LGB 22771-040 20-tooth drive gear used LGB Porter (newer style, uses standard Boehler Motor)

LGB-22771-040 20-tooth drive gear used LGB Porter, ToyTrain and the Emma locomotive 

This gear works specially with the porter style locomotives that use the Buhler motor 

Note:
The were different versions of the Porter engine made, for more information about the different  wheels, Gears and Motors (Click here)