Dealer Service
29
MAN0632 (5/15/2007)
GEARBOX REPAIR
(ON CAST/CROWN TOP BB48X, BB60X,
BB72X - S/N 1159929 AND ABOVE ONLY)
(Figure 19)
NOTE:
Repair to this gearbox is limited to replacing
bearings, seals, and gaskets. Replacing gears, shafts,
and a housing is not cost effective. Purchasing a com
-
plete gearbox is more economical.
NOTE:
Replacing a complete flat top gearbox with
a complete crown top gearbox will require replac
-
ing the cross bar assembly. See pages 44 and 45.
Gearbox is heavy: do not attempt to move without
mechanical assistance.)
Remove Gearbox from Cutter
1.
Disconnect and remove the rear driveline from the
gearbox.
2.
Remove vent plug (9) and siphon gear lube from
housing through this opening.
3.
Remove cotter pin or wire, washer, and nut from
vertical shaft and remove crossbar (see
Crossbar
Removal, page 31
).
4.
Remove the four bolts that attach gearbox to cutter
and remove gearbox.
Disassemble Gearbox
1.
Remove plug from side of gearbox and pour out
remaining gear oil.
2.
Support housing in vise in a vertical position.
3.
Remove input seal (4) (to be replaced).
4.
Remove retaining rings (6) and (8).
5.
Remove the six cap screws (24), washers (23) and
top cover (2) from housing.
6.
Remove retaining ring (6) behind gear (3).
7.
Support gearbox in hand press and pull input shaft
(5) through gear (3). Remove ball bearing (21).
8.
Remove ball bearing (20) and gear spacer (7) from
input shaft (5).
9.
Support housing in vise in a horizontal position.
10.
With the hub/stump jumper/crossbar, castle nut,
cotter pin, wire and washer already removed,
remove the four cap screws (13), lock washers (12)
and output cap (17).
11.
Remove output gaskets (11) and (10).
12.
Push output shaft and pinion (19) down and
remove ball bearing (20) or tapered roller bearings
(25), output bearing spacer (18), and retaining ring
(6). Remove output shaft and pinion (19).
NOTE:
On gearboxes with tapered roller bearings,
it will be necessary to use a punch to drive out
bearing cups.
13.
Inspect gears for broken teeth and wear. Some
wear is normal and will show on loaded side.
Forged gear surfaces are rough when new. Check
that wear pattern is smooth.
14.
Inspect vertical and horizontal shafts for grooves,
nicks, or bumps in the areas where the seals seat.
Resurface any damage with emery cloth.
15.
Inspect housing and caps for cracks or other
damage.
Reassemble Gearbox - Cast Top (BB48X)
1.
Clean housing, paying specific attention to areas
where gaskets will be installed.
2.
Wash housing and all components thoroughly.
Select a clean area for gearbox assembly. Replace
all seals, bearings, and gaskets. All parts must be
clean and lightly oiled before reassembling.
3.
Slide ball bearing (20) on to output shaft and pinion
(19). Place against gear and secure with retaining
ring (6).
4.
Push output shaft and pinion (19), ball bearing (20)
and retaining ring (6) into housing until ball bearing
(20) seats flat in housing socket.
5.
Insert output bearing spacer (18) and ball bearing
(20) over output shaft until seats against inside
roller bearing (20).
6.
Secure output cap (17) with new output seal (16)
installed to bottom of gearbox housing using the
four 10mm x 1.5 x 25 cap screws (13) and lock
washers (12).
NOTE:
Be sure output gaskets (10 and 11) are in
place. Apply grease to output seal (16) lip for easy
installation.
7.
Place ball bearing (21) at back of housing and
press in socket using a round tube of the correct
diameter and a hand press until fully seated.
8.
Insert input shaft (5) part way through housing and
slide gear (3) and retaining ring (6) over input shaft
(5). Keep gear (3) and retaining ring (6) loose.
9.
Insert input shaft (5) into roller bearing (21) until
seated against each other.
10.
Slide gear (3) forward and attach retaining ring (6)
in groove closest to front of input shaft (5). Slide
gear (3) back against retaining ring (6).
(Rev. 5/11/2010)
