LOADING AND UNLOADING CARS 375 
An overhead cahlcway sj^stem which is supported on two spars 
from 500 to 600 feet ai)art and spanning the railroad track on which 
the logs are brought in, is sometimes employed where logs are 
stored in piles. 
An ingenious device called a log dump is in use at some plants. 
One built in Washington has two dumps separated by 30 feet 
of stationary track, the entire structure being supported on 
piling.^ The platform of each dump is 40 feet long and has 
four latch timbers {A)~, which are 11 feet long and a fifth timber 
(B), known as the trip timber, which is 36 feet long and of larger 
size. The frame is hung on a roller timber (C) 18 by 18 inches 
square and 40 feet 2 inches long which rests on heavy cast-iron 
sills. The roller timber is bound with an iron cylinder to facili- 
tate its rotation. This roller is placed off-center, the distance 
between the rail on the land side and the center of the roller 
timber being 25 inches. When the latches (D) holding the frame 
are released the weight of the load will automatically tip the 
frame toward the brow skid (E) through an arc of 15 degrees. 
The cars are run on the dump, the chains holding the logs on the 
cars removed, and the latches (D) opened. The dump then 
revolves until the car bunk rests on the brow skid (E). Man}' 
logs will roll off, but some may have to be started by means of 
a cable passing through a block rigged on a gin-pole and pulled 
by a locomotive. The dump will not tip when the load is heaviest 
on the land side, in which case it is tilted by prying up on the 
end of the trip timber (B). After the logs are off the car the dump 
is brought to a horizontal position by having men walk out 
on the trip timber (B). 
The double dump will handle two cars of 40-foot logs, or one 
car of long logs by spotting one truck on each track. Three 
men can unload a car in two and one-half minutes and can un- 
load 350,000 board feet or more daily. 
One efficient unloader has a hoisting engine and two drums 
mounted on a car equipped with a rigid boom. The railroad 
track is built parallel to the rollway and the unloader runs on 
an additional track on the land side of the dump. The boom 
is so placed that it projects at right angles over the far edge 
of the railroad track. The unloader can travel back and forth 
1 The Timberman, August, 1912, p. 68. 
2. See Figs. 131 and 132. 
