NEW GENERAL PURPOSE RELAY 1045 



in manufacture, as the restoring spring tension is normally just sufficient 

 to overcome the tension of the make twin wires and hold tlu; ;unuiture 

 against the backstop within acceptable force limits. Close control of the 

 tension bends in the wires and restoring springs reduces the fi'e(|uenc.y 

 with which adjustments are needed and a large portion of the relays do 

 not require this adjustment. 



Types of factor)^ adjustment which are common on other relays but 

 which have been eliminated entirely on the AF relay include adjustments 

 for contact force, individual adjustment of contacts for contact operate 

 point, and adjustment for armature travel. Contact force is controlled 

 by means of the large predeflections of the twin wires as mentioned 

 previously. Individual contact adjustment is eliminated by close control 

 of tolerances combined with the single card method of actuation, and 

 by the simpler gang adjustment used when necessary. Adjustment for 

 armature travel is eliminated by the use of close tolerances on the con- 

 trolling dimensions of the parts. 



Adjustments of worn relays in the field may be limited to gang adjust- 

 ment of the contacts and back tension adjustment as described above. 

 Other adjustments may include burnishing the contacts to remove sur- 

 face irregularities, replacement of contacts and individual contact adjust- 

 ment as mentioned previously, and replacement of the card if it should 

 become badly worn or damaged. If card replacement is necessary this 

 may be done without dismounting the relay from the mounting plate 

 and without disconnecting the associated wiring. 



10. RELAY PERFORMANCE 



As previously stated, the broad objective in the design of the AF relay 

 has been to reduce the annual charges for the use of this relay in the 

 telephone system. Part of this reduction comes from lower manufacturing 

 costs; the remainder comes from savings associated with the improved 

 performance characteristics, such as long life with relatively low main- 

 tenance expense, reduced power consumption, and increased speed which 

 reduces the number of units of certain types of equipment, such as 

 markers, needed for telephone central offices. A brief description of some 

 of the principal characteristics of the new relay follows. 



Load and Pull Characteristics 



Typical load and pull curves for a wire spring relay with twelve early 

 break-make transfer contacts are shown in Fig. 17. The abscissa shows 

 the motion of the armature as it travels from the luioperated position 



