Thread: Some contemplations on overdrive

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Originally Posted by JoelGrimes

You guys think about all the angles! Since a fluid does not compress, why not build a drag car with the engine set to run at max torque (after warm up) and put the power through to the drive wheels hydrostatically, using a higher volume pump than the motor, and use a positive control valve controlling bypass, linkaged to the pedal on the right, you could theoretically turn the rear tires 300 + mph as soon as you got the go light! can you imagine the flying parts? Seriously though, I wondered about the logic of gear ratios as a youngster when I discovered that sprocket ratio on a bicycle was affected by the throw length (stroke) on the pedal cranks. Am I getting it?

I think there has been an issue of parasitic loss in the hydrostatic drives. But in theory if you could put the engine at the peak of the torque curve and vary the multiplication to keep it at peak that would be a good thing.
You bicycle analogy is a good simplification of crankshaft stroke.

FWIW Ford does have a constant variable transmission in a few of it's smaller cars. ZF builds it.