How the Expanding Pulley Mechanism Works

This model represents an expanding pulley. When the small pinion is turned to the right or left, a similar motion is imparted to the wheel, which, through curved slots cut into it, thrusts the studs fastened to the arms of the pulley outward or inward, thus increasing or decreasing the size of the pulley.
It's worth mentioning that this is a very old mechanical solution, and because the expanded red pieces are no longer concentric, the mechanism is not very practical for use with a belt and pulley. However, the mechanism has many practical uses and is still worth knowing about.
A complete 3D model is available at Part Community via the following link:
bit.ly/PartCom...
If you enjoyed watching the video, please consider supporting me by subscribing to the channel.
Thanks!
Twitter: / eng_workout
#mechanism #engineering #3dmodeling #mechanicalengineering #engineering #machinery

[@TinganHamada86]

Hello kita hadir nonton video 👍

[@placebomandingo2095]

It expands, but does it rotate?

[@EngineeringWorkout]

This is simplified version and it can't rotate, but in reality it can be made rotational. - The issue with this solution is that when expanded, the pulley is no more circular shape... Thanks for watching!

[@placebomandingo2095]

​@@EngineeringWorkout if the outer wheel sections overlapped to the next spoke it would telescope out to size, maybe. If they were sprung a bit it would adjust and stay rigid and round.

[@EngineeringWorkout]

​@@placebomandingo2095 The wheel sections are not flexible, therefore they will always keep the same radius...

[@placebomandingo2095]

@@EngineeringWorkout I understand that. I was postulating. That's how we solved problems before CAD.

[@shaunp9592]

Seems like a huge waste of machining for all those teeth around the big gear when it only needs 4 to 6 inches of travel to expand and contract the pully.

[@EngineeringWorkout]

Great point! The video is just a representation of the mechanism. A gear is good if you'd like to support the torque with another stepper on the lower side, but it can be much simpler if no precision and positioning is needed - even without gears and a stepper, one cylinder can do the job. Thanks for watching!"