Adjusting the kingpin bearings

Front drive axle kingpin bearings are preload adjustable

The torque required to smoothly turn the fist should be 0.5-0.8 kgm, which corresponds to a force of 2-2.4 kg applied to the hole of the steering trapezoid lever.

In this case, the bearings must be lubricated with the grease indicated in the lubrication chart, the axle shaft 22 (see Fig. 1) is removed, the oil seal 20 of the steering knuckle housing is removed, and the nuts securing the lining of the steering knuckle housing are tightened to a torque of 16-18 kGm.

Axial movement of bearings is not allowed.

Drive to the wheels of the front axle ZIL-131

The lack of axial movement can be checked without removing the front drive axle from the vehicle.

To do this, you need to raise the front axle on the goats, unscrew the plug 33 in the lower lining 31 of the steering knuckle housing, install the indicator on the lining, resting its leg against the end of the kingpin

And using a jack or lever, try to move the steering knuckle housing upwards, the movement of the indicator arrow will indicate the presence of axial movement in the bearings and the need to adjust them.

In order to eliminate the axial movement resulting from bearing wear, it is necessary to remove the required number of shims - 30 from under the bottom lining, since the bottom bearing is usually worn more.

If during disassembly of the units it turned out that the bearing wear is approximately the same, you need to remove the same number of gaskets from under the upper and lower linings.

In case of severe wear of the lower kingpin bearing, it is recommended to swap the bearings; in this case, the pads must be removed from under the top pad.

When installing new bearings of increased accuracy, having the number 27308У (see the stamp on the end face of the bearing ring), after the final adjustment of the preload, sets of shims must be installed under the upper and lower linings, which must have the same thickness.

The difference in the thickness of the gasket sets under the upper and lower linings is allowed no more than 0.05 mm.

When installing new bearings of normal precision, bearing part number 27308, you must first measure their mounting height (measurement from the bearing face of the outer ring to the bearing face of the inner ring).

The thickness of the set of shims installed on the side of the bearing with a large mounting height must be correspondingly greater by the difference in mounting heights of the bearings.

Failure to follow the above rules for installing shims leads to misalignment of the steering knuckle housing and ball joint.

After final adjustment of new bearings, at least ten 0.1 mm thick shims must be included in each of the shim sets, two 0.05 mm thick shims and one 0.1 mm thick shim must be installed in the housing side shim set 29 of the steering knuckle, and the remaining thin gaskets on the side of the lining 31 (or pivot arm 18) to obtain a tight, leak-free connection.

During the adjustment process, it is necessary to rotate the steering knuckle housing several times so that the bearing rollers take the correct position between the bearing rings.

Adjusting wheel bearings

With correctly adjusted tapered roller bearings of the hub 1 (see Fig. 2), the wheels should rotate freely by hand, but not have noticeable pitching.

ZIL-131 middle and rear axle hub

Checking the bearing alignment is done:

  • a) for the rear and middle axles - with the axle shaft 3 removed;
  • b) for the front drive axle - with a holy flange 2 (Fig. 1) of the axle joint fist.

In order to adjust the wheel hub bearings, it is necessary to tighten the nut 8 (see Fig. 2) of the bearing fastening until the hub brakes and then loosen approximately ¼ of a turn, until the locking pin of the nut coincides with the nearest hole in the lock washer.

The tightening torque of the locknut 7 after the end of the adjustment should be equal to 12-15 kgm.

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