The power take-off (PTO) is single-stage, mounted on the right side of the gearbox housing and is designed to drive auxiliary equipment.
The PTO is manufactured in two versions: with pump (Fig. 1) and with flange (Fig. 2).
Engage the power take-off when the air pressure in the vehicle's pneumatic system is at least 500 kPa (5 kgf/cm2) and the clutch is disengaged.
Adjusting shims are installed between the flanges of the gearbox and power take-off housings, which are used to adjust the gear backlash (by noise).
If it is necessary to replace the shims with new ones, their thickness must be maintained.
The power take-off control is pneumatic and consists of a control valve, an engagement mechanism and air lines.
To provide remote engagement of the power take-off, a control valve is installed on a bracket in the cab, to the right of the driver, on the lower edge of the instrument panel.
When the power take-off is disengaged, lever 8 (Fig. 3) is in the upper position, stem 7 is in the right position.
Valve 3, under the action of spring 2, is pressed against its seat 4 and no air passes through the valve.
When the power take-off is engaged, the valve lever 8 is moved to the lower position.
Stem 7 moves to the extreme left position, presses on valve 3 and moves it away from seat 4.
Compressed air passes through the air lines into the diaphragm chamber of the engagement mechanism.
Diaphragm 6 (see Fig. 1), via rod 10 and fork 9, engages the driven shaft gear 5 with the drive gear 3.
When the power take-off is disengaged, the valve lever 8 (see Fig. 3) is moved back to the upper position.
Stem 7, under the action of spring 5, moves to the extreme right position, thereby separating from valve 3.
Through a hole in the rod 10 (see Fig. 1), the engagement mechanism chamber of the PTO is vented to the atmosphere; air is exhausted from the chamber and, under spring action, the rod and fork 9 disengage the driven shaft gear 14 from the drive gear 3.
Simultaneously with the exhaust of air to the atmosphere, valve 3 (see Fig. 3), under the action of spring 2, is pressed against its seat 4 and isolates the inlet and outlet ports of the valve.
Auxiliary power take-off
Power is taken from the input shaft of the transfer case through a sliding sleeve 2 (Fig. 4) and is intended to drive the winch.
The auxiliary power take-off can only operate when the transfer case gear shift sleeve is in the neutral position.
To lubricate the gears and shaft bearings, a plunger pump is installed in the auxiliary power take-off.
The pump consists of a piston 17 with delivery valve 18, a relief valve 20 and a body 22.
The piston with connecting rod is mounted on the eccentric of shaft 3 and reciprocates as it rotates.
To prevent excessive pressure with increasing rotational speed, the suction valve is of the differential type with a cylindrical spring.
Oil is drawn in through a pipe connected to the oil sump of the transfer case, and from the pump it is supplied to the gear bearings through channels made in shaft 3 and in the input shaft of the transfer case.
Some of the oil penetrates through the clearances and lubricates the shaft bearings.
To provide remote engagement of the auxiliary power take-off, a control valve is installed on a bracket in the cab, to the right of the driver, on the lower edge of the instrument panel.
When the auxiliary power take-off is disengaged, lever 8 (see Fig. 3) is in the upper position, stem 7 is in the right position.
The valve, under the action of its spring, is pressed against its seat 4 and no air passes through the valve.
When the handle is moved to the lower position, stem 7 moves to the extreme left position, presses on the valve and moves it away from its seat.
Compressed air enters the engagement chamber and engages the auxiliary power take-off, compressing spring 8 (see Fig. 4).
When disengaging the auxiliary power take-off, the valve lever is moved back to the upper position.
The stem, under spring action, moves to the extreme forward position, thereby separating from the valve.
Through a hole in the stem, the engagement chamber of the PTO is vented to the atmosphere; air is exhausted from the chamber and the spring disengages the PTO.
Simultaneously with the exhaust of air to the atmosphere, the valve, under spring action, is pressed against its seat and isolates the inlet and outlet ports of the valve.
The control valve lever is locked in the disengaged position by a screw installed on the valve bracket.
During prolonged operation of the auxiliary power take-off, there should be no excessive heating of the transfer case input shaft bearings and the power take-off shaft.
Excessive heating indicates a fault in the oil pump.
Check the pump serviceability with two people.
To check the pump operation:
- - fully apply the parking brake lever;
- - set the transfer case gear shift lever to the neutral position;
- - disengage the winch by moving the lever on the right chassis side member downwards;
- - unscrew plug 19 in the pump body;
- - start the engine, engage the auxiliary power take-off and one of the gears in the gearbox;
- - check the pump serviceability by covering the plug hole with your finger.
If the pump is serviceable, oil pulsation can be felt in the plug hole.
It is forbidden to operate with a faulty pump.
