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

Hydraulics System Issue

Hydraulics System Issue

Hydraulics System Issue

Hello Team / Hydraulic experts

We are in a situation as described below.

we have a turret punching machine. the machine is equipped with hydraulic system for rapid punching. the system has a Yuken A37770 Double piston pump. Pump One is supposed to deliver 9 MPA and Pump Two is supposed to deliver 21 MPA . both lines are going to main hydraulic cylinder with individual Accumulators.
Now when the machine is started both the Gauges show same pressure 20 MPA. We tried adjusting the Pressure of One Pump....the output of other pump also changes , either which way....increase or decrease.
thinking that the Pump may have some defect...we replaced the Pump....with Good working pump. but result is same.
the safety valves , release valves are working OK...
what and where is something wrong..? may be the Main cylinder ? or something somewhere is getting blocked or getting open?

any expert comment on this will put us in right direction..?


RE: Hydraulics System Issue

That sounds like the equivalent of a 'short circuit'. Something is open when it shouldn't be, so the 21 MPA from Pump 2 is leaking into the Pump 1 side. Maybe.

Can you use dye to trace leaks through valves?

(Beware that such issues often turn out to be something that you didn't describe.)

RE: Hydraulics System Issue

why "aircraft" forum ? why not "mechanical" ?

another day in paradise, or is paradise one day closer ?

RE: Hydraulics System Issue

This should be posted in the fluid power forum and would get more relevant traffic there, so hopefully it can be moved.

Can you post a schematic? Without one we're just guessing and can't help you nearly as well.

If the lines from each pump to the cylinder are common, with no valving to isolate them, then they will have the same pressure in them. Is there something that is supposed to isolate the pumps from each other?

The other thing to keep in mind is that piston pumps are positive displacement pumps, and as such will deliver the same flow rate regardless of how high the pressure rises, until one of a few things happen (depending on how the system is configured): a relief valve opens to vent excess flow, thereby limiting the pressure; the pump destrokes to limit the flow and/or pressure (this applies only to variable piston pumps); something fails (motor stall, shear coupling slips, pump internals break etc). Note that the last one should never happen, but sometimes things don't operate as intended.

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


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