Made in: Japan
Manufacturer: NACHI
Model: Load Sensing Valve

Features

Provides all functions required for mini excavator

• Anti-saturation function
• Pressure compensation function according to self loaded pressure
• Cooperative system with engine speed
• No need for independent pump of swing motor
• LS control + constant horsepower control
• Good for straight traveling of wheel motors
• Various kinds of attached valves

Perfomance

1. Characteristics of pressure compensation

2. Characteristics of anti-saturation function

When supply flow is sufficient:

When supply flow is insufficient:

• Same secondary pressure is supplied to every compensator
• Supply flow for all actuators is distributed in proportion to spool stroke.

3. Interconnected control stroke for engine rotation speed – Characteristics of flow

Normal load sensing system

Cooperative system with engine speed

Target LS differential pressure is cooperative with engine speed
Much finer control with gentle gain between stroke and flow rate.

Application

• Ideal for construction equipment such as mini excavator
• If you use this unit in a set with our company’s PVK series load sensing variable piston pump the unit contributes to energy saving in the mother machine through load sensing control.

Specifications

Valve size		T04 (A/B port)
Maximum working pressure (pump port)		25MPa
Maximum working pressure actuator port		28MPa
Maximum pump flow		120 L/min
Maximum control flow (1 function)		90 L/min
Tank port allowable back pressure		0.3 MPa (1.5 MPa at peak)
Internal leakage (A/B port)		5cm2/min at 5MPa
Internal leakage (boom lock valve)		1cm2/min at 5MPa
Operating method		* Hydraulic pilot
		* Manual
		* Electromagnetic proportional valve
Structure of attached valves (Can be built-in)		* Overload relief
		* Vacuum check valve
		* Boom lock valve (anti-drift valve)
		* Safety lock valve
		* Very slow-speed mode
Applicable mini excavator (example)		3 – 5-ton
Operating conditions	Hydraulic oil	ISOVG 32 to 68
	Oil temperature (for common use)	-20 to 100°C(5 to 80°C)
	Viscosity	10 to 1000mm2/s
	Ambient temperature	-20 to 60°C

Operational theory

1. Secondary pressure feedback system with reducing valve

2. Self-load pressure-dependent pressure compensating valve

A2=A3=A , k=A/A1 PIN A1=PLS A2+PLA3 P=PIN-PL=k PLS-(1-k)+PLPIN : Pressure at upper stream PL : Loaded pressure PLS : Secondary pressure through regulator Valve(=P-PLmax) PLmax : Maximum loaded pressure k : Area ratio

Measurement