This is a duplexing unit for an HP 8150 Printer (for printing double-sided sheets). The interesting thing about this machine is the engineers knew that not every sheet being sent to the printer would be double-sided. So they  made a device that would send sheets forward even when the machine was sending some sheets back to be flipped to print on the back sides.  This translates into a machine that has a motor that turns in two directions, clockwise and counter-clockwise directions, and a gear mechanism that will turn those two directions into one clockwise direction, GENIUS!!!

These are the one-way clutches. the axle in the center will spin free when turned in one direction and grab and turn the gear when turned in the other direction. there are two one-way clutches that engage in opposite directions. They work by letting rollers spin free against the axle in one direction and being jammed against the axle in the other direction "grabbing it".

These are the same one-way clutches, one of them is turned around so they engage in opposite directions. Here they are sandwiched together.

As you can see when the axle is turned clockwise, it engages the top one-way clutch. follow the gear path to the last slave gear.

When the axle is turned in a counter-clockwise direction, it engages the bottom one-way clutch. Now follow the top gear path with the black reversing gear to the last slave gear.

The reversing gear is just an extra gear in the path to reverse the direction. the question is what is happening to the bottom gears when this gear is doing its job!!!

These bottom gears are just conveying the direction  from the axle. This and the above picture are good ones to print out to really stare at until you have a clear animated picture in your mind of what is happening. How do the top gears allow the bottom gears to turn?

No matter which way the axle turns, it is still the same clockwise direction at the end of the gear train.

TEST:


If you turned the Last gear (the end slave gear) counter-clockwise, what direction would it turn the axle (input shaft)? 


Answer: The mechanism would not allow you to turn it in that direction 


If you understood this question please send me an email with the word test in it . thank you!