hydraulic excavators (classnote-1)

Hydraulic Excavators

By

Er. Ashok Shrestha (DoR)

IOE-BEM

Construction Equipment (Elective) August 2010

Hydraulic ExcavatorHydraulic Excavator is the most commonly used construction machine. it has bucket with

specified volumetric capacity.

Hydraulic power is the key utility to operate the

hydraulic excavators.

Excavator can work above and under the ground level where it rest.

It can work at all gradient and difficult terrain and even under water excavation work where other

machine can not be used.

With various front attachments, it can be used for

diversified purposes.

Most excavators are mounted on track base, but

smaller model may be mounted on wheels base.

16 August 2010 Slide No. 2IOE-BEM-CE(Elective): Excavators: By Ashok Shrestha

Hydraulic Excavator: Main Parts• A hydraulic Excavator consists THREE major parts

1. Work EquipmentThis part consist

working tools for

digging and loading

2. Upper StructureThis part consist engine, cabin

and holds components such as

operator’s seat controlling

joysticks and monitoring gauges

3. UndercarriageThis part consist Crawler/

track chain or Wheel for

moving machine on the

ground.


Arm Cylinder

Work Equipment: Work equipment is designed

to run by hydraulic cylinders

Oil Pressure Inside the

cylinder is the key factor to

overcome require FORCE to

do work.

Oil flow rate inside

cylinder is key factor to

move and speed up and

down of work equipment

Rod Cylinder

Piston

Force

=

Pressure x Area


Upper Structure: Cabin Interior

Depending on

moving direction of control Lever/

Pedals Machine

can move

straight or turn

left or right.

Depending on moving direction of control Joystick Boom, Arm or Bucket can

be moved for doing work or machine can swing to require degree of rotation

Cabin Interior

Travel LeversMachine monitoring units

(Temp., Press. Gauges)

Work equipment

control Joystick

Engine starting

switch

Fuel gauge

Lights / Other

switches

Travel

Pedals

Work equipment

control Joystick

Operator’s

seat


Arm/Swing Controls (Left Joystick)move forward and backward to move Arm out and in

move left and right to control direction of swing

Boom/Bucket Controls (Right Joystick)move forward and backward to lower and raise boom

move left and right to control bucket curl and dump

Excavators: Swing mechanism

Pinion Outer race

Inner race

Ball bearings

SWING CIRCLE

The outer race fixed at upper structure turns with the “Pinion” that spins along with the inner race fixed at the lower structure.

The part between the outer race and the inner race turns smoothly on the ball bearings.

This part enables an hydraulic excavator to turn around

Stick/Swing Controls (Left Joystick)move forward and backward to move stick out and inmove left and right to control direction of swing


Lower Structure:UndercarriageMost are Crawler/ Track type.

Compared to the Wheel type, the

Crawler type has more part touching

the ground. Which enables them to

work on muddy surface where Wheel

type can not be used.

WHEEL

(TYRE)

Seen from the sides

Seen from the underneath

CRAWLER / TRACK

The part touching the

ground surface

Wheel type excavator

make use of supports/

Stabilizers during work.

Can also be fitted with dozing blade . (Optional)


Hydraulic Excavators: How it Works ?

Arm Cylinder Control Valves

Hydraulic Pump

Engine

Hydraulic Oil Tank

Swing Motor

Travel Motors

Boom Cylinder

Bucket Cylinder

Hydraulic Power is the key utility to operate all Hydraulic Excavators


Excavators : Types• Based on feet mounted on undercarriage they

are classified as:

1. Crawler or Track type

2. Wheel type

Both front SHOVEL type or HOE type Excavator can be mounted on either on a Crawler or a Wheel tractor base.

• Based on types of Bucket mounted or digging motion of bucket they are classified as:

1. Shovel type

2. Hoe type


Hydraulic Excavator: Front Shovel

• An upward motion unit is know as “front shovel”

• Hydraulic front Shovel excavators are used mainly for hard digging

above track level and for loading

hauling units.

• A shovel develops breakout force

by crowding material away from the machine.

• The boom of a shovel swings upward to load; so the machine

requires a material face above

the ground level

Basic Features:


Hydraulic Excavator: Hoe

• A downward arc unit is classified

as Hoe

• Hydraulic Hoe excavators are used primarily to excavate below natural

surface of the ground on which machine rest

• It develops excavation breakout force by pulling the bucket towards

the machine and curling the bucket

inward.

• The downward swing of a hoe

dictates usage for excavating below the ground level at which

machine rest

Basic Features:


Hydraulic Excavator• The hydraulic excavators are fully hydraulically

control machine which provides:

– Faster cycle time

– Less noisy

– Smoothness and ease of operation

– High overall efficiency

– Greater accuracy and precision

• It is a versatile machine that can be used for almost all kind of applications.

• A quick coupler enables to quick change with different type attachments and perform a variety of tasks in rapid succession


Excavator Specifications• Machine (Make/ Model/ Sr. No., overall dimension)

• Operating Weight (kN) (with operator,

cabin and all standard items & accessories)

• Engine (Make/ Model/ Sr. No./Type, Cly. No./stroke,

• CI/SI, Torque/ RPM/ Cooling type

• Flywheel Power (kW)

• Undercarriage (Track shoe size type,

• roller no., track length, ground pressure etc.)

• Hydraulic System– Swing Mechanism (Speed/ Torque)

– Drive System (Travel speed / Drawbar-pull)

– Work Implements (Pressure, Cylinder type size)

• Bucket (model, Cubic capacity)

• Performance Data (Working range, Arm force/ Bucket force)

16 August 2010 Slide No. 13IOE-BEM-CE(Elective): Dozers: By Ashok Shrestha

Hydraulic Excavator: Application• Hydraulic hoe has evolved from a single purpose

excavating machine into a versatile multipurpose tool.

• It is a versatile machine that can be used for almost all kind of applications.

• Typical general applications are:– Digging under or above the ground level

– Canal/ Trench excavating and pipe laying

– Loading hauling units

– Lifting construction materials

• A quick coupler enables the hoe to change attachments and perform a variety of tasks in rapid succession. Some common attachments are:– Hydraulic breaker - Crane

– Clamshell - Rock driller

– Impact hammer - Demolition jaw

– Cutters - Land clearing grapple


Typical Applications


Attachments

Handling Scrap materialsBuilding demolishing

Various types of attachments


Commonly used terminologies related to shovel/ bucket size rating

• Struck Capacity : – The volume actually enclosed

by the bucket with no allowance for bucket teeth

• Heaped Capacity:– Both PCSA and SAE uses a

1:1 angle of repose for evaluating heaped Capacity. CECE specifies 2:1 angle of repose.


PCSA – Power Crane and Shovel Association

SAE – Society of Automotive Engineers

CECE – Committee on European Construction Equipment

Fill FactorsFill factors:

The actual amount of material in a bucket needed for shovel production calculation. Fill factor are express in percentage which when multiplied by heaped capacity, adjust the volume by accounting for how specific material will load into the bucket.


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