triangular set of paired dump arms. The other two anglesof the arms are hinged to the bucket cylinder rod and tothe dipper stick.Dump arms supply the required around-a-curvereach and prevent the cylinder from being pulled inagainst the dipper stick when extending. The arm isnecessary, because the bucket has such an extended arcof rotary movement around the dipper stick hinge thatthe piston arm could not follow it. When the hydrauliccylinder is extended, the bucket teeth move inward in acurling or digging motion. When the hydraulic cylinderis retracted, the bucket dumps, opens, or extends.BucketThe bucket can be attached to the bucket mountingin a variety of ways. One way is the slow process ofremoving cotter pins and manually driving out hingepins to change the attachment. Another way is a“quick-latch” mounting where the pins are retained inthe attachment and the quick-latch mounting latches onthe pins and is secured to the attachment by a large bolt.A third way is a quick disconnect that uses hydrauliccontrolled locking pins that the operator controls fromthe cab.Buckets are supplied in a number of widths, rangingfrom 24 to 59 inches or more. A bucket is usually slightlywider at the opening to reduce friction at the sides whendigging and to allow easier dumping. Narrow bucketstend to be deep in proportion to width and may fill poorlyin chunky or rocky digging, while wide buckets mayhave poor penetration. The digging edge is almostalways equipped with teeth that are removable forreversing, sharping, or replacement (fig. 9-60).In the NCF, there are other attachments that are usedin excavator operations. These attachments range froma grader blade, hydraulic power compactor, perforateddredge bucket, bull prick (jackhammer), ripper, and soFigure 9-60.-Detachable tooth.forth. These attachments are maintained by theattachment custodian in the transportation yard.When you are using attachments, remember theserules: (1) always maintain clearance between theattachment and the cab to prevent equipment damageand possible injury; (2) when not in use, storeattachments on a hardstand or wood to keep the itemsout of sand, mud, and water; and (3) seal hydraulic linesand fittings for protection from dirt and moisture.DIGGING PROCEDURESIf you are unfamiliar with the control or basicallyhave not operated a backhoe in a while, use a slowengine speed while you familiarize yourself with eachcontrol. At first, operate the controls separately, thenoperate two or more controls at the same time. Basicdigging procedures are as follows:1. Wear the proper personal protective equipmentfor the job, including steel toe safety shoes, a hard hat,and gloves.2. Check the ground conditions before you startto dig.3. Obtain a digging permit and know the locationof any underground cables and pipelines.4. Check for overhead obstructions, such aselectric lines, tree limbs, and awnings.5. Remove large rocks, stumps, or otherobstructions before you begin to dig.6. When you are digging, use a digging stroke thatwill fill the bucket. Full buckets are more efficient andfaster than half-full buckets.7. Try different digging angles with the bucket tofind the best cutting effort for the material you areremoving. The best digging angle cuts the material asyou fill the bucket.8. When filling the bucket, keep the bottom of thebucket parallel with the cut, as shown in figure 9-61,view A.9. Let the bucket teeth and the cutting edge cutthrough the ground like a knife blade, as shown in figure9-61, view B.10. Curl the bucket to retain the cut material, asshown in figure 9-61, view C.11. The type of material excavated will determinehow much material can be excavated with each cycle.9-26
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