Constant force simulator

[victors]

I have an application where a ball screw and motor are lifting and lowereing a platten ~ 14 inches loaded with either 160 pounds or 250 pounds depending on the product model. I currently am using barbell weights to simulate the load that would normally be seen in the field in the form of a steel cover; the barbell weights are manually set on the platten by 2 people as we have a single man 40 pound lifting rule. Short of purchasing a bulky hoist, I would prefer to simulate the weight via sometype of dynamic mechanism that would allow for a selectable form (160, 250 lbs) of constant force over the 12 inches of travel as my test sequence cycles between upper and lower positions. Does anyone have any suggestions?

 

[sreid]

How about an air cylindr and a pressure regulator. Good releving regulators have only a couple of pounds of differential pressure between inlet and exhaust.

 

[GregLocock]

How many tests per minute? at what velocity?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[hydtools]

How about a container of water? Pump in enough for 160 pounds. Run the test. Pump in more for 250 pounds. Run the test. Drain the container and remove from the table. Put the container on a scale to measure the container and water weight and add the weight of the scale for the total weight on the table.

Ted

 

[amorrison]

A (long) bar(lever) and a fulcrum.
Change the radius (notched position ?) of the counterweight location to get loads desired.