679
Model Code Page
42 Gearbox
1. 8. 1998
11420
6000--8750
1. 4. 1997
Differential
Note! The differential is the same as on Valmet 505---905
tractors.
The crown wheel and differential case are mounted in the
gearbox housing on taper roller bearings. Bearing preload
and tooth backlash between the pinion and the crown
wheel are adjusted with threaded flanges.
On 6000---6400 and 8000 tractors, the differential has two
differential pinions. Tractors 6600---6900 and 8050---8750
have four differential pinions in the differential. The side
bevel gears and pinions in the differential case have plain
bearings.
Figure 11. Cross---section of differential
1. Loctite 270 on the crown wheel bolt threads
2. Note the position of the tension pin
3. On models 6000 ---6400 and 8000, the differential pinion
shaft is locked with a tension pin (2) (1 pc).
4. On models 6600 ---6900, 8050 ---8750, the shorter diff.
pinion shafts are locked with tension pins (two pins are
needed).
5. Oil hole for lubricating oil from the PTO unit lubricating
oil pipe hole.
6. Pressurised oil to the differential lock
7. Threaded flanges for adjusting differential bearing pre-
load and tooth backlash between pinion / crown wheel
Differential lock
The differential lock is an electro---hydraulically controlled
multi---disc clutch. The solenoid valve for the lock is placed
ontheservovalveblockonthelefthandsideofthegear-
box.
The low pressure pump supplies oil to the servo valve block
via an external oil hose. A pressure---limiting valve on the
servo valve block limits the diff. lock oil pressure to 1,8 MPa.
Pressurised oil from the servo valve block to the diff. lock is
conducted through a pipe inside the gearbox housing.
Inthedifferentialcasecoverthereisapistonwhichpresses
the clutch discs together, thus connecting the differential
bevel side gear to the differential casing.
The diff. lock can be engaged while driving. The differential
lock disengages automatically, if the brake pedals (or one
pedal) are pressed.
Note! On the earlier tractors the differential lock has 5 fric-
tion discs and 4 steel discs. On the latest tractors there are
5 friction discs and 6 steel discs, which are thinner, since
the disc locatio n is the same. The new discs pack can be
fitted int o the earl ier tractors without modifications. Max.
thickness of the disc pack is 21,5 mm.
(30) & 40 km/h
3
2
4
1
40---50 Nm
300
390
460
650
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