Maintenance Instructions

REPLACING/REPAIRING

Blade Overload Shear Bolts

The cutting blade is keyed to the blade hub by two

(2)shear bolts (10-24 x 5/8 in. stainless steel ma- chine 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 ft-lb (81.3 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 describes the blade removal and installation procedure.

After reinstalling the blade, check blade timing by moving blades through one (1) complete revolution . Make sure blade tips pass clear of each other. If timing is incorrect, refer to Mower Deck Gearbox Replacement in this section.

PTO Shear Pin

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 primary 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.

Set Screw

Shear Pin

Split Spring Pin

U-Joint

Tube Assembly

U-Joint

Shaft Assembly

Cotter 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 overload 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, refer to Mower Deck Gearbox Replacement in this section.

Mower Blades

Mower blades are removed and remounted as described in the Sharpen Mower Blades instructions. During the course of sharpening and inspecting mower blades, if there are any of the following conditions of wear or damage, blades should be replaced for reasons of safety and performance of the machine:

•An excessive amount of the flat section of the blade has been ground away (removed) when the blade is sharpened. Replace the blade when less than a 3/4 in. (19 mm) flat section remains at the blade tip.

61