3-Point Hitch Hitch Pin Torque

[reb]

Just acquired a JD rotary cutter. The lower hitch pins are relocatable, with a high position for large tractors and a low position for small tractors. I assume that the 1500D is in the latter category. The manual states the torque on the lock nuts should be 435 lb-ft. That is beyond the capability of my torque wrench. Why is the spec so high? What are the likely consequences if they are tightened somewhat less than that?

reb

 

[Ozarker]

The likely consequence is that they will loosen from vibration.

 

[JJT]

I can attest to that. The pins on my tiller are torqued as tight as my impact will go, and they have lock washers. I had to double nut them to keep them from vibrating loose.

 

[EdKing]

Do a search in the Parts/Repairs forum, and the Attachment forum, for "torque multiplier". There is quite a bit of info on using a torque multuplier to increase the amount of torque you can apply with your torque wrench.

 

[Anonymous Poster]

You can also drill an 1/8" hole in the corner of the nut and another one in the pin and then safety wire them together. I had to do this to the rear wheel bolts of my YM200B. They backed out on me 3 different times. The last time I was down to the last bolt hanging by a thread before I noticed. I posted some pictures of this in one of Roger Scotty's miscelaneous files. I think it was at the second Yanmar Yahoo club, but I'm not sure. If Roger know's where they are maybe he could post a link. Ernie

 

[roger_scotty]

Reb, I don't know of anything that uses that large of a torque, but if you do a search on the old messages you'll see that Yanmar's ability to make mistakes when converting from metric measurements is well known. I recommend that you always look up the factory torque in metric values and do the conversion yourself. And particularly when the value is so unusual.

 

[Ozarker]

Of course that didn't occur to me. Here is an online conversion calculator.

<A target="_blank" HREF=http://www.onlineconversion.com/torque.htm>http://www.onlineconversion.com/torque.htm</A>

 

[reb]

Roger: The conversion checks out.

Ed pointed me in the right direction. A post there addressed the same question. A torque multiplier will fix the problem. However, the cost would be hard to justify. If I can find a way to take them off, maybe I can get it to the local mechanic to tighten after I move them down. Or maybe I should just weld them on.

The same problem exists in the spec for tightening the blade hardware, tho. Maybe I need to submit a request to the treasurer for a torque multiplier. Trouble with that is that the associated costs (new dresses, living room furniture, sewing machines, etc) of such requests can get out of hand.

Thanx for the help.

reb

 

[hosejockey2002]

I don't have a rotary cutter, but I've got a tiller. I tightened the hitch pin nuts as tight as I could with a 12" crescent wrench and check them periodically. They've never loosened. Maybe you could just get them as tight as you can and check them often at first. If they loosen, I wonder if some Locktite might help. I don't have much experience with this, I'm just throwing out ideas.

 

[Anonymous Poster]

From time to time, I start thinking folks are overdoing it a bit when it comes to reading and implementing spec sheets.
Most likely, a set of hitch pins is never going to get reloacated after they are installed, and the only concern is tightening them up the first time, and keeping them there.
When setting up a machine, it is always a good idea to leave things a bit loose to aid assembly, and then torque them down when you're satisfied.
After torquing, a prick punch or cold chisel does a wonderful job of upsetting a few threads and prevents loosening from vibration, as well as tampering and parts borrowing.
As far as acheiving 400 ft# of torque on a thread, a 100# woman dangling from a 4 foot piece of pipe on the handle of a wrench equals 400 ft# of torque. If you can't find a hundred pound woman, adjust the length of the pipe to your body weight. Chances are pretty slim any bolt capable of being torqued to 400ft#s will break when you are hanging on a wrench handle. Dang cheap torque multiplier and readily available.

 

[Soundguy]

Also green loctite ( after assembly ) can be added, as well as jock nuts, or lock washers and double nuts. A safety pin can be added ( as pointed out earlier ) by drilling the bolt, and using a crown nut ( and wire ) etc.

Soundguy


""As far as acheiving 400 ft# of torque on a thread, a 100# woman dangling from a 4 foot piece of pipe on the handle of a wrench equals 400 ft# of torque. If you can't find a hundred pound woman, adjust the length of the pipe to your body weight. Chances are pretty slim any bolt capable of being torqued to 400ft#s will break when you are hanging on a wrench handle. Dang cheap torque multiplier and readily available. ""

 

[pennwalk]

I would use blue locktite and make the bolt as tight as you can. Remember that a long pipe will do bad things to a ratchet wrench if you push it to far. It's not like this is a critical connection. There is plenty of room for error.

Chris

 

[TBone]

<font color=blue>"It's not like this is a critical connection. There is plenty of room for error."</font color=blue>

I agree - It's not that critical but it is a pain in the A$$$ to have the hitch pins to work loose and you are 2 or 3 miles away from the tools you need to tighten them.

I have a heavy duty 6' Howse cutter that I put all my 200 lbs. on a 3 foot cheater pipe/pull handle to tighten the pins. If I don't they work loose.

I thought about drilling a hole through the nut and bolt and pinning them but I can't get to it to drill after it's on the cutter.

I haven't tried the wire but I'm not sure if this will work with the excessive vibration.

Anyway the 3' cheater pipe and pull handle works pretty good. Even with this I have had to re-tighten them a couple of times. Rotary cutters doing extremely heavy cutting are notorious for this problem.

TBone

 

[Anonymous Poster]

You can also "double-nut" it or use a "nylon-lock" nut as the secondary nut (after you've torqued it down with the 3' extension...

You're right... the rotary cutters fasteners loosen up as time goes on... due to the nature of the beast from all the vibration... get into a habit of checking/tightening them every month (or sooner-depending on usage of cutter)...

 

[Anonymous Poster]

Tbone
I'm posting a link to a website that talks about safety wiring. Ignore the ad for the ultra-light and scroll towards the bottom of the page. There are some very good drawings of the proper safety wire technique. Don't worry about the special pliers for twisting the wire. It's just as easy doing it by hand. I'm an aircraft mechanic by trade, and I can guarantee you that vibration is not a problem. We safety everything on an airplane from the inner workings of an engine to the flight controls. safety wiring is designed to counter act the vibrations that loosen up the hardware. I figure if it's good enough for the space shuttle it's good enough for my Yanmar. Ernie
http://www.ultralightnews.com/pilotslounge/safetywire.htm

 

[Corm]

The hitch pins on my grader blade kept coming loose no matter how long a pipe I put over my breaker bar handle... I ended up using my arc welder and just put two small dabs of weld on each pin. No more problem /w3tcompact/icons/smile.gif. If I ever need to remove them, it would be an easy matter to grind off the dabs and remove the nuts.

Corm

 

[TBone]

John,

The double nut idea is a good one except for one thing. The threads on the pin that I use are not long enough for a second nut (only about 3 or 4 threads out past the nut).

The pins with the longer threads are so long I can't get a regular socket all the way up on the first nut to tighten it and I can't get a crescent wrench on it either. If I can find a deep socket that size I will probably try that.

Corm,

I have done the spot welding trick on hitch pins before and that cures the problem. On this cutter though, the threaded ends of the pins are in a recessed location that you wouldn't be able to get a grinder in if you needed to get them off. I guess you could use a cutting torch and cut the whole pin off.

Ernie,

I have never wired anything before - I might give it a try. I couldn't tell for sure - does the wire go through the nut and bolt or just through the nut?

TBone

 

[Anonymous Poster]

TBone
Just drill the nut . From one flat to an adjacent flat, not through the center of the nut. Don't penetrate the threads just catch a corner of the nut. When you wire it, pretend that you are tightening the nut with the wire. If you are pulling it in the tightening direction then you are correct. If I can help in any other way let me know Ernie

P.S. If you do a google search on safety wire or aviation, you might find a few better pictures.

 

[Anonymous Poster]

TBone
I just looked at that link again. Those safety wire pictures are the heads of the bolts, not the nuts. I'm sorry I didn't pay closer attention to the pics. You definitely don't want to drill through the whole thing. You'd never get the holes lined up again if you removed it. Plus it wouldn't be worth wiring it then, you would just install a cotter pin. Ernie

 

[Anonymous Poster]

If you have access to a welder tack the pin on one side of the flat bar in a spot where you or the next owner can easily grind it off w/ a small hand grinder. Then tack the nut on the outboard side, again where it can easily be removed. I'm talking just a tack. Don't get carried away.