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Pic. 25. Brake mechanisms of wheels.
1. Springs of fingers of fastening of pads; 2. Cotter pin; 3. Clamping spring pads; 4. Brake pads; 5. Brake caliper; 6. Disc brake; 7. Protective cover; 8. Pin for fastening brake pads; 9. Fitting for pumping the drive of the brake mechanism; 10. Connecting tube of cylinders; 11. Piston; 12. Wheel cylinder; 13. Piston O-ring; 14. Friction lining pads; 15. Piston protective cap; 16. Cylinder retainer; 17. Rivet for fastening the support and guide plates of the shoes; 18. Lower coupling spring pads; 19. Guide plate; 20. Brake shoe; 21. Rear parking brake cable; 22. Rear cable spring; 23. Rear cable end; 24. Parking brake lever; 25. Brake pad spacer; 26. Finger lever drive pads; 27. Wheel cylinder body; 28. Piston spacer; 29. Fitting for pumping the rear brake drive; 30. Fitting of the brake fluid supply pipe; 31. Piston O-ring; 32. Cylinder piston; 33. Protective cap of the wheel cylinder; 34. Shoe stop; 35. Top coupling spring pads; 36. Friction lining pads; 37. Rib pads; 38. Spring; 39. Axis; 40. Spring bushing; 41. Friction washers; 42. Automatic device axis bushing; 43. Rope sheath; 44. Guide spring; 45. Support shield of the brake mechanism; 46. Pad support plate I. Front wheel brake; II. Rear wheel brake.
1. Springs of fingers of fastening of pads; 2. Cotter pin; 3. Clamping spring pads; 4. Brake pads; 5. Brake caliper; 6. Disc brake; 7. Protective cover; 8. Pin for fastening brake pads; 9. Fitting for pumping the drive of the brake mechanism; 10. Connecting tube of cylinders; 11. Piston; 12. Wheel cylinder; 13. Piston O-ring; 14. Friction lining pads; 15. Piston protective cap; 16. Cylinder retainer; 17. Rivet for fastening the support and guide plates of the shoes; 18. Lower coupling spring pads; 19. Guide plate; 20. Brake shoe; 21. Rear parking brake cable; 22. Rear cable spring; 23. Rear cable end; 24. Parking brake lever; 25. Brake pad spacer; 26. Finger lever drive pads; 27. Wheel cylinder body; 28. Piston spacer; 29. Fitting for pumping the rear brake drive; 30. Fitting of the brake fluid supply pipe; 31. Piston O-ring; 32. Cylinder piston; 33. Protective cap of the wheel cylinder; 34. Shoe stop; 35. Top coupling spring pads; 36. Friction lining pads; 37. Rib pads; 38. Spring; 39. Axis; 40. Spring bushing; 41. Friction washers; 42. Automatic device axis bushing; 43. Rope sheath; 44. Guide spring; 45. Support shield of the brake mechanism; 46. Pad support plate I. Front wheel brake; II. Rear wheel brake.
Brake mechanisms of wheels are mounted directly in wheels of the car. They are designed to create resistance to the movement of the car.
The brake mechanism of a forward wheel is disk. It consists of a caliper 5 assembled with working cylinders 12, two brake shoes 4, pins 8 for fastening the shoes and pipelines.
The caliper is cast from ductile iron. It is attached to the flange of the steering knuckle together with the protective cover 7 and the rotary lever. The caliper has a radial groove to accommodate the brake disc and two transverse grooves in which the brake pads are located. In the lugs of the caliper, there are two windows with guide grooves, in which two opposite wheel cylinders 12 are installed. The exact location of the cylinders relative to the caliper is ensured by spring retainers 16. When the cylinder is installed in the caliper groove, the latch, under the action of a spring, enters a special side groove of the caliper.
The body of the working cylinder 12 is cast from an aluminum alloy. The cylinder contains a steel hollow piston 11, sealed with a rubber ring 13. It is located in the groove of the cylinder and serves not only to seal the gap, but also to return the piston to its original position when released. The cylinder cavity is protected from contamination by a rubber cap 15, the outer edge of which is held on the cylinder shoulder, and the inner edge covers the piston seat band. The working cavities of the cylinders are interconnected by a tube 10. A fitting 9 is screwed into the outer cylinder for pumping the front brake drive, and into the inner one - a fitting for supplying fluid. Pistons 11 abut against brake pads 4, on which friction linings are glued. The pads are mounted on guide pins 8, which are kept from axial displacement by cotter pins 2, and in order to avoid vibration of the pads on the fingers, springs 3 are used to press the pads to the fingers. Springs 1 are installed under the finger heads.
When braking, the pistons, under fluid pressure, move out of the wheel cylinders and carry along the sealing rings 13, which are then twisted. When released, when the pressure in the drive drops, the pistons are pushed back into the cylinders due to the elastic deformation of the rings 13. In this case, the linings 14 of the brake pads will be in light contact with the brake disc. As the pads wear, as the gap in the brake mechanism increases, more fluid pressure is created in the actuator to create a braking torque. Under the action of fluid pressure, the pistons 11 slip relative to the rings 13 and take a new position in the cylinders, which provides an optimal clearance between the disc and the pads.
The brake mechanism of the rear wheel is drum, mounted on the support shield 45, which is bolted to the flange of the rear axle beam. A package of plates is attached to the bottom of the shield with two rivets 17, of which plate 46 is a support for pads 20, and plates 19 limit the axial movement of the bottom of the pads. The inner curved plate limits the movement of the cable 21 towards the shield. In the upper part of the shield 45, a wheel cylinder 27 is fastened with two bolts. Outside, a fitting 29 is screwed into the threaded hole of the cylinder for pumping the brake drive and a fitting 30 of the tube for supplying fluid to the cylinder.
On both sides, pistons 32 with sealing rings 31 are installed in the cylinder, which are pressed against the end of the pistons by a spring 28 through the support cups. Stops 34 are pressed into the pistons, into the slots of which the upper part of the shoe enters. The cavity of the wheel cylinder is protected from contamination by rubber caps 33, which are put on the pistons with the inner edge, and the cylinder body with the outer edge. The brake pads are tightened by springs 35 and 18, which press the pads to the lower support and stops of the wheel cylinder pistons. Due to the non-rigid connection of the pads to the brake shield, they self-align themselves at the moment of contact with the brake drum, which improves braking efficiency and leads to more even lining wear.
To automatically adjust the gap between the shoes and the drum, special devices are mounted on the shoes. Each of them consists of an axle 39 welded to the brake axle and a friction element. Axis 39 passes through the oval hole of the pad rib. Two bushings 40 and 42 screwed together are installed with a gap on the axle. Between the flanges of the bushings there is a spring 38, its support cups and two friction washers 41, which clamp the edge of the shoe with a certain force. This force is such that the return springs 18 and 35 cannot move the pads relative to the friction washers, despite the oval holes in the ribs of the pads. But when the pads 36 are worn, when the driver has to increase the force on the brake pedal, the pressure in the rear brake drive circuit increases, the pistons move the pads relative to the friction washers, pressing the pads against the drum. In this case, the pads will take a new position relative to the drum. With further braking, the pads will move by the amount of the gap between the sleeve 42 and the axle 39. This gap provides a tight pressing of the pads to the drum and the necessary braking torque. When releasing the pads, they are removed from the drum by coupling springs by the amount of the gap between the sleeve 42 and the axle 39.
Since 1986, brake mechanisms have been installed on cars with a device for automatically adjusting the gap, which is mounted in the wheel cylinder. It is unified with similar devices installed on cars of the VAZ-2105, 2107 family.