1088 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1953 



Fig. 34 — Pull-up magnet and lift superstructure. 



as is depicted by Fig. 35. Accordingly, when the dynamic unit needs to 

 be serviced, it may be taken to a location suitable for the purpose and 

 meanwhile the translator may be continued in service by substituting 

 a spare dynamic unit. 



REMOVAL OF THE UNIT 



To remove the dynamic unit, the cards first either have to be removed 

 from a translator or in some way they have to be supported clear of 

 the code select and card support bars. In some cases it will be possible 

 to service the unit in a few minutes, and in such cases, should the cards 

 have to be removed, their handling would constitute the major effort. 

 The pull-up magnets could be energized in which event the cards would 

 be suspended clear of the solenoid operated bars thus permitting the re- 

 moval of the unit. However, conditions might be such that the pull-up 

 magnet thus would have to be kept energized for a comparatively long 

 time and this would be undesirable because the current drain is heavy. 

 In any event, suspension of the cards by the pull-up magnet for this 

 purpose would be hazardous because should the circuit be interrupted 

 only momentarily, the cards would fall and considerable damage no 

 doubt would result. Accordingly, mechanical means were provided 

 whereby the cards may be elevated quickly and held suspended safely 



