Go BottomQuestion on RC s with swing-arm top hitch
 | gearnoise
Join Date: Jun 2010 Posts: 19 Davidson, NC 
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2010-07-13 172276
I use a 60" rotary cutter on rough uneven somewhat hilly (gullied) ground, with a 30hp compact (AC 5030 - think Kubota L for size). So the setting of the toplink comes into play. A lot. My first cutter some 25 years ago was a Howse Economy which has a slot hitch point for attaching the top link and allows some 4 inches of play. Aside from a flimsy deck it was perfect. I kept using it until I warped it (those two tree trunks looked a little further apart than they were, so I didn't slow down to check!), and even a few years after until I broke a blade.
Then I picked up a (very) used KK and cannibalized a few things off the Howse for it. It's top hitchpoint was much higher than the Howse and has a swing arm to connect to (a large freeswinging U shaped piece of metal with 3 holes on each side, one for the implement). I was never happy with the KK, and it needs some rusted sheetmetal replacement, so when I had an opportunity to pick up a new Befco tornado recently at half price I jumped at it.
The Befco also has a swing arm for a top hitch, and like the KK, it actually allows too much play, and I have to be careful raising the implement so as not to have the PTO shaft come into contact with the deck. There is a midpoint toplink hole on the swingarm, but if it swings to the bottom rather than the top (and it wants to swing to the bottom), the hitch pin hangs up on the implement's hitch structure.
After some swapping around I found that the short toplink pin off one of my other tractors will clear the structure once I add a couple 3/4" washers to the Befco between space and arms. I will try this out the next time I do some brush cutting.
But I am wondering, is this issue unique to my tractor setup or does it happen to others, and if so, what is the best solution?
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 | Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada 
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2010-07-13 172277
A 'standard' 3pth (if there is such a thing) is actually a lot more adjustable than people would think.
First off though, I always advise people using an RC on uneven ground to leave the upper link on the shelf in the shed. Instead use a piece of chain the same length with a shackle at each end. This will allow the RC to lift at the rear if the front wheels pivot upwards without damage.
Next, when placing the upper link, always use the lowest hole on the tractor end, this will make the back of the mower deck rise faster than the front, giving more room between the deck and driveshaft.
The final point, is to use the adjustable stop on the 3pth control lever next to the operator, prior to starting work, adjust it so that the 3pth will only lift until just before the driveshaft and deck meet.
If the deck rubs the driveshaft it will cut the tube of the driveshaft very quickly. Even if it only rubs for a short time it will significantly weaken the tube.
Trust me, you won't like what happens if the far end of the PTO shaft becomes free to swing around under load!
Best of luck. ....
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 | greg_g
Join Date: Jan 2004 Posts: 1816 Western Kentucky 
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2010-07-13 172278
The flexible toplink concept is great to even out the cut on uneven ground. But it's a bit of a pain in the way you describe. One thing that hasn't been mentioned though, is that there are two different positions that the flex link should be used. During transport, the tractor's toplink should be adjusted to the shortest length possible. That permits you to carry the deck higher, without worry about bending the driveshaft. Then - just before you start mowing - lengthen the toplink to where the flex link is about 90 degrees from the transport position. Then your mower tail wheel won't lift on uneven ground.
This is one of the many reasons that I find a hydraulic toplink to be the most valuable aftermarket utility tractor purchase I've ever made. It permits me to do just what I described above, without ever leaving the seat.
//greg// ....
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| gearnoise
Join Date: Jun 2010 Posts: 19 Davidson, NC
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2010-07-13 172279
Murf, thanks for the advice. All three points. Thinking about it, the physics of using a chain for the toplink seems so applicable that I'm surprised the various RC manufacturers' operators manuals don't mention it. It will take a little experimentation to determine the best chain length to use with that swinging hitch arm, but then moving a shackle to another link is a task that even I can handle! (I'll start with the screw pin type).
....
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| greg_g
Join Date: Jan 2004 Posts: 1816 Western Kentucky
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2010-07-13 172281
Each man's safety is of his own doing, but I personally would NEVER use a chain in place of a rigid toplink. Have you ever tried to PUSH a chain? There have been too many sad reports of guys who've tried this, and ended up having their mowers flip up when not paying attention in reverse. At best, it damages the driveline. At worst it kills the operator.
Now chain in place of the straps between the A-frame and the tail wheel - in some cases I can agree with that. But the fact that chain is more expensive than flat steel goes a long way to explaining why you don't see the idea on new cutters.
//greg// ....
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| gearnoise
Join Date: Jun 2010 Posts: 19 Davidson, NC
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2010-07-13 172282
Well Greg_g, your follow-on about using a chain as a toplink got me worried, so I called up Befco and talked to a VP there. Although he didn't know much about using a chain, he recommended against it. And instead suggested doing what I thought, that is find a short enough hitch pin (my other tractor's toplink pin) that doesn't get hung up on the A-frame where it is supposed to swing through.
I will though make sure to use Murf's other two points, especially trying out the lowest position for the toplink pin. ....
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| Murf
Join Date: Dec 1999 Posts: 7249 Toronto Area, Ontario, Canada
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2010-07-13 172284
I'm only an engineer in two different disciplines and a 9th generation farmer.
Somebody needs to explain to me how a chain between the A-frame and the tailwheel is different from a chain between the A-frame and the tractor.
Or how a couple of pieces of 3/8" (if that) flat bar would stop even the slightest upwards pressure of a mower.
Or for that matter, how someone could back up into something big enough to flip an RC up to a hazardous level. I think in order to be able to back over it, you would have had to drive over it first. I suspect you'd notice that.
Even if it was beside you and you turned as you reversed, it would have to be a pretty 'special' operator who missed it in the first place.
Best of luck. ....
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 | earthwrks
Join Date: Dec 2003 Posts: 3853 Home Office in Flat Rock, Michigan
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2010-07-13 172285
So Murf (tongue in cheek) with your farming and ed-u-ma-cation is it fair to say you're "out standing in your field"?
Anywho...my KK RFM came with a chain BUT the chain is tethered to a sort of spring bar that is suppose to take up the slack.
And like Greg I have a hydraulic toplink which does add much in the way of transport height for a RC and even makes for mulching trees and shrubs by being able to raise up high into the tree/shrub and mulch it in place as I lower it. The RC originally came with the swinging U. I got rid of that and in its place welded two shackles on the outside rear edges of RC. (2) 2" ratchet straps connect back to the shackles and up to the toplink area. (I say "area" because I have a hydraulic quick attach plate for all my implements) The straps dampen/absorb the shock from the rapid raising of the toplink or during transport. ....
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 | kthompson
Join Date: Oct 2005 Posts: 5275 South Carolina
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2010-07-13 172286
I tried a flail mower on 3 pth once. As the suggestion of a friend who runs one disconnected the third arm while mowing. In mowing the yard backed the mower up the road shoulder as it was to step to run on sideways and to sharp an angle for tractor and mower where the should met yard. Very fortunate in the only damaged done to the tractor was with the mid mount PTO from the rear PTO shaft pushing due to the mower rolling up. Would the 3rd arm have prevented that if connect, not sure for it bent slightly from a rough cut mower if memory is correct on what bent it. I think a 3rd arm would help prevent some flip ups but not all.
But I no longer run any 3 pth hitch anything with out 3rd arm connected. Have seen the chain from the A frame to the rear wheel area on a nephew's RC mower but not sure if factory or later installed. As to allowing the mower to roll up would think that it would as well as if no 3rd arm or chain was used there. ....
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| gearnoise
Join Date: Jun 2010 Posts: 19 Davidson, NC
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2010-07-14 172299
Regarding factory models with chains from the A-frame to rear, I believe older BushHog Squealers had that; I was going to buy a used one from a local dealer last year but it sold before I had the money gathered. I wondered why the newer models dropped the chains, didn't know if it was a safety issue, never thought about cost before.
Regarding top link via chain vs adjustable, I guess I will experiment with both the next time I do some brush cutting (August). I'll just need to figure out some sort of side sleaves or a Y to keep the RC-end shackle from sliding to one side. I'll post anything interesting then.
By the way, having a forum like this is really neat. I wish it was around before I bought my first tractor -- I wouldn't have wasted my money back then on that Satoh Beaver with its Cat 0 hitch and toy implements. ....
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