I replied, and didn't look at the Age! What are the size of your Rams? Are you running a PTO gear pump?
Does anybody understand Hydraulics?
- Thread starter imagineero
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I will go ahead and address one of the things that was brought up and that is the part about the PS being different with each stage of his cylinder. Without gong back and re-reading, I think the psi numbers where something like 600psi first stage, 1500psi second stage and 2200 third stage. I assume the pressure gauge was between the control valve and the cylinder. I would not consider different pressure reading depending on which stage being used, to be unusual. The first and second stages of the cylinder would have larger piston areas than the third and final stage. The pump will only make pressure according to the amount of resistace it encounters. The first stage of the cylinder with the largest piston would need the least amount of pressure because of the sqin area of the piston and would use only the amount of pump pressure needed to overcome the resistance it encounters as it starts the lift. The second stage of the cylinder should see less resistance but because of the smaller surface area of its piston, pressure might be expected to rise if it takes more force to overcome the resistance. The third stage would have the least amount of resistance, but the piston size once again decreases and again more pressure would be needed to to the work. The only way to really check pump pressure would to be raise the dump bed to full raised position and dead head it by continuing to raise the bed. At this point the pump would create maximum pressure and give a more accurate ideal of what the pump is capable of, up to the point that the relief is set. Usually the relief can be adjusted somewhat to allow the pump to create some more pressure. Now it is possible that there is some pressure bypass in each of the cylinder stages, but I would suspect the bypass would become worse the more the cylinder is extended, not less. One could eliminate the cyl during the pressure test by simply removing the hydraulic line from the cyl and capping it (hose)off. You could then just bump the control valve and watch the pressure reading at the gauge. Of course this method risk blowing hoses and taking a oil bath, but excess pressure should just dump over the relief back to tank. Capping the hose wouldnt be any different than dead heading the cyl and if you tested the pressure using both methods, it would give you some ideal of how much, if any, pressure is bypassing in the cylinder. I also wouldnt be suprised if there isnt some pressure bypass inside the control valve. This is not unusual with older hydraulic systems and a little more complicated to check.
ChoppyChoppy
Tree Freak
5" on the first stage. Yes gear pump mounted to the trans
