1. Left wheel drive. 2. Power unit. 3. Right wheel drive. 4. Body of the outer hinge. 5, 13. Dirt deflector. 6, 17. Hinge holder. 7, 14. Ball. 8, 18. Separator. 9, 21. Protective cover. 10. Internal collar. 11. Wheel drive shaft. 12. A lock ring of a cogwheel of a semiaxis. 15. The body of the internal hinge. 18. Retaining ring. 19. Retainer of the internal hinge. 20. Outer collar of the cover.
In front-wheel drive vehicles, the front steered wheels are also driving. To transmit torque to them, wheel drives are used, each of which consists of a shaft 11 and two cardan joints of equal angular velocities. This type of hinge provides uniform (synchronous) speed of rotation of the driving and driven links of the hinge when they break (turning the front wheels). In these cases, a conventional hinge quickly fails, since when its driving and driven links deviate, an uneven angular velocity transmission of rotation to the driven link is created.
Synchronous cardan joints are mounted at the ends of the shaft 11. The outer joint, connected to the front wheel hub, is of a rigid type, with an angular degree of freedom, the inner joint is of a universal type, with an angular and axial degree of freedom. It connects to the semi-axial gear of the differential. Due to the axial movement of the internal hinge parts, the length of the wheel drive changes, which is necessary to compensate for the movements caused by oscillations of the front suspension and the power unit.
The drives of the left 1 and right 3 wheels have the same design, but different lengths. The latter is explained by the shift of the gearbox to the left side of the vehicle axis.
The outer hinge consists of a body 4, a separator 8, an inner cage 6 and six balls 7. Radius swing paths are made in the body of the hinge and in the cage, the curvature of which has a meridian direction. In these paths there are balls that connect the body 4 and the inner cage 6. The balls are placed in the windows of the separator 8 and are held in the same plane. As a result, the inner race and the hinge body are centered. The working angle of rotation of the outer hinge is up to 42°.
The inner cage of the hinge is mounted on the splines of the shaft 11 and is fixed on them with a retaining ring 16.
The separator has a spherical surface and ball windows. It ensures synchronous rotation of the shafts connected by the hinge by installing balls in the sectorless plane of the angle of the intersecting axes of the hinge links, i.e., it acts as a divider. As a result, regardless of the angle of rotation of the hinge, the balls are always kept in the plane of constant speed. At the same time, torque is transmitted through the separator.
To seal the hinge cavity, a corrugated rubber boot 9 is used, which is fastened to the hinge body and to the wheel drive shaft 11 with clamps 10 and 20. The tightness of the boot seats is ensured by annular grooves on the hinge housing, into which the boot is pressed when the clamp is tightened. On the opposite side of the cover, the grooves are made in the cover itself, they create a labyrinth seal. Axial fixation of the cover on the shaft is achieved by thrust collars on the drive shaft. Tightening collars are made of steel tape, on which three nests and one fixing tooth are stamped. Two nests serve to tighten the clamp with a special device, a fixing tooth enters the third nest. The front wheel hub is mounted on the splined tip of the hinge housing. It is attached to the slots with a self-locking nut.
The inner joint is connected to the side gear of the differential. It has minor structural differences compared to the external hinge, primarily in that the tracks in the hinge body 15 and in the cage 17 are made straight, and not radial, which allows the hinge parts to move in the longitudinal direction, and due to the sphericity of the surface of the separator 18, turn on angle up to 18°. This is necessary to compensate for movements caused by oscillations of the front suspension and power unit. Longitudinal movement of the cage in the hinge body is limited by a wire retainer 19, which is installed in the groove of the hinge body 15. The shank of the hinge body is connected by means of a spline to the side gear of the differential. The side gear is held on the splines of the shank by a retaining ring 12.
Protection of the inner hinge parts from moisture and dirt is carried out in the same way as for the outer hinge. When assembling the cardan joints, a special lubricant SHRUS-4 is laid in them. When operating the car, the lubricant is not replaced if the covers ensure the tightness of the hinges.
Front wheel drives operate under the most severe and adverse conditions, as they are located in the area of the greatest exposure to moisture and dirt and transmit torque to the wheels at constantly changing angles and loads. High precision manufacturing of hinge parts, the use of high-quality materials and lubricants ensure reliable operation of the unit even under these difficult conditions, but only while maintaining the tightness of the hinges. Therefore, it is important to periodically check the condition of protective covers and clamps in order to timely detect cracks, deformations or traces of rubbing against the road surface on them and take measures to replace them. This prevents premature wear of the hinges.