Small Engine variable drive (reversible)

I believe that what you saw was a CVT or Continuously Variable Transmission or something like it. There are several types of these and, like you, I find them interesting. Interesting enough to want to experiment on a go-cart.

Try Zero Max. I've used these things before, and they work fairly well.

The go-cart application would be ideal, as it would add a reliable reverse to the cart.

I looked at the zero-max setups already, and talked to an application engineer at their facility. The difference, and downfall of their design is that the boxes they create require the operator to "shift" the box from forward to reverse with a seperate lever. In the design of the machine, this is not desirable.

I have rough designed a drive convertor that would enable a constant input, and have a variable output from neutral to max ratio in both forward and reverse, but would rather buy it if I can find it.

How about an engine running a hydraulic pump/motor combo with a flow control valve? A 4-way valve for reverse.

The only problem with that, which may be the way I go anyway, is the additional cost, and added components to the system ie. Hosing, reservoir, most likely a cooler due to this being mobile, and on and on. I have actually seen this box on a machine with my own eye's, so I know they exist, I just can't find the darn thing.

Mechanically coupled, with this low requirement for torque and HP, would be ideal.

Just as pointed out it is automatic transmission say CVT but manually controlled , that machine may probably be , cutting machine , brushing saw , lawn movers.

search for google through CVT ,lawn movers

What kind of machine is a "Granite State Machine?"

How about one of these Variable Speed Pulleys?

Why is Walt Kelly our enemy? ffeJ

That was an observation put into words by Pogo, the comic strip 'possum created by Walt Kelly, after he and one or two other comic strip characters walked through the swamp in which they lived, which was littered with trash.

What's "ffje?"

The pulleys are variable, but not reversible without gearing somehow to change the output shaft rotation.

The Granite State Machine, Model 5101 was the tag on the unit I saw that was controlling the drive of a small machine. The drive mechanism was directly coupled by chain to the output shaft of this unit. The input was a constant speed small gas engine. The operator had one lever, off of this unit to direct the machine forward or backwards, or neutral with zero output. It was all done with one lever, no secondary shifting.

I googled "granite state machine" and got their address and phone:

Granite State Manufacturing
124 Joliette St
Manchester, NH 03102-3017
(603) 668-1900

'Couldn't find a website, unfortunately. Just give them a call?

What you saw was, without doubt a hydrostatic gearbox. This comprises of an axial piston pump with a swash plate control. The swash plate is connected to the pintal lever that you saw. It sits at 90° to the central axis of the pump and can be moved 15°-25° either forwards or backwards. The variable swash plate determines the displacement of the pump hence the output at the wheels increases or decreases.

Small units are commonly found on golf course grass cutters and large units found on agricultural harvesters and heavy earth moving equipment.

They are expensive and inefficient but used for their adaptability to precisely control speed and direction with one lever. Priceless!

They are generally closed loop and require a semi-supercharged pump but only require a small amount of oil and a good heat exchanger. This makes them ideal for mobile plant.

I agree, its a hydrostatic transmission of one type or another. Generally they can produce a tremendous amount of torque on the shaft, but your not going to win any land speed events.

The great benefit of them, is you can dial in your engine for one RPM, the hydrostatic transmission takes care of the rest. You can tune intake runners, exhaust headers, spark timing and cam timing and lift to be "ideal" at that one RPM. Which is a benefit all engines (engineers) would dream of having, but with the wide RPM ranges that most engines operate, comprimises are made.

I don't think anyone has mentioned this kind of drive yet. I have seen them in more than one application. The input side is a flat disc (usually steel) and the driven side is a smooth wheel (usually an elastomer) that contacts the disc. The axles of the two devices are perpendicular to one another. Moving the wheel such that the radius it contacts the disc changes, will increase or decrease the output drive speed. If you move the driven wheel beyond the centerline of the disc the driven wheel direction of rotation changes.

Based on your lever control description this is possibly the type of drive it is. This arrangement is obviously torque limited since they rely on steel to elastomer friction but I believe they are very simple (thats good) considering you get variable speed output and forward/reverse in one unit. A common place this drive arrangement is used is on rear drive Snapper lawn mowers.

That is more along the lines of what I am expecting to see inside a drive like this. I have been designing construction equpiment from the ground up for over 20 years now. I know it isn't a hydrostat, there was no reservoir or any cooling fins on the exterior.

I am going to see if the contractor who has this machine has one I can take apart. When I figure this out, I will post the results. But I still can't find the company. Granite State Manufacturing isn't it, the tag on this unit says Granite State Machine. I called them a couple days ago.

I like these, because they are so incredibly simple. Nissan uses a similar concept in their continuously variable trans, with steel-to-steel drive, using a special friction fluid.

"A common place this drive arrangement is used is on rear drive Snapper lawn mowers". I meant to say rear engine, not just rear drive.

I know that it doesnt have to look as a hydaustat.

Pump en motor and tank are intergated in one part. Cooling is the one and only critical point. Often the small drive from lawn mowers have cooling ribs, sometimes a small fan for cooling.

Check the folowing link http://hydraulics.eaton.com/products/trans_light_duty.htm

Maybe not as efficient as a mechanical drive but small, lightweight, hightorque and reliabel.

Harmen Beskers, Netherlands

"I recently saw a machine with a small gas engine that was directly coupled to a gear box looking device. The unit had one control lever which was moved to center for neutral (no output), one direction for cw output shaft rotation, and the other direction for ccw output rotation. The more the lever was moved the higher the output shaft speed. All with a constant input speed from the gas engine.

The unit had a tag, Granite State Machine, model 5101.

I can not find this unit, or anything like it.

Anyone have any ideas where to find a comparible unit"

To the guest who inquired about the granite state machine model 5101: I am not sure if there are variations of the 5101, but you can check this site (www.brutusroller.com ) - a specialty manufacturer that sells power rollers and repair/replacement parts for them. A master parts list has the price at 850 for it.

That is actually the machine I first saw the transmission on. I looked at an older model that a contractor has locally. I was trying to fing the manufacturer of the box itself. I retrieved all the information from the tag on the unit that you would think you would need, but it leads absolutely no where.

Granite State Manufacturing is not the manufacturer of this component.

Thanks

Hi . I think I have the solution. If you are in a rural area. Keep your eyes open for hydrostatic wheel-line movers. There are three kinds that I have noticed. Usually the ones with 6' wheels have either a hydro or a belt to chain ratio divider. The hydros have cooling fins. Now the one u describe is usually used on a 5' wheel mover. I just took one off a mover yesterday. Its model # was 5101.