Rotary Cutter Possible buyers remorse on Bush Hog SQ720

[greg_g]

Attaches fine with plenty of overlap.

Be careful there, the overlap changes as you raise/lower the implement. Disconnect the shaft and pull it apart. Make sure both tubes are the same length. That ensures you have equal inside and outside overlap. Reassemble it, and compress it down to it's shortest length. Measure the length of the tube only (not the U-joints).

Then attach it to the tractor PTO spline, start the engine, raise/lower the hydraulics between min/max height. Stop the hydraulics at the point where the shaft becomes longest. Measure the new tube length. Subtract the 1st number from 2nd, that's your minimum overlap. Rule of thumb suggests that minimum overlap never be less than 1/3 the closed length. Example, a 48" tube should not be used when the minimum overlap is less than 16"

Otherwise, FWJ pretty much covered your other concerns.

//greg//

 

[botemout]

Be careful there, the overlap changes as you raise/lower the implement. Disconnect the shaft and pull it apart. Make sure both tubes are the same length. That ensures you have equal inside and outside overlap. Reassemble it, and compress it down to it's shortest length. Measure the length of the tube only (not the U-joints).

Then attach it to the tractor PTO spline, start the engine, raise/lower the hydraulics between min/max height. Stop the hydraulics at the point where the shaft becomes longest. Measure the new tube length. Subtract the 1st number from 2nd, that's your minimum overlap. Rule of thumb suggests that minimum overlap never be less than 1/3 the closed length. Example, a 48" tube should not be used when the minimum overlap is less than 16"

//greg//

Great! Thanks. I'll do that as soon as I can.

 

[greg_g]

I also see you have the mower on an "N" Ford. You'd be well served to get an over-running clutch. That'll serve as a pto shaft extention...

That was my original thought as well, but I wasn't sure. Assuming that the info I found on TractorData.com is correct, the 860 is listed with a live PTO. But you clearly have more experience than me on these older Fords. If you can confirm the TractorData info as valid for the 860, then - if an extension becomes necessary -a simple PTO extender would be a less expensive solution.

//greg//

 

[botemout]

That was my original thought as well, but I wasn't sure. Assuming that the info I found on TractorData.com is correct, the 860 is listed with a live PTO. But you clearly have more experience than me on these older Fords. If you can confirm the TractorData info as valid for the 860, then - if an extension becomes necessary -a simple PTO extender would be a less expensive solution.

//greg//

My 860 does have a live PTO.

So there is some relationship between the over-running clutch and the live PTO? I don't understand this yet. If my overlap is fine and, given the live PTO, would you still recommend the over-running clutch for safety?

 

[Builder]

I found you an SQ720 manual, but I can't post the source here.

I'll PM it to you.

 

[botemout]

I found you an SQ720 manual, but I can't post the source here.

I'll PM it to you.

Nice! Thanks much ;-)

 

[MarkV]

Just a couple of things to check, given that you are new to Bush Hog mowers. The flexible attachment point for the top link is to allow the mower to move up and down on hills and ditches. That is a good thing. As the mower moves up and down the PTO shaft is going to slid in and out as needed. Check and make sure that there is still adequate over lap when it is in its most extended position. You don't want that thing coming apart with the tractor running. Also understand that the over lap needs to be checked on the actual metal PTO shaft not the yellow plastic guard you see on the outside.

Don't get stressed about dings and dents on the mower deck. It is going to happen. The only thing I would check, given that the output shaft was replaced, is that the stump jumper is not bent. The stump jumper is the large round metal disk that the blades attach to. Measure from the blade to the deck, spin 180 degrees to the second and measure again. The two should be very close to the same measurement.

MarkV

 

[Farmwithjunk]

Thanks for the info, farmwithJunk (great name)!

1) output shaft, not axle. Got it ;-)
2) I'm going outside right now to grease it; I'll see if I can find the one for the PTO shaft you're talking about.
3) I'm researching what an "over-running clutch" is. I know that my Ford 860 has a live PTO but I suspect that's not related to what you're talking about. I think it may not be an issue though because, as you can see from the other posts above, I didn't understand that a PTO shaft is telescoping and so was unaware that I could just pull it out to reach (give me another couple years; I'll get this stuff down ;-)
4) As for price: I've got $1000 in it; for a $1000 I'm sure I could have gotten a very nice new KK or some similar model from TSC. Do you think that that would have been a smarter move? Or, are implements of the quality of a BH really that much better built that, if it works at all, it'll probably last longer than the, probably, more feature filled KK? It's academic at this point, of course, but the answer might help in the future.

Thanks again, JR

I was mistaken....From the picture, I thought you had a Ford N, and NOT the 860 you actually do have. Live power eliminates the need for the over-running clutch. And as I see, you found out that the pto shaft was in fact long enough.

The lighter duty rated Bush Hogs aren't that much different than a light duty mower from other brands.... The biggest difference will be you have a slip clutch which isn't standard equipment on the light duty KK's as far as I know. From my own experience with BH, they have tremendous parts support.

 

[Farmwithjunk]

That was my original thought as well, but I wasn't sure. Assuming that the info I found on TractorData.com is correct, the 860 is listed with a live PTO. But you clearly have more experience than me on these older Fords. If you can confirm the TractorData info as valid for the 860, then - if an extension becomes necessary -a simple PTO extender would be a less expensive solution.

//greg//

His 860 does in fact have live power. From a quick glance at the picture, I was thinking he had an older "N" Ford which would NOT have had live power. No need for ORC. And it appears as if the PTO shaft will extend (safely) enough to eliminate the need for the extention altogether.

 

[greg_g]

So there is some relationship between the over-running clutch and the live PTO? I don't understand this yet. If my overlap is fine and, given the live PTO, would you still recommend the over-running clutch for safety?

No and no. A live PTO means that the tractor PTO spline disengages (like going into PTO-neutral) when you kick in the clutch. Other tractors of your vintage (including the Ford 850) had a transmission-driven PTO. When you kicked in the clutch, the PTO spline stayed engaged.

The drawback to this is mowing downhill. The heavy blades are spinning fast and generate a lot of kinetic energy. They can actually transfer this energy backwards through the PTO driveshaft. When you're trying to go slow downhill - or stop on a hillside - or turn around slowly at the bottom - the energy transfer can "push" the tractor to places the operator doesn't want to go.

The solution is a device called the over-running clutch (ORC). Goes between the PTO spline and the PTO driveline, and has a gearing setup that engages as long as the PTO spline is applying torque to it. When you back off on the throttle, the torque is removed - and the ORC just spins internally (like PTO neutral). That way the energy feedback from the mower blades has no effect on forward motion of the tractor.

Long story short, the live PTO on your 860 means you don't need an ORC. You want to disengage the PTO driveline, just kick in the clutch.

//greg//