Shafts for "bearingless" hydraulic motors

[EngMark]

The manufacturers of low speed gerotor / geroler type hydraulic motors often offer a "bearingless" version of their motors which don't have the output shaft and bearings included. These are to be used with a device such as a gearbox which has a shaft with internal splines and bearings. The machine I'm working on has shaft loads higher than the standard hydraulic motor shafts will handle so I'm heading in the direction of using a bearingless motor and an externally supplied shaft and set of bearings. My package space allows me to move the bearings further apart than the spacing which is available in the standard motors. My quesion is where can I get a shaft which is ~ 6 inches long on the output end and which has the required geometry to mate with the motor? I have the machining capability to modify a shaft which has the motor interface geometry (internal spline). Eaton is the only supplier which I can find that offers a machinable shaft for bearingless motors but the shaft they offer doesn't differ in length significantly from the shafts they sell in their complete motors so it isn't of use to me. See page c_1-12 of their .pdf catalog (

http://www.eatonhydraulics.com/products/pdfs/E-MOLO-MC001-E3_Disc_C.pdf

) for their shaft offering. It seems that there are many bearingless motors being sold, so someone should be selling shafts or adaptors which mate with them. Does anyone know where I could find them?

Mark

 

[budt]

In all the years I've spes'd. Hydraulic Motors I never sold one without bearings. I've offered the option to customers but never had one take it up.

I've also added bearings to meet Side Load requirements beyond the limit of the motor specified and coupled the motor to the bearing arrangement.

Have you checked with Eaton, Danfoss or other Motor manufacturers?


Bud Trinkel, Fluid Power Consultant
HYDRA-PNEU CONSULTING

 

[hydtools]

I would ask Eaton to make you a custom length shaft. Since they offer a shaft machined to mate to their motor, it should not be a stretch for them to make the ouput end as long as you want it.

Ted

 

[EngMark]

Bud: Yes, I've checked Eaton , Danfoss, many others, and a bunch of Googlin, and nothing except for one supplier of overhanging load adaptors (out of Australia if I recall correctly) which weren't what I needed.

Ted: I'm not a regular user of the hydraulic parts suppliers, but isn't asking Eaton to make me a custom shaft something akin to asking Ford to make me a taller seat? I'd think that they're a huge company that makes many of these shafts to a print at a time and wouldn't want to mess with 1? 5? 10? parts. Being more familiar with this industry than I am, does it seem different to you? If there is a chance, should I ask through a distributor or directly to some Eaton 800 number?

Any other thoughts?

Mark

 

[MikeHalloran]

I can't speak for Eaton, but some of the world's "large" companies are actually pretty thin, comprising a small core group that manages global issues, and hundreds of small satellite units that do the actual manufacturing, and retain the independence and flexibility of a small operation. I.e., it can't hurt to ask.



Mike Halloran
Pembroke Pines, FL, USA

 

[EdDanzer]

We have looked at doing what you are interested in doing to the point of ordering the shaft through our local dealer. The value was in the actual splined sleeve as the shaft is too small in diameter for our application. We never did build the prototype as the shaft would have to be case hardened after welding the sleeve into our larger shaft.

The other option is to have the spline shaper cut by a gear shop. This could be expensive for a few parts. Overhung load adaptors or planetary reductions are an off shelf way to increase side load if you have the room.

The 2000 series is not modifiable but we have added a needle bearing to a 6000 series to increase side load for a couple of special applications.

White has their RE/530, 531 series wheel motor that will provide higher side loads than the 2000 series Char Lynn.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[hydtools]

I'd ask. Many companies have a model shop that does just that kind of low volume work. Start with a distributor or dealer.

Ted