new hydraulic pump installed and questions about pressure

[kubotaman]

i just finished installing a new hydraulic pump and i have a pressure guage on the line . i did not have a guage before , i plumbed it in while trying to check for pressure on the old pump . i have noticed on the loader that i am seeing more pressure on the line when the bucket is going down than there is when its going up ( significantly more ) and was wondering whether this was normal . i dead headed the old pump when i reversed the loader lines during a power steering install . all the lines are correct now . i just want to make sure this is normal cause i sure dont wanna blow another pump . i dont see the same fluctuation with the rear lift . wondering if there was a problem in the loader valve , but maybe this is normal i just dont know . by the way , many thanks to you guys that offered tips and advice on diagnosing my pump problems , especially vic . this site is a great rescource and a lifesaver to a do it yourselfer that dont have a clue lol

 

[firejunkie]

Which line did you plumb it into ? Is it the main line out to valves? or the the return to tank? or the unloader valve line, compensator line, etc. each will differ in there readings, thats why there are many test ports on the system to allow a tech to read what the system is doing and when/where/what the pressures are for diagnostics. depending on the design of the system you could have different readings between up/down/dump/curl etc etc.

 

[eserv]

Are you using a power beyond type loader valve with a Hydraulic line going to the TPH valve AND a line going to the transmission case? If not then Higher pressure going down is normal because of the amplification effect from double acting cylinders. When you choose down significantly more oil returns to the system than is applied to it because of the difference in volume between the rod end of the cylinder and the butt end. If you can draw a diagram for us of how you have hooked it up it will help.
Ed

 

[kubotaman]

i tapped into the high pressure line per vics video when i installed the power steering . one line comes from the pump and goes to the in side of the loader control valve and the other line comes from the out port on the loader control valve and returns to the high pressure line and continues on through the system . the guage is mounted in the line between the pump and the in line on the control valve . i kinda thought the higher pressure might be from the fluid re entering the system when the bucket is lowered . i will try to post some pics tomorrow.

 

[firejunkie]

many times the cylinders or valves will have an orifice to prevent the arm from coming down too fast due to gravity and weight of the load, you need more flow(not pressure) going up for breakout force. you will see a pressure increase on the down side due to mayby this orifice, and maybe return to tank flow.