Jumpy Hydraulics

[GenrlCub]

Touch control is outta control. Cannot adjust mower height--slightest touch on the lever and it will jump up all the way, go down all the way, sometimes it bounces up and down nonstop. Cannot get it to desired height.

Started this behavior after we replaced the touch control operating rod O-ring to stop a leak. that procedure went according to plan. I topped off the fluid w/about a pint and 1/2, bled the air out with about 40 full up-down rotations. Following week repeated the lead-out and it took a tad more fluid.

Worked great for 10 years, now this. Do I have an air-lock? Should I drain all the hy-tran out and fill again? Help Make my Hydraulics Great Again! Any clues?

[tst]

sounds air bound, take the fill plug out and cycle it more, you fill it with the rockshaft in the up position

[Glen]

Hi,
The Cub operator's manual says to check the Touch Control fluid level the last time after filling it, with the arms in the rear or down position.
There is an airspace in the top of the block. The fluid rises in the block as the arms go to the rear or down position. If you fill it to the filler plug hole with the arms ahead, it will have too much fluid in it.

[GenrlCub]

Lever was in the rear each time I filled with hy-tran. level was just below the fill hole. Could I still have air-lock, and would I benefit from completely draining and refilling/bleading?

[Jim Becker]

When you put the control lever in an intermediate position, does it stay there or does it move by itself as the rockshaft moves?

[GenrlCub]

Jim it often continues to move by itself when set in an intermediate position, and sometimes cycles up and down repeatedly by itself.

[Jim Becker]

Check all the linkage between the control lever, control valve, and piston for any binding. Make sure the friction pad on the control lever is providing some friction.

What happens if you hold the lever in an intermediate position?

[GenrlCub]

if moved the slightest bit, it often shoots the mower to the extreme up or down i.e., engages the hydraulics fully. And as mentioned, sometimes starts to auto-cycle up, down, up, down until I extend the lever to one extreme or the other forward or back. Puzzled by this--it adjusted normally before changing the O-ring--just leaked.

[Dale Finch]

Are you sure you got the linkage to the control rod back on correctly? There are limit tabs, for example, that a rounded part of the linkage must ride between. Also, the rod from the hand lever has nuts that adjust where those limits are reached.