I purchased a Vio35 with 3500hrs. Hydraulics appear strong on all circuits, however the Arm ram is slow ONLY on extension (ie when pulling towards the cab).
I first started by checking pump hydraulic pressure on the arm circuit (pump 1) which is at 3000psi (what it should be). The arm psi should be set at approx 3700psi, so went about trying to increase the pump 1 system pressure and subsequent circuit pressure. I can only get around 1800psi MAX on the arm extend circuit and any adjustments made seem inconsistent (ie, on occasion screwing IN has resulted in lower pressure).
I smelt a rat when adjusting the valve pressures. The valve in question has a fabricated end cap, not factory. I had thought GREAT, this will be the issue and perhaps it hasnt been machined correctly, say with inadequate travel internally stopping the valve from opening fully. I went about swapping the valve cap to a factory one from another circuit and tested. The same slow ram is still there so hunch was not right. I'd also swapped the relief valves on each end of the same valve thinking it would make the retraction slow, not the extension, but it didn't, so i suspect the pressure reliefs are okay.
All this messing about with valves has gotten me nowhere. Is it possible something in the ram is at fault if it is slow only on extension? The ram visually looks okay, ie not bent and only very minor weeping consistent with age. No visual signs of hoses pinched or damaged.
I've also put new hydraulic oil and filters in the machine. I've swapped to 'backhoe' mode so joystick controls are swapped and problem is still there.
The valve 'hisses' like your just creeping the joystick when you've got it fully pulled. I so thought it was valve rod travel issue.
Any advice would be much welcomed!
I first started by checking pump hydraulic pressure on the arm circuit (pump 1) which is at 3000psi (what it should be). The arm psi should be set at approx 3700psi, so went about trying to increase the pump 1 system pressure and subsequent circuit pressure. I can only get around 1800psi MAX on the arm extend circuit and any adjustments made seem inconsistent (ie, on occasion screwing IN has resulted in lower pressure).
I smelt a rat when adjusting the valve pressures. The valve in question has a fabricated end cap, not factory. I had thought GREAT, this will be the issue and perhaps it hasnt been machined correctly, say with inadequate travel internally stopping the valve from opening fully. I went about swapping the valve cap to a factory one from another circuit and tested. The same slow ram is still there so hunch was not right. I'd also swapped the relief valves on each end of the same valve thinking it would make the retraction slow, not the extension, but it didn't, so i suspect the pressure reliefs are okay.
All this messing about with valves has gotten me nowhere. Is it possible something in the ram is at fault if it is slow only on extension? The ram visually looks okay, ie not bent and only very minor weeping consistent with age. No visual signs of hoses pinched or damaged.
I've also put new hydraulic oil and filters in the machine. I've swapped to 'backhoe' mode so joystick controls are swapped and problem is still there.
The valve 'hisses' like your just creeping the joystick when you've got it fully pulled. I so thought it was valve rod travel issue.
Any advice would be much welcomed!
