Trolly cracked drive gear

[g-guage_trains]

Hi, I have a Bachmann Trolly (Streetcar) with both drive gears cracked. It is 24 tooth on a 1/4" axle. I found the Northwest Shortline Gear part No. 2223-6, 24 tooth, 15.5 mm OD diameter, bore 1/4". Can someone tell me if the diameter is bottom of the tooth or top of tooth?
Thank, alanrr

[armorsmith]

Alan,

I am by no means an expert on Bachmann or NWSL gears, but 'normally' gears are expressed in terms of Pitch Diameter.  Without the means to measure that diameter, and neither manufacturer states the pitch diameter, Outside Diameter would be the next best diameter to measure / state.  The best recommendation I can give is to measure the OD of the gear on the trolley and if what you measure is real close to the 15.5mm (.6102in) of the NWSL gear, go with it.  It will most likely work well.

I am sure there are others that will chime in as well.  Happy New Year and Happy Railroading.

Bob C.