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  #11  
Old 05-01-2012, 10:11 PM
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Re: Differential Transmission (Simpler than Planetary!)

One of the major problems with the differentials is that when they are under high stress, the differentials tend to flex alot thus adding more friction than necessary. Thats why my team made our own differentials that are only slightly wider however much much stronger.

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  #12  
Old 05-04-2012, 09:34 PM
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Re: Differential Transmission (Simpler than Planetary!)

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Originally Posted by anthonyl14107096 View Post
One of the major problems with the differentials is that when they are under high stress, the differentials tend to flex alot thus adding more friction than necessary. Thats why my team made our own differentials that are only slightly wider however much much stronger.
I've just been thinking about how to implement a differential speed-changer and as a result I'm looking for a way to make nice differentials (like yours).
When I look at that differential, it just looks like the axles are going to hit the cut C-channels. Have you had any issues with the screws loosening and the differentials getting jammed?


As an edit to my first post:
Line 6 of the High-Torque how-to should read:
" Diff3 is turning at 3/10 the speed of Diff1 (3/5 * 1/2) "
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  #13  
Old 05-05-2012, 12:42 PM
mr. giggums mr. giggums is offline
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I have been thinking about differential gears and multi speed transmissions and I have come up with an idea but it is so simple I can't see why no one has come up with it. This leads me to think that there is something wrong with the idea.

Anyway my idea is to put 2 motors into the bevel gears as inputs but first gear up our down the motors to make sure that they are different. Then the output is the differential's housing

For example you can gear one motor up 2:1 for speed. When turning in the same direction the final gear ratio is (2+1)/2 = 1.5 or 3:2 for speed. When turning in the other direction the gear ratio is (2-1)/2 = .5 or 1:2 for torque.
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  #14  
Old 05-05-2012, 01:07 PM
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Re: Differential Transmission (Simpler than Planetary!)

Quote:
Originally Posted by mr. giggums View Post
I have been thinking about differential gears and multi speed transmissions and I have come up with an idea but it is so simple I can't see why no one has come up with it. This leads me to think that there is something wrong with the idea.

Anyway my idea is to put 2 motors into the bevel gears as inputs but first gear up our down the motors to make sure that they are different. Then the output is the differential's housing

For example you can gear one motor up 2:1 for speed. When turning in the same direction the final gear ratio is (2+1)/2 = 1.5 or 3:2 for speed. When turning in the other direction the gear ratio is (2-1)/2 = .5 or 1:2 for torque.
Yes there is something wrong with it

The resultant torque of that kind of differential setup is only as high as twice the smallest input torque. So if one of your motors is geared 1:2 for speed into one of the inputs, and the other input is a motor geared 1:1:
Running in same direction: Speed is x1.5 and Torque is 1x (the torque of a single motor).
Running in opposite direction: Speed is x.5 and Torque is 1x (the torque of a single motor).
This is just like what Paul Copioli was describing in his CCT.

You want both inputs of the differential to be the same torque and running in the same direction to get any kind of output.
I am currently working on a differential two-speed transmission with (only!) two differentials and requiring the use of pneumatics to switch between speeds (but there are no gears that need to mesh, so it's better than a traditional gear-shifter).

As far as I know, it is impossible to output a torque larger than one of the inputs of a differential or a planetary gear set (if there are two powered inputs). This is because whatever is fighting the output only has to overcome one of the inputs.
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  #15  
Old 06-25-2012, 09:20 AM
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Re: Differential Transmission (Simpler than Planetary!)

There is a much, much simpler and easier to make this. you simple have one gear rotating the encasing of the bevel gears and then another motor rotating the bevel gears themselves. mix up the encasing gear to change your speeds.
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  #16  
Old 07-03-2012, 09:13 PM
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Re: Differential Transmission (Simpler than Planetary!)

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Originally Posted by twosided View Post
There is a much, much simpler and easier to make this. you simple have one gear rotating the encasing of the bevel gears and then another motor rotating the bevel gears themselves. mix up the encasing gear to change your speeds.
Do you have a Picture/Drawing or Video??

Would you use Multiple Motors with different gears to drive the Encasing?? How do you disengage the the Motors not needed?
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