In rough country the use of the incline has been a great help and has
proved to be entirely practical and quite economical. Grades as high as
sixty or even seventy per cent can be safely taken with an incline if
the proper measures are taken to prevent accidents.
A typical incline is successfully operated by the Meickeljohn, Brown
Logging Company near Monroe, Washington. It is fifteen hundred feet long
and the steepest grade is twenty-eight per cent. An 11-in. x 14-in.
roader donkey located at the top of the incline snubs the loads down and
hauls up the empty trucks. A one and one-eighth inch wire cable is
thrown around the logs and made fast by means of a clevis. This holds
the truck and prevents the logs from slipping forward and injuring the
driver. On all inclines, the line should be choked around the logs
rather than simply attached to the truck to prevent them from slipping
ahead.
The snubbing device consists of an ordinary donkey engine fitted with a
hand brake of extra large size and special air valves so that air is
sucked into the cylinders and let out of the exhaust when the engine is
being pulled backwards by the weight of the load. The load is controlled
by the amount of air let out of the valves. The braking action is very
positive and the load can be stopped in a few revolutions of the crank
shaft.
The average time to lower the load down the incline is three and a half
minutes. At the bottom of the incline, the cable is released and the
truck goes on its way. The cable is attached to the waiting truck by
means of a ring fastened to the frame and the donkey pulls the empty
truck to the top. The time taken to raise the trucks is three minutes.
On grades too steep to operate a truck safely with the ordinary brakes
and yet not steep enough to warrant the expense of the donkey snubber,
the difficulty is overcome by means of a friction snubber. This consists
simply of a cable which is hooked to the truck and extends through a
system of three or four pulleys and thence on down the track. The
friction of this line dragging on the ground and passing through the
pulleys is enough to hold the load so that the truck engine must exert
power to pull the load down the grade. The line is made long enough so
that as the load reaches the bottom of the grade, the free end of the
cable has been pulled up to the system of pulleys and is ready to be
attached to the next load. This system is efficient for small grades, is
inexpensive to install, and requires no further attention.
By the use of the incline with the donkey engine snubber, very heavy
grades can be taken. The construction of the incline is the same as the
rest of the road and is only slightly more expensive to build because of
the inconvenience of laying it on such a steep slope. The use of the
incline will not slow up the operation to any great extent as from fifty
to seventy thousand feet of logs (which is about the average yarding and
loading capacity of one motor-truck side), can be taken over it in a
day. This method of hauling down steep grades is used in several
operations and has been found to be entirely successful.