AUTOMATIC TESTING IN TELEPHONE MANUFACTUEE 1131 



operators. In many cases it is feasible for all steps to be taken automat- 

 ically. The bulk of our accomplishment in automatic testing, however, 

 has been in steps 2 through 6. We do not ordinarily use "automatic" to 

 describe rudimentary automaticity in combinations among steps 3, 4, 

 and 5. 



The present models of many of our machines have evolved from earlier 

 models, either because of changed product or test requirements or 

 through improved designs worked out for plant expansion or cost reduc- 

 tion. The names of engineers associated with the various developments 

 mentioned are included in the references. About 1927 there were put in 

 use at Hawthorne two machines, one for gaging a number of critical 

 dimensions and performing a breakdown test on carbon protector 

 blocks,^" and the other for heat coils.^^ In the protector block machine 

 the blocks follow a linear course drawn by an indexing chain conveyor 

 through a number of positions where the various checks are performed. 

 Failure of any block at a position causes a jet of air to blow the block 

 into the opening of a chute which conducts it to a reject pan. Good blocks 

 are delivered into a pan at the end of the run. The heat coil machine has 

 an indexing turret over a ring of ports which open selectively to permit 

 good or rejected coils to fall into chutes. The test parameters are three 

 ,<!;aged dimensions and dc resistance. 



In 1929 a machine with an indexing turret was put in use, testing paper 

 capacitors for dielectric strength and leakage resistance,^^ and sorting 

 them into 13 cells for capacitance grouped around a nominal 1 mf. The 

 13 cells correspond to 13 segments in a commutator disposed along the 

 scale of a microfarad meter. For a given test capacitor, when the meter 

 needle reaches its deflection a bow depresses it against the nearest seg- 

 ment, establishing a circuit through a relay. A system of relays then 

 locks up and serves as a memory to operate a solenoid later when the 

 turret has brought the capacitor to the point of disposition. Action of 

 the proper solenoid causes the capacitor to be deposited in its cell. The 

 cells are arranged as parallel files in a horizontal plane and, starting with 

 the cells empty, the machine will in effect produce a stovepipe distribu- 

 tion curve. Capacitors from the middle cell and its upper neighbors may 

 be used as 1 mf capacitors, and those from more remote cells combined, 

 large with small, to make 2-mf capacitors. 



Also in 1929 a turret type machine was first used for sorting mica lam- 

 inations. ^^ The sorting parameter was ac dielectric strength, the criterion 

 being failure at 1760 volts r.m.s. The individual laminations were carried 

 from position to position by vacuum fingers mounted on a turret. Again 

 locking relays were used, in this case to operate a solenoid controlled 



