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11.6. Replacement of back brake shoes on drum brakes

Elements of a back drum brake

1 – razzhimny level,
2 – clamp,
3 – regulator wheel,
4 – regulator lever,
5 – regulator lever spring,
6 – regulator lever arm,
7 – lever of the emergency brake,
8 – top returnable spring

Check

PERFORMANCE ORDER
1. For check of brake shoes it is recommended to remove the brake drum. In this case it is possible to check a condition of the working brake cylinder also.
2. Wear of overlays of brake shoes can be checked also without removal of the brake drum through viewing openings in a brake board after removal of a cap from an opening.
3. Using a small lamp and a mirror, through an opening in a brake board check thickness of an overlay of a brake shoe.
4. Even if the limit of wear was reached by only one brake shoe, surely replace all back brake shoes in a set.

Replacement

PERFORMANCE ORDER
1. In the presence take off caps of back wheels, then weaken bolts of fastening of wheels.
2. Lift a back part of the car and record on supports.
3. Remove back wheels.
4. Completely release the emergency brake.
5. Unscrew the screw of fastening of the brake drum and remove the brake drum.
6. If the brake drum is kept by brake shoes, remove a cap from a viewing opening of a brake board and through an opening move a control lever of the emergency brake to a brake shoe, at the same time brake shoes will depart from a drum and the drum will easily be removed.
7. Note the adjusting provision of all elements of a back brake.
8. Measure thickness of a frictional overlay of a brake shoe and at wear it in any point to minimum admissible thickness replace all four brake shoes.
9. Also blocks need to be replaced if at least one of blocks is polluted by oil as there is no way of degreasing of brake shoes.
10. If brake shoes are unevenly worn-out or polluted by oil, establish and eliminate the reason of it before installation of new brake shoes.
11. Using flat-nose pliers, remove a plate (it is specified by an arrow) springs of fixing of a block, pressing a plate and turning it on 90 °.
12. Remove a spring and take clamp pins.
13. Disconnect a cable of the emergency brake from a control lever (the arrow specified fastening of a cable to the lever of the emergency brake).
14. Disconnect the top returnable spring from brake shoes and remove blocks from a brake board.
15. If necessary remove brake shoes together with a spring and a razzhimny level.
16. Remove a nave. Be careful not to damage rubber covers of the working brake cylinder. Before removal note the provision of a returnable spring and adjusting level.
17. Do not remove at the same time brake shoes of the left and right back wheel not to mix a detail of brake shoes.
18. For prevention of an exit of pistons from the working brake cylinder install an elastic band on pistons or fix them by a spring bracket. Do not press a brake pedal at the removed brake drum.
19. Observing care and security measures, clear all traces of brake dust from a brake board.
20. Apply a thin film of high-temperature lubricant on places of contact of brake shoes and a brake board.
21. If on overlays of brake shoes there is a liquid which flowed out from the working brake cylinder or the hug bearing, define the reason of an effluence and eliminate it.
22. If brake shoes were removed assembled, note the provision of elements and separate from each other brake shoes, springs and a razzhimny level.
23. If brake shoes of the left and right back wheel were removed at the same time, do not mix a detail. Cores with a carving of adjusting levels of the left and right wheel are noted by the letters L or R, and other details are identified in color: black – for the left side and silvery for the right side.
24. Sort and clear an adjusting level.
25. Check a condition of returnable springs and, if necessary, replace them.
26. If on new brake shoes there is no control lever of the emergency brake remove it from an old brake shoe and establish on new.
27. Fix a hinged finger of a control lever of the emergency brake by a spring ring.
28. If elements of a back brake are established assembled, collect new brake shoes, springs and an adjusting level.
29. For simplification of installation move apart an adjusting razzhimny level.
30. Establish the top returnable spring on brake shoes.
31. Establish a regulator lever spring on the leading brake shoe (the arrow specified the direction of installation).
32. Remove an elastic band or a spring bracket from the working brake cylinder, establish knot of brake shoes on a brake board, at the same time be careful not to damage covers of the working brake cylinder.
33. Establish pins of clamps of brake shoes, springs and plates of fastening of a spring.
34. Connect a cable of the emergency brake to the lever on a back brake shoe, then establish a nave of a back wheel and adjust a side play in the bearing.
35. Rotating a wheel of an adjusting level, reduce length of a razzhimny level to take away brake shoes from the brake drum.
36. Check that the reference point of a stop of the lever of the emergency brake is established against edge of a brake shoe, then install the brake drum.
37. Make replacement of brake shoes on the second back wheel.
38. After replacement of brake shoes adjust a gap between them and the brake drum for what 15–20 times press a brake pedal. When pressing a pedal during the normal work of an adjusting level the clicks published by an adjusting level have to be heard.
39. Check and if it is necessary, adjust the emergency brake.
40. Establish wheels and lower the car on the earth.
41. Tighten bolts of fastening of a wheel the required moment and in the presence establish a wheel cap.
42. After installation of new brake shoes avoid sharp braking during the first 200 km of a run of the car.