adjustable relief in hydro unit?

There’s something on the end? Not sure what it is. It’s hard to get to.

well, as a garden tractor it wasnt very useful to me, but as a yard mule it will dolly a very heavy trailer. so heavy that if it wheelied you could get crushed between jack and steering wheel so i got to thinking front ride, shorten wheelbase, and flatbed.

plus, it donated the perfect tin for my daughters kart



flatbed became dumpbed, dumpbed became hopper for cement mixing..





then that front through-shaft became perfect for a pump and secondary hydraulic system with aux outputs for logsplitter. then a 3pt hydraulic hitch and motor spool made sense for my 40" tiller, which was also easily adapted to a pusher axle for flotation and getting my firewood up the hill.

new baby put the brakes on this but its getting used almost daily in half finished state. i wish id done the bed as a hopper from the get go. i cant get current pics to upload at the moment but its coming along. im using the stock hydraulic system for steering but it needs just a bit more pressure when loaded, tire friction can outweigh the force of the ram

Not what you are looking for but thought you’d find it interesting. I think
You have Model# 11


http://www.eaton.com/Eaton/ProductsServices/Hydraulics/Transmissions/PCT_261208

:dunno:

thats a good place for me to start, thanks.

btw, theres no way these valves have an adjustable relief. the jamnut on yours is almost certainly to preload a ball and spring for detenting a flute in the valve spool. mine has a boss but its not drilled at all.

theres gotta be a system relief because i can hear it dumping pressure to the intake an cavitating like crazy around 500psi, like a bad steering pump at full lock whining away. i dont know that its adjustable or not but i hope so. even for lifting the plow in oem configuration, it never had enough pressure. a little snow on the blade and it wouldnt lift.

Spring assist.

mike_belben said:

mine could barely lift a plow, doubt a snowblower. hope to find time soon to get this figured out before i begin my dual transaxle articulated build.

Click to expand...

I was using two large helper springs but I was using the two stage blower. When I used single stage I only needed one Keep the pictures coming.
:dunno: :wwp:

TUDOR said:

On page 13 of the PDF in the link for the Technical Data, it states that an 800 psi relief is optional. That should help with your lift issues, if you can find the correct spring.

http://www.mytractorforum.com/showthread.php?t=271168

Maybe email Eaton directly?

Click to expand...

I can assure you that from past issues that Eaton will not tell you anything. After many calls to them I was finally able to chat with an engineer. The second time I called I was put on hold indefinately I finally hung up and gave up. That company is afraid of giving out 40 year old technology it would scare anyone.

Deerlope said:

I can assure you that from past issues that Eaton will not tell you anything. After many calls to them I was finally able to chat with an engineer. The second time I called I was put on hold indefinately I finally hung up and gave up. That company is afraid of giving out 40 year old technology it would scare anyone.

Click to expand...

Hmm. Somebody needs a seminar on customer relations!

a note of caution to others out there who may read this and try turning up their charge pump-

hydrostatic charge pumps never shut off or uncouple from a system. if set for 800psi to run a loader via the takeoff port of a hydrostatic rear, then your starter will be required to crank that 800psi, even in the absolute dead of a frigid winter night, which it may not be capable of. expect drastically reduced starter life under drastic load and excessive amps from the jumpbox and cables youll surely try to hook up.

i built a dumptruck from a bolens hydrostatic machine. the hydro drive is intact and full of hydraulic fluid because the charge pump takeoff pressure (500psig) is used to steer, which is a constant load. a separate 10gpm pump was lovejoy coupled to the front PTO output running probably 1500-2500 psi, whatever the open center valve is relieved at, ive never checked.

needless to say thats a lot of fluid friction, and the starter cannot turn it in winter no matter how many amps. one time i uncoupled the front pump and was just barely able to get it running after putting a bottle torch to the pump pickup tube to thin the oil headed into the hydro pump.

the 500psi isnt adequate to steer the machine at full load anyway. moral of the story, charge pumps are a huge, all the time fuel consuming load, even idling in place. run minimum charge pump pressure and dont design around hydrostatic charge pump takeoff. youll need huge cylinders to get the force required and that will mean slow operating times from that trickle of charge pump flow down a -4 line. its good for lifting a mower deck, power steering and maybe a power sleeve hitch. mine was inadequate for the snow plow and sure couldnt run a loader. i will switch the hydro fluid to ATF and probably try to add a blockheater on this machine because its completely useless below 40f right now. future designs will always incorporate uncoupling of the entire hydraulic system via dc clutch or belt idler, to ease winter cold cranking loads.

otoh, my 10gpm high pressure system can lift half a cord of wood at idle, or catapult it at half throttle. it also has lots of auxiliary takeoff potential. itll run a full sized backhoe as if still mounted to the machine.

Wow, what you are doing inspires an idea suggestion, instead of trying to get more pressure out of one pump. Why don't you find another rear and put it in the front backwards, put the motor in the center to drive both pumps.

Now the big change would to make it even longer, then make it pivit in the center for steering. This would give 4 wheel drive with dual pumps for pressure, use a 2nd power steering cylinder to turn the pivot.

One thing tho, one pump can be an eaton, but the other pump has to be a sundstrand, so it can be switched to left hand drive in the front.

That thing would be a tank of a mule.

i almost built a 4wd articulating machine. couple things to consider:

1. tearing apart a machine that runs, does what you built it for and is depended upon is never a good idea.
2. that means not one, but two 500 psi charge pumps for the starter to overcome, exacerbating the problem.
3. rigging up the common driveshaft to spin both pumps at 3600 rpm and articulate to 40* is asking for big vibrations and blown prop shaft joints.
4. if you could overcome #3 your next challenge is to accurately control both hydro directional valves simultaneously, through all ranges of articulation. cables could probably do it but stout ones are pretty expensive. the big issue id expect is hydro creep. when one rear wants to walk backwards and the other forwards when both should be in neutral. ive battled a lot of hydro creep on all tired pumps with worn control circuits.

one more thought on articulating machines- theyre tippy, even fullsize machines that articulate are less stable on sidehills when turned than on steer machines. the case 222/224/etc hydraulic transaxles are the widest and easiest to fab into a 4wd articulator. bolens are way too narrow.


i bought a set of narrowed dana 44 steering axles with 5.89s and lockers for my 4wd project. not certain what i want it to do just yet, so im not gonna start for a while. thinking wheel dozer with a 6way and rear skid winch or grapple.