Belt drives

[roozle]

I am looking at an application where, I am employing a belt drive system into a speed reducer.

Specification:

** Output speed = 500rpm
** Output Torque = 1.5 lb-ft (2Nm)
** Ratio = ~9:1

Also noise is an big issue. Having never specified a bel-drive system before, please can anyone advise me of the following.

1) What belt profile gives the best noise isolating properties?? (Standard type only, flat, Vee, timing etc.)

2) Where I can find calcuations (via a website or spreadsheet) on how to calculate the what pulley sizes, pitches and widths.

3) Does the belt material make a difference to the noise characteristics.

Thanks for your help,
Russell Tannner....

 

[Roach]

Is this electric motor driven (1/7 HP????)? Please give more detail for the system. Do you want the sheave (pulley) drive on the output of motor and input of gear reducer? Are you saying the gear reducer is 9:1? What speed motor are you using? (1750, 3500?)
Sorry for all the questions, but pulley ratios are real easy once the system and space limitations are stated.
Gates Belt catalog does a good job of describing belt selection, and the end use is also very necessary to determine what type (Vee, timing, etc.). Shock loads, safety concerns, etc. play a role as well.

Roach

 

[roozle]

Thanks Roach for your reply,

The motor is supplied by our customer and I'm not sure what it is, but the input speed is 4500 RPM.

The belt drive unit needs to be 9:1 ratio. The motor is attached directly to the unit. ie. the motor shaft has the input pulley mounted to it.

Thanks,
Russell..

 

[Roach]

I have never dealt with a system this small(HP), but to put things into perspective, in order to achieve a 9:1 with sheaves(pulleys), your diameter ratio must be 9:1. So if you could find(??????) a 1" sheave that would fit the shaft on your motor, you would need a 9" sheave opposing. There is also an issue with something called arc of contact. When there is a ratio this large, if the sheaves are not far enough apart, there will not be enough belt engagement on the smaller sheave. Gates belt catalog has a formula for this. I personally have never seen a ratio this large on a belt drive b/c of space limitations. The driven pulley gets to be so large that it just isn't practical. Not to say that it isn't practical for your case! Hope this is good ifo.

Roach

 

[sprintcar]

9:1 is going to create problems with belt wrap on the drive (small) sheave. Either have the customer get a slower motor or consider using a jackshaft arrangement to drop the speed with 2 pulley sets, or just use a gear reducer which will be a lot safer and probably just as cost effective when you factor costs of long belts and safety guards. Falk and other companies have small reducers that you can direct couple to the motor and your gizmo on a baseplate. This also addresses the noise issue. Keep the wheels on the ground
Bob
showshine@aol.com