Smells like a school project?
I am looking for some help comming up with a linear pull test.
I am testing a drive motor setup that is attached to a cable. The cable needs to be pulled over a distance of 70" with the load a 0" being as close to Zero LBS as posible and at 70" it needs to be 210 LBS.
I was thinking of using a torsion spring and a drum with a cable but would consider other sugestions.
trying to stay on the inexpensive side if possibel.
thanks
Daniel
Smells like a school project?
Think of a very long extension spring, like used on some manual garage doors.
If it doesn't have to be pretty, I'd use a pulley. Place the motor on a table,mount,or whatever with a cable that runs horizontal and through the pulley. Run the cable down through some weights and space them so after 70" you have a tension load of 210lbs. The system is much like a home gym system.
Torsion springs typically have a limited range of motion (most are under 360deg). So achieve 70" of travel, you'd need a pretty big drum (~2ft diameter).
I'm with jboggs - I'd find a long tension spring with a spring constant of 3 lbs/in. That would be the ideal way of doing it. Depending on how accurate you need it to be, Azekial's solution is probably less expensive if you can scavenge the parts.