7.3. Parking brake system
Fig. 6.15. Parking brake mechanism: 1 – adjusting fork; 2 – lock-nut; 3 – draft of the drive; 4 – razzhimny cracker; 5 – cap; 6 – drive lever; 7 – adjusting screw; 8 – block support; 9 – pusher of the razzhimny mechanism; 10 – case of balls; 11 – case of the razzhimny mechanism; 12 – brake drum; 13,18 – blocks; 14 – coupling spring of blocks; 15 – cap; 16 – ball of the razzhimny mechanism; 17 – bolt; 19 – brake board; 20 – case of the adjusting mechanism; 21 – core;
22 – spring; 23 – spring cup; and – a view with the brake drum; – a look without brake drum
The parking brake mechanism of drum type (fig. 6.15) is installed on the transfer case and affects the back driveshaft of the car.
Periodically remove the brake drum and check a condition of its working surface and degree of wear of brake frictional slips.
Clear blocks of dirt; when "oiling" surfaces of slips smooth out them a grinding skin.
Razzhimna periodically disassemble the mechanism, clear of dirt and put fresh lubricant, at the same time lubricant should not get on a drum and frictional slips.
Pay attention to correctness of gearing of a doggie and the sector of the lever of the parking brake system and a condition of their teeth.
You make adjustment when the working course of the lever of the drive becomes more than a half of its maximum course and is insufficient for full braking.
Increase in the course of the lever can happen for two reasons: because of big gaps between blocks and the brake drum – in this case adjust a gap, or because of an excessive free wheeling in the drive – in this case adjust draft length (a cable on cars of family UAZ-3741).
You make adjustment of gaps between blocks and the brake drum in the following order:
1. Install the lever of inclusion of the lowering transfer in the transfer case to neutral situation and include the forward bridge.
2. Move the drive lever to extreme forward situation.
3. Lift a jack one back wheel of the car.
4. Wrap the adjusting screw (fig. 6.16) so that the brake drum was not turned from effort of a hand.
5. Unscrew the adjusting screw on 4–6 clicks (0,3–0,5 turns) that the drum was rotated freely without zadevaniye for blocks.
3 (see fig. 6.15) the drive regulate length of draft in the following order:
1. Put the drive lever in extreme forward position.
2. Turn off a lock-nut 2 adjusting screws 1, a rasshplintuyta and take out the finger connecting a fork 1 and the lever 6 of the drive.
3. Rotating an adjusting fork, choose all gaps in the drive that the lever of the drive concerned the case of balls of the razzhimny mechanism.
4. Turn off an adjusting fork on 1,5–2 turns, combine openings in a fork and the lever, implant a finger, its zashplintuyta and tighten a lock-nut.
Drive cable length on cars of family UAZ-3741 (fig. 6.17) is similarly regulated.
At the correct adjustment of the parking brake system the car has to slow down at installation of a doggie of the lever in the third or fourth hollow of the sector, considering from a back part.
You make repair of blocks and the brake drum of the parking brake system as it is specified in the section "Repair". The most admissible diameter of the chiseled brake drum — 199 mm. At repair use these tab. 6.1.
Removal, dismantling and assembly of the parking brake mechanism
You make removal of brake shoes in the following order:
1. Disconnect the back driveshaft from the transfer case.
2. Unscrew two screws of fastening of the brake drum to a flange and remove it. For simplification of removal of a drum completely turn out the adjusting screw.
3. Remove the top cups of squeezing springs, remove springs, the lower cups and take out cores.
4. Remove coupling springs and brake shoes. You make installation of blocks and assembly of the brake mechanism upside-down, having paid attention that the block rim concerning an edge is asymmetrical, and it is necessary to establish blocks so that to a brake board they were turned by the party with a smaller departure.
You make removal and dismantling of the razzhimny mechanism in the following order:
1. Turn off two bolts of fastening of the case of the razzhimny mechanism.
2. Remove the limiter of the case of balls.
3. Remove the case of the razzhimny mechanism.
4. Take out from the case of the razzhimny mechanism the case of balls with balls and pushers.
At removal and dismantling of the razzhimny mechanism be careful not to lose pushers or balls. The cap from the case of the adjusting mechanism should not be pressed off.
It is not recommended to make full dismantling of the adjusting mechanism as for this purpose it is necessary to press off a cap from the case. At partial dismantling for removal of support of blocks it is not necessary to remove the adjusting mechanism from a board.