7.7.4. Check of details

Wheel cylinders. Check purity of working surfaces of the cylinder, pistons and persistent rings. Surfaces have to be absolutely smooth, without roughnesses that there was no leak of liquid and premature wear of sealants and pistons. Eliminate defects on a mirror of the cylinder with grinding in or grinding. However increase in internal diameter of the cylinder is not allowed.

Fig. 7-17. Details of the wheel cylinder: 1 — the piston assembled; 2 — the cylinder case; 3 — the persistent screw; 4 — a persistent ring; 5 — crackers; 6 — a spring; 7 — a basic cup; 8 — a sealant; 9 — the piston; 10 — a protective cap

Check a condition of the persistent screw 3 (see fig. 7-17), springs 6, a basic cup 7 and crackers 5. If necessary replace the damaged details new.
Replace a sealant 8 new. Check a condition of protective caps 10 and if necessary replace them.
Blocks. Attentively check whether is not present on blocks of damages or deformations.
Check elasticity of coupling springs both top, and lower; if necessary replace them new.
Springs should not have residual deformations at stretching by effort of 343 N (35 kgfs) of the lower springs and 411 N (42 kgfs) — top.
Check purity of slips if dirt or traces of lubricant are found, carefully clear slips a metal brush and wash out white spirit, besides, check whether there is no leak of lubricant or oil in a drum; eliminate malfunctions. Replace blocks new if thickness of slips became less than 1,5-2 mm.
Brake drums. Examine brake drums. If on a working surface there are deep risks or excessive ovality, chisel drums on the machine.
Then on the lathe abrasive fine-grained whetstones to a proshlifuyta drums. It increases durability of slips and improves uniformity and efficiency of braking.
The greatest admissible increase in nominal diameter of a drum (250 mm) after boring and grinding — 1 mm. Limits of this admission have to be observed strictly, otherwise the drum durability, and also efficiency of braking is broken.