Part 4 (1/2)

One of the big advantages of the concrete road is the large gain in traction secured when operating on steep grades. A motor truck will haul up a twelve per cent and down a fifteen per cent grade in wet weather on concrete due to the roughened surface on which the tires do not easily slip. This, of course, would be dangerous to attempt on the other types of roads. Another advantage is the small item of upkeep necessary. A road well laid in the first place should need no repair except to replace worn guard rails as they show signs of weakening. The concrete road, however, will not be generally used except on the mainline by the larger concerns, or for short distances on steep grades where greater traction is desired.

BRIDGES

In most cases the construction of bridges is unnecessary on account of the steep grades the trucks can take and because they can negotiate sharp curves, which make it easier to avoid expensive bridge work.

Where they are absolutely necessary a serviceable bridge is made of cribwork.

The Esary Logging Company of Camano Island, Was.h.i.+ngton, operates over a crib bridge 175 feet long and 15 feet high. The sub-structure of this bridge is made of logs laid alternately crosswise in tiers. Six by twelve inch plank are laid diagonally on the cribbing and four by twelve inch plank are placed on crosswise to the road on top. This makes a b.u.mpy surface. A better one could be made with cross-ties placed on the cribbing with fore and aft planking on top. A guard rail is placed on all bridges.

Short bridges up to eighty or ninety feet in length are constructed by the use of two large logs hewn flat on the upper surface. The logs should be at least thirty-six inches in diameter and perfectly sound.

They are placed at the proper gauge and the regular road on cross-ties constructed on top. On such short stretches this type of bridge has been operated over without supports. It is not used, however, for long stretches. The long bridges are, of course, constructed of bents or piling but are very seldom used in connection with motor truck transportation on account of the expensive construction and because they are usually unnecessary.

TURNING DEVICES AND TURNOUTS

When the truck and trailer reach the place where they are to be loaded, some method must be used to turn them around. Various means are used to accomplish this. One is the motor truck turn-table. The turn-table should be slightly longer than the length of the truck and trailer combined. It is constructed of heavy plank and timbers so that each track is about 16 inches wide and tapers in thickness from about 14 inches at the center to 4 inches at the ends. The two tracks are held together at the center and each end by heavy timbers. A heavy timber is sunk to the level of the road and at the center two circular saws are laid. A king bolt through the center brace of the turn-table and through the two saws into the sunken timber provides a pivot upon which the table turns. When properly balanced and with a little oil between the surfaces of the saws, the turn-table can be operated by hand with very little effort. It is usually placed at the end of the road. A turn-table can be loaded on the truck and trailer when it is desired to move it, so that as the road is extended into the timber, a means of turning the truck can be obtained close to the point where the logs are to be loaded. This device can be built at a cost of from $75 to $125 and is very serviceable. The main objection to its use is that the setting has to be just right to make it work satisfactorily and it is sometimes difficult to get a spot that is level enough. It is always a difficult problem and a different one for each set-up.

The use of the ”back around” is more common with truck loggers at present because it is easier to build. The back-around is simply a pocket or short spur along the road above the landing ground which is planked solid. The truck and trailer are backed into this far enough so that the truck can pull ahead in the opposite direction. This method of turning the truck requires only a little extra clearing and grading and is less expensive and more easily constructed than a turn-table.

[Ill.u.s.tration: Turn out on fore-and-aft plank road.]

When two or more truck units are to be used on a single track, a careful calculation must be made to determine the best pa.s.sing places. The location of these points may determine the success of the operation.

They should be placed so that the truck returning empty can reach the turnout before the loaded one comes along in order that the loaded one may not be held up. At the same time, the turnout should not be so far away from the loading ground that the loading crew will be idle for any length of time while waiting for an empty truck. It is better to have an extra turnout, even if seldom used, than conditions that would hinder efficient operation or might even result in a collision which would tie up the logging for several days.

A few loggers build a turnout of the same material as the main road for a short distance to the side. An ill.u.s.tration of this type of turnout is shown above. Most of them, however, simply clear off a right of way and put in a gravel bottom for the road as the waiting truck at this point is empty and will not ordinarily sink into the ground and get stalled. A few heavy planks laid fore and aft in the form of a track are sometimes used. The construction of pa.s.sing places is very simple--the only important thing to be taken into consideration is the proper point at which the trucks should pa.s.s in order to keep the operation going at maximum efficiency.

TELEPHONES

In connection with the pa.s.sing places, the installation of a telephone line is an important but often neglected item. With two or more transportation units, a telephone line is a handy if not well nigh indispensable accessory. It is a great advantage to have such a system with stations at each end of the road and also at the pa.s.sing places, as unavoidable delays will frequently allow a waiting truck to move on to another pa.s.sing place, thus saving time. To avoid accidents, the driver at the pa.s.sing place should call the loader at the spar tree to see if the road is clear before coming any farther.

Very often something breaks on the yarding or loading donkey. With the telephone, perhaps a half day of shutdown may be saved by calling the main camp for the repair parts and having them brought up by the next truck. The saving due to avoided accidents and the saving of time more than pays for the initial expense of installation. The telephone line should not be neglected at the larger operations.

INCLINES

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, Was.h.i.+ngton. It is fifteen hundred feet long and the steepest grade is twenty-eight per cent. An 11-in. 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.