Hi all, new to this forum and to farming so bear with me!
Got a 7740 SLE here with the 16x16 powershift transmission which has become more and more tetchy of late. The low hydraulic pressure light is on and apparently has been for years without a problem. The farmer has known about a problem with the PTO clutch for a while where the clutch is constantly disengaged (with the engine running can't get it in to 540 or 1000 without horrible noises!), PTO kicks in violently but once it's in, it works fine and turns off on the switch. I'm guessing the clutch relies on hydraulic pressure to work properly? Another supposedly unrelated (but I believe related) problem is having to calibrate the clutch packs. It used to need calibrating if left unused for a few days, now it needs calibrating every time it is used and often refuses to calibrate if warm. A variety of fault codes come up - E24, E28 and E32, a different one every time. There is no drive forward or reverse when these come up, must be calibrated to move it. Calibrate it when first started up and you can often complete a steady job like mowing, problems start when you drop the engine revs too low or (god forbid) turn it off! Once it loses drive and an error comes up, you cannot move it for a few hours until it has cooled down, then it will allow you to calibrate the clutch packs. When calibrating, numbers on the dash climb from about 30 and are supposed to stop from 120 -180, this keeps going to well over 210 before it stops, is the number any kind of indicator on wear? Others say that theirs work fine at 200 or more, but I think it could be a clue. Thirdly, I believe the rear lift capacity is poor (makes sense with the low pressure light on the dashboard) and from what I gather, all 3 systems use the same pump? Obviously if it's a pressure problem, it's not going to get better when it's warm due to the lower viscosity of the oil. Power steering is fine, does this use a separate pump? So what would be a good start to the investigation? I'm going to change the filters but they are no where near due replacement yet. Could there be an internal leak? Valves anywhere? Obviously worst case would be pump replacement at £2000! Or does anyone think they're unrelated problems with worn clutch packs maybe? Finally, does the tractor have a conventional clutch on the back of the engine? I have very little experience with tractors so may be overlooking something simple but have reasonable mechanical knowledge so would like to think I can solve this with some help!
Thanks - James
Got a 7740 SLE here with the 16x16 powershift transmission which has become more and more tetchy of late. The low hydraulic pressure light is on and apparently has been for years without a problem. The farmer has known about a problem with the PTO clutch for a while where the clutch is constantly disengaged (with the engine running can't get it in to 540 or 1000 without horrible noises!), PTO kicks in violently but once it's in, it works fine and turns off on the switch. I'm guessing the clutch relies on hydraulic pressure to work properly? Another supposedly unrelated (but I believe related) problem is having to calibrate the clutch packs. It used to need calibrating if left unused for a few days, now it needs calibrating every time it is used and often refuses to calibrate if warm. A variety of fault codes come up - E24, E28 and E32, a different one every time. There is no drive forward or reverse when these come up, must be calibrated to move it. Calibrate it when first started up and you can often complete a steady job like mowing, problems start when you drop the engine revs too low or (god forbid) turn it off! Once it loses drive and an error comes up, you cannot move it for a few hours until it has cooled down, then it will allow you to calibrate the clutch packs. When calibrating, numbers on the dash climb from about 30 and are supposed to stop from 120 -180, this keeps going to well over 210 before it stops, is the number any kind of indicator on wear? Others say that theirs work fine at 200 or more, but I think it could be a clue. Thirdly, I believe the rear lift capacity is poor (makes sense with the low pressure light on the dashboard) and from what I gather, all 3 systems use the same pump? Obviously if it's a pressure problem, it's not going to get better when it's warm due to the lower viscosity of the oil. Power steering is fine, does this use a separate pump? So what would be a good start to the investigation? I'm going to change the filters but they are no where near due replacement yet. Could there be an internal leak? Valves anywhere? Obviously worst case would be pump replacement at £2000! Or does anyone think they're unrelated problems with worn clutch packs maybe? Finally, does the tractor have a conventional clutch on the back of the engine? I have very little experience with tractors so may be overlooking something simple but have reasonable mechanical knowledge so would like to think I can solve this with some help!
Thanks - James