Hydraulic freewheeling limiters??

[Brian Rupnow]

I have to source something for a machine I am designing, and I have absolutely no idea of what it is called. Basicaly, a man is rotating a large flywheel by hand. The flywheel is heavy, and so it has a lot of inertia. Consequently, if the man rotates it too fast, it becomes a real pig to slow it down again. I know that in a situation where I am dealing with linear motion, rather than rotary motion, I can tie in whatever is moving in a linear movement to a hydraulic cylinder and put in a "restrictor" (needle valve) so that as oil is moved from one end of the cylinder to the other through a hydraulic hose and through the needle valve, it limits how fast the linear motion can be. Is there a similar hydraulic speed limiter for rotary motion? I have never seen one, but I'm sure that they must exist, and be commercially available.---Brian

 

[kennyd]

I just replied over at HSM...

You could use a hydraulic motor mechanically linked to the flywheel, and a adjustable flow control valve. It will act as a "pump" moving fluid from on port to the other, and the flow valve will limit or stop fluid movement, just like you described with the cylinder.

 

[raggle]

On a skip (dumpster) unit I was developing in the 80s we ran into a similar problem in the linear sense. Two cylinders of unequal bore but equal stroke were connected in such a fashion that the head of one piston drove the underside of the other. In the development stage we were still using flexible hose between the two and found that ALL air must be purged in what was a closed system. Failing this it was possible for the volume to increase as the reaction loads came into force as the bubbles expanded. Lifting presented no problem but lowering a full heavy skip would drop one arm and not the other.

With the valuable help from our hydraulics suppliers we cured it with a restrictor (no more than a small hole in the line end fitting) though it gave an audible scream. This was finally piped in parallel with a one-way ball valve. I know you were asking for a rotary motion cure, but I think the overrun condition is the same. Or at least I do until someone comes by to correct my dangerous assumption.

In the meantime I don't think I'd dare ask about the price of these
http://www.boschrexroth.com/busines...omventile/02_prop_stromregelventile/index.jsp

 

[Brian Rupnow]

I just replied over at HSM...

You could use a hydraulic motor mechanically linked to the flywheel, and a adjustable flow control valve. It will act as a "pump" moving fluid from on port to the other, and the flow valve will limit or stop fluid movement, just like you described with the cylinder.

And I just answered you on the other site, saying "Great Idea, but I was hoping for a little cheaper solution than a hydraulic motor".

 

[kennyd]

And I just answered you on the other site, saying "Great Idea, but I was hoping for a little cheaper solution than a hydraulic motor".

Oh You wanted cheap to? ;D

Not sure then...

 

[Brian Rupnow]

Found 'em.---Thanks guys.
http://www.efdyn.com/rotation_dampers.html