Calculating mechanical advantage for mechanism
Calculating mechanical advantage for mechanism
(OP)
Hello,
I have an application where I use a motor to turn a shaft and this shaft is linked to a coupler that moves a piston back and forth.
Basically a four bar linkage that produces linear motion from rotary motion of a motor. I am using the linear motion to puncture holes into PTFE.
Question:
How do I calculate the mechanical advantage gained?
ie
If I know what the torque produced by the motor at a given speed, what is the force that the piston has at the other end?
I have an application where I use a motor to turn a shaft and this shaft is linked to a coupler that moves a piston back and forth.
Basically a four bar linkage that produces linear motion from rotary motion of a motor. I am using the linear motion to puncture holes into PTFE.
Question:
How do I calculate the mechanical advantage gained?
ie
If I know what the torque produced by the motor at a given speed, what is the force that the piston has at the other end?





RE: Calculating mechanical advantage for mechanism
RE: Calculating mechanical advantage for mechanism
RE: Calculating mechanical advantage for mechanism
The advantage of this is thatyou don't need to draw a free body diagram.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RE: Calculating mechanical advantage for mechanism
To find the force at the piston for a given position during the crank rotation you need to produce a velocity and subsquently an acceleration diagram for your mechanism.
You will also need to know the inertia's of the links and piston.
A book like "Mechanics of Machines" by J.Hannah & R.C.Stephens should help with this problem.
Regards
desertfox
RE: Calculating mechanical advantage for mechanism
Then you can write
T*d@=F*dx
and
T=F*dx/d@
where
d@ incemental small angle in radians
dx incremental distance
T input torque
But since the energy is absorbed over a small time, one usually adds a flywheel so that the motor which can put energy into the flywheel over 360 degrees of motion while energy is absorbed over a tiny fraction of the angular motion, thus cosiderably reducing the power demands on the motor.