Pneumatics Math Help

[Monochron]

Originally Posted by Richard Wallace

Back in the day at Georgia Tech, the level of commitment (read: hours of homework) required by that class was a wake-up call for engineering students -- either you do the work needed to learn statics, or you find another major. I will be truly astonished if someone tells me it is not like that today.

Having graduated 3.5 years ago, yep it's still the case . Though at Clemson Mech Eng had to take a combined Statics&Dynamics class. Twice the credit hours of the statics class that other major took. So many ex-engineering students after that class, heh.

[euhlmann]

If you plan on orienting this vertically, you'll want some sort of counterbalance otherwise your cylinder will need to be unnecessarily hefty to work against gravity. A coil spring or elastic material (surgical tubing) would approximately work. Or you could make a true counterbalance by extending the end of the actuated arm and adding a weight such that the torques cancel out

[GeeTwo]

Originally Posted by euhlmann

..you'll want some sort of counterbalance..

If you're looking at repeatedly lifting a load and leaving it there, using a counterbalance (whether gravity, spring, or otherwise) will buy you a factor of two in the amount of work you need to do in each half stroke. That is, you can do work both on the upstroke (lifting the load with spring/counterbalance help) and the down stroke (adding energy to the spring/counterbalance). When using pneumatics for a lift, deciding whether the complexity of the counterbalance is worth having a smaller cylinder is usually a real engineering question (meaning that the answer is "it depends"). In my experience, counterbalancing a pneumatic actuator is less frequently an improvement than in the case of an electric actuator. This is especially true when you do not need to pressurize both sides of a cylinder, but get a "free" light spring or gravity return.