hydraulic motor gears

[brents]

Hello all, I am trying to design a hydraulic motor. I am not very experienced in this so here is my question.

I have seen the gears in some hydraulic motors, and they seem to be a "spur type" gear configuration, but they seem a little different than a typical spur gear..

I have been all over the internet, and I can't find any information on gears for hydraulic motors..i have looked in the Machinerys handbook and they only talk about spur gears..Is there any information, whether a website or book, that I could buy out there that describes dimensions of the gear?

I would need to make a blueprint of the gears so i can have a machine shop make them, but I don't have enough information on the gears to make a print..


Any help would be greatly appreciated..

thanks,
Brent

 

[MikeHalloran]

You're right, the profile is not exactly like that of power transmission gears. Biggest difference is that they're intended to run with zero/tiny lash and/or tip clearance, to minimize internal leakage.

Clearance is such an issue that some popular hydraulic motors and pumps are assembled with negative clearance to the aluminum housing, turned with a big wrench after assembly, and the resulting chips are mostly/usually removed before shipment.

You could get custom gear stock made by Grob. Your local machine shop has a better chance of making the parts for a piston type motor than a gear type motor, but the design is more difficult.

If you're going into the gear motor business, you'd best rent some expert help to get you started. If you only need a few, you'll be way ahead to just buy them.



Mike Halloran
Pembroke Pines, FL, USA

 

[EdDanzer]

My first question is why would you want to design and build a gear motor when you can buy them?
The cost of making the gears is the single largest expense. The gear tooth form is usually a company secret. These are usually hardened and ground with a profile that reduces running clearance and pressure trapping when the gear tip enters the gullet between teeth of the mating gear.