hydraulic pump sizing for a 6 tonne cargo lift

[tojojoseph]

We are fabricating a 6 tonne cargo lift , piston is having a stroke 3m, cylinder dia 80 mm shaft Dia 40 and we are facing problem in finding a right pump for our cargo lift.

 

[MikeHalloran]

You have to decide how fast you want to lift the load.


Mike Halloran
Pembroke Pines, FL, USA

 

[tojojoseph]

Speed of lift is nearly 18 mt/min

 

[hydromech]

You will need at least 90 ltrs / min.

Pressure to lift 6000kg or 58.860kN is 117 BAR or 11.7 MPa

Power required, assuming 80% efficiency is 21.9kW, say 25kW to be safe.

Adrian

 

[tojojoseph]

Thanks Adrian

The capacity of pump which you had calculated 90 lit /min is way too much .
Piston which has a length of 3m and Diaz of 80 mm will be around 28 lit/min
So Kw should go down?.

 

[hydromech]

Checking...

Assuming pushing on full bore of cylinder.

Bore = 80mm
Area = 80^2xPI/4 = 0.005027m^2
Length = 3m

So volume = 3 x 0.005027 = 0.01508m^3 = 15 litres

You want 18mtrs/min, so that's 6 x 15 = 90

The pressure at 6000kg = 117 BAR

To lift 6000 kg with that cylinder at that velocity will take 22kW at 80% eff.

I can't see where you would get 28 litres/ min from...please explain.

Cheers

Adrian

 

[hydtools]

Flow rate should be velocity x area
18 x 0.005027 = 0.0905 Same result, 90lpm

Ted

 

[Oldhydroman]

Never mind the pump - have a very careful look at the buckling strength of your cylinder rod before you go much further. A lot depends on how you mount the cylinder, but if we assume a front trunion mount and a rod end bearing, your effective buckling length will be around 3500 mm. To lift 6 Te with this arrangement your rod diameter needs to be something like 70 mm.

DOL

 

[hydromech]

Steady there DOL...You'll scare him off

When he agrees with volumetric flow required we can ask him the more difficult questions about buckling calcs and motion control valves.

Then we can finish him off with CE marking and LOLER regulation compliance.

Adrian