komatsu hydraulics

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Section 2Section 2

Basic Komatsu EquipmentBasic Komatsu Equipment09/0209/02

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Characteristics of Pressure of Static Fluid – Pascal’s Law

Pressure is transmitted in static fluid Pressure is transmitted in static fluid with the following characteristics:with the following characteristics:

– Pressure acts at a right angle Pressure acts at a right angle to every surface. to every surface.

– Pressure at every point of fluid Pressure at every point of fluid acts in equal strength in every acts in equal strength in every direction.direction.

– Pressure applied to a certain Pressure applied to a certain part of fluid in enclosed part of fluid in enclosed container is transmitted to container is transmitted to every part of the fluid in the every part of the fluid in the original strength.original strength.


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Piston A(Cylinder)

Piston B(Cylinder)

Area 1 cm2 Area 10 cm2

Hydraulic force

Hydraulic force10kg/cm2

10kg x 10 = 100kgWhich means the force of 10 times is obtainable.

Transmission of Power – Pascal’s Law

The force of 10kg The force of 10kg pushing Piston A pushing Piston A with the area of with the area of 1cm1cm²² becomes the becomes the hydraulic force of hydraulic force of 10kg/cm10kg/cm²², which , which pushes up Piston B pushes up Piston B in accordance with in accordance with Pascal’s law. Pascal’s law.

The piston B having The piston B having the area of 10cmthe area of 10cm²² can produce the can produce the force of 100kg/cmforce of 100kg/cm². ². ThThis is 10 times the is is 10 times the original force.original force.

Pushing with the force of 10kg

The force of 100kg is obtainable


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Piston A(Cylinder)

Piston B(Cylinder)

Hydraulic force10kg/cm2

The volume of oil The volume of oil pushed out by pushed out by small piston A is small piston A is the same as that the same as that is fed to large is fed to large piston B. piston B.

The distance The distance piston B moves piston B moves will be smaller will be smaller than that of than that of piston A.piston A.

Hydraulic force

LargeSmall

10kg x 10 = 100kgWhich means the force of 10 times is obtainable.

Area 1 cm2 Area 10 cm2

Pushing with the force of 10kg

The force of 100kg is obtainable

Transmission of Power – Pascal’s Law (Cont)


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Hydraulic cylinder and motorHydraulic

pump

Hydraulic tank

Control valve

High pressure oil

Controlled oil

Return

Low pressure oil

Using a hydraulic system to perform your work…Using a hydraulic system to perform your work…

Hydraulic system Hydraulic system consists of the consists of the following 5 basic following 5 basic elements:elements:1.1. Hydraulic pumpHydraulic pump2.2. Control valveControl valve3.3. Hydraulic Hydraulic

cylinder and cylinder and hydraulic motorhydraulic motor

4.4. Hydraulic oil Hydraulic oil tanktank

5.5. Piping and other Piping and other accessoriesaccessories

Hydraulic System Components


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GearPump

PistonPump

Hydraulic Pumps A hydraulic pump is the equipment with which mechanical energy, from an A hydraulic pump is the equipment with which mechanical energy, from an

engine, is converted to fluid energy.engine, is converted to fluid energy.

It sucks hydraulic oil from tank to pushes it to discharge.It sucks hydraulic oil from tank to pushes it to discharge.

Here are three types of hydraulic pumps:Here are three types of hydraulic pumps:

Vane Vane PumpPump


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In a gear pump oil In a gear pump oil fills the space fills the space between the gear between the gear case and gears. case and gears. As the gears As the gears rotate they rotate they perform a perform a pumping action pumping action that moves the oil that moves the oil from the suction from the suction to the discharge to the discharge side.side.

Rotation of a Gear Pump


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A piston pump performs A piston pump performs pumping action through pumping action through reciprocation of the reciprocation of the piston. piston.

Being small in size and Being small in size and in order to reduce in order to reduce pulsation, it is necessary pulsation, it is necessary to run at fast speed.to run at fast speed.

Multi-piston type is used Multi-piston type is used with an odd number of with an odd number of pistons for prevention of pistons for prevention of pulsation. pulsation.

Reciprocating Motion of Piston PumpReciprocating Motion of Piston Pump

Hydraulic Piston Pump


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Piston pump

Axial piston pump

Radial piston pump

Swash plate type

Angled axial type

Two Types of Piston Pumps

There are 2 types of There are 2 types of piston pumps:piston pumps:

– Axial piston pump Axial piston pump

– Radial piston Radial piston pumppump

In addition, there are In addition, there are 2 types of axial 2 types of axial piston pumpspiston pumps

– Swash plateSwash plate

– Angled axialAngled axial


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While the working While the working principle is basically the principle is basically the same, piston pumps same, piston pumps with the input shaft and with the input shaft and cylinder block on the cylinder block on the same axis, and with a same axis, and with a swash plate installed to swash plate installed to it, are called it, are called SWASH SWASH PLATE TYPEPLATE TYPE. .

Those which have the Those which have the input shaft and cylinder input shaft and cylinder block at an angle are block at an angle are called called ANGLED AXIAL ANGLED AXIAL TYPETYPE. .

Axial Piston Pumps

Angled Axial Type

Swash Plate Type


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The pistons are installed The pistons are installed to the swash plate.to the swash plate.

The input shaft and The input shaft and cylinder block are on the cylinder block are on the same axis. The cylinder same axis. The cylinder is installed on the input is installed on the input shaft.shaft.

The inclination of the The inclination of the swash plate causes the swash plate causes the piston to move back and piston to move back and forth for repeated forth for repeated suction and discharge of suction and discharge of oil, which results in a oil, which results in a pumping action.pumping action.

Swash Plate Type Axial Piston Pump

Inclination of swash plate

Input shaftCylinder

Suction

Pistons move as cylinder rotates

Discharge


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Hydraulic Control Valve

The hydraulic The hydraulic control valve control valve controls the action controls the action of various of various hydraulic hydraulic equipment.equipment.

These valves are These valves are combined and are combined and are installed as a installed as a combined valve combined valve (Control Valve)(Control Valve)


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Controls the Controls the pressure of oil.pressure of oil.

Relief Valve and Safety Valve

A safety valve A safety valve releases circuit releases circuit pressure when it pressure when it reaches an reaches an abnormal level. abnormal level.

(Installed between (Installed between control valve and control valve and cylinder.)cylinder.)


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A safety valve A safety valve releases circuit releases circuit pressure when it pressure when it reaches an reaches an abnormal level. abnormal level.

(Installed between (Installed between control valve and control valve and cylinder.)cylinder.)


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If oil is sent If oil is sent continuously, even continuously, even when cylinder is at when cylinder is at stroke end or if it stroke end or if it stops moving due stops moving due to excessive load, to excessive load, pressure will keep pressure will keep increasing until increasing until hose ruptures.hose ruptures.


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This is the valve This is the valve which releases the which releases the oil totally or oil totally or partially to control partially to control the pressure the pressure under such under such circumstances.circumstances.

(Installed between (Installed between pump and control)pump and control)


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A hydraulic cylinder is A hydraulic cylinder is comprised of a piston, comprised of a piston, a rod, and a cylinder. a rod, and a cylinder.

The oil sent from the The oil sent from the pump into cylinder pump into cylinder pushes piston.pushes piston.

The rod is pushed The rod is pushed together to move the together to move the work equipment.work equipment.

Hydraulic Cylinder

A hydraulic cylinder A hydraulic cylinder converts hydraulic power converts hydraulic power to linear motion.to linear motion.

Piston

Cylinder

Rod


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Entering oil alternately Entering oil alternately to inlet and outlet for oil, to inlet and outlet for oil, causes piston to causes piston to reciprocate.reciprocate.

Hydraulic Cylinder

A hydraulic cylinder A hydraulic cylinder converts hydraulic power converts hydraulic power to linear motion.to linear motion.

Oil sent from pump


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Hydraulic Motor

It is the hydraulic It is the hydraulic motor that receives motor that receives hydraulic pressure hydraulic pressure from the pump and from the pump and performs rotational performs rotational motion.motion.

Converts hydraulic Converts hydraulic oil to rotating motion.oil to rotating motion.


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Hydraulic Motor

With the hydraulic With the hydraulic pressure sent from pressure sent from the pump through the pump through the port block, the port block, rotational torque is rotational torque is output from the output from the output shaft and output shaft and transmitted.transmitted.


Pressureoil


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Hydraulic Motor

Controlling the Controlling the swash plate swash plate inclination enables inclination enables variable motor variable motor output (rotation and output (rotation and torque)torque)


Output shaftPiston Swash plate


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Hydraulic Oil Tank

• Disperses heat Disperses heat generated in the generated in the hydraulic systemhydraulic system

• Replenishes oil Replenishes oil reduced by reduced by leakage and leakage and settling dust and settling dust and rust in worked oil.rust in worked oil.

Duties of the Duties of the hydraulic tank:hydraulic tank:


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Swivel Joint

The swivel joint The swivel joint connects the piping connects the piping between swinging and between swinging and stationary parts, as stationary parts, as seen in the case of a seen in the case of a hydraulic excavator.hydraulic excavator.

The joint that is not The joint that is not twisted if rotated.twisted if rotated.


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Swivel Joint

The swivel joint The swivel joint consists of a shaft and consists of a shaft and rotor, either of which rotor, either of which rotates together with rotates together with swinging side. swinging side.

On the periphery of the On the periphery of the shaft, the grooves are shaft, the grooves are provided in a required provided in a required number of connections number of connections to be made in order for to be made in order for oil to enter and exit.oil to enter and exit.

The joint that is not The joint that is not twisted if rotated.twisted if rotated.

Port

Oil from control valve

Oil returning to tank

From undercarriage

Rotor

Shaft

To undercarriage


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Types of Hydraulic Systems

CLOSED CENTER – CLOSED CENTER – LOAD SENSING SYSTEMLOAD SENSING SYSTEM

CLOSED CENTER – CLOSED CENTER – LOAD SENSING SYSTEMLOAD SENSING SYSTEM

OPEN CENTER – OPEN CENTER – LOAD SENSING SYSTEMLOAD SENSING SYSTEM

OPEN CENTER – OPEN CENTER – LOAD SENSING SYSTEMLOAD SENSING SYSTEM




MENUMENU

Electronic-Open Center Load Electronic-Open Center Load Sensing Hydraulic System Sensing Hydraulic System

E-OLSSE-OLSS


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E-OLSS Hydraulic SystemThe PC600-6 and larger excavators uses the field proven E-OLSS (Electronic - Open center Load Sensing System) hydraulic system. This system has proven itself to be powerful, as well as fuel efficient, and provides the operator with the following features.

• Working ModesWorking Modes

– DH:DH: High pressure and High pressure and speedspeed

– H: H: High productionHigh production

– G: G: Fuel efficient Fuel efficient productionproduction

• NC Control: Neutral loss control, NC Control: Neutral loss control, for precise operationfor precise operation

• CO Control: Relief loss controlCO Control: Relief loss control

• CO Control Cancel: For faster CO Control Cancel: For faster operationsoperations

• Auto DecelerationAuto Deceleration

• Heavy Lift ModeHeavy Lift Mode

• 2-Stage Boom Push Force2-Stage Boom Push Force

• Straight TravelStraight Travel

• Shockless Boom ControlShockless Boom Control

• Swing PrioritySwing Priority

• Automatic Hi-Lo Travel Speed Automatic Hi-Lo Travel Speed ShiftingShifting

Engine Hydraulic pump

Control lever

Cut-off cancel

TVC valve

Pump absorption torque control (delivery amount)

Monitor

Working mode

Mode setting

Electrical

Control valve

Hydraulic

Control valve

NCNC

CO CO

Hydraulic pump

S S

S S


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Why OLSS and not CLSS

Emphasis onEmphasis onSpeed and Fuel Speed and Fuel

ConsumptionConsumption

(Not Precise Control and (Not Precise Control and Compound Operations asCompound Operations as

with small/medium with small/medium machines.)machines.)

Large machines are mostly used for digging and loading, where emphasis is placed on power and speed. Furthermore, fuel consumption is a major concern for the large machine owner. As a result, OLSS is used because it meets both the power/speed and efficiency needs. In addition, the OLSS hydraulic system has a long history of dependability in this market.


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How OLSS Works

The five devices used are:The five devices used are:• SERVO VALVESERVO VALVE - controls - controls

swash plate angle of the main swash plate angle of the main pump.pump.

• TVC VALVETVC VALVE - provides work - provides work mode capabilities and prevents mode capabilities and prevents pumps from stalling the engine.pumps from stalling the engine.

• CO VALVECO VALVE - controls flow as - controls flow as system nears relief pressure.system nears relief pressure.

• NC VALVENC VALVE - controls neutral - controls neutral loss and flow during fine loss and flow during fine control.control.

• JET SENSORJET SENSOR - signals NC - signals NC valve.valve.

Control Valve

TVC Valve

Jet Sensor Jet Sensor

Chargingpump

NC Valve

CO Valve

Servo Valve

NC Valve

CO Valve

Servo Valve

Controller

>>

> >>

<> > > >

< >

>> >

>

<>

RearPump

FrontPump

OLSS works with five devices to OLSS works with five devices to control oil loss while maintaining control oil loss while maintaining maximum speed, power, and maximum speed, power, and efficiency. As a result the efficiency. As a result the pumps are not overworked and pumps are not overworked and neutral flow loss is minimized.neutral flow loss is minimized.


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2-Pump, 2-Valve System

2-PUMP 2-VALVE E-OLSS2-PUMP 2-VALVE E-OLSS

BOOM CYLINDERBOOM CYLINDER

BUCKET CYLINDERBUCKET CYLINDER

ARM CYLINDERARM CYLINDER

M

TRAVEL(R)TRAVEL(R)

BOOMBOOM

BUCKETBUCKET

ARMARM

SWINGSWING

BOOMBOOM

ARMARM

BUCKETBUCKET

TRAVEL(L)TRAVEL(L)

TRAVEL TRAVEL MOTOR MOTOR

(R)(R)


(L)(L)

SWINGSWINGMOTORMOTOR

3-PUMP 3-VALVE E-OLSS3-PUMP 3-VALVE E-OLSS

PC650-5

BOOM CYLINDERBOOM CYLINDER

BUCKET CYLINDERBUCKET CYLINDER

ARM CYLINDERARM CYLINDER

TRAVEL(R)TRAVEL(R)

BOOMBOOM

BUCKETBUCKET

ARMARM

SERVICESERVICE

BOOMBOOM

ARMARM

BUCKETBUCKET

TRAVEL(L)TRAVEL(L)


(R)(R)


(L)(L)

SWINGSWINGMOTORMOTOR

SWINGSWING

M

PC600-6

The 3-pump, 3-valve (3P3V) system used on the PC650-5 has been The 3-pump, 3-valve (3P3V) system used on the PC650-5 has been changed to a 2-pump, 2-valve (2P2V) system on the PC600-6.changed to a 2-pump, 2-valve (2P2V) system on the PC600-6.


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Why Use 2P2V System

The PC600-6 was designed to provide greater production The PC600-6 was designed to provide greater production

and efficiency. The technically advanced 2P2V system and efficiency. The technically advanced 2P2V system

provides superior swing performance over the 3P3V provides superior swing performance over the 3P3V

(independent swing) system. (independent swing) system.

In addition, with the 2P2V system the swing pump can In addition, with the 2P2V system the swing pump can

back-up the work equipment when the swing circuit is not back-up the work equipment when the swing circuit is not

being usedbeing used.. This gives the PC600-6 its increased speed This gives the PC600-6 its increased speed

and force during the digging cycle. Furthermore, the and force during the digging cycle. Furthermore, the

hydraulic system has been simplified, thereby lowering the hydraulic system has been simplified, thereby lowering the

opportunities for oil leaks and pressure loss.opportunities for oil leaks and pressure loss.

Emphasis on Speed and ReliabilityEmphasis on Speed and Reliability


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Filtration

An ultra clean hydraulic An ultra clean hydraulic system is used to reduce system is used to reduce down-time. The High down-time. The High Pressure, In-Line Filter is Pressure, In-Line Filter is used to guard against debris used to guard against debris in the unlikely event of a in the unlikely event of a major hydraulic failure. major hydraulic failure.

Komatsu is the only Komatsu is the only manufacturer to provide 3 manufacturer to provide 3 levels of protection as levels of protection as standard equipment. standard equipment.

Other filters such as the Other filters such as the suction strainer, a Hybrid 8 suction strainer, a Hybrid 8 micron return filter, and PPC micron return filter, and PPC filter are used to ensure a filter are used to ensure a clean running hydraulic clean running hydraulic system.system.

A 100 micron screen


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Machines with E-OLSS Hydraulic Systems

PC1250LC-7PC1250LC-7

PC600LC-6PC600LC-6




MENUMENU

Closed Center Load Sensing Closed Center Load Sensing Hydraulic SystemHydraulic System

CLSSCLSS


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Basics of Hydraulics

FLOWFLOW - determines the speed of the work equipment. - determines the speed of the work equipment.

The speed of work equipment is determined by the amount of pump flow.The speed of work equipment is determined by the amount of pump flow.

– The greater the pump flow the greater the speed.The greater the pump flow the greater the speed.

– Lesser pump flow creates slower speeds.Lesser pump flow creates slower speeds.

– Pump flow rate is determined by the pump swash plate angle and engine/pump rpm.Pump flow rate is determined by the pump swash plate angle and engine/pump rpm.

PRESSUREPRESSURE - determines the amount of force the work equipment can exert on an object. - determines the amount of force the work equipment can exert on an object.

Pressure is determined by resistance up until maximum relief pressure is reached.Pressure is determined by resistance up until maximum relief pressure is reached.

– Resistance can come in two formsResistance can come in two forms

• Flow rate and size of port the oil must travel through (restriction).Flow rate and size of port the oil must travel through (restriction).

• Amount of resistance the work equipment meets.Amount of resistance the work equipment meets.

– When maximum relief pressure is reached the machine cannot exert any more force When maximum relief pressure is reached the machine cannot exert any more force and the work equipment stops in order to prevent system damage.and the work equipment stops in order to prevent system damage.

POWERPOWER - combination of FLOW and PRESSURE. - combination of FLOW and PRESSURE.

Hydraulics can be broken down into three main principles:


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Basic Principle of HydrauMind1.1. Speed = StrokeSpeed = Stroke

Pump delivery is proportional to lever Pump delivery is proportional to lever stroke giving the operator control over the stroke giving the operator control over the speed of the equipment.speed of the equipment.

2.2. Consistent Compound OperationsConsistent Compound Operations

Equipment speed is consistent even if the Equipment speed is consistent even if the load changes in one actuator circuit. load changes in one actuator circuit.


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Speed = StrokePump delivers oil in proportion to lever stroke due to the LS Valve (Load Sensing). Pump delivers oil in proportion to lever stroke due to the LS Valve (Load Sensing). The LS Valve is designed to keep a +20 kg/cmThe LS Valve is designed to keep a +20 kg/cm22 pressure differential on the pump pressure differential on the pump side of the control valve. In this way the operator controls speed not the load.side of the control valve. In this way the operator controls speed not the load.

Valve Stationary Valve Opened Valve Closed

With no movement of valve With no movement of valve system stays balanced with system stays balanced with +20 kg/cm+20 kg/cm22 on pump side. on pump side.

When the operator opens the When the operator opens the valve more, the +20 kg/cmvalve more, the +20 kg/cm22 differential drops and the LS differential drops and the LS Valve increases pump flow to Valve increases pump flow to increase the pressure increase the pressure differential.differential.

When the operator closes When the operator closes the valve more, the +20 the valve more, the +20 kg/cmkg/cm22 differential increases differential increases and the LS Valve decreases and the LS Valve decreases pump flow to decrease the pump flow to decrease the pressure differential.pressure differential.


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Clean Hydraulic System

This is a representative drawing of a Komatsu Hydraulic system.


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Benefits of Speed = StrokeThe benefits of Speed = Stroke are:The benefits of Speed = Stroke are:

– The lever movement provides The lever movement provides direct and consistent direct and consistent equipment speed.equipment speed.

– The operator controls speed, The operator controls speed, not the load. not the load.

– There is less feathering of There is less feathering of controls during operations, controls during operations, making work easier.making work easier.

• Attachment movements are smooth and powerfulAttachment movements are smooth and powerful • Pipes are moved with minimal sway and Pipes are moved with minimal sway and greater controlgreater control

• Full power even during fine control operationsFull power even during fine control operations• Smoothing operations are easy and consistentSmoothing operations are easy and consistent

CONTROL


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Consistent Compound OperationsPressure Compensating Valves are used to keep system pressure constant Pressure Compensating Valves are used to keep system pressure constant when the load is uneven. As a result, one function does not over power the when the load is uneven. As a result, one function does not over power the

other and the work equipment moves smoothly.other and the work equipment moves smoothly.

When the loads are even the Pressure Comp. Valves are inactive because system pressure is even.

When the loads are uneven the Pressure Comp. Valves are activated and suppress

the flow on the lighter side.

valve


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• Equipment moves at consistent Equipment moves at consistent speeds even with multi-function speeds even with multi-function attachmentsattachments

• Buckets load easier and retain load longerBuckets load easier and retain load longer• Shaking reduced by eliminating overcompensationShaking reduced by eliminating overcompensation

• Greater control under full power for easier operationGreater control under full power for easier operation

Benefits of Pressure Compensation ValveAutomatically balances the system Automatically balances the system flow when using several functions at flow when using several functions at one time.one time.

– The operator does not compensate The operator does not compensate for the machine, rather the machine for the machine, rather the machine automatically compensates itself.automatically compensates itself.

– Reduces operating effort and Reduces operating effort and operator fatigue thus increasing operator fatigue thus increasing productivity.productivity.

LESS

EFFORT


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Exclusively HydrauMindPressure

Compensating ValveAutomatically adjusts pressure between circuits being used, to control loads.

LS (Load Sensing) Valve

Tells the pump when to stroke and destroke to maintain a constant differential pressure between pump side and actuator side of the control valve. Signals servo valve to change pump displacement.

LS EPC ValveEnhances fuel efficiency by receiving signals from the governor and pump controller and then sending a proportional signal to the LS Valve.

Pump Merge/Divide Valve

Improves cycle time and fuel efficiently by merging or separating the 2 pump flow. Divided for travel, fine control, and boom up when swinging.

LS Select ValveIncreases ease of operation when using swing with the work equipment. Prevents the high LS pressure of the swing circuit from affecting other LS Circuits.

LS Bypass ValveImproves dynamic stability during operation by relieving residual pressure in the LS circuit.

This is a representative drawing of a Komatsu Hydraulic system.


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Machines with CLSS Hydraulic Systems

PC300LC-6PC300LC-6

PC200LC-7PC200LC-7

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