150 



BULLETIN 711, U. S. DEPARTMENT OF AGRICULTURE. 



H'UUNG U1C 



hook when the hook is in use, and automatically drops over the point 

 of the hook when the hook is run back by the trip line, thereby 

 protecting the point and preventing the hook from catching or 

 hanging up when the line is run back. This hook costs from $13 

 to $17, depending on the size. 



Miscellaneous equipment. — Practically all the differences in equip- 

 ment between roading and ground yarding wall be suggested by the 

 peculiarities of the two methods, making it unnecessar}^ to enter 

 into- a discussion of the miscellaneous equipment used in roading. 



Special equipment. — When the road is. so steep that the turn of 

 logs runs, special'devices are sometimes used. 



(«) One of these, the cable grip, is shown in figure 60. At one 

 camp where the grip is used the operator had to contend with the 

 following conditions : 



The topography of the country was such that the logs had to be 

 hauled from one-half to 2 miles over pole roads by road engines. 



The aim was to secure a 

 favorable grade of about 5 

 per cent. Too often the to- 

 pography of the country 

 was such that the grade in 

 places was much steeper 

 than this, amounting to 50 

 per cent at times. At one 

 time two roads, each of which was from three-fourths to 1 mile in 

 length, were used. One of these had a rise of 150 feet in the first 

 2,000 feet ; from then on for a distance of 2,000 feet the rise was 550 

 feet, giving an average grade of 27^ per cent. A part of the road in 

 the last stretch rose 350 feet in 1,000 feet, the grade for 300 amount- 

 ing to 50 per cent. While the aim was to make the roads as straight 

 as possible, it was necessary to put in curves to cheapen the con- 

 struction cost. 



About 100,000 feet of timber per day was hauled over this pole 

 road. This output, however, only indicated the possibilities of the 

 method under these conditions; considerably more, without doubt, 

 could have been handled. On another road, which was about If 

 miles in length and had grades equally bad, a little more than six 

 trips per day were made, 15 logs, having an average volume of 1,200 

 feet, being taken at a turn. 



The success of these long hauls was attributed to the cable grip 

 (fig. 57), by means of which the turn of logs is attached to the haul- 

 ing line. It consists of two jaws which have a gripping action when 

 the strain of the load is brought to bear on it. This action auto- 

 matically clamps the line between the jaws with sufficient force to 



Fig. 57. — Road cable gfip. 



