I am currently designing a hydraulic system where i am restricted to use a fixed displacement pump (existing on equipment).

The pump delivers 400 lpm @ 3000 psi

I need to add an aux system that requires 100 lpm @ 2500 psi. Remaining 300 lpm goes to the orignal system on the machine.

Please suggest the best possible approach to achieve the above design goal.

Things that come to my mind - gear flow divider to divide the flow in required volumes!!

Thanks,

Losty!

quote:

Things that come to my mind - gear flow divider to divide the flow in required volumes!!

Used that approach many times with great success.
You must address possible problems with INTENSIFICTION of PRESSURE when the separate circuts opeated individually. I often use a separate Relief Valve on each branch circuit for safety and/or to allow different force limits to be individually set. In essence, using a Motor Type Flow Divider can make a Single Output pump perform as a multiple output pump.


Look in the Circuits design EBook here:
http://www.hydraulicspneumatic.../Article/True/84133/ at Chapter 11 pages FD24-25 to see how Intensification works.

This thread is simmilar to the one you posted a year ago...

I just would like to ask some questions...

1) How much($$$) is the flow divider that you could possibly buy/use in the system?!
2) Is there an 80 gpm(or a little bit higher) gear pump? Is there a 27 gpm gear pump(or a little bit higher)? Or, is there a possible double pump combination for this two displacements? Prime mover rpm is around 1800...
3) Your pump is single stage(one displacement chamber?!?!?!)??? I cant imagine a single stage internal/external gear pump with say 106 GPM at 1800 rpm(havent seen... I dont know... maybe I am wrong)...
3) Your auxilliary system is conventional(no precision needed?)?

Most hydraulic design starts/revolve around the work to be done and normally end with the pump specification(set prime mover specs aside).

Your design starts/revolves around the pump(existing)... it is not impossible, but depends on what you want, what your budget can, etc etc...

Maglub,

You are right ...i did ask the question earlier as well. With new members joining in all the time, no harm in getting opinions as new products are introduced in fluid power industry all the time.

In reference to questions you have asked:

1) How much($$$) is the flow divider that you could possibly buy/use in the system?! Approx $USD1000.
2) Is there an 80 gpm(or a little bit higher) gear pump? Is there a 27 gpm gear pump(or a little bit higher)? Or, is there a possible double pump combination for this two displacements? Prime mover rpm is around 1800...Not possible as the existing pump is a single pump.
3) Your pump is single stage(one displacement chamber?!?!?!)??? I cant imagine a single stage internal/external gear pump with say 106 GPM at 1800 rpm(havent seen... I dont know... maybe I am wrong)...The pump i am referring to is geartek brand which does 112 gpm @ 1800 rpm.
3) Your auxiliary system is conventional(no precision needed?)?..Good question..i should have mentioned this in my last post - no precision is required as the aux system is run by a fixed displacement gear motor.

Thanks,