ce-excavating and lifting

7/27/2019 CE-Excavating and Lifting

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Excavating and Lifting

M.C. Josept Revuelta Acosta

ProfessorUniversity of Veracruz


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Shovels

The hydraulic shovel is also called a front shovel

or hydraulic excavator-front shovel.


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Shovels

The hydraulic shovel digs with a combination of

crowding force and breakout force.


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Shovels

Both front-dump and bottom-dump buckets are

available for hydraulic sholves.


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Shovels

Although the shovel has a limited ability to dig

below track level, it is most efficient when

digging above track level. The shovel shouldhave a vertical face to dig against for most

effective digging. This surface, known as the

digging face, is easily formed when excavating

a bank or hillside. The ability of the shovel toform its own roadway as it advances is a major

advantage.


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Shovels


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Shovels


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Shovels


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Shovels

Other possible applications of the shovel include

dressing slopes, loading hoppers, and digging

shallow trenches.


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Shovels-Production Estimating

Production for hydraulic shovels mat be

estimated using following equation:


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Shovels-Production Estimating

Exercise:


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Shovels- Job Management

The two major factors controlling shovel

production are the swing angle and lost time

during the production cycle. Therefore, the

angle of swing between digging and dumpingpositions should always be kept to a mnimum.

Haul units must be positioned to minimize the

tome lost as units enter and leave the loadingposition.


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Draglines

The dragline is a very versatile machine that

has the longest reach for digging and dumping

of any member of the crane-shovel family. It

can dig from adove machine level to significantdepths in soft to medium-hard material.

Bucket teeth and weight produce digging

action as the drag cable pulls the bucketacross the ground surface.


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Draglines


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Draglines


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Draglines

Buckets are available in a wide range of sizes

and weights, solid and perforated.

While the dragline is a very versatile

excavator, it does not have the positive

digging action or lateral control of the sholve.

Hence the bucket may bounce or move

sideways during hard digging.Also, more spillage must be expected in

loading operations than would occur with a

shovel.


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Draglines-Production Estimating


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Draglines-Job Management

Trial operations may be necessary to select the

boom length, boom angle, bucket size and weight,

and the attachment position of the drag chain that

yield maximum production. As in shovel operation,maximum production is obtained with a minimum

swing angle. In general, the lightest bucket capable

of satisfactory digging should be used, since this

increases the allowable bucket size and reduces

cycle time. It has been found that the most efficient

digging area is located within 15 forward and back

of a vertical line through the boom point.


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Draglines-Job Management


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Backhoes

A backhoe (or simply hoe) is an excavator

designed primarily for excavation below grade.


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Backhoes


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Backhoes

Back hoe digs by pulling the dipper back toward

the machine; hence the name backhoe. The

backhoe shares the characteristics of positive

digging action and precise lateral control with the

shovel. Cable-operated backhoes exist but are

largely being replaced by hydraulic models

because of their superior speed and ease ofcontrol. Backhoe attachments are also available for

loaders and tractors.


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Backhoes

The backhoe is widely utilized for trenching work. In addition to

excavating the trench, it can perform many other trenching

functions, such as laying pipe bedding, placing pipe, pulling

trench shields, and backfilling the trench.


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Backhoes

A special form of hydraulic excavator which utilizes a rigid

telescoping boom in place of the boom and dipper arm of a

conventional hydraulic backhoe.


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Backhoes-Production Estimating


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Backhoes-Job Management


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ClamshellsWhen the crane-shovel is equipped with a crane

boom and clamshell bucket, it becomes an

excavator known as a clamshell. The clamshellis capable of excavating to great depths but

lacks the positive digging action and precise

lateral control of the shovel and backhoe.


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Clamshells


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Clamshells

Clamshells are commonly used for excavating

vertical shafts and footings, unloading bulk

materials from rail cars and ships, andmoving bulk material from stockpiles to bins,

hoppers, or haul units.

No standard production tables are available

for the clamshell.


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Clamshells


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Clamshells


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Clamshells


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Clamshells

The maximum allowable load (bucket weight

plus soil weight) on a clamshell should be

obtained from the manufacturer's clamshellloading chart for continuous operation. If a

clamshell loading chart is not available, limit

the load to 80% of the safe lifting capacity

given by the crane capacity chart for rubber-tired equipment or 90% for crawler-mounted

equipment.

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