Wheel Hubs/Bearings. Midland Belly/Bottom Dump Trailer 4.6MB, Belly/Bottom Dump Trailer

5.2.5 WHEEL HUBS/BEARINGS

All axles use an oil bath design for lubricating wheel bearings. It is a virtual zero maintenance system providing that the oil remains in the hub.

Visually check the hub every day for leaks when checking tire pressure during pre-trip, daily, refueling, on any hub, repair the leak and refill the hub before

5. Check wheel hub oil levels.

A. Oil Leaks:

Visually inspect the hub for leaks every time the tire pressures are checked. Leaks will normally be visible as dust collects on the escaping oil. Stop and correct the leak immediately to prevent running the hub low on oil. Running low or without oil will quickly overheat the hub and cause the bearings to seize.

Change the oil in the hub when installing new seals to correct a leak.

B. Oil Level:

1. Check the oil level in each wheel hub every 5,000 miles (8,000 km) or weekly and whenever an oil leak is found. Clean the end plate of the hub to remove the dust, dirt or mud build-up.

The oil should be visible to the top of the outer concentric circle of the end cap. Add oil as required through the fill plug in the hub. Always use clean oil and prevent contaminants from entering the hub when adding or changing oil.

2. Change the oil every 100,000 miles (160,000 km), annually or whenever the axle nuts are retorqued or the brakes are relined. The hub cavities must be opened when retorquing axle nuts or relining the brakes and

Fig. 59 OIL LEVEL changing oil should be done as part of the procedure.

Hub

59

5.2.5 WHEEL HUBS/BEARINGS (cont'd)

C. Wheel Bearings:

Wheel bearings carry and transmit the load between the wheels and the axles. In addition to proper lubrication, the bearings must have the recommended pre-load to perform as expected.

Bearing pre-load is set and controlled by the torque of the wheel nuts on the end of each spindle. Each hub must seat securely on its bearings to prevent wobble or slop in the system.

Turning the wheel or wobbling it indicates the condition and tightness of the hub/bearing assembly.

1. Turning/Wobble: a. Park the trailer on a level, hard surface and release the brakes.

b. Place chocks in front of and behind each wheel.

c. Jack each axle up until the tire clears the ground.

d. Support the axle on a safety stand to prevent slipping or tipping.

e. Turning the wheel slowly to check the condition of the bearings and to determine if the brakes are dragging.

Fig. 60 WHEELS

f. Dragging Brakes: Can be felt as a steady drag on the turning of the wheel or at the same position or arc of the rotation. Adjust the brakes to eliminate the drag before resuming work.

g. Bearing Condition: Can be felt as the wheel turns. Bearings in good condition turn easily and smoothly. Bearings in poor or bad condition can be felt through the wheels as scraping, grinding, dragging or bumps. Replace bearings before resuming work.

h. Wobble: Grasp each side of the wheel or tire and wiggle the wheel and assembly.

If the wheel or hub wobble on the spindle, the bearings have lost their pre-load and the wheel bearing adjusting nut requires tightening.

NOTE

If the bearings are not in good condition, replace them before setting the pre-load.

60

C. Wheel Bearings (cont'd):

2. Bearing Pre-Load: a. Place a pan under the hub drain plug.

b. Remove the drain plug from the hub and drain the oil.

c. Remove the hub end plate and lay to the side.

d. Remove the set screw from the jam nut.

e. Remove the jam nut and perforated lock washer from the spindle.

f. Use a torque wrench to tighten the adjusting nut 100 ft-lbs.

(136 N.m) while rotating the wheel assembly in both directions.

g. Back the adjusting nut off to zero torque.

h. Retorque the adjusting nut again to 50 ft-lbs

(68 N.m) of torque while rotating the wheel assembly in both directions.

i. Loosen the nut 1/4 turn.

j. Install the perforated lock washer. Be sure the adjusting nut pin aligns with the hole in the lock washer. Turn washer over and/ or adjusting parts as required.

k. Install jam nut and tighten to 250-300 ft-lbs. (340-408

N.m).

ITEM

14

15

16

17

18

9

10

11

12

13

19

20

21

4

5

6

7

8

1

2

3

DESCRIPTION

Capscrew

Lockwasher

Hub cap

Gasket

Wheel bearing jam nut

Lockwasher

Wheel bearing adjusting nut

Cone outer wheel bearing

Cup - bearing outer

Brake drum

Cup - bearing inner

Cone - bearing inner

Seal wheel-bearing

Bushing anchor pin

Pin anchor

Beam axle

Camshaft (left)

Camshaft (right)

Washer

Seal

Bushing

Fig. 61 SPINDLE COMPONENTS

ITEM

38

39

40

41

33

34

35

36

37

28

29

30

31

32

22

23

24

25

26

27

DESCRIPTION

Snap ring

Capscrew

Air chamber

Lockwasher

Locknut

Camshaft busing assembly

Capscrew

Washer slack adjuster

Locknut - slack adjuster

Automatic slack adjuster

Washer slack adjuster

Snap ring slack adjuster

Spring - brake shoe return

Brake show and lining assy.

Spring - brake shoe retaining

Retainer - brake shoe roller

Roller - brake shoe

Pin - shoe return spring

Dust shield

Hub

61

l. Check bearing end play by:

i. Attaching a magnetic base dial gauge indicator to the end of the spindle.

ii. Push the wheel in while rotating the wheel slightly until the dial gauge reading doesn't change.

iii. Zero dial gauge.

iv. Pull wheel assembly out while rotating wheel slightly until dial reading doesn't change.

v. Dial indicator will read bearing end play.

vi. If end play does not register between 0.001-0.010 inches

(0.025-0.25 mm), replace bearings or hub components until it does.

m. Install a new gasket on hub face cap.

n. Install hub face cap and tighten mounting cap screws to their specified torque.

o. Add the specified amount of oil to the hub and secure fill plug. Check for leaks. Correct leaks before resuming operation.

p. Remove safety stand from under axle and lower wheel to the ground.

q. Repeat checks on all other axles.

In

Fig. 62 DIAL INDICATOR

Out

62