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Unread 17-01-2014, 19:15
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VEX Robotics Engineer
AKA: Arthur Dutra IV; NERD #18
FRC #0148 (Robowranglers)
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Re: VexPro Pancake Shifter Question

Quote:
Originally Posted by ohdan56 View Post
Would one of you be so kind as to explain to me the use/application of a pancake shifter? I am not familiar with this equipment. How does gearbox interact with the pneumatic cylinder? Thanks, I'm learning!
The pancake pneumatic cylinder is a type of pneumatic cylinder that is as compact as possible.

Here is a drawing for a typical 3/4in diameter bore, 1/2in stroke (travel) pneumatic cylinder that is identical to what you can order from Bimba:
http://www.mcmaster.com/#6498k631/=qanv3j

As you can see, even through the stroke is only 1/2in, the overall length of the pneumatic cylinder is 5.03in long when fully retracted. The pancake cylinders in comparison were designed to be as short as possible for a given stroke; if you look at the same PDF I posted earlier a 3/4in bore, 1/2in stroke pancake cylinder is only 1.19in long. For shifting gearboxes there is no operational difference between a typical and pancake pneumatic cylinder, however the pancake cylinder is smaller and lighter.

For both the ball shifter and the dog shifter, the pneumatic cylinder is connected to a shifter shaft coaxially within another gearbox shaft. The smaller inner shaft can move in and out, while the gearbox shaft transmits the torque. For the ball shifter, there are balls in the gearbox shaft that can be pushed outwards via a step in the shifter shaft to engage into a gear and the gearbox shaft at the same time to transmit torque. For the dog shifter, a pin or screw attaches a dog to the coaxial shifter shaft to slide the dog to engage a gear into the gearbox shaft.
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Art Dutra IV
Robotics Engineer, VEX Robotics, Inc., a subsidiary of Innovation First International (IFI)
Robowranglers Team 148 | GUS Robotics Team 228 (Alumni) | Rho Beta Epsilon (Alumni) | @arthurdutra

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