The power take-off (Fig. 1) is reversible, serves to drive the winch and is mounted on the flange of the gearbox hatch
The drive unit 16 gears and the intermediate gear 13 are mounted on fixed axles 11 and 14 on roller bearings 17
The shaft 10 rotates on two ball bearings 8. The gear wheel 9 of the gear shift slides along the splines of the shaft.
A flange 22 is installed at the shaft outlet, sealed with collar 23.
Installation of the flange on the shaft, if necessary, can be carried out both to transmit momentum forward along the course of the car, and backward, by appropriately shifting the shaft 10.
The gears are switched on by the fork 4, which is fixedly fixed on the rod 1. There is a cuff 2 at the output of the rod.
All PTO gears are spur gears.
The power take-off is controlled through the hatch in the cabin floor with the S=46 key from the driver's tool kit, used as an extension of the power take-off lever and inserted into the sleeve on the lever
The pinion of the drive unit 16 of the power take-off is in constant engagement with the gear wheel of the reverse unit of the gearbox.
Incorrect installation of the power take-off increases the noise of the gear pairs and leads to their accelerated wear.
For correct installation, tighten the stud nuts evenly crosswise while turning the shaft 10.
Sealing gasket 31 between the mating planes of the gearbox and power take-off flanges should be 0.3-0.4 mm thick (a gasket from under the gearbox hatch cover is used).
When the power take-off is correctly installed, shaft 10 rotates freely (without sticking the gear wheels) by hand force applied to the output end of the shaft.
The maintenance of the power take-off is the same as for the gearboxes.
After carrying out maintenance of the power take-off or replacing it, it is necessary to check that the power take-off lever is in the neutral position.
Failure to do so may result in the winch cable breaking when starting the engine.
The device of the power take-off from the transfer case (KOM-1)
A single-speed power take-off (Fig. 2) is installed on the top hatch of the transfer case.
This makes it possible to take power from the transmission to drive various special units used by the consumer when using the car chassis as a transport base.
The single speed power take-off is designed for short-term operation.
The duration of continuous operation depends on the actual value of the power taken off and is checked in each specific case by preliminary tests.
The parts of the single-speed power take-off are mounted in a cast iron crankcase 1 (see fig. 2).
The gear unit is mounted on a fixed axle 27 on two roller bearings 29, between which there is a spacer ring 30.
The axle is pressed into the front and rear walls of the crankcase and locked with a plate.
Support washers 28 are installed on the axle at the ends of the hub of the gear unit, which prevent wear of the crankcase support ends.
The axle has axial and radial holes for supplying oil from the crankcase to the roller bearings. The axial hole is closed from the outside with a conical plug 26.
When the power take-off is turned on, the gear-carriage 7, which is movably mounted on the splines of the shaft 5, engages with the gear 25.
To prevent self-shutdown, the output shaft has a slot-lock.
A spacer sleeve 2 is installed between the splined part of the shaft and the front bearing 6. The bearing and the spacer sleeve are tightened with a nut 3.
The locking of the nut is carried out by pressing the thin edge of the nut into the groove of the shaft 5.
The shaft rotates on two ball bearings 6 and 23, the outer rings of which are installed in the housings of the crankcase, and the inner rings are pressed onto the shaft necks.
In the axial direction, the secondary shaft is fixed by bearing caps 4 and 18. A cuff is installed in cover 18, which protects the box from dirt and oil leakage.
On the splined end of the shaft 5, a flange 19 for fastening the cardan shaft is installed. The flange is fixed with nut 20, which is locked in the same way as nut 3.
The power take-off is switched on with a fork 31. The fork is fixed motionless on the rod 15 with a bolt 33, which is locked with a wire.
In the front wall of the crankcase there is a hole in which the rod 15 moves. This hole is closed with a plug 8.
Upper hatch of the mo selection box closed with a lid.
A fitting 32 is installed on the cover, connected by a rubber hose to a ventilation tube attached to the rear wall of the cab. The fitting is protected from direct oil ingress by a shield 10.
Electro-pneumatic control is carried out by a button installed on the instrument panel in the cab.
The button opens and closes the electrical control circuit of the air valve actuator solenoid relay.
The relay is installed on the engine shield in the engine compartment above the relay for turning on the front axle electromagnet.
When the power take-off is turned on with the switch, the relay is activated and closes the power supply circuit of the electromagnet.
The core of the electromagnet, moving down, presses on the air valve activation rod and opens it.
Air through the inlet valve enters the switching chamber and, acting on the membrane 13, moves the stem 15 connected to the power take-off fork.
The switch 11 of the signaling device for turning off the power take-off is installed on the body of the switching chamber.
When the rod is moved, the switch contacts close and the red indicator lights up.
When the power take-off is turned off, the power supply circuit of the electromagnet opens, the air valve closes, the return spring of the membrane chamber moves the stem with the fork to its original position.
Gear-carriage 7 disengages, and the power take-off is turned off, while the contacts of the signaling device switch open and the signaling device goes out.
Maintenance for a single speed power take-off is the same as for a transfer case.
Power take-off repair
Before removing the power take-off, you must first drain the oil from the gearbox housing and the power take-off by unscrewing the two drain plugs.
Disconnect the cardan drive of the winch drive, unscrew the nuts securing the power take-off on the flange of the crankcase hatch and manually remove the power take-off from the studs of the gearbox hatch.
Removing the flange
Unscrew the flange fastening nut with a socket wrench, remove the washer.
When unscrewing the nut, it is necessary to keep the shaft from turning with a copper or aluminum mandrel, inserting it between the gears of the box (Fig. 3).
Remove the shift lever, after unpinning it with pliers and removing the axle and connecting pins with the fork rod.
Install puller 20P-7973 on the flange and use it to remove the flange from the shaft (Fig. 4).
Remove the bolts securing the covers, lightly tap the covers with a hammer and remove the covers and gaskets.
To remove the locking plate of the axes of the gear units, unscrew the bolt securing the plates and remove the plate
Removing the gear set
Install the box on a press and press out (in the direction of the end with a groove) the axis of the gear block (Fig. 5), remove the gear block from the crankcase, remove the thrust washers, remove two roller bearings and the spacer from the block.
Removing gear 25 (see Fig. 2) of constant engagement is carried out in the same way as a gear set.
In this case, the gear 7 of the gear must be disengaged from the gear of constant engagement.
Dismantling the main shaft
Install the box body on a press, press out (Fig. 6) the main shaft until the rings of one bearing come out of the box and remove the bearing and engagement gear.
Press the second bearing off the main shaft using a puller mod. 20P-7973.
Unpin the locking bolt of the selector fork with pliers and unscrew it.
Then unscrew the retainer plug and remove the spring and retainer ball from the socket.
Then remove the stem while removing the shift fork from it.
The rod seal is removed from the socket only when it is replaced.
Requirements for repairs to the crankcase, gears, shafts and other parts of the power take-off are similar to the requirements for parts of the gearbox.
Assembly of the power take-off
Parts prepared for assembly should be dimensionally checked, washed in a degreasing solution and blown with compressed air.
In case of wear or damage to the main shaft bearing seals and stem seals, they must be replaced be new.
Assembly of the power take-off is carried out in the reverse order of disassembly.
When installing the shift fork, it must be secured with a locking bolt and cottered.
Installation and fastening of the rod retainer must be carried out after installing the gear shift gear on the main shaft.
The axial clearance of the main shaft is adjusted with shims 20 (see Fig. 1▲), reducing or increasing the number of shims located under the covers.
The bearings are adjusted correctly if the shaft rotates freely by hand (in the absence of a cuff) and does not have a noticeable axial clearance.
When adjusting the bearings, the cap bolts (front and rear) must be tightened to failure with a wrench by hand.
The power take-off is mounted on the gearbox hatch flange.
The sealing gasket is used from under the hatch cover of the gearbox housing or a new gasket 0.3-0.4 mm thick is installed.
The nuts of the power take-off fastening studs must be tightened evenly crosswise while turning the main shaft by hand, which ensures that the box is correctly installed along the contact patch of the teeth in the gear engagement.
When the power take-off is correctly installed, the main shaft rotates freely (without gears jamming) by hand force applied to the output end of the shaft.
Incorrect installation of the power take-off leads to an increase in the noise of the gear pairs and their accelerated wear.
After installing the power take-off, the position of the shift lever 26 must be adjusted (see fig. 1▲).
To do this, remove the plug in the cabin floor and, by changing the position of the bracket 30 in the axial direction, achieve the orientation of the upper end of the lever approximately in the middle of the hole in the cabin floor.
After that, it is necessary to tighten the lock nuts securing the bracket 30 with the neutral position in the power take-off.
Adjusting the reversible power take-off and its drive
To drive the winch, the power take-off box 5 (see fig. 7◄) has two gears: first gear I for winding the cable (when turned on, lever 6 is moved forward); second gear II for unwinding the cable (when turned on, lever 6 is moved back).
The lever in the neutral position is locked with a latch 7 installed on the cab floor.
In the reversible power take-off, the preload of the main shaft bearings and the position of the gearbox control lever are adjusted.
The preload of the main shaft bearings is obtained from the axial clearance of the shaft.
The axial clearance of the main shaft is adjusted with spacers.
Reducing or increasing the number of shims under the front bearing cover sets the required axial clearance.
At the same time, it is considered that the bearings are adjusted correctly if the shaft turns freely by hand (in the absence of an oil seal) and does not have a noticeable axial clearance.
When adjusting the preload of the bearings, the cap bolts (front and rear) must be tightened to failure by hand over the length of the wrench.
In the neutral position, the lever 6 must correspond exactly to the neutral position of the gear, and the rod 1 connected to the lever 6 must be securely fixed.
If the position of the power take-off control lever 6 does not meet the specified requirement, then it is necessary to adjust it with a nut 3 with a loose lock nut 4, moving the bracket 2 of the lever 6 in the axial direction to the desired position.
After completing the adjustment, fix the nut 8 of the bracket with the locknut 4.
The adjustment of the lever position should be checked by shifting gears with lever 6 when engaging the first gear (winding) and when engaging the second gear (unwinding).