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New Holland CX720, CX740, CX760, CX780, CX820, CX840, CX860, CX880. Operator's Manual - page 16

DISTRIBUTION SYSTEMS - PRIMARY HYDRAULIC POWER SYSTEM

PRIMARY HYDRAULIC POWER SYSTEM - Static description (A.10.A

- C.30.A.20)

The high pressure circuit operates all of the work hydraulics and steering. The circuit is fed by a closed centre load

sensing variable displacement pump (4). Oil is drawn by the pump, from the main reservoir, shared with the hydro-

static system, through the inline pressure filter to the mainframe valve block.

The oil enters the main frame valve block at the priority valve slice and there the oil is split, dependant on demand, to

the steering valve, which has priority, or to the other hydraulic functions.

The unloading tube control, drum variator control and header height control are served by the main frame stack.

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The straw elevator and header reverser, lateral flotation control, reel vertical and horizontal adjustment and reel speed

control are served by the straw elevator stack valve. The straw elevator stack valve is an extension of the main

frame stack valve and is connected with pressure (31a), return (31b), and load sensing lines (31c), via quick release

couplings.

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The last section of the straw elevator stack valve is a flush valve. This valve allows a very small oil flow through the

stack valves, when no services are being operated, allowing warm oil to bring the stack valve assembly gradually up

to temperature.

The circuit return oil flows through to the return side filter back to the pump or to the reservoir.

The high pressure circuit is linked with the hydrostatic circuit. The hydrostatic pump (3) feeds the hydrostatic circuit.

The charge return and case drain oil flows through to the thermostat and cooler back to the reservoir or high pressure

circuit.

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HIGH PRESSURE SYSTEM - COMPONENT LOCATION

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HIGH PRESSURE SYSTEM - COMPONENT LOCATION

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PRIMARY HYDRAULIC POWER SYSTEM - Component localisation

(A.10.A - C.40.B.20)

NOTE: The reference numbers used in the illustrations and text relate to the identification numbers used on the High

Pressure Circuit Diagram, PRIMARY HYDRAULIC POWER SYSTEM - Hydraulic schema (A.10.A-C.20.B.20).

(3) Hydrostatic Pump

Although not part of the high pressure system, the return oil from the hydrostatic motors is used as charge pressure

oil for the high pressure CCLS pump.

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(4) Closed Centre Load Sensing (CCLS) Pump

Provides the oil for the high pressure system. Will supply the pressure as demanded by the services in use due to its

load sensing and variable displacement capability. Has the advantage over a fixed pump in that it reduces the engine

power absorbed when maximum pump flow is not required.

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(5) Low Pressure Gear Pump

Totally separate from the high pressure system. Mounted on the CCLS pump from where it takes its drive.

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(6) Load Sensing Valve (mounted on CCLS pump)

(7) High Pressure Relief Valve (mounted on CCLS pump)

Output from the CCLS pump is determined by adjusting the angle of the swash plate. The load sensing valve senses

the circuit operating pressure and adjusts the swash plate angle to control pump output. If pump output rises to 197

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DISTRIBUTION SYSTEMS - PRIMARY HYDRAULIC POWER SYSTEM

bar (2857 psi) the high pressure relief valve over rides the load sensing valve and adjusts the swash plate angle to

limit maximum system pressure.

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(8) In Line High Pressure Filter

A replaceable filter located between the CCLS pump output and the high pressure system priority valve.

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(12) Steering Motor

Supplied oil via the priority valve in the main frame stack. The steering motor directs and controls oil to the steering

cylinders, based on input via movement of the steering wheel.

There are 2 different motors available. An OSPF 315 cc load sensing fixed capacity unit for North America only and

an OSPQ 160/320 cc load sensing variable capacity unit for all other locations.

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(13) Steering Cylinders

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(23) Header Lift Cylinder

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Main Frame Stack Valve Assembly

(9)

Priority Valve

Located in the main frame stack valve, receives the output oil from the CCLS pump and will

provide steering with the priority for oil. Actuated by pressure within the load sense lines.

(10)

Load Sense / Steering Relief Valve

Located in the priority valve. When the pressure in the load sense circuit or steering circuit

exceeds a preset value the relief valve will blow and then maintain a maximum pressure in

the load sense or steering circuits.

(11)

Load Sensing Shuttle Valve

Located in each valve slice. Allows the function with the highest pressure demand to send

sensing pressure to the load sensing valve on the CCLS pump.

(14)

Header Height Pressure Valve

Controls the pressure within the header height cylinders.

Contains the high pressure relief valve (15), accumulator lock out valve (16) and pressure

sensor (18).

(16)

Accumulator Lock Out Valve

Solenoid controlled valve which isolates the accumulator from the raise and lower circuit.

(19)

Header Height Control Valve

Controls the raising and lowering of the header. Contains the PWM raise and lower valves

and compensation valve.

(20)

Header Raise Valve

A PWM controlled valve, allows pressure oil to the raise cylinder.

(21)

Header Lower Valve

A PWM controlled valve, allows oil to be released from the lift cylinders under control.

(22)

Header Pressure Compensation Valve

Ensures that height raise speed is consistent in all operating conditions, provides

compensation to pressure spikes in the system.

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(25)

Drum Variator Control Valve

Controls the plunger within the variator drum drive unit to provide adjustable variator speed.

Solenoid operated valves either allow pressure oil to provide a speed increase or release

oil pressure to decrease speed.

(27)

Unloading Tube Control Valve

Controls the unloading tube cylinder. Consists of two electrically operated solenoid valves.

(15) High Pressure Relief Valve

This acts as a shock relief valve for the header. Sudden rises in pressure, as felt at the lift cylinders, are relieved

through this valve.

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(17) Header Suspension Accumulator

Absorbs the slight movement to the header encountered during normal operating. The accumulator is rated at 70 bar

pressure with a volume of 0.5 L.

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(18) Pressure Sensor

Measures the hydraulic pressure within the header circuit. Sends a signal to the header electronic control unit.

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(24) Electronic Control Unit

Controls the header height via the PWM controlled raise and lower solenoids, based on the signal sent by the operator

cab controls.

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(26) Drum Variator Adjustment Plunger

Operated via the drum variator valve, the plunger is a hydraulic cylinder that operates a floating disc within the variator

assembly to alter variator speed.

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(28) Unloading Tube Lockout Block

Isolates the unload cylinder from the control valve and pipework. Ensures that the unload tube will remain in the

required position until the control valve is activated. When pressure oil is applied to the lock out block, a bleed line is

supplied to the opposite side which releases the lock valve and allows oil to escape. When the pressure oil is removed

the lock out valves close and prevent cylinder movement.

(29) Unload Tube Cylinder

Operates the unload arm, controlled by the unload tube control valve and lock out block.

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(31) Quick Attach Couplers

Connects the main stack valve block to the header valve block assembly.

(31a) = Pressure supply

(31b) = Return line

(31c) = Load sensing line

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NOTE: The return line must always be correctly connected. The quick attach coupler of the return line incorporates

check valves allowing flow back to the main frame stack valve. If the engine is started with the return line disconnected

oil will escape from the valve block.

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Straw Elevator Valve Stack

(33) Straw Elevator and Header Reversing Valve

Controls the motor for the straw elevator and header reverser. Contains two electrically controlled solenoids which

move a spool to obtain forward, reverse or a float position on the motor.

(35) Lateral Flotation Control Valve

Controls the lateral flotation cylinder. Consists of two electrically controlled solenoids, a pressure compensation valve

and a lock out valve.

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(36) Lateral Float Pressure Compensation Valve

Ensures that lateral float operation is consistent in all operating conditions, provides compensation to pressure spikes

in the system.

(40) Lateral Float Minimum Pressure Valve

This is a resistant valve and prevents the header from jerky counterclockwise movement and jerky operation when

the cylinder is retracted. This is necessary because of the non-North American header being heavier on the left hand

side. The valve is set at approximately 60 bar (870 psi).

(41) Reel Horizontal Adjustment Valve

(42) Reel Horizontal Adjustment Cylinders

Controls the horizontal position of the reel. The valve consists of two electrically operated solenoids and a lock out

valve.

(43) Reel Vertical Adjustment Valve

Controls the vertical adjustment cylinders. Consists of two electrically operated solenoids and a lock out valve.

(44) Reel Vertical Adjustment Cylinders

Two cylinders, a master and a slave, supplied oil from the vertical adjustment valve (43). The slave is powered by the

rod end oil of the master cylinder.

(49) Flush Valve

When there are no services in use, charge pressure oil is allowed to join the return circuit through the flush valve.

This function allows a flow of oil through the header stack valve thereby circulating warm oil through the valves.

(34) Straw Elevator and Header Reversing Motor

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(37) Lateral Flotation Cylinder

Adjusts header angle in relation to the combine.

(38) Lateral Float Accumulator - Lowering side - 50 bar (725 psi)

(39) Lateral Float Accumulator - Raise Side - 75 bar (1088 psi)

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(50) Return Filter with Bypass

(51) Return Filter Element Differential Drop Indicator.

Electrical switch to indicate pressure differential as the filter becomes clogged during service.

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(52) Thermostat Valve

Cooler bypass valve, directs cold oil away from the cooler and back into the return circuit. As the oil progressively

warms up the oil is then allowed, by the thermostat valve, through the cooler. A relief valve is incorporated to allow

direct routing to the return circuit when the pressure is too high for the system to cope with.

(53) Cooler

Hydraulic oil cooler, mounted with the engine cooler on the right hand side of the vehicle.

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(54) Suction Filter

Located in the base of the reservoir in the suction line supplying the hydrostatic pump.

(55) Filler Cap With Breather

(56) Minimum level electrical switch for hydraulic oil reservoir. (high pressure system and hydrostatic system oil).

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(57) Hydraulic Oil Reservoir (high pressure system and hydrostatic system oil).

(59) Temperature Sensor

Measures hydraulic oil temperature, high oil temperature indicated at 85 °C (185 °F).

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(60) Header Hoses Quick Release Coupling.

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PRIMARY HYDRAULIC POWER SYSTEM - Hydraulic symbol (A.10.A

- C.20.C.20)

Engine

Reservoir

Hydraulic pump, direction

Hydraulic pump single

with variable displacement

direction fixed displacement

Hydraulic pump, directional

Steering motor

with displacement

(bi-directional)

Motor, single direction fixed

Motor bi-directional fixed

displacement

displacement

2 position valve

3 position valve

Proportional (PWM) valve

Pressure relief valve

Solenoid controlled

Proportional solenoid

movement

movement (Pulse Width

Modulation)

Movement by or against

Movement by or against

spring tension

adjustable spring tension

Movement by or against oil

Lock-out valve

pressure

Non return valve

Non return valve, pressure

controlled

Quick coupler with non

Flexible hose

return valve

Restrictor

Thermostat

Hydro-pneumatic

Cylinder

accumulator

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Filter

Filter opening

Shuttle valve

Temperature sender

Pressure sensor

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