The wheel gear (Fig. 1) is a planetary gearbox consisting of spur gears with external and internal gearing

From the drive gear of the wheel drive, rotation is transmitted to four satellites 14, evenly spaced around the circumference around the drive gear.

MAZ wheel drive

The satellites rotate on axles 10, fixed in the holes of the movable carrier 12, connected with bolts to the hub of the drive wheels, in the direction opposite to the direction of rotation of the drive gear.

Rotating on their axes, the satellites roll over the teeth of the internal gearing of the driven gear 15, which is fixedly fixed by means of the hub 16 on the splined end of the bridge beam trunnion.

The drive gear has a hole with involute splines that mate with splines on the outer end of the half shaft.

The axial movement of the pinion on the axle shaft is limited by a snap ring. The axial movement of the axle shaft is limited by the cracker 7 and the stop of the axle shaft 8.

The satellites with needle bearings are mounted on the axis, placed in the coaxial holes of the carrier 12 and fixed in it from axial movement by spring retaining rings.

On the axis of the satellite, washers are put on, excluding the contact of the gears and bearings of the axles of the satellites with the planet carrier.

The driven gear 15 of the wheel drive rests with its internal gear rim on the gear rim of the external gear of the hub 16 of the driven gear, and with its splined end this hub is mounted on the splined part of the trunnion of the axle beam.

Such a connection does not allow rotation of the driven gear, while the axial movement of the gear is limited by a spring ring that enters the groove of the driven gear ring gear and abuts against the inner end of the hub ring gear 16.

On the axis of the satellite, washers are put on, excluding the contact of the gears and bearings of the axles of the satellites with the planet carrier.

The carrier is closed from the outside with a cover 9 and, in conjunction with the wheel hub, is sealed with a rubber ring 13.

Gears and wheel gear bearings are lubricated with sprayed oil, which is poured through the hole in the cover 9, closed with plug 5. The lower edge of this hole determines the required oil level in the wheel gear.

The drain hole, closed by plug 3, is made in the wheel hub, since the cavities of the wheel gear and the wheel hub communicate.

When the car is moving, the oil in the wheel drive cavity and wheel hubs mixes and flows to the gear bearings to the wheel hubs and gears.

To improve the supply of lubrication to the bearings of the satellite axles, the axles are hollow and radial holes are made in them to supply oil to the bearings.

The main gear of the middle drive axle MAZ-64227 consists of a central gearbox and planetary wheel gears located in the wheel hubs.

Repair of wheel drive and rear wheel hub

Disassembly of the wheel drive and removal of the rear wheel hub must be done in the following sequence:

  • - loosen the rear wheel nuts;
  • - place the jack under one side of the rear axle beam and raise the hub with the wheels.
  • - Substitute the stand and remove the jack;
  • - unscrew the nuts of the rear wheels, remove the clamps, the outer wheel, the spacer ring and the inner wheel, having previously disconnected the bracket for attaching the valve extension;
  • - drain the oil from the wheel drive by unscrewing the plug and remove the cover 9 (see Fig. 1);
  • - unscrew the fastening bolts and remove the carrier 12 of the wheel gear assembly with satellites;
  • - take out the axle shaft 6 together with the drive gear of the wheel drive;
  • - take out 10 satellites one by one, supporting the satellites with bearings;
  • - remove satellites 14 with bearings and support washers from carrier;
  • - use a special wrench to unscrew the lock nut 2 of the bearings of the hub 16 of the driven gear, remove the lock washer 1, unscrew the nut 33 of the bearings and remove the hub 16 together with the driven gear 15 and the inner race of the bearing 18;
  • - supporting the hub 17 by the bearing ring 18, remove it with the brake drum 29 and the disc assembly.

If it is necessary to replace the oil seal and the hub bearing, then do the following;

  • - remove the oil catcher 25 and the stuffing box cover 27 by unscrewing the fastening bolts;
  • - remove the stuffing box from the cover and, using a special mandrel, press new oil seals into the cover, avoiding damage and distortion;

Universal puller for removing middle and rear axle bearings

  • - remove inner ringshub bearings with a puller (see fig. 2);
  • - press out the outer races of the outer and inner bearing of the hub using the puller shown in fig. 3.

Removing the outer races of the inner and outer wheel bearings of the middle and rear axles and rear axles

If a leak is detected at the ring seal 32 (see Fig. 1) or the hub fastening bolts are loosened, it is necessary to unscrew the bolts, if necessary, replace the ring and tighten the bolts with their subsequent locking with plates.

The wheel drive parts and the hub are washed and carefully inspected. On the surface of the gear teeth, chipping of the cementation layer is not allowed. In the presence of cracks and broken teeth, the gears must be replaced.

The installation of the hubs and the assembly of the wheel drive are carried out in the reverse order of disassembly.

After installing the hub, the bearing preload must be adjusted as follows:

when turning the hub, tighten the nut 33 with a torque of 40-50 kgcm, then unscrew it by 60-75˚ and check the hub for rotation. It should rotate freely, but without play;

  • - after adjustment, install washer 1 (see Fig. 1), if the nut pin does not match the washer hole, unscrew the nut until the nearest washer hole matches;
  • - tighten the locknut 2 with a torque of 40 - 50 kgcm.

The axle shafts of the middle axle are installed so that the short axle shaft is on the right side along the vehicle.

The device for installing the axle shaft of the driving axles is shown in fig. 4.

Drive axle installer

To install the axle shaft you need:

  • 1. Put the nut of the tool on the retaining ring of the axle shaft.
  • 2. By rotating the handle of the device, ensure that the device with the semi-axis becomes, as it were, one whole, i.e., get an interference fit.
  • 3. Leaning on the final drive gear, using it as a fulcrum, and the semi-axle with a device as a lever, it is necessary to engage the second end of the semi-axle with the spline of the drive axle differential gear.
  • 4. After completing the previous operation, carefully engage the bead gears with the side gear.
  • 5. Remove the tool from the retaining ring and install the axle shaft in its place.