DITCHERS

A ditcher, despite its name, is seldom used for digging a ditch, which is a slot cut in the earth's surface and left open. The ditcher is a mechanical excavator used to dig trenches, which is a temporary cut in the earth for underground utilities, such as pipelines and conduit to handle water, fuel, electric cable, and sewage. Once these materials are placed, the trench is covered. Additionally, the ditcher may also be used to dig footers for building foundations.

All ditchers have bucket teeth (fig. 9-64). The ditcher teeth cut the earth and play a major role in how

Figure 9-64.-Two basic bucket teeth designs.

Figure ^9-65.-Wheel ditcher.

your machine performs. Figure 9-64 shows two examples of teeth patterns normally used. When the teeth wear down about one-half inch and before the face of the bucket shows wear, ensure the teeth are reversed or replaced.

NOTE: Always install a complete set of teeth on a bucket when reversing or replacing teeth.

If only a few new teeth are installed here and there along the bucket line, the new teeth will cut the most and wear down much faster than would a whole new set. However, if only one or two teeth show too much wear or are broken or chipped, they may be reversed or new ones installed in their place if the rest of them are in good shape.

Three types of ditchers used in the NCF are the wheel ditcher, the ladder ditcher, and the chain ditcher. The most common ditcher is the ladder ditcher. Read the operator's manual to obtain detailed information on the care, maintenance, and operation of a given ditcher.

WHEEL DITCHER

On the wheel ditcher (fig. 9-65), the digging buckets are mounted on a large wheel. The wheel is attached to a frame type of horizontal boom that can be raised and lowered, and the ditcher has a spoil conveyor for carrying the excavated material out to either side of the machine.

To start a cut, lower the turning wheel into the ground, and then watch the bucket teeth start to dig. As the ditcher itself is stationary, apply enough pressure to the buckets so they fill "heaping" without gouging deep enough to slow the wheel.

The ditch will have a rounded beginning, as shown in figure 9-66, views A and B. Be sure the position of the center of the wheel is over the starting point for the full depth of the ditch, so the ditcher has enough room to dig down to the desired depth at the beginning of the cut (fig. 9-66, view B).

NOTE: Before starting any excavation, you must ensure a valid digging permit is attained that covers the area you are tasked to ditch.

Digging

When the wheel is at the correct depth, you should move the machine forward just fast enough to keep the buckets reasonably full. Crowding too hard overworks the engine and strains the digging parts without adding to the output.

Soft rock usually responds best to a high-wheel speed with very slow walking speed. If dirt is soft, you may crowd it so the dirt in excess of the bucket capacity piles on each side of the ditch without damage.

Experience will help when selecting the right combination of digging and travel speeds for various types of soil; however, consult the operator's manual for

Figure 9-66.-Starting a cut with a wheel ditcher.

guidance on digging and travel speeds for the type of ditcher used.

Obstructions

Where boulders, heavy roots, or pipelines could be met, you should adhere to the following guidelines: . Both walking and wheel speeds should be slow.

. Soft boulders are cut through by the teeth.

Depending on how buried a hard boulder is, it may be pulled to the surface or forced forward. This is because the deeper boulder not only is held down by a greater weight of dirt but also the direction of the tooth contact tends to force it forward, rather than up.

. The wheel will usually ride over embedded boulders that cannot be removed by the ditcher. If a large boulder is near the surface of the cut, it may stop the forward motion of the machine; in which case, power should be cut off promptly.

. If a boulder is pulled to the surface, it may land in an inconvenient spot, forward of the wheel and between the tracks. You may have to lift the wheel into transporting position, work forward until clear of the rock, push it out of the way, and backup until the wheel can be lowered to the ditch bottom. If the boulder is too large for the wheel to clear, release the wheel drive clutch so the wheel can turn as it is pulled over it.

. When the wheel is lifted above grade to clear any obstruction, it maybe worked back to grade at the other side in the same way the cut is started.

. Turn with caution while digging. Slight turns cause the wheel to move sideways in the trench. If the buckets have long side teeth or side-cutting bars and the earth is soft, you can make a gradual turn without damaging the wheel assembly. Sharp turns may cause severe damage, such as bending the wheel frame, bending the wheel itself, or pulling the wheel frame off the vertical track.