Hi, Can anyone provide further advice on identifying the cause of a power converter issue on a D6N (ALY2066-up)? The machine has around 15,000 hours on the clock and lacks the power to drive in gears above 1.5F under load. The stall test also fails in gears above 1.5F, and the converter output shaft does not spin. The engine runs well and delivers full power during this situation. After adjusting the power converter outlet relief, replacing the inlet relief valve, and adjusting the transmission relief, I obtained the following pressure readings: Power converter outlet pressure: 410 kPa (takes about 30 seconds to reach this reading — is that normal?) Power converter inlet pressure: 890 kPa at cold start and 450 kPa when warm (spec should be 700 ± 70 kPa) Transmission main pressure: 3100 kPa Then I tested the transmission feed pump flow rate and the transmission feed line. The result was 40 L/min at approximately 40 °C oil temperature (normal should be 54L/min at 1800rpm and warm oil). After replacing the pump, the pressure readings were similar, but the readings were reached slightly faster. The problem remains the same — no power to pull above 1.5F gear under load. Is it possible that the scavenge screen is blocked at the power converter housing, or that the converter itself is faulty (e.g. internal leakage), any other idea? Thanks for feedback..
You mean to say you replaced a pump without first checking the screens (there are two of them by the way) for debris.? Question: If you lift the floor plate and with the engine turning at Low Idle RPM engage any gear (FWD or REV), does the drive shaft between the torque converter and the transmission stop turning immediately.?
There are two screens — one in the main suction line at the transmission hose fitting, and another in the torque converter housing. I thought the screens had been cleaned during previous maintenance, but it seems that wasn’t the case. I’ll need to check them now. After replacing the pump, I noticed an improvement in pressure build-up time — so the old pump was worn. When the engine is at low idle and a gear above 1.5F or 1.5R is selected, the output shaft does not rotate. In 1.5F and 1.5R machine can handle loads when pushing materials.
All I need to know is whether the shaft stops turning in ALL gears, FWD & REV. Don't worry about the MVP system, just see what happens in 1st, 2nd, & 3rd speed in both direction. Not interested in pushing power at this point. Be sure to post photos of whatever you find in each screen.
Power converter? To me it will, say take 12 or 24 volts and jump it up to say 120VAC? Is it a torque converter? Or something else I know nothing about?
The scavenge screens are clean. The shaft stops rotating in all gears at low RPM when the service brake is applied. At high RPM, the shaft starts rotating in 1.5F and 1.5R gears, and the machine attempts to move, transferring power through the brakes to the final drives. The customer says that the machine should have power to move in 2F and 2R gears under loads - so machine should be able to move during a stall test in 2F gear as well... i think so. When measuring pressures then the inlet pressure is fine when the oil is cold, but when it warms up, the inlet pressure drops to 400-500kPa — it should be 700 kPa. The outlet pressure increases to 410 kPa when the oil is warm. Oultet relief regulated, inlet relief and pump changed, screens are clean...
My mistake, the correct title should be Torque Converter
I think you may be misunderstanding the specifications. The only specification for converter inlet pressure is with warm oil (around 75 DegC), not cold. Having said that if there is a big difference between hot and cold pressures then internal leakage in the powertrain oil system is most likely to be the cause. That is still significantly below the minimum allowable pressure, and way below the specified pressure. Have you measured the Priority Valve pressures with warm oil.? The customer is NOT correct. With the system at operating temperature and everything correct the only gear that should be able to push (and even then only slightly) through the brakes is 1st speed in both directions. The tractor should not move against the brakes in either 2nd or 3rd speed. Just because the tractor can push dirt with the blade in 2nd speed does not mean it will push through the brakes in that speed when it is stopped and the torque converter is stalled. If I were you I would forget about the Multi Velocity Program (the 1.5, 2.5, etc speeds) for now. It is only confusing the diagnosis. Focus on the basic 1st, 2nd, & 3rd transmission speeds.
A delay of 30 seconds to reach maximum pressure is definitely NOT normal. It should hit max pressure within 5 seconds or less from engine startup. As I mentioned above my suggestion would be to measure Priority Valve pressures to eliminate the possibility of leakage in the brake system. With 15,000 hours on the machine if the transmission has not been previously rebuilt it is probably about time it was done. The same comment would probably apply to the brakes.