Motor Truck Logging Methods: Engineering Experiment Station Series, Bulletin No. 12Knapp, Frederick Malcolm
Science
Motor Truck Logging Methods: Engineering Experiment Station Series, Bulletin No. 12
Knapp, Frederick Malcolm
Lumbering
The Meicklejohn and Brown Logging Company near Monroe, Washington,
operate over a pole road with three poles for each wheel. The poles are
from ten to twelve inches in diameter at the small end and are hewn to a
six inch face, giving an eighteen inch bearing surface for each wheel.
(See illustration on page 29.) The minimum sized pole that should be
used for roads of this character is one eight inches in diameter at the
small end. The road is constructed the same way as the single pole road
and the poles are laid on cross ties twelve inches in diameter placed
from eight to ten feet apart. Where the road is off the ground as when
crossing over a small depression, these sleepers must not be over five
feet apart. The guard rails at this operation are held in place by means
of a wooden brace nailed from each end of the rail to a near-by stump.
The ends of the poles used for the track are adzed so that they match
evenly. By breaking the joints and hewing them the road presents a level
surface with no bumps.
In planning the curves, it is necessary to make the tracks somewhat
wider than on straight stretches in order to keep the trailer from
running off. The track should be three feet wide on sharp curves and
provided with a stout guard rail if there is any danger of the truck
leaving the track. The curves are banked on the opposite side from that
used on railroad curves. That is, the inner rail is raised about three
inches. This is to throw the load to the outside away from the inner
guard rail, making it easier to make the turn without the rear wheels
binding. In this way a 35 degree curve may be negotiated with forty or
fifty foot logs. As the curves have to be passed at a much reduced
speed, there is little danger of the logs rolling off due to the raised
inner rail.
The grading for a road of this construction is usually light. The grades
should, if possible, be kept below five per cent. A truck will operate
better on a ten per cent grade in dry weather than on a five per cent
one in wet weather. On a road of this type, grades up to ten per cent
can be operated over unless there is snow. When the grades are above
this and the weather is wet, traction still may be secured by sanding
the road or by tacking an old half inch steel cable to the road in the
form of a figure "s". If this is sanded in addition, the truck may
safely be taken up a steeper grade than it would be safe to bring it
down without sanding.
The pole road could be greatly improved by hewing the faces of the poles
where they come together side by side so that an even fit is made. The
details of this improved form of construction are shown in figure 1,
page 30.
[Illustration: The most common type of motor truck logging road--a
fore-and-aft pole road.]
[Illustration: Figure 1. Cross section of pole road. Scale--1 inch
equals 2 feet.]
Public-domain text, read in full here on John Shaqi.
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