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Pic. 15: 1. Clutch release master cylinder. 2. Brake master cylinder. 3. Vacuum amplifier. 4. Bracket for clutch and brake pedals. 5. Internal bushings for clutch and brake pedals. 6. Servo spring hook. 7. Distance sleeve. 8. Axis of clutch and brake pedals. 9. Outer bushings for clutch and brake pedals. 10. Brake pedal return spring. 11. Servo spring. 12. Tank plug. 13. Cork reflector. 14. Master cylinder reservoir. 15. Brake pedal. 16. Clutch pedal return spring. 17. Clutch pedal stop screw. 18. Clutch pedal. 19. Retract spring plate. 20. Pusher. 21. Cork. 22. Master cylinder housing. 23. Piston spring. 24. Master cylinder piston. 25. Lock washer. 26. Fitting. 27. Fitting gasket. 28. Sealant. 29. Pusher piston. 30. Retaining ring. 31. Protective cap. 32. Flywheel. 33. Driven disk. 34. Pressure plate. 35. Pressure spring. 36. Clutch cover. 37. Clutch release bearing. 38. The primary shaft of the gearbox. 39. Plug of the body of the working cylinder. 40. Fitting. 41. The body of the working cylinder. 42. Clutch release fork pusher. 43. The piston of the working cylinder. 44. Support plate. 45. Spring. 46. Support washer. 47. Ball joint of the clutch release fork. 48. Clutch release fork. 49. Adjusting nut. 50. Locknut. 51. Compression spring retainer. I - Scheme of the hydraulic clutch.
The clutch is disengaged via a hydraulic drive with a suspension pedal. This type of drive ensures smooth engagement of the clutch, which, in turn, reduces dynamic loads on transmission parts and increases driving comfort. The hydraulic drive is reliable and durable, the labor intensity of its maintenance is reduced to a minimum. The drive includes a servo spring 11, which significantly reduces the clutch release force.
The clutch and brake pedals are suspended from the bracket 4 on the same axis 8, made in the form of a bolt. A thrust washer is installed under its head, and a nut with a spring washer is screwed onto its end. Pedal hubs are equipped with external plastic bushings 9, which do not require lubrication during vehicle operation. The rotation of the pedals occurs on the inner metal bushings 5, put on the axle. A distance plastic sleeve 7 is installed between the brake pedal and the cheek of the bracket.
The clutch pedal is pivotally connected to the pusher 20 and the release spring plate 19. They are held on the finger with a cotter pin. The retractable spring 16 holds the clutch pedal in its original position, in which the pedal rests against the cap 17 of the pedal limiter. The other end of the pusher enters the piston seat 29 of the master cylinder. The pedal stroke limiter can be used to adjust the gap between the hemispherical end of the pusher and piston 29.
A bracket is welded to the upper end of the pedal, into the cutout of which hook 6 enters; the other end of the hook is connected to the servo spring 11. The servo spring tends to turn the upper part of the pedal in the direction of disengaging the clutch, which significantly reduces the force applied to the clutch pedal.
The master cylinder 1 of the clutch release actuator is mounted on two studs to the end plate of the brake and clutch pedal bracket. The vacuum booster 3 with the master cylinder 2 of the brake drive is attached to the same plate.
A return spring 23 and two pistons 24 and 29 are installed in the cavity of the main cylinder. The spring abuts with one end against the plug 21, the other against the shoulder of the piston 24 and serves to return the pistons to their original position. Due to the installation of two pistons, the radial loads on the piston 24 are reduced when the pusher 20 acts on the piston 29, and the sealing of the pistons is also improved, since the sealing ring 28 is compressed between them.
The piston of the main cylinder is sealed with a rubber ring, which is located in the piston groove and creates tightness in the working cavity of the cylinder. In order to simultaneously improve the sealing of the piston as the pressure in the working cavity increases, an axial channel is made in its shank, connecting with radial holes that open into the groove of the O-ring. When the pressure in the working cavity of the cylinder increases, then under its influence the sealing ring expands along the radius, i.e., it fits more closely to the cylinder mirror. At the same time, the piston sealing ring is a valve through which the cylinder cavity communicates with reservoir 14. This occurs at the rearmost position of the master cylinder pistons, when the sealing ring does not block the compensation hole.
All parts of the main cylinder are held in the cavity by a retaining ring 30. A protective cap 31 protects the cylinder cavity from contamination. A pipeline is fixed in the holes of the cylinder body, which drains fluid from the main cylinder to the working one, and fitting 26, connected by a hose to the hydraulic drive reservoir. The fitting 26 in the socket of the body tide is sealed with a rubber gasket 27 and fastened with a lock washer 25.
Slave cylinder 24 (see fig. 14) the clutch release actuator is attached with two bolts to the clutch housing 13. The upper bolt simultaneously secures the release spring plate 25, which returns the clutch release fork to its original position.
Piston 43 is located in the cylinder body (see sheet 15) with two sealing rings. The rear ring 28 is installed in the piston groove, the front ring is constantly pressed through the support plate 44 by the spring 45 to the end surface of the piston. The other end of the spring rests against the support washer 46, which is held on the piston shank by a retaining ring.
The working cavity of the cylinder communicates with the groove of the sealing ring through the axial channel and radial holes, which ensures a tighter fit of the ring to the cylinder mirror when the clutch is released, when fluid pressure is created in the working cavity.
A plug is screwed into the body, into the threaded hole of which a hose tip is screwed. A fitting 40 is screwed into the tide of the body for pumping the clutch drive. The reservoir 14 of the clutch hydraulic drive is fixed on the bracket of the front end of the body. It is made of translucent plastic, which makes it easy to check the fluid level in the actuator. The stopper 12 of the tank has a corrugated rubber reflector 13, which protects the cavity of the tank from contamination and is a liquid damper. In addition, the reflector does not allow direct contact of liquid with air, which increases its service life. The cavity of the tank is connected to the atmosphere through a hole in the plug. When the liquid level in the tank decreases, the air pressure above the reflector eliminates the vacuum that occurs in the tank. At the bottom of the tank there is a fitting on which a hose is fixed for supplying fluid to the cavity of the master cylinder.
Clutch work
The clutch is permanently closed, type, i.e. constantly on if the driver does not act on the clutch pedal. In this case, there is a gap of 1.5 - 2 mm between the clutch release bearing and the thrust flange lining. The pressure spring 35, due to its elasticity, presses on the annular protrusion of the pressure plate 34 and presses it against the driven disk 33, which, moving along the splines of the input shaft 38, is pressed against the surface of the flywheel. Clamped between the surfaces of the flywheel and the pressure plate, the driven disc 33 transmits torque through the transmission elements to the driving wheels of the vehicle. When the clutch is engaged, the driving and driven parts of the clutch rotate as one.
To disengage the clutch, press the pedal 18. The force from the pedal through the pusher is transmitted to the pistons 29 and 24, which, moving in the cylinder, compress the spring 23. The front sealing ring covers the compensation hole, and the cylinder cavity is separated from the tank. Under pressure from the piston, the fluid from the master cylinder through the tube and hose enters the cavity of the working cylinder, creating pressure on the piston 43. Under this pressure, the piston moves in the cylinder and through the pusher 42 and the adjusting nut 49 transmits force to the fork 48 of the clutch. Turning on the ball bearing 47, the fork moves the clutch release bearing 37. Initially, the clearance between the bearing and the friction ring of the thrust flange is selected. This ends the free travel of the clutch pedal, which is 25-35 mm, provided that the clutch actuator is correctly adjusted. With further pedal travel, the thrust flange presses on the petals of the pressure spring, which, bending on the support rings, pulls the pressure plate 34 from the driven disk 33 through the clamps 51, after which the transmission of torque to the input shaft of the gearbox stops. At this point, bumpless gear shifting or braking is carried out.
The total travel of the clutch pedal is approximately 140 mm. With this stroke, the pressure plate is retracted from the driven by 1.4-1.7 mm.
When the clutch pedal is released, the parts of the main and working cylinders and the pedal itself return to their original position under the action of return springs. The front sealing ring moves away from the compensation hole, which leads to the communication of the cavities of the master cylinder with the reservoir. The pressure in the drive system is supplied, and the pressure plate, under the action of the elasticity of the pressure spring 35, presses the driven disc against the surface of the flywheel. Due to the elastic wave-like surface, the driven disc initially slips and clamps gradually, which ensures smooth engagement of the clutch. In this case, the torque is transmitted from the flywheel to the clutch cover 36 and pressure plate 34, and then due to friction forces - to the driven disc 33. From it through the elastic elements of the damper to the hub of the driven disc and through the spline connection to the input shaft 38 of the gearbox.
With a sharp change in the magnitude of the torque and the occurrence of torsional vibrations, the driven disk 33, together with the damper plates, rotates at a certain angle relative to the hub 8 (see sheet 14). In this case, friction occurs between the surfaces of the hub and the friction rings of the damper, and the springs 9 are compressed. The angle of rotation of the driven disk, and hence the compression stroke of the springs, depends on the magnitude of the transmitted moment. The rotation of the driven disk relative to the hub is limited by the stop of the fingers 5 in the horseshoe cutouts of the hub, after which the action of the elastic element of the damper stops. Due to the elastic element of the damper, the energy of torsional vibrations is absorbed. This reduces the maximum stresses in the transmission parts, protecting them from breakage and premature wear.
With a sharp release of the clutch pedal, the liquid does not have time to fill the released piston 24 (see fig. 15) volume and a vacuum is created in the working cavity of the main cylinder. Under its action, the liquid through the hole in the cylinder body, the gap between the rear end of the sealing ring and the piston groove passes through the radial hole in the piston into the working cavity of the cylinder, which ensures that the drive is always ready for effective action.
Accurate clutch operation is ensured by certain gaps in the clutch drive. So, to completely disengage the clutch, a gap is required between the pusher 20 and the piston 29 of the main cylinder, which should be in the range of 0.2-0.5 mm, which corresponds to a free travel of the clutch pedal of 0.4-2 mm. If there is no this gap, then the piston cannot fully return to its original position, and excess pressure will remain in the working cavity of the cylinder and in the drive when the pedal is released. As a result, the clutch will not fully engage, and its discs will slip. This gap is regulated by the limit screw 17 of the pedal travel.
For the same reason, a clearance of 2 mm is required between the clutch release bearing and the thrust flange friction ring. In sum, these two gaps provide a clutch pedal free play of 25-35 mm. The clearance between the clutch release bearing and the thrust flange is adjusted by nut 44.
At the same time, changing the specified gaps in the direction of increasing will lead to the opposite phenomenon - incomplete disengagement of the clutch (clutch "leads"). These two main malfunctions have their own signs and causes.
When the clutch slips, when the torque is not fully transmitted to the drive wheels, the vehicle's driving dynamics are reduced.
This is especially felt when the load increases: when overcoming climbs, difficult sections of the road, during sudden acceleration. At the same time, fuel consumption increases. Due to the slipping of the clutch discs, the friction linings of the driven disc burn out. In this case, a specific smell is possible.
When slipping the clutch discs, first of all, you should check for gaps in the clutch drive: the gap between the pedal pusher and the piston, equal to 0.1-0.5 mm, and the gap between the bearing and the thrust flange ring. The first gap is determined by the amount of pedal free play (0.4-2mm), the second largest free play of the pusher of the working cylinder, which should be 4-5 mm. The gap is adjusted with the limit screw 17 of the pedal stroke and the adjusting nut 49. With proper adjustment, the free play of the clutch pedal should be 25-35 mm.
Additional causes of clutch slippage include wear, burnt or oily clutch discs, or damaged or seized clutch actuator. For these reasons, the malfunction is eliminated by replacing or repairing worn or damaged parts.
When the clutch doesn't fully disengage ("leads"), then this is determined by the difficult inclusion of gears, especially reverse gear, when knocking is possible, because. this transmission is out of sync. With this malfunction, first of all, check and, if necessary, adjust the clearances in the clutch release drive, as indicated above. In addition, incomplete clutch disengagement occurs when fluid leaks or air enters the drive, when the discs are warped or damaged, or the driven disc hub seizes on the splines of the input shaft. In these cases, the malfunction is eliminated by bleeding the clutch actuator or replacing damaged or worn parts.