Valve help

[ptsg]

Reinventing the wheel ?

Just the feeling you get to see a complex project that you built all by yourself, working as you want, makes it all worth it IMHO. To me, it's just priceless. And I know what I'm talking.

It's not always about the money, but more about being able to do it by yourself and to test yourself with hard challenges... It's easy to go out and just buy it. But where is the fun of that? Plus you get to make it the way you want and need it.

 

[CADplans]

Is your design going to use an open center type gear pump for flow? (a fixed displacement pump)
If so, any restriction to the oil flow converts all the oil not going to the hydraulic motors directly to HEAT!!

If you have 20HP driving a suitable size pump, and restrict the flow by 50% for half speed,,,
10HP will be directly heating your hydraulic oil.

To restrict flow, you need the type pump that is used on closed center hydraulics,,
that type pump produces variable flow rate, based on demand, open the valve more, the pump generates more GPM,,,

 

[balsam]

Cadplans
It will be an axial piston, variable displacement pump. This greatly reduces heat generation as the flow rate is determined by the pumps swash plate angle. Of course there is always heat build up from the “charge pump”, pump slippage, etc. I may not use a closed loop circuit, eliminating the charge pump and create reverse with a directional control valve.
A little heat will be generated from the steering valves but using the “bleed off” valves that were suggested earlier, heat will be minimized as the fluid is dumped at system pressure and not relief pressure.
I like the idea of using the oils heat to heat the cab. Perhaps an electric/oil hybrid system.
Usually if the reservoir is big enough heat is not a factor. I once designed a system to drive a snowblower and because the oil was so cold and viscous, it kept blowing the case seals out of the motor, despite the being a case drain...has to put a heater on the reservoir. Jeez!

 

[balsam]

Well said! I have been looking into a project, to keep me busy and this seems like a lot of fun.
I have gotten a lot of great ideas already from you guy. Over the next couple of days I will sit down and think about this stuff.
So much stuff invoved with this project. I would like to start the actual construction, the beginning of January.

 

[oldnslo]

If you using one pump and motors in parallel you can not use a bleed off circuit unless you have a flow divider. Reason for this is oil will take the path of least resistance and all of the oil will bleed off slowing down both tracks.

A benefit of the meter in approach is you potentially still have power to both tracks so you can power steer. Sometimes this might be helpful.

Good luck on this project

 

[balsam]

If you using one pump and motors in parallel you can not use a bleed off circuit unless you have a flow divider. Reason for this is oil will take the path of least resistance and all of the oil will bleed off slowing down both tracks.

A benefit of the meter in approach is you potentially still have power to both tracks so you can power steer. Sometimes this might be helpful.

Good luck on this project

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.

 

[balsam]

OLDNSLO
Also, if I do use metered out, the overrunning track would drive the motor on it like a pump so I would have to use relief between the pump and flow control......probably, what I call, a shuttle valve. Not sure that’s the proper term.
Does that make sense?

 

[thepumpguysc]

I might be way off base here so feel free to ignore it..
I was cruzing around face book the other day & this short video popped up showing a small SUV{front wheel drive} backing into some tracks..
Then they pulled forward & drove into more tracks.. THEN it showed the suv hitting a snow pile & going off road.. like a snowmobile..
U strap these tracks onto your existing wheels & let the machines wheels do all the work via rollers that generate the power to the tracks..
It was very kool.. I don't get snow but if I did.. oh brother, I'd have me a set..
I'm sure they would work on a nice cabbed, heated ATV.?? Go do a search..

 

[farm boy00]

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

 

[aczlan]

If you using one pump and motors in parallel you can not use a bleed off circuit unless you have a flow divider. Reason for this is oil will take the path of least resistance and all of the oil will bleed off slowing down both tracks.
A benefit of the meter in approach is you potentially still have power to both tracks so you can power steer. Sometimes this might be helpful.
Good luck on this project

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