360 



THE WORLD'S ADVANCE 



solid joint much stronger than could be 

 secured with wooden pegs results. 

 Contributed by 



ARTHUR CALL. 



Spot Welding on Locomotives 



A novel method of attaching a non- 

 conducting, heat-resisting lining to sheet 

 steel is used on the cabs of modern elec- 



,/nner cod sheeting 

 Outer cab sheeting 



V lv>^RX 



Copper rod 



&&$, 



r~/g.1 



Push rod X' 



trie locomotives. This lining of asbestos 

 board is necessary to keep the engineer's 

 traveling quarters comfortable at all 

 times warm in winter and cool in sum- 

 mer. . 



One-inch nails are electrically spot 

 welded by their heads to the inner sur- 

 face of the outer steel sheeting of the 

 cab, as shown in Fig. I. The asbestos 

 lining is driven home on the nails, which 

 are then tightly clinched over large tin 

 washers. A thin metal sheeting is ap- 

 plied over all, giving a smooth, finished 

 appearance to the interior of the cab. 



A more detailed description of the spot 

 welding equipment is given, in the hope 

 that it may suggest further uses of a 

 similar nature. 



A special transformer, capable of 

 transforming about six kilowatts from a 

 5 50- volt shop circuit to a working pres- 

 sure of from three to five volts, is used. 

 At this low voltage a current of from 

 fifteen hundred to two thousand amperes 

 gives good results. 



One of the low-voltage terminals of 

 the transformer is connected by heavy 

 cables to the locomotive frame, while 

 from the other a heavy, flexible conduc- 

 tor (cable) carries the current to a 

 sturdy copper terminal arranged to grip 

 the nail for welding. A fibre sleeve, fit- 



ted over this terminal, furnishes a handle 

 for the operator. The terminal is shown 

 in detail in Fig. 2. 



The primary circuit of the transformer 

 is closed by a small, oil-immersed con- 

 tactor energized by a no- volt circuit. As 

 approximately two pounds of nails are 

 required for each cab, the operator must 

 lose no time in making and breaking con- 

 nections. An ordinary snap switch was 

 found to be too slow and awkward to 

 handle. A push-button control switch 

 was made up from an old cartridge fuse 

 and so arranged that the workman can 

 close the circuit by pressing the rod, A, 

 shown in Fig. 3, against the cab or loco- 

 motive frame. 



Contributed by 



HANDYMAN. 



Grinding Ball Bearings 



Bicycle hub cones, which have become 

 deeply rutted by continued wear or not 

 enough oil, can be renewed by placing 

 them in a lathe and grinding down with 

 an emery stone and fine sandpaper. 



Contributed by 



ARTHUR EDGAR. 



Gives Warning When Lock is Touched 



Door locks of the type wherein the 

 bolt slides in and out of the rest of the 

 mechanism, as shown in the drawing, 



can be made "tamper-proof" by screw- 

 ing two springs above the bolt, so that 

 when the bolt is withdrawn from them 

 they are separated. If the springs are 

 placed in an electric circuit composed of 

 dry cells and a doorbell, when the lock 

 is tampered with, the bell will sound an 

 alarm. 



Contributed by F. T. STURTEVANT. 



