Reverse direction of shaft driven by toothed belt.

[Peter BellParticipant @peterbell11509]

Hello, nice simple question

I want to reverse the direction of rotation of a shaft driven by a toothed belt.
I assume I need to resort to gears to do this?

Thanks

[Peter BellParticipant @peterbell11509]

[JasonBModerator @jasonb]

Unless you can move the driving motor to the opposite side of the belt.

[Brian WoodParticipant @brianwood45127]

Hello Peter,

I think you are correct. 

In the old days of flat belts you could put a twist in the belt and where they crossed one just slid past the other. I don't know if that is possible with toothed belting without a snarl up of the teeth at the crossing. Might be interesting to test it out!

Brian

Edited By Brian Wood on 28/08/2022 10:16:13

[Peter BellParticipant @peterbell11509]

Thanks. It’s shaft driven by a shaft then the motor and never seen a twisted toothed belt (intentionally anyway!) before so assuming it’s not possible but just checking in case I’d missed something.

Peter

[Kiwi BlokeParticipant @kiwibloke62605]

Well, it's a bit nasty, but if the belt's run is long enough, and there's enough room for an idler to replace the motor's pulley (in a similar position), arrange for the belt to be driven from the middle of a long run, with the motor's axis at 90 degrees to the plane of the belt. To do this, the belt has to be twisted 90 degrees. Twist it one way, and drive it from the appropriate side, and it'll go one way; twist it the other way, so you can drive it from t'other side, and it will go in the opposite direction. You'd need to arrange suitable idlers to get enough belt wrap. Of course, this means arranging for the motor's axis to be rotated 90 degrees, so it's pointing at the side of the (untwisted) belt, ie at 90 degrees to the driven pulley's axis. Hope this is clear…

Otherwise, arrange idlers to provide a lot of belt wrap, and drive the belt from its 'outside', as if a flat belt.

Resorting to gears is probably not such a bad idea…

[Peter Cook 6Participant @petercook6]

Reverse the motor?

[RobinParticipant @robin]

Can you still get double-sided tooth belts? That'd do it

[Tim StevensParticipant @timstevens64731]

Sorry, my mistake …

Tim

Edited By Tim Stevens on 28/08/2022 10:56:25

[John PParticipant @johnp77052]

Have a look on here for double sided toothed belts

https://www.bearingboys.co.uk/?catid=2564&display=&orderby=&att1=5.08mm+%3D+1%2F5inch&att2=&att3=&att4=&att5=

[Anthony KnightsParticipant @anthonyknights16741]

Seems to be getting over complicated here. Peter Cook 6 has the best suggestion- reverse the motor (KISS).

[HopperParticipant @hopper]

Bit more info on what exactly you want to reverse might bring out some more useful suggestions. Makes a big difference whether it is the leadscrew on a hobby lathe or the main drive on a 100HP snowmobile.

[Paul LousickParticipant @paullousick59116]

How would a double sided tooth belt reverse the direction of the driven shaft ?

When a flat belt is twisted to reverse the direction, the same side of the belt is in contact with both pulleys.

[not done it yetParticipant @notdoneityet]

It might depend on how the belt is tensioned. If it has a separate tensioner it will be on the wrong side of the motor. If it is the motor that is moved, to apply the correct tension, no real bother – I think.

[Peter BellParticipant @peterbell11509]

Thanks for all the suggestions.

The motor drives the first shaft, and that shaft then drives the other shaft which is which is the one that that I want to reverse so I can’t just reverse the motor.

It’s only a 10mm belt so low power but it needs to be reasonably tight to avoid timing issues.
As it’s stepper motor driven had considered using another stepper and synchronising them on switch on but sounds complicated!

I see some reasonably priced Delrin change wheel gears on eBay, which looks like the solution.

Peter.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Paul Lousick on 28/08/2022 11:41:08:

How would a double sided tooth belt reverse the direction of the driven shaft ?

.

Briefly …

• Motor drives an idler shaft [using the teeth on the inside of the belt]
• Output is taken from the teeth on the outside of the belt.

MichaelG.

[Author]

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