Anonymous-0
Well-known Member
A while back I posted about my 1026 hydro tractor surging which I never fixed yet but am looking into further now. I studied an IH service manual on the principles of how this hydro system works. The way I understand it, the hydrostatic drive pump will swash one way or another (up to 18 degrees) depending on whether going forward or reverse. For the forward direction it will increase the output motor speed untill the pump reaches its maximum angle, and then the motor starts to decrease its swashplate angle in order to increase motor speed even more. Now with my tractor it will never surge going in reverse. If I go about the same speed forward as it was the fastest possible speed I was going in reverse, that is about the speed and a little bit faster where the speed will surge...
As a test I was running the tractor in my driveway with the engine at about 1300 RPM I believe. In high range I could increase speed steadily from 0 to 4 mph. At 4 mph it was in the range to where it would possibly surge between 3 and 4 mph. If it was traveling a steady 4mph and if I applied the brakes momentarily to put load on it, the speed would drop to 3 mph and stay there after releasing the brakes. Also in that range there is a gap where the speed control lever is not responsive, you could move the lever up to a quarter of an inch without noticing any change in speed. At high engine RPM's the surging in this range is much more pronounced. So my question to you is, do you think this issue is somehow related to the tradeoff between pump going to maximum angle and motor starting to move? Could there be an issue with play in the motor swash control linkage or something? This issue has me baffled and I dont want to tear into something without knowing for sure, lol. Any input is greatly apprecieated! Thanks!
As a test I was running the tractor in my driveway with the engine at about 1300 RPM I believe. In high range I could increase speed steadily from 0 to 4 mph. At 4 mph it was in the range to where it would possibly surge between 3 and 4 mph. If it was traveling a steady 4mph and if I applied the brakes momentarily to put load on it, the speed would drop to 3 mph and stay there after releasing the brakes. Also in that range there is a gap where the speed control lever is not responsive, you could move the lever up to a quarter of an inch without noticing any change in speed. At high engine RPM's the surging in this range is much more pronounced. So my question to you is, do you think this issue is somehow related to the tradeoff between pump going to maximum angle and motor starting to move? Could there be an issue with play in the motor swash control linkage or something? This issue has me baffled and I dont want to tear into something without knowing for sure, lol. Any input is greatly apprecieated! Thanks!