Hello- great forum. I've done a bunch of searches and can't seem to find anything that addresses my problem; if I've missed it please point me in the right direction.... My "new" 1978 Bobcat 722 has a very loose fit between both of the tilt cylinders and the pin that connects to the Bob-tach. In speaking to my Bobcat dealer, they indicate that this model does not use a bushing in the hydraulic piston eye, but rather the pin rides directly on the cylinder eye itself. I'm assuming that the play (probably almost 1/4 of an inch), is from a combination of wear on the pin (replaceable) and the eye on the end of the piston (not replaceable unless I had a new eye welded onto the piston). I haven't pulled it apart yet, so I'll know more once I do. Interestingly, all of the other pins on the machine are pretty tight. . So here are my questions. The dealer recommended replacing either both cylinders and pins or just the pistons and the pins- both are expensive options. Has anyone had a custom bronze bushing machined to press fit into the piston eye to take up the slack? Would bronze hold up in this enviroment (the machine will see only occasional light duty around my property). Is it likely that most of the wear has occurred on the pin and a new pin will reduce much of the slop? Any other ideas on a fix that will stand up to relatively light use? Thanks very much for any thoughts.
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Do you have a hydraulic repair shop reasonably close? I think your most expensive repair would involve Bobcat just because those older cylinders parts are expensive. If you can remove the cylinders and take them to a shop it they will tell you the least expensive way. Actually if you can remove the rods from the cylinders you will save quite a bit. A brass bushing would certainly be good enough but the rod ends will have to be bored out first. It depends on the equipment the shop has, some shops would just drill and ream the holes for the bushings and some would bore them out , others would not be set up for it so they would cut the old rod eyes off and weld on new. If you have a friend with a lathe you can get through most of it on your own but if you weld the rod it should be done professionally because sooner or later someone will be standing in the bucket up about 8 feet and you don't want it to break off.
this has been addressed before ..but i don't know how to use the search function . the easiest thing is take the cylinders apart ..not that hard... take the rods to a machine shop and have them bore the end out to fit a bushing ... i got the inner race from a needle bearing ,they come in nominal sizes ie. 1" 1.25" 1.5' i used a new bobcat pin and the appropriate race . make sure to tell them to make it a press fit ..best thing is to get the race first and take it to the shop with the rod. i think bronze would be a little soft for this app. there is a lot of impact going on in this area..when i have a cylinder apart for the first time i take all of the seals and o rings to the hydraulic shop and have them make up several sets ...enough for todays job and a set or two to keep in the shop in a labeled zip lock for spares...a seal kit from bobcat may cost 30 bucks but the same seals bought from the hydro shop about 10 bucks...
OldMachinist
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I've bored out and pressed in bronze bushings in all the pin locations on my Bobtach and the rod ends and they are holding up real good. I bored them to accept standard size bushings that I can change out as needed. Bushing are cheap enough that even if I had to change them a couple of times a year it would only cost around $30 plus my labor. The other thing I did was drill a small grease hole down the center of the rod end pins with cross holes so that grease could get to all the bushings. The original design only greased the rod ends and the welded in bushings where the rod end pins went though didn't get any. If you find that bronze wears too quickly you could always have steel bushings made that would press in their place.
Great feedback, thanks Jerry. According to the dealer, most newer Bobcats have a bushing in this location- I guess that back in the late 70's Bobcat didn't count on me/we still running these machines 30 years later. Everything else on the machine seems very solid; runs well, great chrome on all of the cylinders, no leaks, and no strange noises. 2500 hours on the meter, but who knows for sure. Hard to kill those old Ford engines- 30 hp out of a 1.6 liter engine isn't exactly over stressed. I'll know more when I pull it apart- I wonder if more of the wear will have occurred on the pin than on the piston eye- would be nice if the pin was made out of a softer metal that would wear quicker than the eye but that doesn't seem likely. Thanks again for the insight.
Thats correct, my old 731 was a 78 model and didn't have bushings. I machined a new *eye* and welded it on as the rod was also bent but thats another story.
I agree if you can get the rod out and take it to a machine shop then can put it in a mill and bore the worn hole out and make a wear sleeve to press in. It doesn't matter how big the hole cleans up at, just make the bushing to suit. You don't need to use bronze, even mild steel for home/farm use would work just fine. Commercial or high use I'd go bronze or 4140 steel.
You are not the first to have this issue believe me
you will find a shop that can do the work for you, a lot of earth moving gear has this problem so its not a new job for a machine shop.Thanks all; lots of good information. Nice to know others have been down this road before. Does anyone have a recommendation of a good machine shop in the CT/NY area? Most of the ones that I've called don't seem to be too interested in such a small job.Thats correct, my old 731 was a 78 model and didn't have bushings. I machined a new *eye* and welded it on as the rod was also bent but thats another story.
I agree if you can get the rod out and take it to a machine shop then can put it in a mill and bore the worn hole out and make a wear sleeve to press in. It doesn't matter how big the hole cleans up at, just make the bushing to suit. You don't need to use bronze, even mild steel for home/farm use would work just fine. Commercial or high use I'd go bronze or 4140 steel.
You are not the first to have this issue believe me
try this web site for a shop location. Otherwise check with any logging or earthmoving equipment dealers and see what shop they use. Industrial bearing and hydraulic supply places are sometimes helpful. good luck
http://www.machineshopweb.com/shopsA2Z/nya2j.htm
