Mechanical Lift - Ideas - Rotary Mechanical Actuator

[Superslinky]

Hey all, I'm looking for ideas on building a test fixture for an actuator we're building. In a nutshell, I need to rotate the actuator 180 deg. and lift approx. 4000lbs. I'm trying to think of ways to run it up and then down and then switch the side of the load. In other words when I rotate it clockwise I'll lift 4000lbs, then run counter clockwise down resisting 4000lbs but continue on with the counter clockwise motion for it to travel back up lifting the 4000lb load on the "other side" of the actuator planetary set and then repeat the process.

Please ask questions. I'm sure that didn't give anyone a clear picture but I'm open to any and all ideas.

Thanks for any insight.

 

[IRstuff]

A picture might clarify, but I don't see what difference the rotation is making; in either position the actuator is extending, is it not?

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[zekeman]

I think you should add a counterweight so that you are dealing only with the rotation of a balanced mass.

 

[Superslinky]

It's essentially a motor with a reducer on it. The output is a shaft that rotates. So I need to convert rotation to lift. Think of any SEW gear motor when picturing this. The reason for lifting in "both" directions is to put force on both sides of the gearbox teeth during testing.

 

[dvd]

Disc brake?

 

[Jboggs]

Sounds like you need a dynamometer setup. You could drive a liquid coupling in both directions using the viscosity of the liquid to create a resistive force in both directions.

 

[zekeman]

Two clutches disposed opposite , engaging opposite racks and pinions.

 

[zekeman]

Or perhaps a Zero-Max drive with reversing arm engage only one rack and pinion.

 

[MikeHalloran]

Put a crank on the output shaft.
Suspend a weight from the distal end of the crank by means of a chain.
Put a limit switch at TDC of crank travel.

If that's too imprecise, add a sprocket to the output shaft and let it drive a larger sprocket on a jackshaft, where you can position any number of switches or position transducers and go nuts with control and monitoring logic.





Mike Halloran
Pembroke Pines, FL, USA

 

[kwb74]

If I understand this right you need to control flipping over 4000# connected to an arm of your gizmo?
I did something similar once - numbers were bigger but what we did was just made a part that fit into the piece of equipment and poured a concrete brick of appropriate size to get the weight we wanted.

I hope the gearbox you have for this is a wormgear for its inherent inability to backdrive itself.

As far as testing if it works - pickup and setdown points are your highest torque but controls wise if you do this with hydraulics visa 40bar linkage the tricky spot is going from lifting to lowering.

I have no affilation but there is a great hydraulic rotary actuator that can replace a lot of linkage and/or gear boxes made by Helac out of Enumclaw Washington.

 

[btrueblood]

You want resistive torque to a rotary drive shaft that cycles between clockwise and anti-clockwise rotation, if I read you correctly. I'd think rotating a weight on a bearing pad would get you there, e.g. a large concrete block sitting on a smooth steel plate, which is supported by teflon or high-density polyethylene pads. The fluid coupling could work, think of two pressure relief valves alternately disposed between two hydraulic cyclinders. Put a crank from the shaft out to the ends of the cylinders. Driving one way, relief valve "A" controls pressure in cylinder A to give you the requisite torque, cylinder A fluid is transfered through the relief valve A to cylinder B. Flow thru relief valve "B" would be blocked by a check valve. Driving the other way, valve "B" holds pressure in cylinder B to generate resistance torque, flow thru valve "A" in the reverse direction again blocked by a check valve. Both methods would dissipate the work done by the actuator as heat, and thus would be limited as to speed/duty cycle that could be achieved before something overheated.

 

[Superslinky]

What are the thoughts on using a planetary gearbox and drive it backwards? Can this be done? I'm thinking if I need to "lift" 4000lbs I can emulate that by using a reducer and running it backwards. For example if I had a reduction of 16:1 I could effectively push 250lbs but my actuator would see the a load of 4000lbs. Sort of like a torque multiplier.

Any thoughts?

Thanks for the ideas so far!