Walker MBK23 Operator's Manual

Contents

60Maintenance Instructions REPLACING/REPAIRINGBlade Overload Shear BoltsOn gear driven decks each cutting blade is keyed toa blade hub by two (2) shear bolts (10-24 x 5/8 in.stainless steel machine screws). These bolts aredesigned to shear and protect the blade drive gear-box from damage if the blade encounters a shockload.Cutting BladeShear BoltsCutting Blade Shear BoltsNOTE: Tightening the 5/8-18 blade mounting nutto 60 lb·ft (81 N·m) is also important for propershock 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 installnew bolts. Refer to CHECKING/SERVICING inthis section for Sharpen Mower Blades which de-scribes the blade removal and installation proce-dure.After reinstalling the blade, check blade timing (ongear driven decks) by moving blades through one(1) complete revolution. Make sure blade tipspass clear of each other. If timing is incorrect, con-tact your Walker dealer.PTO Shear PinThe PTO drive shaft connection to the deck gearboxhas a shear pin to provide shock load protection tothe mower deck drive. This system provides pri-mary shock protection in case of blade impact andwill normally shear before the individual shear boltson the blade hub.When the PTO pin has sheared, use the followingprocedure to replace it:1. Loosen the two bolts securing the PTO shaftguard on the deck; lift the guard off. (Holes inguard are slotted for easy removal.)2. Rotate U-joint on shaft to align the shear pinhole with the hole (and shear pin fragment) inthe shaft. Use a punch to drive the remainingportion of the old shear pin out.3. Install new shear pin and secure with cotter pin.U-JointShaft AssemblyCotter PinShear PinSplit Spring PinU-JointTube AssemblyPTO Shear PinIMPORTANT: Use only Walker P/N 8067-13shear pins for replacement to provide propershock protection -- these pins are hardened toshear 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 (ongear driven decks) by moving blades through one(1) complete revolution. Make sure blade tipspass clear of each other. If timing is incorrect, con-tact your Walker dealer.