INCLINES 299 



is regulated by means of heavy band brakes placed on flanges 

 attached on either side of the drum. 



The haul cable is returned to the top of the incline by various 

 devices. One type consists of a small drum placed on one end 

 of the main drum shaft and has a trip line from a yarding engine 

 wrapped two or three times around it. When the main cable is 

 to be wound up, the trip line is tightened by sheave pulleys, and, 

 as it is wound in, the main drum is rotated. 



Another method used is to employ a donkey engine equipped 

 with a large drum and i|-inch cable with the cars attached to 

 the free end. The speed is controlled largely through the car 

 brakes supplemented by friction brakes on the drum. Empties 

 are brought to the head of the incline by winding in the main 

 cable. 



On some inclines the empties are brought up by a gravity 

 plane. The snubbing device consists of a large drum equipped 

 with friction brakes and provided with a cable which is passed 

 three or four times around the drum to prevent slipping. A 

 single track provided with an automatic switch at a point midway 

 between the head and foot of the inchne is used. 



In operation loaded cars are attached to the cable at the 

 head and empty cars at the base. The loaded cars proceed 

 down by gravity, passing the empties on the midway switch. 

 When a loaded car reaches the base the cable is removed and 

 attached to an empty and another loaded car attached at the 

 upper end and the trip repeated. 



Hydraulic machines for controlling the speed of cars lowered 

 on inclines are used to some extent in the Northwest. 



A device^ of this character is shown in Fig. 85, a and h. 



The water cylinders (A') are closed at both ends and are con- 

 nected with the pipe (L) which has a plug valve {M) near the 

 middle. When {M) is closed the water is confined and holds the 

 pistons [H) rigidly in place. Opening the valve {M) allows 

 the water to pass alternately from one end of the cylinder to the 

 other, the speed being governed by the extent to which the valve 

 is opened. The controlling levers are so arranged that the valves 



^ See The Timberman, Portland, Oregon, October, 1909, p. 51. 



