Theoretical Hydrostat question?

[sawdustdad]

I understand that the position of the swash plate determines the direction and speed of rotation of the motor portion of the hydrostat (given a constant input rpm). If you change the input rotation from CCW to CW, would the operation of the swash plate just be reversed? In other words, if the swash plate drove the tractor forward with CCW input, would it go backward with a CW input? Seems like it would...

[Alvy]

I don’t believe so Frank. The suction and return would become reversed and cavitate the pump. Unless maybe you rotate the charge pump 180 but I don’t know exactly for sure, good question though.

[jimbob200521]

I'm sure someone will come along shortly and give a better, more detailed answer but I believe there is a part (of course I can't remember the name :-/) internal to the pump that you can flip over and it will allow the pump to be operated in the opposite rpm. I looked (very) briefly into this when I was debating rotating my snow pusher engine 180 degrees so the warm engine exhaust air would blow into the cab instead out the front. Either way, it's possible.

[jaynjeep]

Interesting question!

I'm with them... I think there is a way to reverse the rotation but there are some modifications that have to be done in the pump. But I don't know much.. this is just a gut feeling guess.

Hopefully someone with hydro knowledge will come along and give us the real answer!

[J-Mech]

The charge pump can be flipped over for CCW rotation of the pump group. Once that is done, the hydrostat can now be driven in the CCW rotation and it will work just the opposite as it did before. In a very simple explanation, in order for the dash lever not to work backwards, the motor swashplate would have to be flipped over.

I don't know if this was just a question of curiosity or purpose, but there are easier ways to change the direction of the transaxle in a Cub. Like, if you are building a reversed tractor, like a forklift, you can just swap the ring gear from one side to the other.

[Alvy]

Originally Posted by J-Mech

The charge pump can be flipped over for CCW rotation of the pump group. Once that is done, the hydrostat can now be driven in the CCW rotation and it will work just the opposite as it did before. In a very simple explanation, in order for the dash lever not to work backwards, the motor swashplate would have to be flipped over.

I don't know if this was just a question of curiosity or purpose, but there are easier ways to change the direction of the transaxle in a Cub. Like, if you are building a reversed tractor, like a forklift, you can just swap the ring gear from one side to the other.

Jon you mean CW as it’s already being driven CCW in our cubs correct?

[J-Mech]

Originally Posted by Alvy

Jon you mean CW as it’s already being driven CCW in our cubs correct?

I always do rotation as viewed from the rear. From the rear, in our Cubs, it is driven CW.

[darkminion_17]

Originally Posted by J-Mech

I always do rotation as viewed from the rear. From the rear, in our Cubs, it is driven CW.

[Alvy]

Originally Posted by J-Mech

I always do rotation as viewed from the rear. From the rear, in our Cubs, it is driven CW.

Originally Posted by darkminion_17

So why are starter generators and rebuild kits for them marketed and sold as “counter clockwise” rotation??

I get that you’re referencing the rotation as viewed from the flywheel end but why is this different?

[darkminion_17]

If you look at the S/G from its pto end so to speak it turns anti clockwise