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

overheating hydraulics

overheating hydraulics

overheating hydraulics

we have several hydraulic systems on site. now and again the hydraulic oil becomes very hot. This results in damaged seals and 'o' rings. Why does the hydraulic oil become so hot and what can be done to prevent it from becoming hot. Im no engineer, but our engineers on site cannot seem to solve this one. thanks

RE: overheating hydraulics

Somewhere in the systems you are having energy losses.  These losses are generating heat.

What are the purposes of the hydraulic systems?

A quick one to check is a relief valve that is set too low.
Or, somewhere there is a flow restriction creating a lost-energy pressure drop.  Pinched hose.  Pinched tubing.  Hydraulic lines too small for the flow rates.

Are there any heatexcahgers in the systems?

A circuit diagraphm would be helpful.

What changes or adjustments have been made to the systems since they were first set up?

Has heat been a problem since the systems were first set up?


RE: overheating hydraulics

Depending on what you are doing with the hydraulic system you get varying amounts of heat into the oil/fluid. A properly designed system will have equipment to get rid of excess heat such as an oil cooler or a properly sized reservoir. In some applications the settings of the relief valve may impact the amount of heat put into the oil. Ambient air temperature has an impact also.

There are some applications such as continuous testing of two hydraulic cylinders working against each other all the energy of the work is absorbed by the oil so a massive cooler could be required in this application. Your application is having intermittent overheating problems so if the application is consistent you should either shut the process down during times of high heat or install an oil cooler in the return to tank line. Wherever you put the oil cooler in the system check the pressure in the line and make sure it does not exceed the oil cooler max pressure rating. The size of the cooler will depend on how much excess heat you are seeing the the cost impact of changing the seals.

RE: overheating hydraulics

if O-rings and seals are damged by the high oil temperature the oil temperature certainly is too high. have you found any relationship between the oil temperature and the ambient temperature and or the type of load on the system? if there is a relationship, a properly dimensioned cooler can solve the problem. if there seems no relation at all, the actual system should be investigated to see whether all the valves in the system are working as they should and especially whether they are closed when they should and not "nearly closed". in the latter case you might be pumping around oil through very narrow orifices which is a certainly a cause for overheating. usually a valve that is not working properly can be heard: it produces a "screaming/whining" sound. another item to look into is oil viscosity. both too high and too low a viscosity might lead to higher temperatures - what viscosity is used in the system and what is the ambient and oil temperature?

RE: overheating hydraulics

Have you ever changed the hydraulic oil, is there a preventive maintenance program?

RE: overheating hydraulics

Your description is too vague.What seals are being damaged?At the relief,the whole system?Do you run oil coolers?A cooling control valve(thermostat)?Working components?Describe your system in detail along with all info on problem ,supply hyd.schematic?And an educated logical approach can be given.BTW it sounds like your engineers need training

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


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