Hydraulic Motor Temperature

[pugs]

The pump is a "fixed displacement" pump
The valve is most likely a closed center, meaning the center neutral posistion is closed to any oilflow. You can also get valves (not sure about in the small RC stuff) that are open center for additional valve blocks or what not beyond the first.

It may be possible to add an additonal work valve and have its cylinder port tied back to tank port, and adjust the transmitter computer to move that servo to full open posistion anytime any other valve is not being used for X amount of time. This would effectively act like a pressure dump valve and remove load from the pump motor. The oil would still heat up as it is being pumped around, just not as fast of heat buildup as if it were under pressure. Could also be done with a solenoid and a few limit switches or prox switches to detect the primary valves center posistion, this method would not use a valuable radio channel.

The ideal setup, being that the pump is electrically driven would be to have the pump shutoff when there is no demand for oil flow, would probably want a check valve at the pump outlet so that if a valve were opened and the pump for some reason was not on a loaded cylinder would not cause the load to suddenly drop by turning the pump in reverse.

I think there is a switch some of the guys have been using that turns the pump on and off as needed, can't recall the name of it.

Depending on the valve construction, one might be able to modify it to be an "power beyond" valve and have the power beyond dump to tank. It has to be built such that any spool movement to feed a cylinder then blocks off the power beyond port. Normally the power beyond port would feed a secondary valve block which you don't want to be operable when the primary is being used.

[Lil Giants]

Originally Posted by pugs

This would effectively act like a pressure dump valve and remove load from the pump motor. The oil would still heat up as it is being pumped around, just not as fast of heat buildup as if it were under pressure. Could also be done with a solenoid and a few limit switches or prox switches to detect the primary valves center posistion, this method would not use a valuable radio channel.

There's an electric device something like this on the market already, it's called Ivy-2 and has a ridiculous price tag of over 400euro.

Leimbach for years has had an auto shutoff device. The servo leads from each valve plug into individual leads of this device & then seperate leads out of this device paralleled to each servo valve plug into the rx dedicated chs. No servo movement for 2 or 3 secs turns off the pump. The split second any one servo/valve is activated, the pump turns on. The valves have to be perfectly centered & absolutely no servo twitch or the pump doesn't shut off. It's kind of a big bulky chunky piece of electronics and there's not alot of extra room inside Stahl's excav body.

What everybody is now doing today is putting an esc on the pump motor & using a sophisticated computer radio with p-mixing capabilities on 4 chs. Turn the pump on via an e-switch such as a Battle Switch from Dimension Engineering, set that ch to run at approx 10% at neutral position and mix each of the three servo valve chs with the pump ch. The greater the servo throw to open the valve, the faster the pump motor rpms.

Here's a video of Kalle's Vario excav showing how the ch mix works.
http://s172.photobucket.com/albums/w...4-20-38-22.mp4
I'm going to use a Spektrum 8ch radio on my JD850 "mix" my hyd controls.

I'm going to use a Spektrum 6ch radio to do the same with my dozer, wheel loader, track loader & adt.

Sidenote about the Leimbach hyd system: I think of their system as closed center b/c all oil flow travels back to the tank thru the relief valve, the system is always under pressure. The valve block is open center.

When a valve is open or neutral, the oil flow never deadends, it can't or the rubber pressure line to the valve from the pump would explode! Even at maxium servo throw/valve open, oil flow can be directed to one valve activated or all three in the block simutaneously. The oil flow will travel 1st to the path of the least resistance... the cylinder(s) hits the end of it's stroke, or the cylinder(s) can no longer push/pull the force against it; the pressure will then travel out of the valve block thru the rubber return hose to release at the relief valve & back into the tank.

[pugs]

Originally Posted by Lil Giants

Sidenote about the Leimbach hyd system: I think of their system as closed center b/c all oil flow travels back to the tank thru the relief valve, the system is always under pressure. The valve block is open center.

Ok, that makes sense, just is way different from what I am used to in ag and industrial hydraulic controls.