rii. in Kgivil'^ ! UK INK "i: "'.' 



In street railway practice the diameter of the driving 

 wheel now almost universally adopted is 33 inches. 

 With II teeth in tli.- pinion and 07 in the gear wheel, 

 wi- find in a well-designed juijiimnt a clearance of 

 1$ of an inch between the casing of the gear wheel and 

 the level of the rail. If we take this to be the least per- 



missible cleanr limited to 0-1 I-".. 



'i 



