Slip Clutch Maintenance

[dmccarty]

I have an MX6 with a slip clutch. I have lots of rock and stumps to feed into the rotary cutter so I went with the slip clutch. The manual tells how to take the thing apart and replace everything but nothing on how to make sure the slip clutch slips.

So how do you know if the slip clutch is set correctly? The manual is clear as mud...

It looks like I'm only going to have to use the MX-6 four maybe five times a year. Thankfully! I really don't like using the cutter. DIRTY DIRTY DIRTY job at my place....

Thanks...
Dan McCarty

 

[JohnMiller3]

{from a previous post, my reply's on jplan...to save some time and repetition...}

I always "slip" my slip-clutches @ the beginning of every season, in spring. It will set all winter and corrosion will bind it up making it useless until you free it up.

{Have the unit hooked up to the tractor PTO shaft w/intended implement to use, and the tractor shut down while making all adjustments}

Depending on what type of slip clutch you have:

Type 1 - If you can see the clutch discs from the side of unit, take a magic marker and mark a line across the discs. Then back off each nut {on the spring load} 2 turns. Stay consistent with your reference points, go to the next nut and do the same, rotating the clutch until all nuts are backed off} Now start the tractor, bring rpm's up around 1600-2000 rpm, engage the PTO {don't feather or baby it, you need the shock for function} for 3-5 seconds, disengage PTO, let unit slow to a stop and repeat 3 to 4 more times. Now shut the PTO off, and tractor down. Inspect your mark across the plates to make sure the discs have slipped {the line should be offset across the plates now} If the line/plates have moved {meaning you have "slipped" the clutch plates}, now tighten/turn the nuts back 2 turns to the original position. If the plates have not moved/slipped, then back off all nuts 1 more full turn and start the PTO shock treatment again. Keep track of your backing off # of turns, you will need to tighten this same number when complete.

Type II - slip-clutch is the type that you can't see the clutch plates, they are hidden under the housing, this type you start off backing the nuts 3 turns and the rest of the above applies, except you can't test it until you’re out in the field. In heavy bush, you'll distinctly "hear" the clutch slip, that just means it’s working. Normally if you see a clutch "smoke,” means clutch plates were stuck, doesn't necessary mean you ruined anything.

For double insurance, you can also put a "shear-pin" in line with the slip-clutch and PTO drive shaft. Rule of thumb is Grade 2 bolt for <45 PTO hp tractors, and Grade 5 bolt for >50 PTO hp.

Hello Kay. First, I’m assuming others will use some common sense and also to apply good judgement. If the implement has a 40 HP gearbox, you would use a Grade 2 bolt, even if you have a 50 PTO HP tractor. On the same token, I don’t believe anyone with a 70 PTO HP tractor would use a 513 rotary cutter. Normally you match the implement to the tractor. I provided this information as a guideline. Nothing is etched in concrete. The manufacturers/owners manual should have precedence over all else.

"You are what you eat, drink, think, say and do..."

 

[dmccarty]

Thanks for the info.

I reread the MX-6 manual for the upteenth time and I still don't see where they talk about how to do this. The closest thing that I can find and what the dealer told me was to make sure that the gap between two plates was 4mm wide. Seems like there should be more to it that that. I think I can hear the clutch slip when I start the mower but I'm not sure. I'll listen for it next time I hook the cutter up. I'm usually listening to the engine.

Thanks....
Dan

 

[DFB]

Dan,

There is a procedure described in the manual for the JD Light Duty Rotary Cutters (413,513,613) for adjusting the slip clutch. I'll lay out for ya what it says.

Use the tractor that will operate the cutter.

Remove access covers
Loosen the eight bolts leaving some tension on the springs.

Start tractor, engage PTO intermittently at low rpm, slipping the clutch 4 or 5 times.

Loosen pinch bolt(s) Remove driveline from machine.

The large driveline shield on the cutter makes it difficult to accurately measure any of the reference points, (spring length or distance on the pressure plate). Removing the clamping yoke off the gearbox gives full access to the clutch pack assembly.

Adjust the eight bolts equally until all spring lengths are the same length. In this case 1.1" (28mm)

Install driveline (tighten cap head pinch bolts min. 43 ftlbs)

Install covers on access holes.


Just as John pointed out you can hear the difference when it slips. There's a hump out in my old pasture that the cutter digs into and slips the clutch just about everytime I go over it./w3tcompact/icons/frown.gif

DFB

 

[dmccarty]

DFB and John,

I sent a note to JD asking about the slip clutch PM. I had talked to my dealer as well. JD got back to me today through the dealer and they mailed me a page on the slip clutch PM. Basically it is what you two have described. The other piece of info is the gap between the clutch plate and the Belleville Spring which in my case is supposed to be 4mm. The gap distance is the only piece of info I could find the MX 6 manual.

The dealer said I was right in that the info was not in the MX 6 manual and I was the first one to bring it to their attention which kinda scares me...

Thanks again...
Dan McCarty