106 BELL SYSTEM TECHNICAL JOURNAL 



soon as the main motor is up to speed. During this acceleration period 

 on the No. 2 Machines a slip of 5% between wire and capstan occurs when 

 the capstans are new, and no slip when the capstans are reduced to the 

 minimum diameter. Curves showing the relative acceleration between 

 main and takeup motors are shown on diagram, Fig. 12, which also repre- 

 sents the improvement of acceleration by the tie-in. An electric time clock 

 is connected into the motor circuit for stopping the machine when the 400 

 lb. reel is full, a time setting being made for each size of wire. On the No. 1 

 Machine the takeup is accelerated by the magnetic clutch to full reel speed 

 of the 1000 lb. reel and the contact made by the time clock re-energizes the 

 clutch so that the takeup will slow down in synchronism with the main 

 motor. 



An under current relay is also interposed in the motor circuit to stop the 

 machine should a break occur while drawing. 



Lubrication 



Introduction of oil lubrication introduced difl&culties in securing effective 

 sealing against oil leakage. It has been our experience that commercial 

 seals are effective when used on shafts revolving at surface speeds below 

 1200 f.p.m., but above this speed they were inadequate. For the capstan 

 bearings the seals have to be effective in both directions to prevent the 

 leakage of mineral oil from the bearings into the wire drawing compound, 

 and also to prevent the wire drawing compound from mixing with the 

 lubricating oil. This has been accomplished very effectively by the use 

 of multiple slingers, the design of which is shown by Fig. 13. The two 

 front slingers throw off the compound which drains back into the com- 

 pound system and the two rear slingers do the same with the oil. There is 

 no friction and corresponding wear between surfaces and only occasionally 

 can small drops of compound be seen in the drain reservoir, which shows 

 the effectiveness of this type of seal. As an extra precaution against con- 

 tamination of oil with wire drawing compound, only a small amount of oil 

 is permitted to flow to the capstan bearings, sufl&cient for adequate lubrica- 

 tion. This is drained to a reservoir and clarified before re-use. 



Another form of seal is shown by Fig. 14. This is used at the takeup arbor 

 where oil was driven through any commercial gasket material by centrif- 

 ugal force. The oil was thrown out into the inside of the reels and caused 

 discoloration during the annealing. This has been effectively sealed by 

 making a ring of dead soft copper wire carefully joined. The end cap is 

 bevelled to force the ring to the inside of the arbor and against the edge of 

 the bearing, making a tight three-point contact. These rings are never 

 used more than once. 



Reels: — The reels are provided with a magazine on the outside of the 



