Hydrostat surges jerky in low range

[Kent R]

I purchased a new KIOTI ck20s in May 2013. I like the tractor over all but the hydro is very jerky especially in low range. It is noticeable mostly on level ground. If I try to ease it like parking in the barn it tends to jerk then surge forward. It is not smooth. When under load it does not do this. Rpm's do not make a difference. Dealer says it will wear in and smooth out. I have 50 hours on it now and am curious if any one else has the same problem.

 

[Leejohn]

Were you going change hyd oil and filter at the 50 hr. service?

 

[rider7767]

According to the troubleshooting tree it says:
"Tractor jerks when traveling slowly."
"Inspect neutral valve"

It is a place for your dealer to start.


2.3.5 NEUTRAL VALVE
Neutral valve is a valve that secures neutral position during starting. When the swash plate’s angle and discharge volume become smaller, the motor does not rotate because the oil flows into the inner passage of case (passage B-drain circuit) via orifice. (Maintaining neutral width) As the swash plate’s angle increases, the oil volume passing the orifice also increases causing high pressure drops in fore and aft of the orifice. According to pressure differences generated at this moment, the oil pressure overrides spring force, then the valve moves toward left by blocking contacts between passages A and B. Accordingly, the discharged oil from the pump that was flowing toward the drain circuit (passage B) flows into motor causing its rotation

 

[k0ua]

I can tell you this much, it is not normal. I have owned 3 hydro tractors, 3 different brands, including my present machine a Kioti, and all were smooth as glass at any speed.

James K0UA

 

[rider7767]

I can tell you this much, it is not normal. I have owned 3 hydro tractors, 3 different brands, including my present machine a Kioti, and all were smooth as glass at any speed.

James K0UA

I agree; I test drove a CK20S HST before I decided on the gear model. It was smooth as silk.

 

[Gil Case]

Keep the RPM's at 2100 or above for best performance of HST, or so I am told by dealer.

 

[k0ua]

Dealer says it will wear in and smooth out. I have 50 hours on it now and am curious if any one else has the same problem.

I have a dollar in my pocket that says if you go back to that dealer and drive a different CK20 on the lot, I bet that it does not jerk. Your tractor is defective and needs to be serviced.

James K0UA

 

[Fuggley]

hummm....wondering if your hydro fluid is low?
I have a CK30H that always gives a few good jerks when first starting off in either forward or reverse and I can't seem to get a good reading on the hydro dipstick. When first pull the stick, there is no fluid on it but when I put it back in and haul it out again it shows max full. Think I need to dump more fluid in it... maybe it will smooth out the drive?

 

[oldnslo]

Kent R,
Are talking about transitioning from sitting still to moving? If yes I would suspect the neutral valve also. My Branson also does this in high range when cold. In low range it is smooth. I have 100 hrs on mine with little or no change in how the HST operates.

 

[GMtb42]

Like others my CK20HST is smooth too, no jerking. Take it back to dealer something is wrong.