892-0000010B OM
169
The transfer box is designed to transmit torque from the gearbox to the cardan drive of
the front drive axle.
The transfer box is mounted on two pins and is secured by bolts to the GB housing on
the right side along tractor travel.
Ground speed drive to the transfer box is carried out from gear 3 of the gearbox through
intermediate gear 11, mounted on two tapered roller bearings on axis 10 in the gearbox
housing boring. The bearings are adjusted by nut 12.
The transfer box (Figure 3.16.8) is a single stage reduction gear unit with free travel
roller coupling and consists of the following main units and parts.
Shaft 5 is mounted in the housing of transfer box 16 on ball bearings. Bushing 7 with
inner toothed crown on needle bearings 6, which is inner ring of the free travel coupling,
moveable toothed coupling 13 and flange 14 for connection to the flange of the intermediate
cardan shaft are mounted on shaft 5. Gear 9 of the transfer box, made in one piece with
outer ring of the free travel coupling and inner toothed crown for positive locking, meshes
with intermediate gear 11. Gear 9 rotates relative to the inner ring of the free travel coupling
on two ball bearings 8. In the profiled slots of gear 9, which form outer ring of the free travel
coupling, eight wedging rollers 4 are located. In working position for wedging each roller is
installed by two pins 2 under the action of spiral springs 1.
Toothed coupling 13 control (Figure 3.16.9) is carried out by link 4 (Figure 3.16.9) through
levers 1 and 7. Guide 8 with lock ball 6 and spring 9 is mounted on link 4, which has three slots,
and pin of guide 8 is mounted in the bushing of bracket 5, which is secured to the gearbox cover.
Lever 7 of the FDA drive control has three fixed positions:
- “FDA off” – lower most (front) position. Disengagement of the free travel coupling is carried
out when coupling 13 is disengaged from the toothed crown of inner ring 7. Lock ball 6 is in this
case in the upper slot of link 4. Use the “FDA off” mode for hauling operations when driving on
hard-surface roads.
- “FDA engages and disengages automatically” – middle position. In this mode automatic
engagement and disengagement of the FDA by means of the free travel coupling depending on
rear wheels slipping occurs. It is provided by connection of toothed crown of inner ring 7 with
toothed crown of coupling 13. In this case lock ball 6 is in the middle slot of link 4.
When the tractor moves forward without slipping inner ring 7 of the coupling, rigidly
connected to the front wheels, has a higher speed than the outer ring. Wedging of rollers
does not occur, torque is not transmitted to the FDA.
If the rear wheels slip above the set value, rotation frequency of the inner ring decreases
until it is equal to rotation frequency of the outer ring. In this case, the coupling rollers wedge
and join two rings in one piece, to ensure that torque is transmitted to the FDA.
Use this mode when performing various field works.
- “FDA positively engaged” – upper most (rear) position.
Positive engagement is carried out by toothed coupling 13, which while moving over
shaft splines, meshes with the inner teeth of gear 9 and, connecting it directly to shaft 5,
blocks the free travel coupling. In case of positive engagement lock ball 6 is in the lower slot
of link 4. Use this mode only in cases of constant slipping of the rear wheels and when
reversing, when engagement of the FDA is required.
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