Tabs that Position Blade Sheared Off

[MNHerbie]

Have a really nice running Sears Platinum mower with 7.5HP engine. Went to pull the blade off yesterday and had 3 or 4 pieces of metal fall into my hands. Looked like bearings, but it was actually the small, round 'tabs' that position & hold the mower blade on the main shaft. The blade is pretty beat up, so obviously something was hit in the past - enough to shear off these tabs, but not enough to shear the flywheel keyway. I can still tighten the blade on with the bolt and washer, but just looking for thoughts on repair and whether or not this is a safety issue. Those tabs (not sure of the correct word) likely provide some assurances that the blade cannot slowly spin loose over time.

 

[Rivets]

Those alignment tabs break off because the blade was not positioned properly when the blade was installed. Probably happened when some one installed it wrong and then did not tighten it properly. You’ll have to replace this blade adapter, because your blade could easily spin loose, creating a dangerous situation.

 

[MNHerbie]

thanks for the reply - I'll take a close look at whats involved to change out the main shaft, but it doesn't look easy. The little tabs are actually part of the shaft. A pic would probably help...

 

[Richard Milhous]

Which way does the blade rotate? If it's clockwise, the general tendency over time will be to tighten the bolt. However if the blade is bent at all, the vibration will always tend to loosen the bolt. Threadlock will help some.

 

[Rivets]

It is not part of the shaft, but an adapter used to fasten the blade to the crankshaft. Most come off easily. Please don’t use any Loctite, you will be sorry down the road.

 

[Richard Milhous]

It is not part of the shaft, but an adapter used to fasten the blade to the crankshaft. Most come off easily. Please don’t use any Loctite, you will be sorry down the road.

Why is that? ...I used Loctite for almost exactly the same fix a dozen acres ago. No issues... yet.

 

[Rivets]

Most people don’t know how to use it properly or which type to use. Second, they don’t have the proper tools to remove the bolt or nut if it is overtorqued when installed. Don’t know how often I’ve had to get out the 1/2” impact gun to remove a blade bolt. A properly installed nut or bolt will self tighten by the spinning of the crankshaft. This is what caused the OP’s original problem, because the blade was not installed or tightened properly. Good clean threads will do the job just fine.

 

[Richard Milhous]

Well I ain't worried then. The original blade nuts on this Crapsman were so tight that I only got them off by hammering rebar (braced against the deck) a foot into the ground and using a 1/2" breaker bar with a 5' (yes, 5') cheater pipe. Loctite ain't got nothing on THAT. Kind of surprised me when the spindles didn't just twist apart.

 

[MNHerbie]

Thanks for all th advise. The part I need to change out is the blade adapter - I didn't know the correct lingo. I also didn't realize it just pulled off after you remove the bolt for the blade. Easy fix - thanks.

 

[VRR.DYNDNS>BIZ]

thanks for the reply - I'll take a close look at whats involved to change out the main shaft, but it doesn't look easy. The little tabs are actually part of the shaft. A pic would probably help...

You do not change the shaft!!!!!!!!The blade adapter he spoke of comes off the shaft and is replaceable.