2000 Posts and climbing!!!
Join Date: Mar 2005
Re: 300X Lift capacity.
The hyd pump does not produce pressure. It produces flow.
Well in principle this is correct, but as it turns out, the pump is "responsible" for pressure as well. And it is "PRESSURE", not "FLOW" that is responsible for "lifting capacity". Pressure is not "made" by any valve. It is "made", or built-up by the pump.
If the pump, or any part of the "high pressure side" of the hyd. circuit suffers from excessive blow-by or leakage (or if the pressure relief valve is malfunctioning - ie: opening at a lower pressure then expected), you will get "all the flow you want" at zero pressure (no load), because at zero pressure blow-by is minimized. Doing a "cycle time" test at "no load" tells you almost nothing about the pump's ability to build pressure and lift weight.
Of course, if the pump produces no flow at all (because it's totally busted), it will naturally be incapable of building pressure as well... but that would be pretty obvious. No cycle-time test required.
If you want to test lifting capacity, here is a simple method (assuming you have a pile of gravel that you mentioned in your original post):
Gravel, loose, dry = 95 lbs / cu. ft.
Gravel, w/sand, natural = 120 lbs / cu. ft.
Gravel, dry 1/4 to 2 inch = 105 lbs / cu. ft.
Gravel, wet 1/4 to 2 inch = 125 lbs / cu. ft.
Measure the volume of a plastic bucket or pail, using whatever means you want, then use the bucket to load the FEL with the requisite amount of gravel, to set the weight. Start with 1000 lbs for example, and keep increasing it, one bucket at a time, until you get to the point you can't lift the FEL any more.