50
- tighten the screws 3 of the master cylinder 7 with the torque 44-56 N.m (4.4-5.6
kgf.m);
- adjust the pedal free travel with the help of the trip 11. The clearance between the push
rod 13 (see Fig. 30) and the piston should be b=0.2-0.6 mm which corresponds to the pedal travel
of 1-3 mm.
5.2.1.5 Priming. During the brake fluid change or in case of faulty hydraulic part of the
drive, prime the system in the following order:
- fill the reverse tank 1 with brake fluid (Fig. 29);
- remove the protective valve cap 2 (Fig.31), put the priming hose on the valve, unscrew
the valve by 1/2-3/4 revolutions and dip the hose the hose end into the glassy container with the
brake fluid;
- loosen the nut 4 (Fig.29) and tighten it when the first fluid drops appear;
- press the clutch pedal 25 abruptly when the valve is open and depress it smoothly when
the valve is closed until the air bubbles from the hose stop. If the air bubbles stopped going out
with the fluid, screw in the drain valve.
Check to be sure that the liquid level in the reverse tank is always above the middle and
the hose end is always dipped into the liquid. Only in this case the master cylinder does not suck
in the air during priming.
The criterion of full priming is a drastic increase of the pedal force when it is pressed by
L
2
=35-40 mm after selecting free travel.
Accelerated priming of the clutch hydraulic drive is also possible with the external
source of compressed air. Follow the steps:
- fill the reverse tank with brake fluid;
- remove the protective valve cap 2 (Fig.31), put the priming hose on the valve, unscrew
the valve by 1/2-3/4 revolutions and dip the hose end into the glassy container with the brake flu-
id;
- put the hose of the external source of compressed air on the cap 2 (Fig.29) of the re-
serve 1;
- if the air pressure is not higher than 200-250 kPa (2.0-2.5 kgf/cm
2
) make sure there are
no air bubbles from the piping.
5.2.1.6 The clutch linkage servicing includes regular inspections of the linkage ele-
ments, cleaning and the checks of the following:
- hydraulic and air parts leakproofness;
- reserve tank fluid level and threaded joints tightening.
5.2.2 Transfer Gearbox
5.2.2.1 The transfer gearbox (Fig. 32) is mechanic, two-step, with an asymmetrical in-
teraxle differential. The transfer gearbox is located on the truck frame fixed by four rubber pads.
The differential is planetary, with four satellite gears, the sun pinion 45 and the crown
gear 44. The sun pinion 45 transfers the torque to the shaft 59 of the front axle drive; the crown
gear 44 transfers the torque to the rear axle drive shaft 34.
With the operating (unblocked) differential all the axes are steadily driven and additional
loads in the transmission are eliminated. Depending on the road conditions the differential can be
switched off (blocked), in this case the front and rear axle drive shafts are rotated as a whole.
