Hydraulic Motor Temperature

[rc_farmer]

For all you guys who run your Leimbach hydraulic pump continously....... Is there a reccomended continuous run time. I ran mine and it got really hot in a very short time.....less than 30 minutes. Had pump connected to a 3 spool valve with only one valve operating. This is just on my test bench. I want to set, test, then install.

Thanks for any feedback.

[Lil Giants]

When I operate my mini hyds, the cyls are always moving so oil flow is not deadheading thru the relief valve to return to the reservior. That trick saves on amperage consumption & helps to keep the oil temp lower.

My dozer would be the only model that the cyls are not constantly moving, oil flow would be straining thru relief valve for possibly as long as 30 sec intervals without cyl movement... however, the pump psi was never changed from factory setting (10bar) & it's still the original to the model circa 2002.

I saw in a Tower Hobbies e-flyer this infra red temp tester, it crossed my mind briefly whether to get it or not for just such a job. :confused:

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LW6004&P=E

[Stuff]

I remember when running joe's dozer there that i was to turn off the pump when not moving. ex driving around or going back down the pile etc. I can see how that would increase battery time and prolong the life.

maybe a small fan into the pump compartment would help with cooling?

[RCLogger]

I do the same with my D8, when backing up or not blading I shut the hyd pump off. Saves battery power and I also don't think it has ever heated up..

greg

[doodlebug]

Ok, if I'm understanding the hydraulic system, you have an "open center" gear pump. Constant flow.
The valve's dead head (closed center) the oilflow in nuetral or hold position, and the pump goes over the relief valve?
I have a set of valve's on my skidsteer grader attachment, no call for flow, the oil is sent back to the tank (diverter solenoid valve). When I activate a function, a solenoid valve changes the flow through the valve, until I let let go of the toggle switch. That way the valves can be converted to open or closed center operation, with out having to build 2 types of spool valves. Just change the valve inlet block.

So???????? has anybody thought about a dump valve to send the oil back to tank at low pressure, and not heated via the relief valve????? Yah I'm long winded!
Hope this make's sense. Later, Neil#2 aka doodlebug

[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]

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. :rolleyes:

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/w20/gcrawler/Hitachi%20470/?action=view&current=video-2011-02-24-20-38-22.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.

[mazdaparts]

There is a better tool to use for the temperature monitoring assuming you don't have a radio with telemetry feedback. http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXHUH3&P=ML This little guy from Venom (other companies also make them) has a probe that will wrap around the motor or tank or whatever you need to monitor. It's pretty small as well and light as well.

[pugs]

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.

[doodlebug]

It's ironic that the German's can give us an O & K RH 400 mining shovel, but yet the rc hydraulic's are still in the stone age!

Pug's, I think you see my point of not being very efficient, in how it run's.

Yes Lil Giants, no it's no completely dead ended, but it's really not efficient at all. The relief valve shouldn't have to open at all. Variable speed pump drive makes the valve's easier to design and build!

It look's like the Hitachi in the link is as good as it get's for now. But why can't it be better!

I'm not very swift with electronic's, But now I have some idea of what need's to be made, (ivy-2) replacement. With a dose of "K.I.S.S" keep it simple stupid!
Later, Neil#2 aka doodlebug

[Lil Giants]

Actually, the technology is already there for rc minature hyds. The only relevant question is how much do you want to spend Neil?!

Speaking of K.I.S.S., why re-invent the wheel?

The possibly of high efficiency from Leimbach's (one example) mini hyd system with a conventional radio is in direct relation to operator skill vs life sized equip with it's computer compensated, load sense systems that does all thinking for an inefficient operator.

This new idea of using a computer programmable radio for ch mix, esc on pump... nothing will ever top that for maxiumizng low amperage consumption for this rc hobby... I betcha a looney. :D

[pugs]

I wonder is a small enough pressure switch could be tied in to run the esc of the pump motor control, thus changing motor speed to just enough to keep the pressure constant?? This would work basically like the one in the vid above but without tieing up a channel.

Could then perhaps also be setup with a small solenoid valve and second relief valve with higher psi setting and have an optional Power Bulge for short periods of time....

[doodlebug]

Hey Lil Giants,
I'm not a hydraulic engineer, but the spool design makes a big difference in how a valve perform's. The relief valve shouldn't be used to unload the pump in the first place. They could just build a real "open center" valve, solve the problem. Yes I know it's more work to build an open center valve. What's my point, The German's half A$$ed there design! And Yes I base my experience from the 1:1 side, and have alot to learn on the rc side of the fence. Reinvent the wheel, not quite, Just use some of the full size trick's, that I've been learning from Brendan Casey, and down size them. I'm sure we have enough machinist's on this forum to beat the German's at there own game!!!!!!!
With time and money, I want to play with the cnc stuff too!!

P.S. that Hitachi run's smoother than my full size Cat 305CCR!

Hey pug's, the simplest idea, I've had so far is reed switch's and magnet's glued to the servo horn's, for a controller. Not perfect but very simple, kinda like the electric forklift's that start the hydraulic pump after the lever has moved slightly. Each lever has a micro switch attached to it, for pump control. I'll put my soap box back in the dungen. Later, Neil#2 aka doodlebug

[ihbuilder]

Actually , open ( Constant ) flow hydros have been around for some time . And is not hard at all to accomplish . just a mater of a little more machine work on the valve and plumbing . But bear in mind , We're using electric motors to run the pumps ,not IC motors where we fill the fuel tank and run a whole day . No mater what way we plumb these systems you do not want the pump running any longer then needed hence short batt life on long periods of run time . Now the constant flow would reduce the strain on the pump .

Wow Neil #2 I thought the 305 was pretty smooth , Well , compared to a Koering 6605 non- pilot control :eek:

[rc_farmer]

There are a lot of you expert machine guys out there and I, for one, would be onboard to invest in a simplier design. This thread has generated a lot of helpfy information. Has anyone seen this design?

http://www.youtube.com/watch?v=vvaYTVBHHYU&feature=related

[doodlebug]

Hey Steve, thank's for the open center input! Valid point about energy consumption. that's why I'm not a fan of the current setup. I think the relief valve make's more heat that the operation of the machine.

It's like taking a John Deere farm tractor, removing the piston pump and pressure/flow controller. Then putting a gear pump in it's place. Just not a happy efficent marriage!

rc farmer, that's a neat little setup!

Lil Giant's, I hope I haven't pi$$ed you off completely! We can out smart the German's!

Anybody that doesn't have an infrared thermometer, there are other option's, like tempil label marking pencil's, make a mark on the hydraulic tank, and check for temperature change (available at welding supply shop's). Or a candy thermometer stuffed in the tank fill port after it's shut down. 180'f is max hydraulic operating temperature.

Steve, As for my Cat 305 CCR, Certain attachment's, like my compaction wheel
(home made) , the super heavy tilt bucket, ripper shank, make life interesting at time's! I'll have a chat with the Cat people in a few week's.
Later, Neil#2 aka doodlebug.

[Lil Giants]

No, not offended... just concerned with some of your chosen words in describing what we currently have to use today...

I've been in this hobby since it's inception in the mid 90's when there was nothing to be had from this continent for "spare parts". If it hadn't been for the germans to share their craft with us then, the rc construction hobby might never have happened here, or not like it currently is anyway. Harald Stahl & Klaus Leimbach were the first to sell internationally, everybody else was content in just supplying the "local" market.

What Leimbach offers works & is cost effective to mass produce quickly to offer to the world market demand. There really isn't anybody else currently capable or willing to do so at the moment. But the local NA market here is starting to show some interest in the manufacturing of rc mini hyds. And maybe a better system will arise from it as well.

All I'm trying to say is let us not forget where our roots came from in this rc constr model hobby, show them the respect & credit they've earned in getting us started... and by all means lets make it bigger & better for everyone in the future. :)

[doodlebug]

Hey Lil Giant's, well said! I will be quizzing everybody in vegas in 2 week's, I hope to find some micro pump option's. Valve's, I will talk to, manufacturer's at the show and see if there is any intrest for our hobby! The Chinese alway's have a large showing, hopefully I can find us some new source's! Later, Neil#2 aka doodlebug.

[Lil Giants]

That'll be great Neil, I look forward to hearing what you find out.

[doodlebug]

Hey Lil Giants, I'm stoked and ready to go, (Conexpo/ConAg/IFPE). Just bought a new camera. Later, Neil#2 aka doodlebug