MAINTENANCE 



151 



gong but not to strike back to the other gong at each movement of the handle. The 

 clapper ball should strike the gongs and rebound just enough to clear the gong. It 

 should lie as close as possible without touching the gong. 



Sometimes the clapper ball tends to rest heavily to one side. If possible" the 

 difficulty should be overcome by moving the gongs or by changing the length of the 

 stroke of the clapper. If the attempt is not successful, bend the clapper rod until the 

 required space is obtained. Then move the gongs to their proper relative positions. 



Fig. 96 Ringer of No. 127-F, extension bell, and Nos. 1317-P, 1317-S, 

 300-N and 1336-J telephones 



(Z>) Testing. When the gongs and clapper ball appear to rest in their propor posi- 

 tions, test the adjustment by turning the handle of the generator - until the clapper 

 ball strikes one gong without striking back to the other. If the tones are not satis- 

 factory, continue the adjustment until a clear ring of the same tone is emitted by 

 each gong, and at the same time the stated spaces between clapper ball and gongs must 

 be maintained. The clamping screws B should be tightened when the adjustment 

 is complete. 



Adjustment of ringers in extension bells differs only in method of testing. The 

 test is made by slowly and slightly tipping the ringer from side to side. It should 

 not be jarred. 



The 292-U loud-ringing extension bell can be more successfully adjusted when 

 it is connected to a line. This allows the adjustment to be tested by signalling to it 

 from some distant telephone. The bell should be installed in a true vertical position; 

 with the clapper pointed either upward or downward. 



The coil to which the clapper is fastened should move freely between the upper 

 and lower pivot screws, but not loosely. This adjustment is made by manipulating 

 the screws on either side of the armature. The space between the clapper ball and 

 gong should be about in. when the clapper ball is held against the other gong. The 

 gongs are adjusted by loosening one at a time the square-headed screws on the face 

 of the gong, turnrng the gongs to the proper position and then tightening this screw 



