Hydrostatic Transmission on 3510

[sandybeach]

As you'd expect, a hydrostatic tranny has no clutch. I assume that it should "shift" fairly smoothly between ground speed ranges. For most work I keep mine in range 2. Range 3 is for highway travel. 1 is for keeping it very slow - as in grading. That said, some things puzzle me.

Sometimes it "pops out of gear," usually from range two. When that happens, it is as if the tractor were "in neutral." I have to shift into one of the ranges - usually back into the range is was using. The problem is that it grinds - a lot, and loudly - as if it were a manual transmission. It can be difficult to get it back "in gear." It can go many hours without doing this. Questions:

1. Why does it spontaneously go into this non-powered state?
2. Why does it grind as if it were a manual tranny?

 

[PoorPlowboy]

What makes you think a hydrostatic transmission doesn't have a clutch? It's grinding and eating the transmission up because you aren't using the clutch before trying to change gears. The pedal on the left....

 

[oldnslo]

If you are still pressing on the pedals for forward or reverse motion while trying to shift the range selector it will grind the gears because the HST is spinning. Remove your foot from the pedals and with the tractor stationary and HST in neutral it should shift between ranges with out grinding. NOTE: you may have to very slightly engage the HST for forward or reverse to get the range selector gears to mesh or shift.

Plowboy:
The clutch on my 2400H is for engaging the PTO and not required for changing gear ranges.

 

[dfkrug]

Why does it grind as if it were a manual tranny?

Well, SB, you have an HST AND a manual trans. The HST drives the input to the manual
gearbox, which has NO synchronizers. That makes it difficult to shift ranges since both the input
shaft and the output shaft have to be at the same speed for the gears to mesh. These
trannies are called "crash boxes" for a reason.

Note that you also have neutrals between both 1-2, and 2-3 ranges. Some range shifter
shafts/forks come OUT of gear very easily, prob due to a weak detent spring. My first
Kubota was like that. Can get a little scary.

 

[sandybeach]

Which left? There are 2 pairs of pedals. One pair is for FWD/REV. The other pair can be tied together. Separately they are left brake/right brake (for turning). Together they are both brakes at the same time. And there is a badly-located rear wheels lock ( for traction).

 

[sandybeach]

You're right! The dealer told me it has 2 trannies, but no clutch (now he tells me). He also said the problem is most likely due to a weak detent spring. I heard that somewhere .... He also said there are some linkage adjustments where adjusting might work ... or not.

Solution:

1. Stop tractor motion
2. Reduce engine speed to idle
3. Try to engage gear in desired range
4. If it won't go into gear, tap the forward or reverse pedal to realign stuff
5. Continue trying 2 and 3 as needed until everything lines up and it shifts smoothly.

Lather - rinse - repeat.

 

[dfkrug]

1. Stop tractor motion
2. Reduce engine speed to idle
3. Try to engage gear in desired range
4. If it won't go into gear, tap the forward or reverse pedal to realign stuff
5. Continue trying 2 and 3 as needed until everything lines up and it shifts smoothly.

Also try:

> take tractor out of 4WD
> make range change on level ground
> some folks find it helps to lift the front wheels off the ground with loader slightly before
shifting

remember:
Any load on the meshed gears will make it hard to shift. This means forward OR reverse loads.
That is why pushing the go pedals F or R a bit helps. This is not alignment; this is
about friction between gear teeth.

 

[dfkrug]

1. Stop tractor motion
2. Reduce engine speed to idle
3. Try to engage gear in desired range
4. If it won't go into gear, tap the forward or reverse pedal to realign stuff
5. Continue trying 2 and 3 as needed until everything lines up and it shifts smoothly.

Also try:

> take tractor out of 4WD
> make range change on level ground
> some folks find it helps to lift the front wheels off the ground with loader slightly before
shifting

remember:
Any load on the meshed gears will make it hard to shift. This means forward OR reverse loads.
That is why pushing the go pedals F or R a bit helps. This is not alignment; this is
about friction between gear teeth.