I have never owned or used any of this equipment so please don't judge my question too harshly. I'm getting my brand new L3560 delivered in two weeks. Also getting an RCR-1860 rotary cutter. This one has the clutch. Debated a lot about shear-bolt vs. clutch but this is what was available so that's what I got. Interesting thing I found out during my research is both the clutch and shear bolt drivelines attach to the gearbox the same way - a 1/2" bolt thru the driveshaft yolk and gearbox shaft. The bolts are the same size but the shear type uses a grade 2, and the clutch type uses a grade 8. I have also read where folks suggest using a grade 5 (in place of the grade 2) to prevent snapping so many bolts. So my question is this; Could I put a grade 5 bolt in this location on my clutch driveshaft and have that be a 'fail-safe' backup in case the clutch isn't adjusted properly or gets locked up? Is this a truly bad idea? Am I the only one to think of this?
Noob with Q's about a Bush Hog
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mcmxi
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Using your logic, why not swap out the grade 8 for a grade 2 shear bolt and bypass the slip clutch altogether. Personally I'd rather use a grade 2 and replace bolts more often than risk damaging the gear box with a grade 5 bolt.
By the way, a grade 5 bolt has about 60% more shear strength than a grade 2 bolt. A 1/2" grade 5 bolt has a yield strength of 92ksi compared to 57ksi for a 1/2" grade 2 bolt.
I have a slip clutch in the RCR1884 and haven't had any issues. The manual describes how to check and set the clutch pack.
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fried1765
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You could swap it to a lower grade bolt to “bypass” the slip clutch unless the clutch and gearbox input are splined and not smooth.
If the clutch housing and gearbox input are smooth you should be good to go.
I’ve ran shear bolts for years, you would be surprised what you can cut down with a bush hog and a grade 2 bolt.
If the clutch housing and gearbox input are smooth you should be good to go.
I’ve ran shear bolts for years, you would be surprised what you can cut down with a bush hog and a grade 2 bolt.
If you go with a backup shear bolt, make sure you have a snap ring on the gearbox so the PTO shaft can't slide off the gearbox if the bolt shears.
Thanks for the replies. Mcfarmall, you get bonus points. That is the one thing I think could be a reason not to do this. In the parts diagram there is no snap ring on the gearbox shaft with the clutch. And I'm not sure if there would be access to install/remove that. Won't know until I get a look first hand. If not, I might still try a grade 5. My thinking here is better to replace a drive shaft or repair some bent parts on my mower than replace a gear box or busted PTO.
Elliott in GA
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LX 2610SU w/535,LP RCR1860,FDR1660,SGC0554,FSP500, DD BBX60005
You could, but why? In addition to the potential problems/issues listed by others, you are defeating the whole value of the slip clutch by using a shear bolt. You only need to service the slip clutch once a year; it takes about an hour (warming up tractor, connecting rotary cutter, slipping the clutch, disconnecting rotary cutter and putting tractor away). You get to choose your day and time; I chose a cool, clear spring day.
If you snap a shear bolt, you have to replace it then and there (or quit). Could be a nice day, or it could be the hottest or coldest day with precipitation.
Slip clutches are extremely reliable (used exclusively on bigger cutters). Maintain your equipment as outlined in the manual, and relax in the knowledge that a hard strike or grounding out will not even delay your work.
FWIW, I have the same cutter, and it has been great. I have had a couple of significant strikes. Were they hard enough to snap a shear bolt, I do not know, and that is the value of a slip clutch.
If you snap a shear bolt, you have to replace it then and there (or quit). Could be a nice day, or it could be the hottest or coldest day with precipitation.
Slip clutches are extremely reliable (used exclusively on bigger cutters). Maintain your equipment as outlined in the manual, and relax in the knowledge that a hard strike or grounding out will not even delay your work.
FWIW, I have the same cutter, and it has been great. I have had a couple of significant strikes. Were they hard enough to snap a shear bolt, I do not know, and that is the value of a slip clutch.
When I bought my Deere 955 back in 1995, I ordered it with Deere's 5' rotary cutter with a slip clutch. As designed/delivered by Deere, the slip clutch was a huge pain because the small access cover for the slip clutch adjustment bolts/springs made it a very tedious task.
After a couple of years of fighting with it, I enlarged the access area and the task became very easy. I suspect the Deere PTO driven tiller I bought at the same time was a slightly older design and the cover for its slip clutch made adjustment easy and I modified the rotary cutter to the same design.
Do NOT neglect the maintenance because if you don't do the at least once a season adjustment then the clutch parts can seize together and the weakest point(s) in the driveline will be revealed when the blade finds a solid object. Don't try to reduce the clutch spring tension to provide more protection, the slip clutch shouldn't slip unless the blades hit something significant. When I was in the shop getting a hydraulic hose made up for my loader, one of the mechanics was replacing the slip clutch on a small Deere cutter because the owner had done that and it was slipping continuously under load and a slip clutch will quickly burn up under those conditions.
I haven't used a RCR 1860 but I presume it has swing mounted blades like most cutters. During your pre-season check, make sure the blades pivot smoothly. With many of these cutters, including my Deere, you don't want to engage at full rated PTO speed but the tractor needs to be above low idle speed to ensure that the blades swing out properly when the PTO is engaged. And remember that rear cutter swings out in a pretty long arc when turning so don't take out a fence post or two while you are getting used to it.
Rodger
After a couple of years of fighting with it, I enlarged the access area and the task became very easy. I suspect the Deere PTO driven tiller I bought at the same time was a slightly older design and the cover for its slip clutch made adjustment easy and I modified the rotary cutter to the same design.
Do NOT neglect the maintenance because if you don't do the at least once a season adjustment then the clutch parts can seize together and the weakest point(s) in the driveline will be revealed when the blade finds a solid object. Don't try to reduce the clutch spring tension to provide more protection, the slip clutch shouldn't slip unless the blades hit something significant. When I was in the shop getting a hydraulic hose made up for my loader, one of the mechanics was replacing the slip clutch on a small Deere cutter because the owner had done that and it was slipping continuously under load and a slip clutch will quickly burn up under those conditions.
I haven't used a RCR 1860 but I presume it has swing mounted blades like most cutters. During your pre-season check, make sure the blades pivot smoothly. With many of these cutters, including my Deere, you don't want to engage at full rated PTO speed but the tractor needs to be above low idle speed to ensure that the blades swing out properly when the PTO is engaged. And remember that rear cutter swings out in a pretty long arc when turning so don't take out a fence post or two while you are getting used to it.
Rodger
mcmxi
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I'm definitely in the camp that says that the clutch is a proven system if free of corrosion and adjusted properly. That said, assuming that there's nothing weird about the yoke in the slip clutch that would contact the snap ring compared to the yoke in the shear bolt model, it looks like it wouldn't be too hard to add a snap ring if you decided to replace the grade 8 bolt with a shear bolt.
Interestingly, the RCR1884 has a splined yoke with two clamping bolts that slides onto the splined input shaft off the gearbox, which is a stronger design and one that wouldn't allow for a shear bolt modification.
I broke 6 shear bolts in 1 day when I first began my tractor/country living odyssey a few years ago. I would recommend relying on the slip clutch as your primary means of drive line protection. I am down to a couple a year now. If you are leaning toward making the shear bolts your primary source of protection make sure you have a few extra on hand. I buy mine at Tractor Supply. Quite often they are out of stock. Good Luck.
I have a new Woods BB 72.30. I have to double check but I believe it has a splined shaft and a tapered Pin, where as some of the other models use the bolt and I'm not sure if the shaft is smooth or not.
Just reiterating what others have said, be sure to double check. I would prefer a shear bolt and always had that prior to now. Just wont work in my case. I did go through the slip clutch test when I got the machine new, it worked fine, but is more of a pain than carrying a few shear bolts.
Just reiterating what others have said, be sure to double check. I would prefer a shear bolt and always had that prior to now. Just wont work in my case. I did go through the slip clutch test when I got the machine new, it worked fine, but is more of a pain than carrying a few shear bolts.