QuestionQUESTION: I have a problem with an Inter 574 tractor, which is somewhat similar to one you dealt with in a question dated 24 April 2008. My 574 is an English made diesel model with standard gear (not hydrostatic) transmission and it definitely has a torque amplifier (with controls to the left of the steering wheel on the dash). It has a front end loader fitted.
Some months ago, the tractor started to go into what I would describe as false neutrals while driving. Typically, you would be moving along normally (say carrying a hay bale on the loader), when the tractor would stop moving or start to coast. If you pressed the clutch and then let it out again, the tractor would appear to re-engage the gear and off you would go again. Most commonly this "loss of gear", which is like the clutch slipping completely and the engine being completely disengaged from the drive wheels, would happen coming down a slight incline, when the load on the engine was lessening.
I sent the tractor to the dealer indicating that I thought the clutch needed replacement. When I got it back (complete with new clutch) the problem was unchanged.
I sent the tractor back to the dealer and this time he checked the torque amplifier. He said that he removed and checked the TA pressure valves, checked transmission pressures, and replaced one of the gearbox pressure springs.
The tractor was better for a very short while but then went back to its old trick of intermittently losing power to the wheels. Again, when you pressed and then released the (new)clutch, the tractor moves off again. Doing front end loader work this loss of power can now happen as often as every 20 seconds.
Clearly the clutch was not the problem, though it was reaching the end of its life. I am convinced that the problem relates to the torque amplifier but (before sending it back to the dealer again) I would appreciate an opinion on what exactly needs to be done to fix the problem. Thanks!
ANSWER: Hello,
Does this problem occur in both hi and low range of the torque amplifier, or only in one range? Usually, this type of problem happens in low range when the sprag (over-running clutch) is worn and starts to slip. Hi range is driven by a hydraulically applied clutch pack. Low range doesn't need any hydraulic pressure. It is only driven by the sprag so there is no pressure test or any other test that can check low range. If it slips in low, the sprag is bad and the torque amplifier will have to be removed and rebuilt. Pushing in the clutch and letting it back out will make the sprag grab again for a little while just as you described.
Good luck,
Arnie
---------- FOLLOW-UP ----------
QUESTION: The problem occurs in both high and low range on the torque amplifier, which I almost never use anyway. The TA is virtually always left in the high position. The dealer suggested that the problem can be affected by the PTO engage lever slipping out of position, though I have never experienced this myself. Can I assume that the best solution is to either rebuild the torque amplifier or to disable it (which I believe is possible)?
Answer Hello,
You can have the TA rebuilt if you want to, but since you don't use it anyway you can get a torque amplifier eliminator that goes inside the transmission in place of the clutch pack. I don't know how much they cost, but it might be a little less expensive than rebuilding the TA. The biggest expense is the labor involved to split the tractor and remove the TA and to put everything back together again.
Arnie
