Spoke and Disc Wheels 



115 



THE POWER REQUIRED TO DRIVE SPOKE AND DISK 

 WHEELS AND PULLEYS. 



Arthur L. Foley and B. Eisenhour. 



Some years ago the senior author of this paper, while working on 

 a problem requiring a high peripheral velocity of a wheel or disk, 

 found that the power required to drive a wire spoke bicycle wheel in- 

 creased with surprising rapidity with increase in rotational speed. He 

 found it impossible with the power at his command to drive a bicycle 

 wheel at the desired speed. A steel disk (a circular saw disk) was 

 readily driven at a much higher speed. This suggested a study of the 

 comparative power required to drive spoke and disk wheels and pulleys. 



An automobile axle was removed from its housing and mounted 



TABLE I.— POWER REQUIRED TO DRIVE SPOKE AND DISK 

 AUTOMOBILE WHEELS 



to run in two plane bearings mounted on a massive wooden framework 

 to minimize vibration. The axle was driven by means of a variable 

 speed motor of the type in which the armature is movable longitudinally 

 in the field, thus giving any desired speed between wide limits. The 

 axle speed was determined by means of a Van Sicklen tachometer, and 

 for convenience in calculation was adjusted in each case to multiples 

 of 100 r.p.m. The shaft was carefully lined up in the bearings and 

 was driven at high speed for several days before any observations were 

 taken. Spoke and disk wheels carrying 32"x3" tires were alternately 

 mounted on the axle and rotated at the speeds indicated in the table. 

 The power required to drive the axle was computed from the terminal 

 voltage and the line current. This, of course, neglects the power lost 

 in the motor itself. However, the study was intended to be comparative 

 only. 



Neither of the two automobile wheels was balanced well enough to 

 permit of very high rotational speeds without dangerous vibration. 



"Proc. Ind. Acad. Sci., vol. 33, 1923 (1924)." 



