Bucket Mounting

The bucket mounting is normally connected to the lower end of the dipper stick by a hinge pin and to a triangular set of paired dump arms. The other two angles of the arms are hinged to the bucket cylinder rod and to the dipper stick.

Dump arms supply the required around-a-curve reach and prevent the cylinder from being pulled in against the dipper stick when extending. The arm is necessary, because the bucket has such an extended arc of rotary movement around the dipper stick hinge that the piston arm could not follow it. When the hydraulic cylinder is extended, the bucket teeth move inward in a curling or digging motion. When the hydraulic cylinder is retracted, the bucket dumps, opens, or extends.

Bucket

The bucket can be attached to the bucket mounting in a variety of ways. One way is the slow process of removing cotter pins and manually driving out hinge pins to change the attachment. Another way is a "quick-latch" mounting where the pins are retained in the attachment and the quick-latch mounting latches on the pins and is secured to the attachment by a large bolt. A third way is a quick disconnect that uses hydraulic controlled locking pins that the operator controls from the cab.

Buckets are supplied in a number of widths, ranging from 24 to 59 inches or more. A bucket is usually slightly wider at the opening to reduce friction at the sides when digging and to allow easier dumping. Narrow buckets tend to be deep in proportion to width and may fill poorly in chunky or rocky digging, while wide buckets may have poor penetration. The digging edge is almost always equipped with teeth that are removable for reversing, sharping, or replacement (fig. 9-60).

In the NCF, there are other attachments that are used in excavator operations. These attachments range from a grader blade, hydraulic power compactor, perforated dredge bucket, bull prick (jackhammer), ripper, and so

Figure 9-60.-Detachable tooth.

forth. These attachments are maintained by the attachment custodian in the transportation yard.

When you are using attachments, remember these rules: (1) always maintain clearance between the attachment and the cab to prevent equipment damage and possible injury; (2) when not in use, store attachments on a hardstand or wood to keep the items out of sand, mud, and water; and (3) seal hydraulic lines and fittings for protection from dirt and moisture.

DIGGING PROCEDURES

If you are unfamiliar with the control or basically have not operated a backhoe in a while, use a slow engine speed while you familiarize yourself with each control. At first, operate the controls separately, then operate two or more controls at the same time. Basic digging procedures are as follows:

1. Wear the proper personal protective equipment for the job, including steel toe safety shoes, a hard hat, and gloves.

2. Check the ground conditions before you start to dig.

3. Obtain a digging permit and know the location of any underground cables and pipelines.

4. Check for overhead obstructions, such as electric lines, tree limbs, and awnings.

5. Remove large rocks, stumps, or other obstructions before you begin to dig.

6. When you are digging, use a digging stroke that will fill the bucket. Full buckets are more efficient and faster than half-full buckets.

7. Try different digging angles with the bucket to find the best cutting effort for the material you are removing. The best digging angle cuts the material as you fill the bucket.

8. When filling the bucket, keep the bottom of the bucket parallel with the cut, as shown in figure 9-61, view A.

9. Let the bucket teeth and the cutting edge cut through the ground like a knife blade, as shown in figure 9-61, view B.

10. Curl the bucket to retain the cut material, as shown in figure 9-61, view C.

11. The type of material excavated will determine how much material can be excavated with each cycle.

Figure 9-61.-Filling the bucket.