Spur Gear Needed

[BerlieParks]

I'm working on a project that requires meshed gears to synchronize timing belts. Unfortunately, I can't find the gears that will work with the belt pulleys used. The pulleys are 10mm pitch, and that means the module I'll need is ~3.183. A search only gave me a few Amazon listings of such gears. Does anyone know of a US vendor who makes or distributes such gears?

Much appreciated for any help you can give.

 

[Jboggs]

You want a spur gear that will mesh with a timing belt pulley? Is that correct? Spur gear teeth and synchronous (timing) belt teeth are two different things, based on completely different design standards. Just because they look alike does not mean they are exactly alike. If you want this to work on a long term basis or transmit any significant power you need to find a different approach, such as mounting a spur gear on the same shaft as your belt pulley. Then drive that spur gear with a mating spur gear. If that absolutely will not work you can try to drive your belt pulley with another belt pulley (non-flanged type). You will very quickly end up with a lot of dust and chips in the floor and worn out pulleys.

 

[Compositepro]

There is steel-linked chain that will mesh with spur gears. It's usually called "silent chain". I've never seen any belts that would work that way.

 

[TheTick]

I used Gates toothed belts on a product once. They also supplied pulley extrusion stock.

 

[BerlieParks]

In my rush, I didn't make myself clear. What I'm actually looking to do is what Jboggs first suggested.

Belt pulley ---> shaft ---> spur gear mated to spur gear ---> shaft ---> belt pulley

For my purposes, I need a gear with the same pitch as the belt pulley (Module 3.183).

Of course, with a recent suggestion of redesign this may be a moot point, but I'd still like to find out if anyone in the US makes or distributes such a spur gear.

 

[tbuelna]

BerlieParks- The tooth form used for timing belt pulleys or silent chain sprockets are not the same as external involute spur gears. So they would not mesh properly. Conventional external involute spur gear teeth mesh with each other along a line of action tangent to the respective base circles, and it is ideally a line contact that is conjugate in nature. Timing belts and silent chains mesh with their pulley/sprocket in a different manner. The belt/chain approaches the pulley/sprocket in a linear direction tangential to the pitch circle, and then transitions to a circumferential path as it wraps around the pulley/sprocket.

 

[BerlieParks]

The spur gears *do not* mesh with the pulleys. The mated gears will each be mounted on a shaft and pulley assembly, so both belt pulleys rotate in sync.

I just need to find spur gears with Module 3.183 (10mm Circular Pitch), and even better if their made or distributed in the US.

 

[TheTick]

Why must the gear be 10mm pitch? All you need to sync is two equal-sized gears of any pitch or diameter.

 

[mikekilroy]

sterling makes nice ones

http://www.sterlinggear.com/

http://www.sdp-si.com/web/html/products.htm

we often use:

http://www.pic-design.com/standard-spur-gears.html

they have a great online sizing tool, good prices, decent delivery.

http://www.KilroyWasHere<dot>com

 

[BerlieParks]

@TheTick
A crucial part of the full design is that the two pulleys have tangential pitch circles.

@MikeKilroy
Thanks so much. That gives me a great place to start.

 

[TheTick]

The gear diameter and spacing still does not dictate the exact pitch of your gears. You only need two gears of any pitch that have the right diameter. There are still lots of options.

Additionally, you may still have a little leeway with gear spacing, depending on your requirements for fit and backlash. If the gears are a skosh small, then your effective pitch circles will still be tangent, but you will have a slightly larger pressure angle. Works dandy. Do it all the time.

 

[tbuelna]

Looking at the sketch, it appears that the only consideration with the spur gears is that they have a ratio that gives the desired speeds at the pulleys. If the pulleys must turn at a ratio of 1:1, then any combination of spur gears that provide a 1:1 ratio and can handle the torque/power levels should work, right? If for some reason a specific pitch diameter and number of teeth are required for the spur gears, it is quite easy to design gears with these characteristics. And since the loads/stresses on the gears would be modest (limited by the capacity of the belt drive) they would not require costly case hardening/grinding operations, and could be manufactured for a reasonable cost.

 

[Tmoose]

Are you using gears because you need to reverse the shaft rotation?