'H III FQl'\ri"V- !'"K I'lIF IMdVMoN j'.i 



NYheii tic- motor - ; ;t!> is geared t<> a main shaft we 

 * the Tii rlvinif in term- of tin- s|eed and 



torque of the motor shaft r of the main shaft ; if ii<> 

 is being done in overcoming friction in the gearing or in 

 the bearings of the motor shaft, the work done on the m. 

 shall is equal to the resistance overcome on the other, and 

 since the motor shaft runs at times the speed of the main 

 shaft, it follow- that the torque on the former i- to that on 

 the latter as 1 is t - 



H-nce, when a motor of induction factor M i- driving 

 a main shaft, on which the torque i< t inch-pounds, the 



torque on the motor shaft is , whet - -ity ratio. 



and the current is This is the current in 



I'll W 



the motor required to overcome the torque / on the main 

 shaft. In practice we shall require more current than 

 this, since there is always some friction to be overcome in 

 the gearing and in the motor itself. 



The main shaft may be connected to the motor shaft 

 either l>y Mtinu' or by toothed gearing. In the former 

 Case v will U- the ratio of the diam.-ter of the pulley 

 on the main shaft to that on the motor shaft In the 

 latter case v will In- the ratio of the numlx-r of teeth in 

 the toothed wheel on the main shaft, which w shall 

 call the gear wheel, to the numl- . ,,f teeth in the 

 toothed wheel on the motor nhnft. which we shall call the 

 pinion. 



The following table giree the numU-r* of teeth in 

 wheel and pinion with the corresponding vel<* 

 often need in rail way mot- 



I 



