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, Washington, 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, Washington. 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.
The average time to lower the load down the incline is three and a half minutes. At the bottom of the incline, the cable is released and the truck goes on its way. The cable is attached to the waiting truck by means of a ring fastened to the frame and the donkey pulls the empty truck to the top. The time taken to raise the trucks is three minutes.
On grades too steep to operate a truck safely with the ordinary brakes and yet not steep enough to warrant the expense of the donkey snubber, the difficulty is overcome by means of a friction snubber. This consists simply of a cable which is hooked to the truck and extends through a system of three or four pulleys and thence on down the track. The friction of this line dragging on the ground and pa.s.sing through the pulleys is enough to hold the load so that the truck engine must exert power to pull the load down the grade. The line is made long enough so that as the load reaches the bottom of the grade, the free end of the cable has been pulled up to the system of pulleys and is ready to be attached to the next load. This system is efficient for small grades, is inexpensive to install, and requires no further attention.
By the use of the incline with the donkey engine snubber, very heavy grades can be taken. The construction of the incline is the same as the rest of the road and is only slightly more expensive to build because of the inconvenience of laying it on such a steep slope. The use of the incline will not slow up the operation to any great extent as from fifty to seventy thousand feet of logs (which is about the average yarding and loading capacity of one motor-truck side), can be taken over it in a day. This method of hauling down steep grades is used in several operations and has been found to be entirely successful.
YARDING
A variety of methods are used by motor truck loggers to get the logs to the landing to be loaded. The larger operations invariably use the high-lead method of yarding as the logs come in quicker and with fewer hang-ups. In a few places the old ground method of yarding with a bull block is still used. The horse team and skid road is used in a small timber where poles and piling are being marketed. The latter is a slow method but will keep one truck busy and is still used in some places where small stands are located along the highway or in other readily accessible places.
LOADING AND UNLOADING
The loading of a motor truck is very much the same proposition as the loading of a flat-car. The princ.i.p.al difficulties that trucks have had to contend with have been poor roads and inefficient methods of loading.
In loading, the main trouble has been in regulating the yarding so that a supply of logs is always on hand. The use of the gin pole and crotch line operated by the straw drum of the yarding donkey ties up the yarding until the truck is loaded. This is being overcome by using a separate engine with the high lead for yarding and doing the logging independently of the yarding as is done in the case of railroad logging.
In this way the yarder can keep ahead of the loading engine and there will be no delay at the landing.
Most of the larger companies load with the Duplex loader and use tongs.
This is a safer way to load than with the crotch line as the logs can be more easily controlled. The danger of dropping a log through the truck or of knocking off the top of the truck or the driver"s seat is greatly lessened.
In pole and piling timber where a skid road and horses are used, loading is done by hand or with a team. A landing is built of cribwork and the logs are simply rolled on the truck with peavies or cant hooks, or a parbuckle system with skids and horses is used. This works fairly well for small operations in small timber.
[Ill.u.s.tration: Loading a motor truck and trailer through the use of a boom.]
The latest development in loading is the boom. An ill.u.s.tration of this method is shown above. The boom itself is a fifty to sixty foot pole about eighteen inches in diameter at the base and is attached to the spar tree by means of a metal strap with two lugs which are fitted into holes bored in the spar to keep the strap from slipping. The base of the boom is fitted with a metal joint which moves freely on an upright pin set in the metal strap. (See A, above.) The whole rig is set high enough on the tree so that it may be swung in a semi-circle and clear the loaded truck by several feet. A light line (B) from the haulback drum of the donkey pa.s.ses through a block attached low on the spar tree and thence to another block on a stump to the right of the landing. From here it pa.s.ses through a third block at the end of the boom and back to the stump again. This secures the needed pulling power from the haulback drum.
The lifting line from the mainline drum pa.s.ses through a block half way up the tree and thence through a free swinging block (C) and back to the tree again. On the second block is a ring to which two one inch lines (D) are attached. These lines pa.s.s through the boom stick on rollers (E) about fifteen feet apart. On the ends of these lines hooks are attached.
These two lines should be so arranged that the hooks remain parallel to the ground. Two three-quarters inch cables (F) with an eye splice in each end are attached to the hooks. These lines, or chokers, are then wrapped around the log and it is lifted clear of the ground by means of the block hold in the main line.
The haulback line (B) from the donkey is slacked and the boom travels over to the truck by means of a line (G) attached from the boom to a dummy log running on a special guy line. A log two feet in diameter and sixteen feet long is wrapped at each end with a cable and fastened to a pulley. The two pulleys and attached dummy log travel up and down the guy line as the boom moves. A line is attached to the boom and runs through a pulley attached to the dummy log and extends back to the boom again. This pulls the boom over above the truck as the dummy log travels down the guy line. The logs are held parallel to the ground above the truck and the truck is run under the boom to the location designated by the head loader. With this system the logs will not drop suddenly on the trucks as the log will fall off while being carried over to the truck if there is any danger of its falling at all. After the log is placed, the boom is pulled back to the landing by the haulback line. This system has worked with success in a number of motor truck operations and is a safer method than loading with tongs because the logs cannot accidentally drop and injure the truck. However, the loading situation should be studied carefully. The most efficient loading device for the particular needs of the operation may be installed as any loss of time in loading seriously affects the output of the operation.
Most of the truck loggers unload their logs into water; either into a lake, a river that can be driven, or into tide-water. A few, however, unload directly into the log pond at the mill or at the log yard in case the mill has no log pond.
The road is usually planked solid at the unloading ground. A great help in unloading is a dock from six to twelve inches higher on one side than on the other so the logs will roll off the truck easily. The brow-skid should be close to the log bunks and just a little lower than these when the truck is tilted. When unloading into shallow water, such as a small river, six or eight skids a foot and a half in diameter are placed so that they slope from the brow-skid to the water at an angle of forty-five degrees. An ill.u.s.tration of this method of unloading is shown below. The skids are so placed that the unloading ground will not be undermined.
[Ill.u.s.tration: Unloading truck and trailer through the use of an incline, showing brow-skids and roll-way.]