transfercase PTO Hydraulics

[Sephirothq]

Isn't it the same system the M35A3 winch uses?

What are you looking to use for a PTO?

 

[aczlan]

You don't want your pump running all the time. They don't make a pump with some sort of "relief" that allows the pump to run all the time. To run the pump all the time you'd really need a closed center system (high dollar and overly complicated for what you're doing).
There are a bunch of things to consider when installing hyd on a truck. What all are you planning on running and what are the GPM and PSI requirements?
Do you understand how a open center hyd system works?

Why not use an open center system? It pumps fluid around all the time using little to no hp because it is at little to no pressure, then (when the flow is impeded by turning a valve on), it builds pressure.
Its the same system used on most tractors under 100HP (excluding some Deere machines that are closed center).

Aaron Z

 

[m16ty]

OK, understood now but what I am wondering is what I lose by having an open system where the fluid not under pressure recircs back to the reservoir when I am simply driving? I know there will be some temp increase in the oil but if the tank is large the heat should dissipate and the HP lost should not be great since the pump isn't pushing 2500psi when the circuit is open. Please explain why an open system is no good for my truck?

A open center system will work fine but I still wouldn't want it running all the time. The reason I said a closed center would work better because no fluid is moving anywhere in a closed center system when not called upon.

You seem set on running the hyd all the time. Go ahead. Just know that you'll be generating a lot of unwanted heat and wear. I don't know how long your pump and valves will last but your wear on the system will probably increase 100 fold because it will be running 99% of the time when you don't need it.

I can't tell you how many dumptrucks I've seen with burned up pumps where the driver forgot to disengage the PTO and headed down the road.

 

[ThatXJGuy]

it seems like it would be much easier to just setup a clutch PTO or at least a clutch on your pump that you could disengage when not in use, the only thing of the ones you mentioned that you would need to do while moving is the front plow, and occasionally a dump on the fly but you're not going to be plowing and dumping on the fly 24/7 and otherwise you would only be using your hydraulics when you're stopped anyway. Why put 100 times more wear on your PTO and pump, and need a big reservoir and/or cooler and waste all of that energy? The way I see it, every MPG you can get is worth it, not that we buy these trucks for MPGs...

 

[Goinmxn]

I'm following this thread because I am in a similar situation. I am setting up plows and sanders on my trucks and need constant hydraulic pressure to run the sanders. Then when I am plowing and not using the sander just the plow, it needs to run for just the plow operation, up down, left and right.

 

[tobyS]

What ever came of this thread? Is there more current ones on this issue?
Does anyone use their truck for a power source for fixed equipment (like a sawmill).

 

[steelcaptain]

What ever came of this thread? Is there more current ones on this issue?
Does anyone use their truck for a power source for fixed equipment (like a sawmill).

I ended up driving my hydraulic pump directly from the transfercase using a pto from an M543 which is fulltime however I also installed an oil cooler in the hydraulic circuit at the return side before the filter and reservoir so I am not getting overheating of the fluid and without a pressure demand on the pump there is not a big draw on engine HP when driving. Will try to get some photos of the install soon.

 

[tobyS]

After reading the thread I had more concern that you would not have hydraulic pressure when you slow or stop rather than a heat problem. In cold weather, depending on the size of the tank, I thought just the opposite, that your fluid would be cold and not move well, perhaps cavitate your pump. Since we run hydraulic pumps at 1750 direct to an electric motor, I didn't think the "full time" (100% duty cycle) would be an issue at all.

How have you gotten around the issue of having little or no pumping pressure when you stop?

In my case, I'm wondering if going through the tranny (Allison auto) will result in a lot of un-necessary wear and tear that I can avoid with a pony engine. Mine is a stationary need, so disconnecting for road use would be important. I'm wondering if anybody has came off the front of the engine, direct drive, although the radiator is in the way, as the pto is only good for about 10 hp and running thru the tranny is a lot of wear and extra fuel.