CRANE. | Handling and Hauling Ore. 213 
Buckets are placed upon low trucks, which are then trans- 
ferred from mine to mill on elevated tramways and handled 
as are cars proper. 
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Fig. 21. A three-quarter set, with lagging, as em- 
ployed in fairly firm ground. 
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There are three general systems of handling ore in buckets 
and cars, which are as follows: Hand tramming, slope or in- 
clined and engine plane haulage, and aerial rope and rail 
methods. 
Hand tramming is by far the most common and is a very 
simple method of procedure, requiring as it does only an 
elevated roadway for the cars or bucket trucks to operate 
upon and a man to pushthem. The tramway tracks should 
be given a grade of at least one-half of one per cent. in favor 
of the loaded cars. 
Occasionally self-acting or gravity and engine planes are 
operated on the tramways, which, however, 
necessitates 
double tracks. 
In the former case two cars, one to each 
track, are connected with a wire rope or cable, which is 
sufficiently long to allow the cars to be at the shaft and mill 
ends of the system at one and the same time; 7. ¢., one is re- 
ceiving while the other is discharging its load. The grade 
is such that the loaded car runs freely from the shaft to the 
mill, and at the same time, acting through the cable, which 
