Hydrostatic question

[drglinski]

General inquiry into how a hydrostatic CC works.....

While slowing the hydro lever on the 147 no matter how smoothly I move it the tractor doesn't respond as such. It tends to be a bit jerky. (sorta hard to explain.) Would this be caused by a worn cam plate slot?

Mind you I worked on the rear end/trunnion last spring. I improved it quite a bit from it's slow uphill and acceleration downhill but it's not perfect. I'm basically just trying to learn more on what would cause that. I did however put a shim between the mounting bracket and the cam plate retaining clip when I was doing the repairs. I reused the old cam plate. New fluid/filter change as well.



Thanks

[Jeff in Pa]

Originally Posted by drglinski

General inquiry into how a hydrostatic CC works.....

While slowing the hydro lever on the 147 no matter how smoothly I move it the tractor doesn't respond as such. It tends to be a bit jerky. (sorta hard to explain.) Would this be caused by a worn cam plate slot?

Mind you I worked on the rear end/trunnion last spring. I improved it quite a bit from it's slow uphill and acceleration downhill but it's not perfect. I'm basically just trying to learn more on what would cause that. I did however put a shim between the mounting bracket and the cam plate retaining clip when I was doing the repairs. I reused the old cam plate. New fluid/filter change as well.



Thanks

Yes, a worn cam plate , worn spring or spring retainers can cause uneven ( jerky ) movement.

You should have perfectly square corners for the best results.

[zippy1]

You said you worked on the trunnion. What did you do to it?
As Jeff mentioned, the corners need to be perfectly square. If you want the best results. When you were in it, what condition were the corners, and end cap, springs?

[ol'George]

Dan,
If you have worn connecting linkage on a high hour machine, you will have jerkiness even if you have a perfect hydro.
It's just the nature of things.
You didn't post what you are working on, but is is more pronounced on the
10 through the 1650's style linkage vs the later 82 series.
I have a high hour 1650 that needs linkage attention, as every joint/pivot in the linkage is worn.
Much like a worn bike chain, just a bit in each link, but combined, a lot of lost motion.
Remove your linkage from the cam plate and see just how much lost motion you have in the linkage back to the friction point.

[drglinski]

Originally Posted by ol'George

You didn't post what you are working on

Sure did. 147.

The trunnion square looked pretty darn good on the corners (a PO had welded on it already.) I got new springs and end caps. I know there is play on the cam plate where the pin slides. I'm thinking the issue is somewhere in there.

If this was a restoration I would def. spring for some new parts. I am at the stage of trying to understand the mechanicals of it better. Thanks for the tips.