Maintenance & Adjustment
180
D760.H03E-001.H1907
During the running-in period, improper adjustment of brake clearance is likely to
ºCcur as the initial thermal expansion of new friction lining is great, which may reduce
brake clearance. In this case, adjust the brake clearance larger manually for 2-3
times.
2. Replacement of friction lining
After replacement with a new friction lining, check the contact between brake
shoe and drum, and make sure the difference of upper and lower shoe symmetric
point clearance falls in the acceptable range (below 0.3mm). Try to keep the upper
and lower shoes contact the drum simultaneously while braking, so as to avoid large
clearance due to braking with one shoe. If the difference of symmetric point clearance
is too large, turn the excircle of brake shoe friction lining or polish the projection of fric-
tion lining with sand paper.
3. Thermal expansion of brake drum
When braking is frequently applied (like on long downhill at mountain area), the
brake drum will expand with heat, and the enlarged clearance (brake drum expansion)
will be adjusted smaller by automatic adjuster, and brake drag may ºCcur after the
brake drum is cooled. In such case, users can adjust brake clearance larger manually
after the brake is cooled.
Method for disabling automatic adjustment function
If the worm shaft cannot be rotated to adjust too small brake clearance larger
during brake drag, users can disable the automatic adjustment function for some time,
and use it as a manual adjuster. Specific method: for automatic adjuster with control
arm, remove the fixing bolt of control arm; for automatic adjuster without control arm,
remove the small pin shaft and gear rack, rotate the worm shaft to make the shoe fric-
tion lining contact the brake drum, and then rotate the worm shaft in reverse direction
by 1/3-2/3 turn, and use a feeler gauge to check that the clearance is 0.5-0.8mm.
After the automatic adjustment function is disabled, please check and replace the
part at Dongfeng service station immediately.
Summary of Contents for DFH4180 Series
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