LOGGING IN THE DOUGLAS FIE REGION. 



77; 



D equals diameter of flange, iii inches. 



(1 equals fliameter of barrel, in inches. 



L equals length between the flanges, in inches. 



C equals constant, varying for each size of line. 



Value of C. 



Size of line. 



J inch. 

 • fe inch 

 finch. 

 •J^inch 

 I inch. 

 A inch 

 finch, 

 finch, 

 finch. 



Constant. 



4.16 

 2.67 

 1.86 

 1.37 

 1.05 

 .828 

 .672 

 .465 

 .342 



Size of line. 



1 inch... 

 IJ- inches 

 li inches 

 if inches 

 IJ inches 

 1| inches 



1 J- inches 

 l| inches 



2 inches . 



Constant. 



0.262 

 .207 

 .167 

 .138 

 .116 

 .099 

 .085 

 .074 

 .066 



' Using the above formula, the drum capacity is obtained by multiplying the 

 sum of one-half the diameter of the flanges and one-half the diameter of the 

 barrel by the difference between one-half of the diameter of the flanges and one- 

 half the diameter of the barrel by the length between the flanges and the con- 

 stant for the size of the line required. Five-eighths inch line is almost uni- 

 versally used for trip lines. The main line varies from 1 inch to If inches in 

 diameter. 



In computing the proportion between the main drum and the trip-drum rope 

 capacities it is assumed that the main line is li inches and the trip line § inch. 



(d) As a matter of relative comparison only, the speed of any line is the speed 

 of the line when the drum is one-half full of cable and engine is running at a 

 piston speed of 600 feet per minute. 



(e) Standard logging engine. — What is kaown as a standard logging engine 

 is a two-drum machine complete with boiler, hood, stack, spark arrester, and 

 one gypsy head. Patented spark arresters, straw-line and loading drums, and 

 the like, are additional equipment, and usually are furnished at extra cost. In 

 the case of narrow drum yarders where a true lead is necessary on the drums, 

 one main line and one trip line fair-leader should be furnished with each engine. 



(/) Boilers. — ^The working pressure of boilers 48 inches or larger in diameter 

 should not be less than 175 pounds. Boilers are rated by their inside diameters 

 and the over-all length of effective shell. Any 'extension below the water leg 

 for the ash pan or any extension above the tube sheet for the breeching is not 

 considered part of the effective shell. 



ig) Pulling power. — The pulling power of any drum can be obtained by the 

 following formula : 



rXGXPXA 



W= 



R 



W= Weight or pull on cable. 

 P=Full boiler pressure. 

 A=Area of one cylinder. 

 r= Radius of crank. 

 R=Radius of drum. 

 G=Gear ratio drum. 



Th6 size of yarding engines varies in different camps. An operator 

 who has given more than the usual amount of attention to this 

 question, and who has a reputation for consistently securing large 

 yarding -outputs, made the following recommendations, based on 

 uphill yarding: 



