Tim C Posted August 1, 2019 Posted August 1, 2019 Hello, this is Tim from CT. I have a Simplicity Landlord 3410 Garden Tractor. I recently bought a parts tractor and it had the Sundstrand Hydraulic drive series 15 U. And the ID tag on pump is 90-1079. It all seamed to work fine when I rigged a belt to test it on parts machine, all seamed good, clean oil and no leaks. So I took it out and carefully cleaned all of it including paint(but not on cooling fins) So its now in my machine and working awesome. How ever its a little bit jerky at takeoff from neutral to forward especially. reverse works just fine. I believe I have two good charge check valves, and There were no shims in the relief valve, Im not sure if is supposed to. So I punched out a few .010 shims and started adding them(I did put in bottom cone plug so I wouldn't drop them) I did remove the set screw that simplicity says to check charge pressure as I was shimming and I raised pressure from 180psi to 210psi.(I realize now that pressure shoulds be reduced a bit. Also I basically rebuilt the control inkage all smooth and no play. After I got in my machine I ran it for a bit to warm up, and then changed oil and filter also new lines to remote filter. Maybe I just need to change oil and filter again. This Trans was not originally in parts tractor so I really dont know its history. But it really works excellent other than the jerky forward control. I really hope Im missing something simple, I really appreciate any help Thank you, Tim Cocchiola
Brettw Posted August 1, 2019 Posted August 1, 2019 Do you have a picture with the drive linkage hooked up?
PhanDad Posted August 1, 2019 Posted August 1, 2019 (edited) 9 hours ago, Brettw said: Do you have a picture with the drive linkage hooked up? The reason Brett asks is the hydro control linkage is very different between the Vickers and Sundstrand hydros. I'm assuming your "3410" was a 3410H and had the Vickers hydro in it. It has what I'll call "hard" control linkage as seen boxed in red: The Sundstrand has "soft" control linkage: Without this linkage setup, the Sundstrand will be "jumpy". A frequent complaint with the Sundstrand is lack of "top end" forward speed. Many times this is caused by a some slight binding such that the soft linkage doesn't full push the control cam all the way in the slot. A solution is to add washers to have a more compressed spring, but the more the spring is compressed, the "jumper" the hydro is. The Vickers hydro must have internal hydraulic damping to avoid the issue. Many of us feel the Vickers is a "smoother" hydro, but it's curse is the pintle shaft leak. There was (is) a detailed write-up of @SmilinSam's conversion to a Sundstrand hydro, but I can't find it on this "new" site. I'm pretty sure he used the "soft" control linkage in the conversion. And welcome to the site. Your 3410 looks well cared for. Edited August 1, 2019 by PhanDad Replaced Sundstrand Pic & Corrected Model # 1
SmilinSam Posted August 2, 2019 Posted August 2, 2019 In all the years I have been doing these tractors, never had a sundstrand system where the pump itself was the problem. Always been control linkage problems or belt drive system problems. In my experience, jerky operating has been due to incorrect control linkage connections, worn out or loose control linkage connections, or loose bevel gear box bolts through/to the frame(allowing the tractor to pivot as it goes over the ground).
Brettw Posted August 2, 2019 Posted August 2, 2019 10 hours ago, SmilinSam said: In all the years I have been doing these tractors, never had a sundstrand system where the pump itself was the problem. Always been control linkage problems or belt drive system problems. In my experience, jerky operating has been due to incorrect control linkage connections, worn out or loose control linkage connections, or loose bevel gear box bolts through/to the frame(allowing the tractor to pivot as it goes over the ground). What he said............... 1
Tim C Posted August 4, 2019 Author Posted August 4, 2019 Jerky Sunstrand Hydro Hi guys thanks for responding. I have some better pic for you. FYI all the linkage is from a Sundstrand Tranny set up, it came with the parts tractor, which someone had hacked it into that machine, linkage was all wrong. the leaking check valve is interesting, I better take out some shims from the pressure relief valve. Also does someone know the best way to purge the system that couldnt hurt because Im planning to go synthetic. I spent alot of time rebuilding the linkage and making sure there was no issues there. Also the belt clutch system is all rebuilt, I even turned up a new spacer and welded it where I cut of old wore one. Remember everything is good except jerky when forward drive is engaged. Here's the new pics, please give advice!
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