CLSSSection 2.2

CLSS - Hydraulic PumpsCLSS - Hydraulic Pumps

Section 2.2Section 2.2

CLSSSection 2.2

Hydraulic Pump

HPV95+95 VARIABLE DISPLACEMENT PISTON PUMPHPV95+95 VARIABLE DISPLACEMENT PISTON PUMP112 CC PER PUMP MAX DISPLACEMENT 112 CC PER PUMP MAX DISPLACEMENT Controlled by 2 LS valves and 2 PC valvesControlled by 2 LS valves and 2 PC valves

With an LS EPC and PC EPC With an LS EPC and PC EPC

mounted on the side of the pump bodymounted on the side of the pump body

CLSSSection 2.2

Hydraulic Pump.

TextFront Pump

The two pumps can work independently or together as one.

Rear Pump

CLSSSection 2.2

Hydraulic Pump.

Input Shaft (front)

Input shaft (front)

Front Seal

Shaft Coupling Input shaft (rear)

CLSSSection 2.2

Hydraulic Pump.

Input Shaft (front)Rocker Cam

Servo-piston

Rod.

(Connection between servo & swash plate)

CLSSSection 2.2

Hydraulic Pump.

Input Shaft (front)Shoes Piston Cylinder Block

Valve Plate

CLSSSection 2.2

Hydraulic Pump.

Control of Discharge Amount.

Servo piston moves in a reciprocal movement, according to the signal pressure from the LS or PC valves. This movement is transmitted through the rod to the rocker cam to increase or decrease swash plate angle.

CLSSSection 2.2

Hydraulic Pump.

Operation of Pump.

Cylinder block is splined onto input shaft and all rotate together.

When the rocker cam is in the minimum swash plate angle. The volume in the inlet and outlet chamber are the same, discharging a small flow of oil.

The rocker cam is moved into the maximum position, volume in the inlet chamber become larger than the out-let. Causing a greater flow of oil.

The swash plate angle on this pump never becomes 0

Minimum Discharge

Maximum Discharge

CLSSSection 2.2

LS Valve.

LS Valve: Detects the load and controls the pump discharge amount.

The pump discharge or flow is proportional to differential pressure.

CLSSSection 2.2

LS Valve.

Differential Pressure.

PLS = PP – PLS.

PP Main pump Pressure.PLS Control valve outlet Pressure

Main Pump Pressure

Spool

Control Valve Outlet Pressure

CLSSSection 2.2

LS Valve

Control of Pump Discharge.

When Differential Pressure

PLS = 0 to 22 pump discharge increases.

PLS = 22 to 30 pump discharge is reduced.

PLS

PP PLS

CLSSSection 2.2

LS Valve

LS Valve Ports.

The LS valve is a three way selector valve.

Depending on the differential pressure this will determine the position of the LS spool.

Pump Pressure

(PP)

LS EPC Solenoid Signal

(PSIG)

PC control Valve Input Port

(PPL)

LS Control Pressure

To Servo Piston Large end.

(PLP)

LS Pressure.

(PLS)

Pump Pressure.

(PP)

CLSSSection 2.2

LS Valve.

Increase Pump Discharge.

When the operator uses the work equipment LS pressure is introduced to the LS valve. Pump pressure is always acting on the LS valve.

With LS pressure (PLS) introduce into the LS valve and with the assistance of the spring and spool area surface is able to over come the pump

pressure (PP) pushing the LS spool to the Left, increasing pump discharge.

PP - PLS = PLS

180 - 170 = 10 Kg/cm2

(Less than 22 Kg/cm2 pump will increase discharge)

PP = 180 Kg/cm2

PLS = 170 Kg/cm2

CLSSSection 2.2

LS Valve.

Decrease Pump Discharge.

When the operator reduces the speed of work equipment or stops working LS pressure is reduced to the LS valve. Pump pressure is always acting

on the LS valve.

With LS pressure (PLS) reduced Pump Pressure is able to overcome LS valve, spring tension and spool area surface. This will push the LS spool

to the Right, decreasing pump discharge.

PP - PLS = PLS

180 - 150 = 30 Kg/cm2

(Greater than 22 Kg/cm2 pump will decrease discharge)

PP = 180 Kg/cm2

PLS 150 Kg/cm2

CLSSSection 2.2

LS Valve.

LS Valve Balanced.

If the work load is maintained at the same flow and load the pump discharge or flow will equalize to the load. When this occurs the pump in neither

increasing of decreasing its discharge. This is the benefit of having CLSS, it will only deliver the oil flow that’s required.

LS pressure, spring tension is equal to Pump Pressure, the LS spool in neither stroking or de-stroking the pump.

PP - PLS = PLS

180 - 158 = 22 Kg/cm2

PP = 180 Kg/cm2

PLS 158 Kg/cm2

CLSSSection 2.2

LS Valve

Control Levers in Neutral.

When the levers are in

the neutral positionThere is no LS pressure (PLS) delivered to the LS

Valve. Pump Pressure (PP) is

able to push the LS spool to the left.

This will introduce PP into the Large end to

servo-piston, because of the difference in servo piston surface area the swash plate is moved to

minimum position.

CLSSSection 2.2

LS Valve

Reduce FlowWhen the control lever When the control lever reduces its stroke the reduces its stroke the

pump pressure increasespump pressure increases and the LS pressure and the LS pressure

drops.drops.PP pressure pushing LS PP pressure pushing LS

spool to the left.spool to the left.

Introducing PP to large Introducing PP to large end of servo piston.end of servo piston.

The pump will reduce its The pump will reduce its flow until the LS valve is flow until the LS valve is

balancedbalanced..

The LS EPC solenoid The LS EPC solenoid supplies a varying supplies a varying

pressure depending on pressure depending on machine condition to machine condition to assist in reducing the assist in reducing the

pump flow pump flow

CLSSSection 2.2

LS Valve

Increase Flow.

When the machine is in use, the LS

pressure (PLS) is introduced to the LS

Valve. Able to overcome Pump Pressure (PP).

Pushing the LS spool to the Right.

This will close off the PP and open the port

back to tank.Draining the Large end to servo-piston allowing the swash plate is moved to

maximum position.

CLSSSection 2.2

LS Valve

Servo Piston Balanced.

When the machine is working at a even

load the pump pressure (PP) will equal LS pressure

(PLS) and spring (4).At this point the

pump is delivering the correct flow

required.The LS spool is

neither introducing PP to the large end of the servo or draining

it off.

At this point the pressure applied to both ends of servo

piston is 3:5.

CLSSSection 2.2

PC Valve

PC Valve

The PC Valve will maintain equal horse power control so that the horse power absorption by the pump does not exceed the engine horsepower.

If the load during operation increases and pump discharge rises, the PC valve will reduce the pump discharge.

CLSSSection 2.2

PC Control Pressure.

(PPL)

PC Control Pressure.

(PPL)

PC Valve

PC Valve Ports.

The PC valve is a three way hydraulic valve situated inside the Servo piston. The valve is regulated by pump controller via an EPC solenoid in order to reach optimum matching between the load (pressure P) and the

flow (Q). Second Pump Pressure

PP2

Pump Pressure

PP1

PC Mode Select Pilot Pressure

(PM)

Pump Pressure.

(PP1)

Drain Port.

(PT)

CLSSSection 2.2

PC Valve

No load conditionNo load conditionWhen the servo piston is atWhen the servo piston is at maximum flow the springmaximum flow the spring

pressure from springs 4 &6pressure from springs 4 &6is low. The spool 3 is forcedis low. The spool 3 is forced

to the right by spring to the right by spring pressure.pressure.

PP1 or PP2 pressure is not PP1 or PP2 pressure is not high enough to over come high enough to over come

the spring tension. the spring tension.

This allows the connection CThis allows the connection Cfrom the LS valve to go to from the LS valve to go to

tank , through the centre of tank , through the centre of spool 3 .spool 3 .

The PC EPC output which isThe PC EPC output which is controlled by the controller controlled by the controller varying the pressure acting varying the pressure acting

on spool 3.on spool 3.Will change the pump torque Will change the pump torque

output.output.

CLSSSection 2.2

PC Valve

High PressureHigh PressureThe pump pressures has The pump pressures has increased enough push increased enough push the PC spool against the the PC spool against the

springs to close off port C springs to close off port C (Return to tank) and (Return to tank) and

introduce Pump pressure. introduce Pump pressure.

This pressure returns to This pressure returns to the large end of the servo the large end of the servo

piston via the LS valve.piston via the LS valve.

As the servo piston is As the servo piston is being pushed back to being pushed back to

reduce the pumps flow, at reduce the pumps flow, at the same time the springs the same time the springs

are being compressingare being compressing

Eventually the spring Eventually the spring tension will equal the pump tension will equal the pump

pressure allowing the pressure allowing the optimum flow at that optimum flow at that particular pressure. particular pressure.

CLSSSection 2.2

Pump Discharge: Pressure and Flow

LS Valve

in control

Engine horse-power unable to maintain

pump out put.

PC Valve

Springs

CLSSSection 2.2

LS & PC EPC Solenoids

PC Prolix Switch ON

If there is a failure in the pump controller, the Prolix Switch can be

switch on to switch to the resistor side, by pass the controller.

When this is done the current becomes

constant so the force pushing the PC valve is

constant. There is no pump sensing.

CLSSSection 2.2

LS & PC EPC Solenoids

EPC Valves

When the solenoid receives a signal from the controller it generates the EPC out-put pressure in proportion

to the electrical signal.

The higher the signal an increased pressure is applied to the LS and PC

valves, this will back the pump off earlier.

LS EPC

PC EPC

CLSSSection 2.2

LS & PC EPC Solenoids

Operation: No Signal.

When there is no signal current flowing from the controller the coil is de-

energized.

The spool is pushed across to the left by spring (3).

Allowing the signal oil to drain back to tank.

CLSSSection 2.2

LS & PC EPS Solenoids

Operation: Signal from Controller

When a signal current flows to the coil, energizes the coil and

propulsion force is generated which pushes the plunger (4).

Moving the spool to the right against the spring.

Opening the oil supply (PEPC) to flow to the LS or PC valve.

As the pressure raises in PSIG plus spring force this will push spool (3) to close and maintain a set pressure

going to the LS & PC valves.

CLSSSection 2.2

LS & PC EPS Solenoids

Selecting Work Mode.

The operator can set the work mode on the monitor panel to suit the

working conditions.

According to the type of work the machine can work using the proper

engine torque and pump absorption.

The modes available are:

A Active.

E Economy.

B Breaker.

L Loading

CLSSSection 2.2

CLSS Hydraulic Pumps

End ofEnd of

Hydraulic Pumps CLSSHydraulic Pumps CLSS