Hydraulic pump selection help needed please

[EngMark]

Strange that there are no clearly defined categories for hydraulic power component questions on Eng Tips...

I think I have a fairly good idea of what I need but I'm getting lost in searching through the online catalogs trying to find it. It seems that there are a lot of pumps that do most of what I want but so far I've been unable to find one that satisfies all my needs. Hopefully someone more into the hydraulic world can point me in the right direction. I'm looking for a variable displacement piston pump which meets the following criteria:
* SAE A or B mounting for close coupled mounting to 28 hp gasoline engine.
* 1-1.5 in^3/rev (16-25 cc/rev).
* ~600 - 3600 RPM
* 3000 psi continuous rating.
* No charge pump needed.
* Prefer if it will pump both directions.
* Prefer if all porting is on back.
* Any form of swash plate actuation OK, will be modified for stepper motor.
* Available individually (non-oem).

Thanks

Mark

 

[tbuelna]

EngMark,

Your requirements seem to be conflicting.

1.5 cu.in/rev @ 3600rpm is 23.3gpm. 23.3gpm @ 3000psi (and 100% efficiency) requires about 41HP. So your 28HP engine won't be adequate for part of your performance envelope.

Also, I don't know of any pump assembly, variable displacement or fixed displacement, that will readily (and efficiently)pump in both directions.

As for commercial, swash plate piston pumps try Bosch-Rexroth:

http://www.boschrexroth.com/country...talogs/Pumps/gear_vane_radialpiston/index.jsp

 

[EngMark]

I think you're thinking fixed displacement. I'm talking about variable displacement swash plate motors. I looked at the Bosch-Rexroth link and they only seem to be offering fixed displacement pumps unless there is more to their site than I'm seeing. Your power calculation is correct if I were to use the pump at full pressure and full displacement simultaneously (like a fixed pump), but I would control it such that those conditions didn't happen simultaneously. Bidirectional pumps are readily available for use in propulsion of ZTR mowing machines and similar equipment, but they are closed circuit pumps requiring charge pumps and additional complexity and most won't go beyond 2200 psi. Here are some examples of those:

http://www.whitedriveproducts.com/productPages/KP.html

http://domweb.sauer-danfoss.com/dom...mation Manual_520L0954_Rev AC_August 2007.pdf

Mark

 

[EdDanzer]

Fluid Power engineering is the forum that may provide more answers. What you are asking for is a hydrostatic drive pump and these are usually used in a closed loop configuration with a motor. Eaton makes a unit as well as several other manufactures.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[EngMark]

My application differs from the usual closed loop hydrostatic setup in that there will be other sources of fluid into the curcuit and relief valve flow out to the tank.

Fluid Power Engineering. Cool. I didn't see that before. Sounds like where I should take my question. Thanks.