pto slip clutch

rickmacheske · Jul 7, 2006

My bushhog has shear pin protection and uses a splined PTO connection. I don't understand how it's automatically round if it's 'ideal for adding slip clutch to rotary cutters with shear pin protection'. I thought that bolt was for mounting the clutch to the tractor without the PTO easy attach. I'll have to call to see if it's splined.

I do have a shroud around the PTO shaft on the tractor 'bota L3400 so that is less of an issue. I wouldn't adjust very often, hopefully, so taking it on and off for adjustment wouldn't be much of an issue.

Just my $.02.

greg_g · Jul 7, 2006

rickmacheske said:
My bushhog has shear pin protection and uses a splined PTO connection. I don't understand how it's automatically round if it's 'ideal for adding slip clutch to rotary cutters with shear pin protection'.

Nope. Think about it for a minute; HOW can a double splined connection slip in the first place? Only way could be if you've bolted a female spline over a male round, or vice versa. When applied correctly, it should be an either-or situation. Either your rotary cutter transmission is shear pin protected, or it's slip clutch protected. And if you use the wrong bolt in a shear pin protected driveline, you have no protection at all. The bolt hole in a splined female slip clutch fitting is for fastening only, and the bolt used should be of a hardness NOT to act as a shear pin (typically GR5 or 8). Implement transmission input shafts that are smooth and round have a a single hole, through which a soft grade bolt (typically GR2) is use as a combination fastener AND shear pin.

And the reason I said "many/most tractors " was because only one of the last four tractors I've owned had a bolt hole drilled horizontally through the center of the PTO spline. And I noticed you skipped over the slip clutch adjustment point I made. If/when you ever buy one, it's a very good bet the operating instructions will include a recommendation to adjust the friction plates every six months - which pretty much goes against your "put it on and leave it on" concept. Slip clutches will almost universally be easier to adjust and maintain when mounted correctly on the implement end of the PTO shaft.

//greg//

rickmacheske · Jul 7, 2006

Greg,
That is probably your configuration. My bush hog attaches with a splined connection. Internal to the bush hog (under the steel cover) is where the shear bolt is. They basically provide a break in the drive train where it is attached together with the shear bolt. I use the proper bolt.

I'm guessing there are different configurations.

firemanpat2910 · Jul 7, 2006

Greg you are assuming all shear bolt set ups look like yours. There is a very crude pic of my set up with 2 splined shafts shear protected in another thread about shear bolts. rickmacheske what grade bolt do you use in your set up? mine will only work with a grade5 2s pop as soon as you engage it.

greg_g · Jul 7, 2006

firemanpat2910 said:
Greg you are assuming all shear bolt set ups look like yours.

Sorry guys, but I've had several variations of both types over the years. With the possible exception of implements like a PHD where driveline clearance is a factor, I wouldn't even own a shear bolt rig anymore. Once I graduated to slip clutches, I never looked back.

It's your money...spend it as you see fit.

//greg//

rickmacheske · Jul 7, 2006

I use 2's and have never had a problem. I have only broke a bolt twice, 1 large rock and 1 chuck of metal while bush hogging.

Soundguy · Jul 7, 2006

Both of my mowers with built in-line slip clutches had a metric splined driveshaft input on the gear box.. on my KK mower with a shear pin.. the input shaft is round, as greg mentions. ( just kicking that out there.. lots of different setups.. of my 2 mowers with slip clutches.. one is by the gearbox.. one is inline near the pto stub... both are oem setups.. )

Soundguy

flusher · Jul 8, 2006

rcmike said:
Not trying to argue with you, I am just a little confused. If a bolt happens to break or the nut came off wouldn't the spring shoot away from the clutch? If that is the case I would think you would want it pointed away from you towards the implement. If it was on the implement end it would fly towards the operator. Or is there some other danger with the springs? I have one on the tractor pto basically to protect my tractor. I have a 4010 and a 4 ft KK rotory cutter. Whenever I would kick in the pto the shock would break a roll pin in the universal joint on the driveshaft from the engine to transmission, even at idle. Now it kicks in smoothly without the jolt. I can't imagine what would happen if I hit something big with it without the clutch.

I prefer not to guess which way the (possible) shrapnel is going to fly. I just protect my backside (see attachment).

rickmacheske · Jul 8, 2006

BTW...I called Agrisupply.... http://www.agrisupplyco.com/cgi-bin/...951.000000&l=1 is splined on the male and female end. They have another that is not splined on either end.