hst surges under load

[red4now]

Believe this is normal. My 2 Kubota HST's do the same thing. Very noticeable in high range.

What he said re: high range - same here.

 

[rglaser]

Thanks to all for the input. I don't think this has anything to do with the engine because sound and tachometer indicate no increase (maybe even a slight decrease) in engine rpm during this surging. My best guess after considering the responses so far and a little thinking is that under a light load, the hst is in some type of bybass mode and when it senses a load it comes out of the bypass mode and applys more power. Just my guess.

-Rob