A GOVERNOR FOR TELEPHONE DIALS 



1303 



shaft rotates during riiiulowii. Fig. 15 is a schematic of the pulsing 

 springs as they appear when the contacts are closed and when open. 



For a short period during each revolution of the pulsing shaft, the puls- 

 ing springs aid the motor spring in driving the gear system. This occurs 

 when the springs are being lowered by the cam just prior to opening of 

 the contacts. For the remaining portion of each revolution the motor 

 spring must pro^•ide energy to overcome frictional losses and lift the 

 springs. These changes in energy required for moving the springs have 

 been combined to give the total instantaneous torque curve also shown 

 on Fig. 14. 



As indicated by the pulsing spring torque analysis, the pulsing mech- 

 anism absorbs an average of only 200 dyne-cm during the period when 

 accelerating up to the critical velocity. For rotation after the critical 

 velocity, the average torque needed to drive the pulsing mechanism is 

 approximately 3,000 dyne-cm. The difference between these average 

 torque values appear at the governor shaft as a 1,500 dyne-cm torque 

 difference. That is, 1,500 dyne-cm more torque is available for driving 

 the governor prior to the time the critical velocity is reached as com- 

 pared to that available after this time. This accounts for one half of the 

 3,000 dyne-cm difference in initial governor torques as calculated by the 



BIFURCATED 

 SPRING ~- 



CAM FOLLOWER 

 ---'SPRING 



=— CONTACTS 



PAWL 



CONTACTS OPEN CONTACTS CLOSED 



Fig. 15 — Pulsing springs of 7-type dial. 



