ON SPHERE AND HOLLER MECHANISM FOR TRANSMITTINa POWER. 487 



siderable danger of flats being ground upon the surfaces in contact. 

 This frequently occurred when the machine was running, and it there- 



FiG. 3. 



fore became absolutely necessary to devise some means to stop the machine 

 when the axis was in the critical position. Fortunately it was found that 



Fig. 4. 



stopping the machine in that position had a great advantage, because it 

 was impossible for the load to run down, the driven wheel being then 



