the trailer when moving in the froward direction without using trailer brakes. This will give the components a forward bias with no binding.

4. Unhook the trailer and support on the landing gear at the normal highway height and parallel to the ground.

5. Install a commercially available axle extender on each axle or remove the wheels to prevent any components from interfering with the measurements.

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5.2.4 AXLE ALIGNMENT (cont’d)

6. Attach an S hook to a steel tape and measure the distance between the kingpin and the end of each axle.

Dimensions A and B should be equal within ± 1/8 inch (0.125 in) (3.1 mm).

7. Adjust the suspension mounting system as required to set dimension

A and B within 1/8 inch (0.125 in) (3.1 mm). Refer to suspension system instruction brochure for detailed adjustment procedure.

Fig. 56 AXLE DIMENSIONS

8. Use a trammel bar to measure the road and curbside dimensions between the first and second axles. Dimensions C and D should be within 1/16 inch (0.0625 in) (1.6 mm).

IMPORTANT

It may be necessary to build a large trammel bar to measure and clear the discharge gates.

9. Set the suspension system as required to set this dimension to its recommended tolerance.

10. Repeat measuring and adjustment procedure on the third axle if so equipped.

11. Tighten all fasteners to their specified torque. Do not allow any suspension system or running gear fasteners to loosen.

IMPORTANT

Always use a torque wrench when tightening fasteners. The correct torque on a fastener provides the proper clamping force on the adjacent components and they will perform as expected.

Fig. 57 TRAMMEL BAR

12. The front axle must be aligned to the kingpin with second and third axles adjusted to the front axle.

13. Always check axle alignment after repairing the suspension system.

Fig. 58 ALIGNED

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