Old brush mower slip clutch questions

[Thunder chicken]

I believe this is a slip clutch on this old mower. (brand unknown)
There are 4 bolts that fasten the PTO shaft to the clutch. I think I see how to adjust the slippage of the clutch but this thing is seized together from years of no use.
I'm thinking I may just use 2- 1/4" bolts on that coupler as shear pins rather than rely on the clutch and go through trying to repair it at the moment. There is not shear pins in the shaft otherwise.
Buying a new PTO shaft is not likely at the cost for what this is used for and for how much it's used.
I'll spend some time trying to free it up but do you think it's a safe bet just using the 2 rather than 4 bolts as it's assembled?
i have ran this machine for many hours as it was before i even though to check for shear bolts or clutch adjustment. I don't really want to damage the tractor! the mowing is volunteer time for our RC plane club.....

 

[David Wayne]

If you run it with two bolts and they shear then that shaft will flop around under power and do alot of damage before you can get it shut down.

 

[CoyPatton]

I agree with David, the way that is designed if you want to use the 2 bolted down spots as a shear bolt location, you are letting loose a major free to sling heavy club. You will likely be replacing the existing PTO shaft if you shear your bolts and repairing lots more damage possibly including your gear box.

It is time to figure how to make that slip clutch operational, or replace the PTO and slip clutch with either a designed shear pin connection that lets a shaft spin but remain inline or with a new slip clutch. Slip clutches are nice, but require maintenance at least yearly

 

[Texasmark]

My experience with worrying about what a PTO shaft will do when disengaged on the implement end is this: Gravity is king!!!!!! Quit worrying about what and where. It will find a corner to settle in somewhere and sit there and wobble.

 

[Thunder chicken]

hhmmm, it does slide on the shaft about an inch to make the plates bolt together....
last season when i first dug this out of the bush and fires it up, the PTO shaft was too short... but i tried it anyway and wouldn't ya know it came apart on a bump. Not something i'd want to have happen again, but maybe i was lucky and nothing was damaged. The new 1/2 shaft i had built was $300. apparently that series of shaft is worth some money and sold by the centimetre...
I'll put some heat on the set screw on what looks to be the tightening bolt, see if that will even come apart....

 

[metalbender]

Take it apart, clean and reassemble, knowing that you have averted a minor or possibly costly disaster.

 

[sodamo]

Likely can even find replacement plates at reasonable cost. Worth the effort to do right.

 

[RoyKing]

Why are you worried about the clutch it looks fine, if it is not slipping just keep running it. That is looks to be a BUSH HOG 300, one best and most copied, parts are on ebay, you can get new plates but probably don't need them. I rebuilt mine new bearings and seals, never had to touch the clutch.

 

[CoyPatton]

Why are you worried about the clutch it looks fine, if it is not slipping just keep running it. That is looks to be a BUSH HOG 300, one best and most copied, parts are on ebay, you can get new plates but probably don't need them. I rebuilt mine new bearings and seals, never had to touch the clutch.

Why be concern about the slip clutch?
Try because the OP has stated he pull it out of brush! This is is extremely likely it has not had maintenance done to it in years. If you have ever experienced a ‘frozen’ clutch and worked to get it ‘unfrozen’ then you understand the potential for damage a frozen clutch could cause to your tractor!
A slip clutch by design, needs to be slipped for routine maintenance for it to function correctly.
Same concept as using shear bolts! You want to pre-determine where your weak link/failure point is to protect your equipment!
His need may go no further than to determine the proper procedure to perform the routine maintenance of his slip clutch and then do so on regular intervals.

 

[RoyKing]

There is no maintenance to do on that slip clutch, you can plainly see it is not rusted up. Check the oil in the gear box, check the hub for nothing rapped around the seal area, the blades swing on the pivots, grease the shaft. Hook it up engage to pto at an idle and see if it runs smooth. I'm running one the same age works fine. Only time you work on it is if it slips.

Yes I had frozen clutch plates, put it in high gear, chain it to the truck and give it a pull, done faster than I can type it.