In need of solution for pulley system. Wire or belt?

Hi,

I would like to make a system that will move a carriage back and forth allong a level suspended rail. The carriage will have roller bearings to reduce friction and will carry loads up to 20Kg. The length of the rail will be upto 2m. The speed will be as slow as 1m per 5minutes. I am planning to use a stepper motor running half step to drive the system and I expect the system to work constantly for upto 1 year without failure.

Can anyone suggest any solutions that will be both cheap and reliable?

I would love to have an open ended timing belt running over and under the rail with a tensioning spring coupling it to the carriage and a pulley at each end but I am worried the cost will be too high.

I am currently considering using wire to do the job but I am not sure how to provide the traction between the motor and the wire? And I am also worried the wire will begin to fray from running over the pulley's. Is there a particulat type of wire that is good in this type of application? I am aware that some electric car window systems use wire and have a good serivce life.

Also, if I decide to take the belt option what size would you reccomend? I was thinking an L or XL belt in either 9mm or 12mm. But could I go as small as the XL in 6mm?

Useful belt info:

http://www.roymech.co.uk/Useful_Tables/Drive/Timing_belts.html

Another issue I am unable to resolve:
What tourque motor should I be looking for (bearing in mind that I am also planning to use roller bearings in the end pulleys as well)?

Thank you in advance for any help/advice you maybe able to provide.

 

[MikeHalloran]

A car window actuator won't run a year continuously.

Of course you realize that you can buy exactly the system you describe, right?

See, slapping it together from whatever you can find, is just fine if you only need it to run for a day or a week, and you'll be there to fuss with it anyway. Asking any system to run for a year requires engineering the system.
If your time is worth more than a dollar an hour, a commercial system will be cheaper by far.



Mike Halloran
Pembroke Pines, FL, USA

 

Hi,

Thanks for the replay and sorry for the late follow-up.

I am not expecting a car window actuator to run 100% duty cycle but I was considering the pulley/wire arrangement. I have since gone off this idea as I do not think the wire will last being run over a pulley for any length of time. Now I am considering a 3m 9mm belt with sealed bearings, what do you think?

I am aware there are products available and I hope mine to add mine to the list.

Many thanks