Valve help

[aczlan]

For both steering and direction control (fowards/reverse) why not use a 2 spool motor directional control valve?
Only problem would be some sort of brake because a motor spool valve let's the motor free wheel

Heres a link for one from surplus center.

2 Spool 25 GPM RD522EEAA5A4B1 OC Motor Spool Valve | Directional Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com

That would let you pick forward/reverse for each track, but not "feather" them without spiking the pressure.

Aaron Z

 

[farm boy00]

That would let you pick forward/reverse for each track, but not "feather" them without spiking the pressure.

Aaron Z

How would it not let you feather them? Would the same principle as a loader valve. Pull it out slowly for slow motion or fast for faster motion.

Would be no different for a pressure spike then using ball valves and it has a built in pressure relief for the inlet so if there was a problem with pressure, it would go off and drain to tank.

 

[balsam]

Incorrect. The one I linked to (1/2 NPT �-16 GPM Wolverine Flow Control Valve w/Relief Valve | Flow Control Valves | Hydraulic Valves | Hydraulics | www.surpluscenter.com) is a Pressure compensated flow control valve, the fluid going to the excess flow port has to go through a pressure relief valve first.

Aaron Z

I知 going to have to do some research on that valve because I don稚 really understand how it works. I thought the pressure compensation meant that the office size would increase or decrease with fluctuations in upstream pressure so the excess fluid flow would remain the same.
I知 gathering then, that it works something like an adjustable flow divider. I will try to get an understanding of it through my thick head.
Thanks for the follow up.

 

[oldnslo]

Yeah, I thought of that overnight. I haven稚 sat down to draw out a diagram yet but I will today. I see I would have to use a flow divider and not sure I want to do that. I知 also wondering if it痴 best to meter the fluid into the motors, or out of them as the slower track would become an overrunning load as it slows??
I would love to use tandem pumps but the cost is exorbitant and I don稚 like the added weight. I seem to find lots of singles in my hp range but not doubles.
I知 trying to keep is as simple and light as I can.
Thanks for your insight. You know your stuff.

You are correct that some form of valve logic will be required to prevent the "unpowered" track from rolling while trying to negotiate a turn. There are different ways to do this with valve logic.

When you start adding up the valve cost and circuit complexity it might be very similar in cost to running two smaller closed loop pumps.

 

[balsam]

You are correct that some form of valve logic will be required to prevent the "unpowered" track from rolling while trying to negotiate a turn. There are different ways to do this with valve logic.

When you start adding up the valve cost and circuit complexity it might be very similar in cost to running two smaller closed loop pumps.

You might be right. I am starting to think my knowledge of hydraulics is borderline dangerous....every time I add a valve, it痴 between $100-$300. I have learned so much from you guys. I looked again at that tandem pump setup at Surplus Center and taking a second look it just might work....also gives me a fixed displacmemt pump for auxiliary痴. The problem is the high pressure to get the hp. given the flow. I haven稚 found a high torque motor that will handle that kind of pressure....5000+psi.
I guess I could look at driving 2 single ones with a gear or chain splitter.
I have to look more at tandem setups.
Thanks for your input.
Thanks

 

[oldnslo]

companies like Poclain, Black Bruin, etc make radial piston motors rated for 5,000 PSI and designed for wheel & track drives

 

[balsam]

Thanks oldmslo(love your moniker)
I looked at those motors but they have huge displacements compared to what I’m looking for....and, OMG, the price. I’m trying to keep this thing down to a price equivalent to a new snowmobile(10-15k), that way I may be able to keep my marriage intact.��
I did find a few reasonable tandem pumps I can consider, that will handle the 20hp per side I need at around 2000psi. Hydrogear has a lot of them with aluminum castings for lightness. The problem with those is determining the exact characteristics of the pumps....everything has to be cross referenced. Prices arn’t to bad, though a few years ago Surplus Center had a lot of those pumps and that’s what got me excited about this project. They seem to be all gone now.
I’ve also been toying with the idea of a hybrid system using a hydrostatic pump and motor driving a differential, with brakes for turning. I would like to keep it all hydraulic, though.
Weight of components is a consideration if I want to keep it buoyant.
Thanks for the input.

 

[oldnslo]

I believe that hydro gear was purchased by Sauer Danfoss so this may affect the surplus center availability. I believe both Eaton & Hydro-gear make the "heavy duty" lawn mower transaxles. A word of caution when looking at this style unit is that they may or may not have work port relief valves. Some of them rely on the wheels spinning to prevent over loading them. With tracks you should have the relief valves to protect the components.

Good luck on finding something.

 

[balsam]

I believe that hydro gear was purchased by Sauer Danfoss so this may affect the surplus center availability. I believe both Eaton & Hydro-gear make the "heavy duty" lawn mower transaxles. A word of caution when looking at this style unit is that they may or may not have work port relief valves. Some of them rely on the wheels spinning to prevent over loading them. With tracks you should have the relief valves to protect the components.

I will check that out for sure. Thanks.
I need “cross line checks” for sure, also a charge pump. I would probably add a “heat shuttle” to the circuit also, although, everytime I put together a system, heat was never the problem I anticipated. I’m not sure I’m using the right terms for these valves.
I have been looking at these Hydrogear pumps and I’m going to call them today to learn about tandem setups and who their distributers are.
Leading Manufacturer of Precision Drive Solutions - Hydro-Gear - Pumps
You must have been in the business because you know your stuff.

 

[muddstopper]

I read thru the thread and still not sure what the op is trying to accomplish. My question is, why not just find a old zero turn and us it. Throw away the mowing deck, add some wheels to the front to run his tracks over, put a cab on it and your done. You can lengthen the frame is it isnt long enough and it would weigh under the 2500 lbs the OP is looking for.