76 BELL SYSTEM TECHNICAL JOURNAL 



While the large capacity units have reached the stage where they 

 give satisfactory operation, there is a field in the telephone business 

 for a much more compact, lighter weight unit of lower capacity and 

 cost, for such work as the opening of trench for subsidiaries, cutting 

 frost, drilling rock for pole hole blasting, etc. With this in mind 

 there has recently been developed in cooperation with an air com- 

 pressor manufacturer, a type of compressor which is suitable for 

 operating either one jack hammer for rock drilling or one tool for 

 street opening with a corresponding capacity for other types of com- 

 pressed air work. It is expected that the weight of this unit can 

 through further study be reduced to such an extend that it will be 

 practicable to mount it upon a Ford one-ton truck and still leave 

 sufficient carrying capacity to handle the necessary guns, steels and 

 hose for operating. Where there will be practically constant use for 

 this lighter unit it may be desirable to mount it permanently upon the 

 truck, while, in cases where the use will be intermittent, a very economi- 

 cal and convenient mounting can be made upon one of the Army type 

 trailers. 



Conclusion 



In this article an endeavor has been made to cover in a very brief 

 way some of the more important items of mechanical application 

 which have a place in telephone construction work. The adaptation 

 of mechanically operated tools and other devices to assist in the neces- 

 sary manual operations will undoubtedly continue to occupy an im- 

 portant place in the work. Further study and development should 

 result in many improvements in the present-day way of doing things 

 which will make not only for marked economies of operation, but for 

 greatly increased features of safety to the men engaged in constructing 

 and maintaining the telephone plant. 



