Belarus 921.6 Operator's Manual page 157

2. Check the pedals free travel. The pedals 8, 9 free travel shall be within range
from 4 to 8 mm. If this requirement is not fulfilled, then adjust the pedals free travel accord-
ing to following directions:
- remove cotter pins from pivots 6 and disconnect forks 3 from pedals 8 and 9 rods;
- unscrew lock nuts 7 by a few revolutions, then screw in or unscrew forks 3 to ex-
tend or retract the rods of the brake main cylinders 1 and 2 to provide for required pedals
free travel;
- lock the nuts 7, install pivots 6 and put cotter pins into them. The pedals free travel
from 4 to 8 mm corresponds to clearance between the piston and plunger of each brake
main cylinder from 0.6 to 1.3 mm;
- the pedals should not come in contact with the cab elements. If necessary, adjust
the pedals pads height using bolts 5 and by the brake main cylinders rods length, mean-
while provide for the pedals free travel from 4 to 8 mm.
3. Check the length of the service brake cylinders 1 and 14 (Figure 5.4.23). Length
of the service cylinders shall be (2232) mm when measured from the point of the cylinder
fastening on the bracket axis to the pivot axis, which connects the levers 5 and 9 to the
forks 3 and 12 correspondingly, and while the rod of the service brake cylinder is fully re-
tracted inside as shown in Figure 5.4.23.If this requirement is not fulfilled, then set dimen-
sion (2232) mm for the service brake cylinders 1 and 14.
Set the length of the service brake cylinders using the forks 3 and 12, bolt-links 6
and 10 according to following directions:
- disconnect the link 4 (Figure 5.4.24) of the parking brake and the link 10 of the
pneumatic valve, for this purpose take out cotter pins and remove pivots 7 and 11 corre-
spondingly.
- unscrew the lock nuts 2 and 13 (Figure 5.4.23) by a few revolutions.
- remove cotter pins and take out pivots 4 and 11, while disconnecting forks 3 and
12 from levers 5 and 9 of the right and left service brakes correspondingly.
- screw in or unscrew forks 3 and 12 from rods of the service brake cylinders 1 and
14 to set dimension (2232) mm.
- lock the lock nuts 2 and 13, install the pivots 4 and 11 and put cotter pins into
them.
4. When adjustments are finished, will the actuator hydraulic system by the brake
fluid and pump the hydraulic system according to following directions:
- fill the tanks 17 and 18 (Figure 5.4.23) of the main brake cylinders 16 and 15 by
brake fluid up to MАХ marks on the tanks. Monitor the fluid level while pumping and pre-
vent its falling below MIN mark.
- use the interlocking piece 21 to interlock pedals 19 and 20;
- clean overflow valves 7 and 8 from dust and dirt, remove caps from them, put the
tube onto the overflow valve of the left service cylinder. Put the other end of the tube into
the transparent vessel of volume at least 0.5 l, which is filled by the brake fluid up to half;
- four or five times press the brake interlocked pedals and while keeping them
pressed unscrew the valve of the left service cylinder by 1/2 - 3/4 revolution, then after the
pedals will move through full travel path, when some of the fluid with air will be released
from the system, screw the valve and release the brake pedals. Press quickly and release
smoothly! Repeat this operation for a few times until air will be completely expelled from the
system. Remove the tube from valve and install the protecting cap;
- perform the same actions to pump the right brake hydraulic actuator;
- top up both tanks 17 and 18 with fluid up to MAX mark ((155) mm from the upper
edge of the tank).
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921.6-0000010 OM