Walker MDD (20.9 HP) - Manual (Page 78)

Maintenance Instructions
REPLACING/REPAIRING
74
Reinstall the blades following procedure from
Sharpen Mower Blades instructions in CHECKING/
SERVICING in this section. If blades are replaced,
always use Walker original equipment blades to
ensure safety and optimum performance. The
quality and performance of replacement blades
offered by other manufacturers cannot be
guaranteed, they could be dangerous.
Mower Deck Gearbox Replacement
NOTE: Deck gearbox(es) may be changed with
the deck mounted on the tractor. However, the deck
may be removed from the tractor making the overall
job of removing the gearbox assembly easier. Refer
to Deck Installation in
Assembly Instructions and re-
verse the procedure to remove the deck.
To replace the mower deck gearbox(es), use the fol-
lowing procedure:
1. Remove mower blades. Refer to procedure in
CHECKING/SERVICING the Sharpen Mower
Blade in this section for instructions.
2. Remove gearbox cover (two machine screws)
and PTO shaft guard (two 1/4-20 bolts).
3. Remove two (2) 3/8-16 mounting bolts from
each blade drive gearbox and lift the entire
gearbox assembly from the deck (including
PTO drive shaft).
4. Remove the screws securing the cover plates
on the gearboxes and remove the covers. Re-
move all covers to be sure oil is completely
drained from all gearboxes.
NOTE: With oil flow throughout the unitized
gear drive assembly; if one gearbox has internal
damage or excessive wear, the remaining gear-
boxes and connector tubes should be complete-
ly disassembled and thoroughly flushed out with
solvent before reassembly.
5. Drain and properly dispose of oil.
6. Remove the four (4) bolts mounting the gearbox
to the connector tube and slide the gearbox off
the splined drive shaft coupling.
7. Install the new gearbox on the spline coupling of
the drive shaft. Establish correct timing of the
blade drive gearboxes by setting flats on the
output shaft at 90 degrees when connecting the
gearbox(es) to the spline coupling. Make sure
the timing is correct before proceeding with as-
sembly.
8. Reinstall the four (4) bolts mounting the gear-
box to the connector tube but do not tighten
them at this time; leave connector tube bolts fin-
ger-tight.
9. Position the gear drive assembly on the deck
and install the 3/8-16 bolts mounting the entire
assembly. Leave the mount bolts finger-tight.
10. Torque all the connector tube bolts to 80 in-lb
(9 N·m); then tighten the deck mount bolts.
NOTE: This fastener tightening sequence
aligns the gearbox assembly with the deck hous-
ing and eliminates the possibility of mounting the
unitized assembly in a bind.
11. Fill gearbox assembly with oil. Refer to
LUBRICATION for Mower Deck Gearbox
Lubrication in this section for instructions.
12. Reassemble remaining items onto deck to com-
plete installation. After installing blades, check
that the blade timing is correct by moving the
blades through one (1) complete revolution.
Make sure blade tips pass clear of each other.
Mower Deck Gearboxes
(Shown with Gearbox Cover Removed for Clarity)
CAUTION
ALWAYS use genuine factory replacement
parts. Substitute parts CAN result in prod-
uct malfunction and possible injury to the
operator.
Mower Deck
Gearboxes
Connector Tubes