CLEARING WITH EQUIPMENT

CLEARING WITH EQUIPMENT

The use of engineer equipment is the most rapid and efficient method of clearing. The use of such equipment is limited only by un-usually large trees, stumps, and terrain that decrease the maneuverability of the equipment and increase maintenance requirements. This type of equipment includes bulldozers; tree-dozer, tractor mounted units; tractor-mounted clearing units; winches; power saws; rippers; and motor graders. In addition, pioneer tools are used for some clearing operations. Table 4-2 summarizes the limitations and proper applications of engineer equipment in clearing operations. Use production rates of equipment under normal operating conditions for determining the total time required for the job. Clearing rates are discussed in FM 5-434. Limitations and applications for each type of equipment follow.







Bulldozer

When clearing an area in dry or temperate forests, the bulldozer is the most efficient mechanical equipment for removing small brush, trees, and stumps up to 6 inches in diameter. Although more time and effort are required, bulldozers can also remove trees up to 30 inches in diameter when tractor-mounted clearing units and power saws are not available. Because of its ability to push, move, and skid felled trees and brush, the bulldozer is used extensively as the primary unit of equipment in all clearing operations.

When clearing with bulldozers, the sequence of operations depends on the type of trees, the terrain, and planned construction. After establishing the boundaries of the clearing, select spoil areas for disposal of all cleared material based on the shortest haul, a downgrade slope, effective camouflage, and general accessibility.

Start clearing at the disposal area and move in each direction away from it. Use one or two dozers to clear the small trees and brush only. Another pair of dozers will remove the larger trees and stumps bypassed by the previous units. If necessary, add more dozers for a third cycle of operation to take care of the heaviest removals.

Move the cleared material to the spoil area by skidding, pushing, or pulling. Disposal should be done with uprooting and removing. It is best to have a separate crew assigned for disposal.

Multiple operations are possible when other types of equipment are available, using each type where it is most effective. Use power saws, for example, to fell large trees. Use clearing units to uproot large stumps and work in areas inaccessible to dozers. Use bulldozers to clear, stockpile, and dispose of light material. The operational methods used by bulldozers in clearing depend on the size of the trees. The methods briefly discussed below are discussed fully in FM 5-434.

Small Trees, 6 Inches or Less in Diameter, and Brush. In clearing small trees and brush, operate the bulldozer with the blade straight and digging slightly. It may be necessary to back up occasionally to clear the blade. The cleared material can either be pushed into windrows for later removal or pushed off to one side of the area to be cleared.

Medium Trees, 6 to 12 Inches in Diameter. To push over trees that range from 6 to 12 inches in diameter, set the blade of the bulldozer as high as possible to gain added leverage (Figure 4-1). As the tree falls, the bulldozer is backed up quickly to clear the roots. With the blade lowered, the dozer travels forward again and digs the roots free by lifting the blade. The felled tree is then ready for removal to the spoil areas.



Large Trees. Removing large trees (over 12 inches in diameter) is much slower and more difficult than clearing brush and small trees. First, gently and cautiously probe the tree for dead limbs that could fall and injure you. Then, position the blade high and center it for maximum leverage. Determine the direction of fall before pushing the tree over; the direction of lean, if any, is usually the direction of fall. If possible, push the tree over the same as you would a medium tree.

However, if the tree has a large, deeply embedded root system, use the following method (Figure 4-2):

Step 1. Opposite the direction of fall, make a cut deep enough to cut some of the large roots. Use a V-ditch cut around the tree, tilted downward laterally toward the tree roots.

Step 2. Cut side two.

Step 3. Cut side three.

Step 4. To obtain greater pushing leverage, buld an earth ramp on the same side as the original cut. Then push the tree over. As the tree starts to fall, reverse the tractor quickly to get away from the rising root mass. After felling the tree, fill the stump hole so that water will not collect in it.



NOTE: The roots on the fourth side may need to be cut also.

Tree-Dozer, Tractor-Mounted Unit

The tree-dozer, or Rome plow, is a tractor with a blade that stings and slices large trees. A sharp projection on the left side of the blade splits the trees, while the cutting edge shears them off at ground level. The operator is protected by a steel canopy and a guide bar that controls the direction of falling trees.

The tree-dozer is a simple and efficient piece of equipment used for military land-clearing operations. It does not appreciably disturb the soil. It provides--
Clear fields of fire and security around cantonments, airfields, and other facilities.
Right-of-way clearance to desired depths along roads and railroads, thereby reducing the enemy's capability of ambush.

Before committing a tractor equipped with the tree-dozer mounting, investigate the soil condition in the area of operation to determine if it will support the equipment. Use the tree-dozer mounting to make cuts through any kind of forest except heavy swampland. Shear trees at ground level, sweep them into piles or windrows, and dispose of them. One tractor equipped with a tree-dozer mounting can clear approximately 1 to 2 acres per hour, depending on the tree density and size. Use one of the following clearing methods:
When the tractor can move forward almost continuously, it shears to ground level anything in its path, Fast production can be obtained by laying out long areas (200 to 400 feet wide) that can be cut from the outside toward the center in a counterclockwise direction. The cut material then slides off the trailing (right) end of the tree-dozer mounting and leaves the uncut area free of fallen debris. The windrows are placed lengthwise on the borders of the areas. Piling is done by sweeping with the tree-dozer mounting. Sweep a blade width at a time. Work from the center of each area, at a right angle to the border (Figure 4-3).
Another method is shown in Figure 4-4. Again, long areas are laid out in 200-to 400-foot widths, but the cutting is done from the center toward the sides in a clockwise direction. This allows the cut material to fall toward the center, which becomes the windrow site. The piling is done with the tree-dozer mounting, following the pattern outlined on the right side of Figure 4-4. When windrowing, the operator keeps the cutting edge on the ground while pushing into the windrow and raises it when backing away. This allows accumulated soil to sift away and lessens soil deposits in the windrow.
On extreme slopes, rapid production is obtained by working in a semicircular pattern, from left to right, at approximately right angles to the windrow (Figure 4-5). If the terrain is steep, the windrows should be on the contour, and the tractor should work from the uphill side and push downhill to the windrow.
Where the vegetation is dense and small, the highest production can be obtained by cutting and windrowing simultaneously. Work from left to right at a 90-degree angle to the windrow, with the trailing edge of the tree-dozer working against the uncut material. This prevents cut material from sliding off the moldboard and allows the cut material to accumulate on the moldboard.







When the moldboard is filled, the operator should stop the tractor and deposit the cut material. The operator should then reverse to the starting point and repeat the operation to the right (Figure 4-6), reducing the time lost in backing up. When the tractor reaches the previously cut material, the operator should deposit cut material and form another windrow.





The area of vegetation should be laid out as shown in Figure 4-6, with the operator working in patches, from inside to outside in a counterclockwise direction and at right angles to the windrows. Sweeping and piling the resulting debris can be accomplished much faster when tractors are used in teams traveling abreast

Winches

Towing winches mounted on tractor-dozer units or trucks are limited in use for clearing operations because of their small capacities in comparison with the tree-and stump-pulling units.

Tractor-Mounted Winch. Use tractor-mounted winches for uprooting trees and stumps up to 24 inches in diameter, hoisting and skidding felled trees, and extricating mired equipment. On the tractor-dozer unit, the winch is mounted in the rear and is directly geared to the rear power take-off on the tractor. The line pull developed varies with the size of the tractor, the speed at which the winch is operated, and the number of layers of rope on the drum. The line pull of a tractor-mounted winch is only about one-half the pull of a standard tree-and stump-pulling unit.

Truck-Mounted Winch. As an expedient, truck-mounted winches can be used on trees up to 6 inches in diameter. Their capacities are too limited for heavy work. Their best use is for skidding felled trees and logs to a disposal area, if the haul road is sufficiently cleared for trucks to operate.

Felling Equipment

Felling can be done with hand tools or power equipment. Axes, two-man saws, shovels, pick-mattocks, and machetes are used to chop or saw down standing timber; dig and uproot stumps: and slash grass, vines, and undergrowth. Clearing by hand is usually too slow and difficult for military requirements unless explosives or mechanical methods are used. When labor is plentiful, forests are dense, and terrain is rough, this method of clearing can be used with good results. Power equipment and chain and circular saws are the principal ways of felling limber.

Ripper

In land clearing, the ripper is used to help in the removal operations of bulldozers and tree-and stump-pulling units. The ripper cuts and breaks tree roots and loosens boulders from the ground. The short depth of shank penetration limits its use to shallow root systems. Prior to stripping operations, the ripper is used to loosen and break up frozen soil or organic material for easier removal by graders or scrapers.

Grader

The grader is used 10 cut grass and weeds, remove small brush, and clear the area of dead vegetation. The terrain must be level and free from boulders and trees. Used with rippers and bulldozers, graders can windrow the cleared material for later removal by other equipment. The grader is extremely limited in most clearing operations.