Pneumatic Motor Help

[jeffsworld]

Hello everyone, I am currently in the process of building a air powered bicycle as part of my senior project. My biggest problem so far is I'm not an expert in motors, so I'm nervous about buying. If anyone has any ideas or helpful hints that may get me in the right direction. I have been researching rotary vane motors, but those that output high torque are way outside my budget. I would just like some help and confidence in buying a motor that I will feel comfortable in knowing I can make this project work. I realize that starting torque to move the bike will depend on weight and gear ratio.

Thanks you

 

[MikeHalloran]

Vane motors are more trouble than their apparent simplicity would suggest.

Try running a small steam engine on air.



Mike Halloran
Pembroke Pines, FL, USA

 

[kcj]

Air tools, like ratchets, have vane motors.
They are used because they are compact sources of power, but not picked for efficiency.
Compare the amount of air used to spin on a bolt with an air ratchet vs. the actual work done. very inefficient because the expansion ratio is so poor.
Agree with mike, some sort of piston engine expansion maybe.

 

[hydtools]

Without knowing more detail of what you are trying to do, it is hard to offer advice.
What are you expecting the pneumatic motor to do?
What compressed air source do you have available?
How would you replenish the exhausted compressed air source?
Vane motors are generally run at high speed and the ouput is put through gearing to arrive at the final form, speed and torque, of output. Air tools have one or more gear stages between the motor and final drive. Piston air motors are fairly large in comparison. Since pneumatic motors are not exhausted from 0psig there is lost power that just goes out the exhaust. Overall pneumatic power may be delivered at no better than 20% total efficiency.

Ted

 

[jeffsworld]

Thanks for everyones replies, I will do some more research on steam engines. One motor I have seen online but unable to pull any specs or pricing on is a rotary motor that employs 3 pistons to turn the rotor.

Thanks again

 

[hydtools]

This article may be of interest.

http://hydraulicspneumatics.com/200...s/Article/False/6422/TechZone-FluidPowerAcces

Ted