. Electric railway journal . TEMPERATURE. DEGREES CHART FOR DETERMINING EXPANSION AND CONTRACTION OFCOPPER BUSBARS bus in tenths of an inch, while the vertical lines repre-sent degrees either Centigrade or Fahrenheit accordingto which of the temperature lines is used. An example in the use of the chart follows: If thebusbar is installed at 77 deg. Fahr. and the lowest tem-perature to which it will be subjected is 50 deg. Fahr.,it will contract a maximum of in. per 100 ft. oflength. If the temperature increases to 130 deg. busbar will expand in. per 100 ft. above itsinstallatio
. Electric railway journal . TEMPERATURE. DEGREES CHART FOR DETERMINING EXPANSION AND CONTRACTION OFCOPPER BUSBARS bus in tenths of an inch, while the vertical lines repre-sent degrees either Centigrade or Fahrenheit accordingto which of the temperature lines is used. An example in the use of the chart follows: If thebusbar is installed at 77 deg. Fahr. and the lowest tem-perature to which it will be subjected is 50 deg. Fahr.,it will contract a maximum of in. per 100 ft. oflength. If the temperature increases to 130 deg. busbar will expand in. per 100 ft. above itsinstallation length. The total change in length for the 80 deg. change in temperature is in. It should beadded that the expansion determined from this chart isthe actual change in the length of the copper and thatthis change is a little greater than the change relativeto the structure on which the busbar is mounted. Thesupporting structure, of course, also expands and con-tracts with changes in temperature, but it is generally. BUSBAR EXPANSION JOINT less affected by such changes and also responds muchmore slowly to variations in temperature than does thecopper busbar. The use of this chart has been suggested by the Gen-eral Devices & Fittings Company, Chicago, 111. Thiscompany has also developed the expansion joint shownabove to take up the changes in busbar length. Thesejoints can be bolted into the bus stack and cause no re-duction in the conductance. Hopper and Conveyor FacilitateUnloading Cars of Ballast For unloading and piling ballast delivered in carsthe Pittsburgh Railways have a rig consisting of abucket running up an incline which leads from beneaththe unloading track to a hopper at the top of a frame-work made of telephone poles. The ballast is dumpedinto the hopper and distributed through steel chutes,not shown in the picture, which can be moved properlyto pile the ballast. The cars of ballast dump into a specially built steelhopper underneath the track, where there is a
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