158 BULLETIISr 111, V. S. DEPARTMENT OP AGEICULTUEE. 



head pole, then through another block of the same size on the tail 

 pole, and thence to the fall block of the hoisting line, where it is 

 attached. With crotch lines attached to the fall block, the largest 

 logs can be lifted from the landing and moved toward or away fi'om 

 the car. 



In one case, the power is furnished by a 9-^- by 10 inch double cjd- 

 inder engine, steam being supplied by a 50 by 120 inch vertical 



Fig. 63. — Overhead loading system. 



boiler, having a working pressure of 175 pounds. The upper or 

 main drum carries the hoisting line. On the front shaft are two 

 drums, one of which carries the trip line, the other the straw line. 

 By means of the straw line, cars can be moved at the pleasure of the 

 engineer, the power furnished being ample to " spot " six loaded 

 cars on a 2^ per cent grade. The three drums are operated by three 

 separate friction devices, maldng them independent of each other. 

 The car and the load are under the control of the loading engineer 

 at all times. The load is lowered by means of a powerful steam 

 brake, thus eliminating the danger of dropping a log, which might 

 injure a loader or break a car. 



In some cases the ^-inch hoisting line, leading from the main 

 drum, passes through a 14 by 3 inch single-sheave corner block at 

 the top of the head pole, then through a fall block of the same size, and 

 thence to the gin pole, where a tail hold is taken. The scheme is 

 shown in figure 61. In other cases, one of the trip-line corner blocks 

 is hung on a li- or 1^ inch guy instead of a tail tree, the guy line, 

 which is called the front guy line, being strung from the top of the 

 head pole to a stump at the back of the landing. The scheme is 

 shown in figure 64. 



The fixed investment in equipment at one side with this method, 

 when a double-sheave corner block is used, is about $4,193, as follows: 



