1114 THE BELL SYSTEM TECHNICAL JOUENAL, SEPTEMBEK 1953 



current is carried from the copper casting by a flexible connection to the 

 bus bar. The surface of the tube is provided with shallow grooves on 

 1-M'' centers to position the wires and the whole contact roll assembly 

 consisting of tube, bearings and shaft can be shifted laterally to bring a 

 new set of grooves into play when wear dictates. 



Pilot plant experience had shown that electrolyte will be carried by 

 the wires to the contact rolls and will spread out over their surface, 

 eventually reaching the bearings and the brush contacting surfaces. Some 

 type of seal had to be provided where the roll passed through the wall of 

 the trough. Various types of commercial seals were tried, but all left much 

 to be desired. The seal finally developed for the application is in two 

 parts: a molded Neoprene double slinger ring on the roll, operating in a 

 molded Neoprene housing inserted in the trough wall. The slinger ring 

 successfully prevents the passage of electrolyte while the housing pie- 

 vents splash from carrying past. This seal has the important further 

 advantage that there is no contact between the fixed and moving parts 

 so that there is no friction loss and no wear. Also, it is a simple molded 

 rubber part which slips into place and requires no fastening. 



The wires, in their travel through the plating machine, are acted upon 

 by nine different electrolytes. An appreciable amount of electrolyte is 

 carried with them and if means were not provided to remove the en- 

 velope of solution, the succeeding baths would be quickly contaminated, 

 and in some cases dangerous gases would be generated. In general, the 

 transition section between dissimilar electrolytes is made up of an air 

 wiper, a water wash and a steam wiper, in order of wire travel. The wiping 

 element at each wire is the convergent blast of steam or air from three 

 small nozzles. Twenty-five sets of these nozzles, one set for each wire 

 channel, are mounted in a manifold. In the case of an air wiper, the 

 spent air and droplets of electrolyte wiped from the wire are directed 

 into an eliminator where the droplets are caused to separate from the 

 air stream by impinging on the metal baffle plates. The steam wiper is 

 of similar construction except that a water-cooled condenser is substi- 

 tuted for the eliminator. The cooling water for the condenser is dis- 

 charged into a typical cell, mounted between the two wipers where it 

 washes the wire and discharges to waste. 



While these washing facilities may appear somewhat elaborate, they 

 are justified on the basis of reliability and safety. The failure of any one 

 of the three services, air, water and steam, will not cause appreciable 

 contamination before repairs can be made. 



At the copper cyanide, brass cyanide and acid copper plating sections, 

 the wipers are preceded by dragout recovery units. A dragout recovery 



