Measuring a volume of oil

[Mechdesignron]

Hello,

I have a chamber that is made up of a cylinder and a piston. It takes 20 PSI to 42 PSI (As the piston actuates further due to spring force) to move the cylinder. This chamber is buried in equipment. I want to know how much volume it takes to move the piston til it stops. There is a range, 33.87 to 67.74 in^3 that the chamber could be. The fluid (hydraulic oil) would have to be delivered through a line (hose).

Does anyone have any ideas on how to measure this? Hopefully I have described what I need well enough.

Thank you

Ron

 

[MatthewL]

Ron,

The way I read your question is the available cylinder volume with the piston at one end of its travel is 33.87 in^3. After adding sufficient fluid at a sufficient pressure to overcome the piston/spring resistance and move it to the other end of its allowable travel, the new volume is 67.74 in^3. Therefore, the maximum volume required once the system is liquid full would be the difference between the two chamber volumes, in your case 33.87 in^3, if the hydraulic oil acts like an ideal fluid. If you are asking a different question, a sketch or drawing would be helpful.

Regards,

Matt

Quality, quantity, cost. Pick two.

 

[LittleInch]

I thought this was a student question to start with, but you've been here many times before so I'll try this;

A sketch would help, but your piston stops moving when the forces become equal between your spring and the hydraulic fluid pressure. Hence you need to know the spring force rate per distance, e.g. N/mm, and the area of your piston time the pressure using the same units. Then it's just two equations, one for 20psi and one for 42 psi, which gives you the movement of the piston. With the area of the piston you then have your volume.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Mechdesignron]

Hello,

Thanks for your posts. Lets try this with more specifics. This is for a clutch/brake application. See attached sketch. The piston stops once it reaches the disc pack. The spring force has to be overcome to move the piston. As the disc pack wears, the piston will move further. I really want to know how much the disc pack is worn. Normally we just measure the piston stroke. In this application the clutch is buried and there is no way to do that. So I was thinking of trying to measure the volume required to move the piston.

I think I could design something but I was wondering if there was something already out there.

Thank you for your help.

Ron

 

[Latexman]

It may be easier to measure the volume change in the oil reservoir. When the brakes on a car get worn, sometimes the low brake fluid level light goes on.

Good luck,
Latexman

Technically, the glass is always full - 1/2 air and 1/2 water.

 

[LittleInch]

I'm finally getting this. The remaining question though is what is the other end of the hydraulic line connected to? Normally this would be another piston? Could it be changed to another piston?

Any sort of flow meter than could be placed in line or clamped on?

Your other way is to measure the pressure and relate that to spring force or is the hydraulic pressure actually related to force on the disc pack - still a little strange to me.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[Mechdesignron]

Normally it is connected to a hydraulic power source up to 500 PSI. You would have to disconnect it or close it off an tee in the gauge. That's what I'm inquiring about, is there something that I could put inline or tie in to measure the volume?

 

[LittleInch]

Something like this?

http://www.hedland.com/index.cfm?fa=prd.detail&sec=406&

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[tbuelna]

Mechdesignron-
Based on the sketch you provided of your clutch/brake design, there is no way to measure wear of the friction discs based on the volume of hydraulic fluid moving in/out of the working chamber unless you first established a baseline volume flow of the hydraulic fluid when the friction discs were new. The springs will always return the piston to the same position when the hydraulic pressure is relieved, and there will be some axial clearance in the stack even when the friction discs are new.

Hope that helps.
Terry