×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Hydraulic motor for very slow rotation

Hydraulic motor for very slow rotation

Hydraulic motor for very slow rotation

(OP)
Hi all,

I am building a hydraulic drive system for a radio dish. The required speed is very low, so I can do it with a 1/2hp gear pump with a flow rate of 0.27GPM. The links to the pump and motor that I am looking at are given below.

The motor is rated for 21hp with a flow rate of 16GPM. I will not be using it at full capacity, but I need the high torque and the ability to hold against strong wind gusts, so I am using hydraulics.

My question is this: Will the motor be happy operating at such a small fraction of its capacity? I plan to use solenoid valves to control the position of the motor. How feasible is this?

https://www.princessauto.com/en/ac-multifunction-h...
https://www.princessauto.com/en/96-cu-in-4-bolt-hy...

RE: Hydraulic motor for very slow rotation

Hydraulic motors have leakage and will not hold position. You need to add a brake. The case drain is there to accommodate this leakage. Some types of motors even have holes drilled in the pistons for lubrication purposes.

It sounds like the correct type of motor for your application is the Char-Lynn type gerotor motor. https://www.eaton.com/Eaton/ProductsbyMarket/Agric...

RE: Hydraulic motor for very slow rotation

I don't think you really want to do it that way. You may think you do, but you don't. I think you really want to do it with a stepper or servo motor with a colossal low-backlash gear reducer on it. No hydraulics. No leakage. Holds position when you want it to. Accuracy as accurate as you want.

RE: Hydraulic motor for very slow rotation

I agree with Brian, a proper gearbox and motor is the way to go. Stepper, servo, or if close enough is ok, an induction motor with VFD or even a DC motor may work. Hydraulics tend to not work the same way hot as they do cold, internal leakage in the pump and motor will change with temperature. Unless the hydraulic motor is designed for very low rpm, it may not even start moving with such little flow. Oh, and look at the prices for hydraulic servo valves and amplifiers if you still think you want hydraulic.

RE: Hydraulic motor for very slow rotation

Sounds like you need a slewing ring or worm gear to drive this. Hydraulic motor inout and the gear ratio slows it down, the worm gear kind of acts like a brake

RE: Hydraulic motor for very slow rotation

We recently sold $250K of hydraulic motion control to India for radar dishes. I have no idea how they are going to be implemented mechanically except they are using closed loop control. They could use hydraulic motors for full rotation or a simple linear hydraulic cylinder connected to an arm of the rotation angle doesn't need to be that wide. The controller can convert linear to rotational positions or back. There is no need to worry about leakage because of the closed loop control with servo quality valves. There is no need for a brake but I am sure they have some sort of POCVs/blocking valves so the dishes don't move without hydraulic pressure.
I concern we have seen in the past is a notch filter to compensate for dish resonances when the wind blows. These can be implemented in the user program.

If the dish isn't too big you can use a Moog Flo-Tork
https://www.flotork.com/content/dam/moog/literatur...
The flotork converts linear motion to rotational. We/our distributor have used flotork and our controllers on test nose wheel landing gear test systems.


Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
http://forum.deltamotion.com/
IFPE Hall of Fame Member

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close