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)
MAN0632 (5/15/2007)