Do you think this device can be useful?

Currmudgeon · Sep 2, 2004

( if it's electric, I don't think it requires any gear change. )

On a lathe or other machine tools, it's not the absolute speed that is critical, but the relative speed between two components, like the chuck rotation and the lead screw. That must be precise so it is usually done with gears. So your absolutely accurate rigid drive would allow me to machine a thread pitch of, say 26.251 threads per inch. Not that I can figure out why I would ever want to, but I think you have an application, there.

Currmudgeon · Sep 2, 2004

( the size of a shoebox. That's how compact it is. )

Compactness vs power transmitting ability. Depending on the power transmission level, a universal joint can be bigger than a shoebox.

This sounds specious to me.

Saving weight may not be a big deal, as tractors are often deliberately heavy. It may not make sense to pay to eliminate weight in one area, and pay to add it back in another.

The infinite selection of gear ratios is the intriguing part

unclehan · Sep 2, 2004

Compactness vs power transmitting ability. Depending on the power transmission level, a universal joint can be bigger than a shoebox.

This sounds specious to me.

By shoebox I meant if the drives was designed for a regular sedan, with similar ratio range and torque load.

The infinite selection of gear ratios is the intriguing part.

I hope so, but it's really only beneficial for tasks where engine parameters and operating conditions is fairly constant.

By the way, what is a "powershift" transmission? What about the Kubota GST?

unclehan · Sep 2, 2004

Regarding the machining issue, why not just use hydrostatic transmission since it can easily offer infinite gear ratio.

I don't think the hydro can offer the precision needed. Correct me if I'm wrong. But I thought the pistons seals are good and long lasting, and they usually don't leak?

so what is this "internal leakage" they talk about? And the need for charge pumps.

Isn't that right? The life of a good seal on the hydro should last 2000 hours before needing to be overhauled?

rtimgray · Sep 3, 2004

I guess the idea sounds okay for a transmission with inifinately variable gears, but that would almost have to be something to be sold the manufacturers. As a user of tractor transmissions, I can't say that I would find it an appealing option (I certainly wouldn't pay more for it over a 8 or 12 speed tractor, but it might be okay if it costs less or the same). The reason I say that is because all of the tractors I've used have had between 3 and 16 gears, and with the exception of the 3 speed tractor, I don't think I've ever used all of the gears available on each tractor. Once you get past about 8 gears, you generally start to get considerable overlap in actual ground speed depending on where you want the engine RPMs to be.

I too would question the advantage of light weight for a tractor (maybe that would be a good prospect for a race car or some sort - tight ratios/fast acceleration/light weight combo?). Most tractors, with the exception of those dedicated to do finish mowing, probably need the extra weight (hence wheel weights, loaded tires, etc). I applaud your skills and impressed with theory, but can't say as I see the proper application regarding the tractor industry.

It's so hard to create and so easy to criticize. Good luck with your invention.

Currmudgeon · Sep 3, 2004

( I don't think the hydro can offer the precision needed. )

I agree. All hydrostatic transmission systems exhibit a little slippage. That's why machine tools are geared.