59
Maintenance Instructions
REPLACING/REPAIRING
Blade Overload Shear Bolts
NOTE:
Blade shear bolts are not used on belt driv-
en decks.
On gear driven decks, each cutting blade is keyed
to the blade hub by
two (2) shear bolts
(10-24 x
5/8 in. stainless steel machine screws). These bolts
are designed to shear and protect the blade drive
gearbox from damage if the blade encounters a
shock load.
Cutting Blade
Shear Bolts
Cutting Blade Shear Bolts
NOTE:
Tightening the
5/8-18 blade mounting nut
to 60 lb·ft (81 N·m)
is also important for proper
shock load protection. It is important to
not
over-
tighten
the mounting nut since this defeats (over-
rides) the function of the shear bolts.
If these bolts shear, remove the blade and install
new bolts. Refer to
CHECKING/SERVICING
in
this section for
Sharpen Mower Blades
which de-
scribes the blade removal and installation proce-
dure.
After reinstalling the blade, check blade timing (on
gear driven decks) by moving blades through
one
(1) complete revolution.
Make sure blade tips
pass clear of each other. If timing is incorrect, con-
tact your Walker dealer.
Shear Pin (If Equipped)
The PTO drive shaft connection to the deck gearbox
has a shear pin to provide shock load protection to
the mower deck drive. This system provides
pri-
mary shock protection
in case of blade impact and
will normally shear before the individual shear bolts
on the blade hub.
When the PTO pin has sheared, use the following
procedure to replace it:
1. Loosen the two bolts securing the PTO shaft
guard on the deck; lift the guard off. (Holes in
guard are slotted for easy removal.)
2. Rotate U-joint on shaft to align the shear pin
hole with the hole (and shear pin fragment) in
the shaft. Use a punch to drive the remaining
portion of the old shear pin out.
3. Install new shear pin and secure with cotter pin.
U-Joint
Shaft Assembly
U-Joint
Tube Assembly
Cotter Pin
Shear Pin
Set Screw
Split Spring Pin
PTO Shear Pin
IMPORTANT:
Use only Walker P/N 8067-13
shear pins for replacement to provide proper
shock protection -- these pins are hardened to
shear under a specific amount of load.
4. Reinstall the PTO shaft guard.
Before operating the deck, inspect the blade over-
load shear bolts and also check blade timing (on
gear driven decks) by moving blades through
one
(1) complete revolution.
Make sure blade tips
pass clear of each other. If timing is incorrect, con-
tact your Walker dealer.
Summary of Contents for B18
Page 73: ...69 Operator s Notes...
Page 74: ...70 Operator s Notes...
