T550, weak lifting

[TheVincentG]

I have a T550 with about 1200 hours on it. I have a service manual as well. My T550 works fine except that the lifting capacity seems to be low. At low rpm the bucket hardly moves up, full throttle it moves pretty good. With a full load of dirt no movement at low rpm and sometimes can't lift it at full rpm. The bucket tilt is very similar but not as bad. I changed the hydro oil recently. I adjusted the pedal linkage. Would the main relief valve cause this? This doesn't make sense based on the more power at higher rpm. Could one of the lift arms be leaking internally? I have some oil around one of the lift arms but I was thinking I filled the hydro oil too full and it was leaking out the side. My sight glass is unreadable(it just is clear) . Thanks for your help!

 

[farmshop]

If you have a bad cylinder the boom would drift down quickly. I would start with the linkages again. Make sure your pedals are centered or even go the extreme in 1 direction to see if it changes. Main relief valve would limit lift. Does your travel work as it should? How about while lifting? You could check drive belt tension

 

[TheVincentG]

If you have a bad cylinder the boom would drift down quickly. I would start with the linkages again. Make sure your pedals are centered or even go the extreme in 1 direction to see if it changes. Main relief valve would limit lift. Does your travel work as it should? How about while lifting? You could check drive belt tension

Thanks, It will hold a load it is just getting it up. I was grappling a heavy tree stump and had to jerk the machine back and forth to get it up when depressing the pedal. It will lift all the way up, and I did adjust the pedal all the way forward so it doesn't go all the way down when fully depressed. On the drive belt I was looking at the shop manual and it said the belt never needs adjustment. It was my thought too but I can adjust the stop adjustment. Would the stop adjustment be what you are talking about? Thanks

 

[farmshop]

Thanks, It will hold a load it is just getting it up. I was grappling a heavy tree stump and had to jerk the machine back and forth to get it up when depressing the pedal. It will lift all the way up, and I did adjust the pedal all the way forward so it doesn't go all the way down when fully depressed. On the drive belt I was looking at the shop manual and it said the belt never needs adjustment. It was my thought too but I can adjust the stop adjustment. Would the stop adjustment be what you are talking about? Thanks

I am not 100% certain on your particular model how the tensioner is but all of ours are some variation of spring loaded whether it's a cam over type spring or a coil spring. Belts stretch over time. If the belt was loose I'd think you'd hear it squealing or notice a lack of traction power but dumber things have happened

 

[Bswwood]

Sounds like a gear pump to me. You can pull the hydraulic filter, which is a canister style filter behind the hydraulic tank, dump it out into a clean container and check for any signs on brass or other metal contamination.

 

[biggie]

If you push against a wall, does the engine RPM drop, almost stall? If it does, it probably not a drive belt issue. When you activate the aux hydraulics, and dead head them (no attachment connected) Does it, draw down the engine rpm? If not, it could be gear pump. The lift and tilt, both have a relief valve.. There is also a Main relief valve for the all of the hydraulic system. I repaired a S590 that had weak lift and tilt. After pressure testing the aux/main relief valves, and doing a direct pump pressure test, all failed. I removed the gear pump and found that the brass inserts on the aux side of the pump were worn and damaged, but the charge pressure side of the pump was fine . (No charge pressure codes) If the drive belt,reliefs, and gear pump are good, you should be able to tip the machine, trying to lift too much weight at full RPM

 

[TheVincentG]

If you push against a wall, does the engine RPM drop, almost stall? If it does, it probably not a drive belt issue. When you activate the aux hydraulics, and dead head them (no attachment connected) Does it, draw down the engine rpm? If not, it could be gear pump. The lift and tilt, both have a relief valve.. There is also a Main relief valve for the all of the hydraulic system. I repaired a S590 that had weak lift and tilt. After pressure testing the aux/main relief valves, and doing a direct pump pressure test, all failed. I removed the gear pump and found that the brass inserts on the aux side of the pump were worn and damaged, but the charge pressure side of the pump was fine . (No charge pressure codes) If the drive belt,reliefs, and gear pump are good, you should be able to tip the machine, trying to lift too much weight at full RPM

To me it seems to have good pressure for the tracks but not for any of the thing operated through the front of machine. I used it yesterday and i was trying to lift a heavy object and after trying for a awhile it shot it up and had good function until it through a code that the hyrdo fluid was too hot. It worked for a while and then it is up to the same thing. I was wondering if it would be actuator or Solenoid Valve, 7304852? Or could it be wiring? If it was a bad gear pump it shouldn't have that kind of pressure intermittently. Thanks, Zach

 

[Bswwood]

To me it seems to have good pressure for the tracks but not for any of the thing operated through the front of machine. I used it yesterday and i was trying to lift a heavy object and after trying for a awhile it shot it up and had good function until it through a code that the hyrdo fluid was too hot. It worked for a while and then it is up to the same thing. I was wondering if it would be actuator or Solenoid Valve, 7304852? Or could it be wiring? If it was a bad gear pump it shouldn't have that kind of pressure intermittently. Thanks, Zach

I agree, gear pump don't usually have intermittent pressure like that. I would check the main relief in the valve body. If oil is bypassing it will get hot and also cause the low pressure in the lift and tilt. Might be the relief valve itself, pull it out and inspect it and try to check the valve seat, might need a bore scope to see in there or maybe put your phone down there and take a picture.

 

[Tazza]

I agree, gear pump don't usually have intermittent pressure like that. I would check the main relief in the valve body. If oil is bypassing it will get hot and also cause the low pressure in the lift and tilt. Might be the relief valve itself, pull it out and inspect it and try to check the valve seat, might need a bore scope to see in there or maybe put your phone down there and take a picture.

Could it even be the aux hydraulics sticking on? it would explain hot oil and the sudden lifting power,

 

[biggie]

Shot in the dark. I've heard, there's a check valve in the control valve that could stick and cause slow lift/ tilt issues. It could also cause slow hydraulic brake release. I think the part number is 7202329 Hope this helps

 

[TheVincentG]

Shot in the dark. I've heard, there's a check valve in the control valve that could stick and cause slow lift/ tilt issues. It could also cause slow hydraulic brake release. I think the part number is 7202329 Hope this helps

I did take out my main relief valve and did a turn on it and seemed to work a little better. Is this check valve the lift load check valve that has a spring and orface? I noticed at an idle it can barely lift the bucked but when I push the pedal initially it moves it up about and inch but then stops but at higher rpm it doesn't have a problem unless with a load.