Hello Everyone My loader runs out fine in all 4 gears, but when I go to dig, push or load the bucket the drive seems to slip. Is this a torque converter issue? There is no grinding sounds or jerky movements. Thanks John
to identify if your problem lies in the torque converter or transmission you need to do this simple test. It will require an assistant. With the engine running and the service brake applied put the transmission in any gear then accelerate the engine to maximum. Does the short drive shaft connecting the converter and the transmission stop turning (and stay stopped when you accelerate the engine) when you do this..? Repeat the test using every gear, forward and reverse. If the shaft stops when you engage any gear your problem is in the torque converter. If the shaft turns in any particular gear you have a transmission clutch issue.
How long have you had this loader? What gear are you trying to dig in? Is the variable torque lever and switch working? We need more information to help you. Later Bob
I was thinking along the same line also. There is a solenoid valve on the converter valve that has a control cable hooked to it. If the push pull cable is not hooked up or someone has put it into the minimum torque position it will act like the converter is slipping. Should be a small rocker switch on the hoist control lever that controls the solenoid that if working properly will over ride the setting on the torque control lever. If I recall correctly on the 988B's power goes to one side of the solenoid and the other side goes back to the rocker switch and it is grounded when switch is pushed forward. Had to do some research and I had forgot that the early 50W6012 and earlier 988B's were wired a little different. On those one side of the solenoid is grounded right at the converter valve, short black wire. The 988B's after 50W6012 are as described above with ground up in cab.
Just wanted to thank everyone for your help, it was a short in the rocker switch.
Glade to hear you solved it that easy. Those are tough old machines and if treated right should give you many hours of service. One word of note. If you are someplace that gets real cold be sure to let the hyd. oil warm up good before moving. We had a problem a couple times with people starting machine and pulling out of parking spot and make a sharp turn to the right or left. Steering stop valves and pressure relief valve can not react fast enough and they can blow a hose! Not fun to change when cold and oil soaked!
What a great thread, eldiablo may have saved many thousands of dollars thanks to the great advice he got here!
Keep an eye on keeping the handbrake lever under the transmission hatch smooth. If it is getting sticky then the brake does not come off completely.
Nige, can I ask 2 questions on this point. 1. What are you refering to as the ' service brake ' ..... the left Brake/clutch pedal, the right brake pedal or what I call the park brake ? 2. With this test, what should the shaft be doing if both the tque-converter & the transmission are in good condition.
Not Nige here but I will try to answer. Service brake would be the right brake pedal. Doing the test while pushing down on the left pedal will not work because that would put the transmission in neutral. I believe Nige intended this only to test the transmission. As he said "If the shaft turns in any particular gear you have a transmission clutch issue." If the shaft did not turn in any of the gears that would indicate the clutches were NOT slipping. Next steps to test the converter would be to do some pressure tests of pressures and a stall speed test among others. Those take around twelve pages of the service manual and proper tools.
Dammit - beaten to it by Hansen...... I was actually penning a reply but got dragged away by SWMBO. Service Brake pedal is the right foot pedal. Transmission neutralizer & brake combined pedal is the left foot pedal. You press it down a hair and (provided the linkage to which it's connected is correctly adjusted) it neutralizes the transmission, press it further and it applies the brake just the same as the right pedal does. 1. At Low Idle engine speed with the transmission in neutral the short (upper) drive shaft between the torque converter and the transmission should be rotating at (give or take) engine speed. 2. At Low Idle press the right pedal fully down and engage any gear. The shaft should stop dead within less then half a revolution and with an audible "clunk". 3. Repeat test 2 by engaging each gear in turn (1, 2, & 3 both F and R) and when you have the gear engaged accelerate the engine to as high an RPM as it will go (this will not be quite the same as High Idle RPM in neutral). Observe the drive shaft between the converter and the transmission. Does it continue to rotate (even slowly) in its normal direction of rotation, or does it not move..? (It will move a bit because you have slop in the drive train all the way from the transmission through the drives shafts, diffs, and final drives) If the transmission input shaft does not move, you could possibly have a converter problem causing your heating issue. If it moves during the test in any specific gear, on the face of it there is a good chance that there is a slipping clutch in the transmission related to that gear (or gears).
Thanks again to both of you for that info. I might test this on the old girl.