Operation and maintenance manual

Section 150-0020
SM 2149 5-02
11
Centre Axle - Differential Drive Head
SM - 1188
Checking Crownwheel and Pinion Mesh
1. Apply thin coating of engineers marking compound
to several consecutive crownwheel teeth.
2. Turn crownwheel for few revolutions in both
directions to make positive tooth contact impression
on crownwheel and pinion teeth.
3. Inspect deposit of marking compound on crownwheel
and pinion teeth and compare them with Fig. 16.
In all cases, action, (if any) to be taken is shown below:
Fig. A - Indicates correct mesh. No further action
required.
Fig. B - Indicates pinion and crownwheel are too far out
of mesh. To remedy, move pinion inwards towards
crownwheel. To maintain backlash, move crownwheel
away from pinion in direction of arrow B.
Fig. C - Indicates pinion and crownwheel too far into
mesh. To remedy, move pinion outwards away from
crownwheel. To maintain backlash, move crownwheel
towards pinion in direction of arrow B.
If any action is required, adjust pinion position by
altering the thickness of pinion setting shims (35) i.e.
add shims to move pinion away from crownwheel and
remove shims to move pinion towards crownwheel.
Helical Pinion/Helical Housing Assembly
1. Press inner bearing cup (32) into gear casing (39).
2. Press bearing cones (30A & 32A) onto helical
pinion (31).
3. Place helical pinion (31) in position on gear
casing (39).
4. Install dowels (37) into their relevant holes in gear
casing (39).
5. Apply a thin coating of Red Hermatite to helical
housing clamping face on gear casing (39) and install
gasket (36) in position.
6. Install helical gear housing (26) onto gear casing
(39) ensuring correct location with dowels (37).
7. Install bolts (119) and washers (118) and tighten to
98 - 108 Nm (72 - 80 lbf ft).
8. Install outer bearing cup (30) onto its bearing cone
Setting Crownwheel and Pinion Backlash
1. Move dial indicator onto crownwheel (46) tooth as
shown in Fig. 15. Hold spiral bevel pinion (33) still and
rock crownwheel (46) backwards and forwards, to
check free play between gears (backlash), and note
variation of indicator reading.
2. Repeat the above steps three more times so that
four readings are taken at positions equally spaced
around crownwheel (46).
Note: The variations of readings on dial indicator must
be within limits of 0.203 - 0.330 mm
(0.008 - 0.013 in). If difference in backlash of more
than half backlash tolerance exists between tooth
mesh positions, then assembly should be further
examined for cause and rectified.
Fig. 15 - Setting Dial Indicator onto Crownwheel Tooth
VIEWS SHOWING
SPLIT PIN IN POSITION
INSTALL FROM
UNDERNEATH
Fig. 14 - Installing Adjusting Nut Split Pins
SM - 1189