Calculating Amount of Manual Pumps

[mdents]

Hello everyone,

Firstly, apologies if I sound stupid for anything I ask...I haven't worked with hydraulics before, and I have tried researching the following without any luck thus far (I think anyway). I have done a quick search of the forum, and can't find anything similar as to what I need.

Basically, I have been tasked with finding how many pumps it would take of a Manual Hydraulic Pump to fully extend three different type of cylinders and their equivalent circuits. I obviously have the specs of the pump and the cylinders, and originally did a simple calculation of the Cylinder Oil Capacity/Oil Displacement per Stroke. However, the manual pump is a two speed pump, so I'm presuming I have to take the 1st and 2nd stage oil displacements into account (I originally only used the 2nd stage displacement as I figured this would give worst case scenario).

Am I going about this the right way, or is there a lot more I need to think about. I have attempted to contact the company from where we have purchased the hydraulics, but have yet to receive feedback. I would be hugely grateful if anyone could help, as it would probably benefit me later in my career too. I am able to provide more information, but want to keep it shorter now so its easier to digest.

Hopefully, with a bit more experience, I can start to help others on the forums too .

Many thanks in advance.

 

[EngineerTex]

It will depend on the load experienced by the cylinder.

Yes - using only the 2nd stage will be the worst case scenario regarding number of strokes. You can also calculate the number of strokes for the first stage and make a table showing that the number of strokes varies based on pressure.

If your load varies as the cylinder extends, then you may want to show it as a graph. If the load will always be constant, then show the number of stokes below [x] pressure and the number of strokes required above [x] pressure.

Engineering is not the science behind building. It is the science behind not building.

 

[mdents]

Thanks EngineerTex, at least I am on the right lines it seems. The use of a graph could be useful too.

But, just for extra clarification before I report back next week...if I have a pump that displaces 126.2cm^3 of oil per stroke and a cylinder with a 516cm^3 oil capacity, it would simply take 4.1 strokes (or 5 in real terms) to fully extend the cylinder? But if the cylinder is under load, then I would have to work out the load on the cylinder per sq/m and go from there.

Many Thanks again for your help thus far...no-one at work can agree on the best way to work this out (surprisingly) so I thought best to ask the experts.

 

[hydtools]

What are the displacements of the 1st and 2nd stage pumps?

Ted