LOADING AND UNLOADING CARS 361 
A power loader has a steam hoisting engine and drums, an 
upright boiler, and a rigid or swinging loading boom. It is 
usually mounted on a truck which is provided with some ap- 
pliance for transporting the machine. Gasoline engines have 
been substituted for steam on some patterns but they are not in 
extensive use. 
Loaders are built with a short swinging base-control boom, a 
long swinging end-control boom, or with a rigid l)oom. The 
first two types are adapted for loading on poor track because 
the logs can be centered on the car and less manual labor is re- 
quired to build the load securely. They also are desirable where 
the logs are scattered. Short booms are not adapted to handling 
long lengths. Rigid booms are used to advantage on good 
track where the logs are abundant and fairly well decked. 
There are two types of loaders. 
(1) Loaders operating from log cars. The Barnhart, Model 
C American, and the Rapid loaders are examples of this type. 
(2) Loaders operating from the main railroad track. The 
Decker, McGiffert, Surry Parker, American Models D and E, 
and the Browning are the more common machines of this type. 
An advantage of the second type of loader is that it may re- 
main in one place until all logs are loaded, while loaders of the 
first type must change their base for every car unless a locomotive 
is in attendance to move the train as desired. 
(a) Barnhart. — This style of loader requires either perma- 
nent or temporary tracks on the log car over which the loader 
passes. When permanent track is used, the rails are laid only 
the length of the car bed, because otherwise they would inter- 
fere when the train rounded sharp curves. The space between 
the rails on each car is spanned with two fl -shaped irons placed 
on the car rails which can be removed as soon as the loader has 
passed over the gap. Temporary tracks are made in three sections. 
The loader rests on one section, another spans the gap between 
the two cars and the third rests on the empty car at the rear 
of the machine. As the loader proceeds along the train the 
tracks are picked up by the loader and moved behind it. 
The engine, drums, booms, and all working parts are mounted 
on a steel frame, which is pivoted to a truck frame carrying 
eight pairs of trucks, with wheels 10 inches in diameter. The 
loader can revolve in a complete circle by means of a geared 
