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GregB

Hydro lift questions

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GregB
I have installed the hydro lift (yea I know Sam, finally) on my Big Ten. I made a 10HP pulley, modifying a McMaster Carr die cast pulley, and adding JB Weld as a spacer/filler material. I have pictures if anyone is interested I can E-mail the results. Don’t know how long it will last, zinc is softer than steel. If I had a easy way to cut 4”steel I would try to make a pulley on my lathe at home. Used the lift it a little bit, but it would not lift my Johnny bucket with dirt in it. With the bucket empty it will lift the tires up off the ground and the bucket itself to full height. I had the lift rod in the highest hole, giving the most height but needing more power to lift. I bought a pump rebuild kit from my local Parker dealer, also all the O-rings listed in Kirks Post. BTW the large o-ring to seal the reservoir is a # 248. Kent, maybe this o-ring size could be added to Kirks O-ring Table? I took the unit out and tore it down; I was surprised how clean it was. Previous owner must have either not used it much, or changed the oil frequently. The pump showed little bit of wear, and luckily the spool had no rust. I will install all the seals tonight. Have not taken the cylinder apart yet. The one thing that worries me is that the pressure relief valve cone, were it seats is really pounded. It is deformed into a notchy ring, like what will happen to a needle valve in a carb when tightened against the seat. Has anyone else seen this? I talked to the maintenance guy here at work about hydraulics/pumps etc. He thinks that the relief valve could have been bouncing open and closed due to a weak/short spring, causing both lack of lift, and damage to the relief pin. Does anyone know what the length the spring is supposed to be? What pound / deflection rate the spring should have? Has anyone found a part # for the relief valve components? Thanks GregB

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HubbardRA
Greg, I wonder if the cone for the old-style units is the same as one for the charge pump on the newer hydrostatic-hydraulic units, like the hydrolift that I installed on my 716H. That cone is still available, since I bought the cone, spring, and shim kit for around $38 a little over a month ago.

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GregB
Rod, I looked at the diagram on Jacks parts look-up. It looks different. I think this whole pump valve assy was supplied by Parker Hanffin. The hydro trans pump was probably Sundstrand. There is a PH cast into the lift pump housing, I thats were I got the pump repair kit. The part is a small 1/4" dia cone on a 1/8" dia pin abount 3/4" long that fits inside the spring. It appears to seat on a square corner in the valve, not tapered like a jet/needle seat. In another post someone had mentioned they shimmed the spring about .030 and it worked for them. I'd like to know how much to shim before I start guessing.

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HubbardRA
Greg, I read somewhere that the pressure in the system like I have is supposed to be in the range of 650 - 750 psi. This is how the valves are supposed to be shimmed - to a pressure, by mounting a gage in the outlet line. On the old type hydrolift, I would assume that you can shim the relief valve to the point that it slightly loads the engine when the cylinder is deadheaded, or the belt begins to slip. I have kept this idea in mind in case I need more lift capacity from my tranny powered hydrolift. The manuals I have found so far, all say that the relief valves (in a hydrostatic tranny) are factory set and the shims should not be messed with. By the way, the cone valve in the Sunstrand is about 1/4 dia with a 1/8 pin to go into the spring, and the whole piece is only about 3/8 long. Might be able to make it work. You could also have one made at a machine shop. A piece of brass rod, a few measurements from the beat up part and some machining time will yield a new part. I have a crude lathe in my garage, so many times, I will make my own pieces, especially if I have one to work from.

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GregB
Rod, Right now I have a two step approach. Re-build every thing with new seals. The relief valve can be removed with the unit installed on the tractor. I will measure the amount of notch in the cone and shim the spring accordingly. I was planning on making a detailed drawing, I'm a Quality Engineer, measure things for a living. I have an ejector pin from a mold that is about the right size with out the angle. If I can grind or turn the angle on the head the replacement part is made. Thanks for your input. GregB

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GregB
Ryan, Thankfully mini-tab makes short work of the picture creating. What I do mostly is work with the R+D guys and project managers to make sure that the new designs perform as expected. I spend alot of time qualifiying new injection molds and process's. Then the plant guys get to live with it every day :D GregB

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HubbardRA
Well Greg and Ryan, I am on the other side. I am an R & D Engineer/Project Manager. I work mainly with new technologies. Don't usually get to build enough parts to implement a quality program.

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