Implements and tools

Attachments and tools

The implements and tools used in construction equipments are given below:

Buckets

Buckets come in many shapes and sizes. Most can be easily replaced or changed quickly ‘‘on the fly.’’ The shape of the bucket and the teeth or penetration edge is greatly influenced by the material that is to be excavated or moved. A bucket designed for moving loose gravel should not be used to dig into the hard material. As the material to be worked becomes harder, typically buckets become slimmer and more elongated. Loaders, backhoes, and excavators typically have standard buckets that can be used for a wide range of material types and uses. Buckets can have jaws or apparatus for grasping irregularly shaped loads such as concrete chunks with rebar protruding or jaws that can be used to cut structural members for a demo.

The size of the bucket and ultimate payload must be matched to the power of the equipment. Weight represents the safe operational pounds that the excavating, hauling, or moving unit can accommodate. Placing a large bucket on a piece of equipment with a small capacity engine will not be efficient. This will overburden the equipment and wear the engine out prematurely. Manufacturer’s suggestions should be followed for the bucket size selection. A broad bucket requires more power to push through the material than a narrow bucket. However, broad larger buckets are ideal for loose sand or gravel moving. Buckets vary in width, depth, and structure depending on the match to the power of the machine and the type of material that is excavated or moved. Narrow sleek buckets with teeth are designed for penetration of a hard digging surface. The buckets used for moving material are typically wider and may not have teeth. The need for penetration power is dependent upon the density of the digging surface. Most equipment models have a standard bucket or range of types and sizes specified for that machine. The bucket typically is included as part of the purchase price. Most equipments have specially designed bucket and attachment systems so that the bucket can be changed easily and quickly. The figure shows basic bucket shapes and teeth designed for the type of digging work to be done.

Fig 1. Types of Bucket

Bucket 1 is for digging in moderate to hard abrasive materials. Pieces welded on the side near the teeth help penetration and holding the load. Bucket 2 is for digging fragmented rock, frozen ground, and highly abrasive compacted materials. It is taller and thinner than bucket 1. The extra pieces on the front bucket edges protect the bucket sides. Bucket 3 is for digging hard rock and work areas where the material is undisturbed or poorly prepared. The thin streamline curved design and sharp irregular teeth configuration make penetration easier. Bucket 4 is for bank forming, ditch cleaning and finishing, and loose material movement. There are no teeth on bucket 4.

Blades

Like buckets, blades should match the expected work task. A typical blade configuration is like a ‘‘C’’ from top to bottom. As the blade is moved forward and tilted, the bottom of the blade acts as a cutting edge and the top edge rolls the materials forward. It is like the material ‘‘boiling’’ in front of the blade. Different types of materials accumulate in front of the blade differently.

Fig 2. Common dozer blades

Angle (A): Used primarily for side casting material; excellent for drainage ditch excavation, wider than an S-blade; used for fine grading and surface removal; not recommended for rock or hard digging surfaces.

Cushion (C): Used primarily with scrapers for ‘‘on the go’’ push loading; can be used for lighter excavation and other general tasks.

Universal (U): Used for moving big loads over longer distances; curved shape and side and top extensions reduce the spillage of loose material; best suited for lighter materials.

Straight (S): Used primarily for shallow surface removal, land clearing; designed to push dirt for short distances, stumps, and demo; versatile, lightweight and maneuverable, handles a wide range of materials.

Rippers

Excavator rippers are ideal for breaking hard ground and in demolition applications. Rip the ground in one hit and reduce your fuel consumption at the same time with a CAT ripper for your excavator or bulldozer. A CAT ripper is shown in the figure below:

Fig 3. Ripper

References

1. Technical book, “Construction Machinery Training”, Instate, Imlambad
2. Harris, F. and McCaffer, “Management of Construction Equipment”, Macmillan Education Ltd. London, UK.
3. Erich J. Schulz, “Diesel Equipment I and II”, Mcgraw-Hill book co.
4. Frank Harries, Ronald McCaffer, “Construction of Plant Excavating and Material Handling”, Granda Publishing.
5. SAE Handbook Volume 4
6. “Caterpillar performance Handbook”, Edition 33, Caterpillar Inc, Peoria, Illinois, USA.