Hydraulic Speed Governor

[Brian Rupnow]

In 50 years of designing machines and mechanical devices of all kinds, I kind of thought that I had "seen it all" in terms of "neat mechanical devices". Last week while researching a machine that is already on the market, I seen something which just blew me away. This is an absolutely brilliant solution to controlling the speed of a rotating shaft. I would have never thought of this in a hundred years. The machine in question runs down an inclined plane, under the force of gravity---but---the speed at which it rolls must be controlled, so that it doesn't "run away" under the force of gravity. The axle which the wheels are attached to, is actually shaped like a crankshaft. The blue cylinder has the rod end mounted on the "throw" of the axle/crankshaft. The clevis at the rear of the cylinder is attached to the framework which supports the rotating axle/crankshaft, in a manner which allows it to pivot. The cylinder is filled with hydraulic oil on both sides of the piston. As the wheels and axle rotate, the axle/crankshaft drives the piston rod in and out of the cylinder body, forcing the oil back and forth from one end of the cylinder to the other. The needle valve fitted to the line which runs to both ends of the cylinder can be adjusted to control how freely the hydraulic fluid can pass from one end of the cylinder to the other,thus making it possible to control the speed at which the axle can rotate. Granted, I don't think it would be a totally constant "drag effect" on the axle, as there would be a bit of a "dead spot" as the piston went over "dead center" at both ends of the stroke, but overall, during the greatest linear part of the stroke in both directions the speed would definitely be controlled. There are probably 25 other ways of achieving the same result to "control speed", but this is the first time I have ever seen this. It is so uniquely "neat" that I just had to show it.---Brian

 

[mcostello]

And with a check valve it would seem to be able to be made to have less resistance in the other direction.

 

[RichD]

Over the years I've seen many hydraulic governors, usually for controlling steam turbine speed. One in particular was used for our turbine-driven standby generator. We would adjust the turbine speed via the hydraulic governor "knob". There were two other "knobs" one for deadband (the span of no reaction) and the other for sensitivity.

We would set the speed to achieve "parity" between two Hertz meters...one being the live load, and the other the generator output.

The manufacturer was "Woodward" governor.

Rich

 

[RonGinger]

Where does the energy go? It can only be turned into heat and heats the oil. Is there any kind of radiator or cooling fins?

 

[Brian Rupnow]

Where does the energy go? It can only be turned into heat and heats the oil. Is there any kind of radiator or cooling fins?

The "vehicle" was only used for very short duration trips. I suppose that yes, if the vehicle travelled a long distance, it would require some means of dissipating the heat.

 

[itowbig]

interesting.

 

[jimjam66]

The principle is identical to that of the front suspension of a motorcycle. The oil transfer process slows down the 'dive' of the nose of the bike under heavy braking. Racing teams have raised questions of oil viscosity, quantity and heat absorption to a high art.

 

[tornitore45]

It would appear that the braking torque is sinusoidal and cyclical at twice the axle speed. Duplication on the same axle or a second one 90* apart would smooth the torque.
If no people are transported then is not very important.

 

[Blogwitch]

I don't know if that system would work because of the different areas on each side of the piston, one side has the piston rod. I would suspect that it would have a very 'lumpy' operation.
I suspect it would require a double ended cylinder with a piston rod at each end to work correctly and smoothly.

John

 

[Cogsy]

Couldn't the design use valves that operate at different pressures to 'normalise' each side of the stroke? Kind of like how shock-absorbers on cars have different valving to accomodate different shockloads and return rates.