196 LOGGING 
TRACTION ENGINES FOR WAGON HAUL 
Traction engines are sometimes used for transporting logs from 
the woods to the mill when the amount of timber to be hauled is 
not great enough to warrant the construction of a railroad, when 
the grades are unfavorable for the use of animals and when 
timber of large size and great weight must be handled. They 
are rapidly being supplanted by motor trucks which are faster 
and more efficient. 
A traction engine to give the best results requires a good stone 
road but it works well on solid earth bottom. The ordinary 
4-wheeled type is not successful in swamp}^ places, on rough roads 
or on dirt bottom during rainy periods because the traction 
wheels soon render the road impassable. 
Four-wheeled. — This traction engine has a locomotive-type 
boiler carrying about 165 pounds' steam pressure, and is equipped 
to burn either coal, wood or oil. The boiler and other parts of 
the engine are mainl}^ supported on two traction wheels running 
on axles attached on opposite sides of the fire box. The diameter 
of these wheels is ordinarily between 5 and 6 feet. The width of 
tire is governed by the character of bottom over which the engine 
is to travel. On ordinary roads from 20- to 24-inch tires are 
adequate even for the largest machines. 
The forward part of the engine is supported on a pair of 
wheels 3| or 4 feet in diameter with from 6- to 10-inch tires. 
These wheels carry only a small proportion of the total weight, 
their chief function being to aid in steering. This is done by 
means of a hand wheel placed at the rear of the engine in close 
reach of the engineer. 
The engine which develops from 20 to 30-horse-power is of 
the single cylinder type with a heavy flywheel. 
The daily fuel requirements range between 1| and 2\ cords 
of hardwood, or between 1 and 1^ tons of coal. About 2500 
gallons of water are needed for the above amount of fuel. 
On a Washington operation a 30-horse-power traction engine 
has made a daily round trip of 30 miles, hauling 20,000 board 
feet of green lumber up 15 per cent grades, and down 30 per cent 
grades. This is probably the maximum capacity of an engine of 
this type. 
Holt Three-wheeled. — This type was developed chiefly for 
use in logging on the Pacific Coast and has a return-tube water- 
