Welcome to the official website of Shanghai Radk-Tech Hydraulic Control System Co., Ltd.
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ABOUT USDedicated to building a company that integrates product R&D, intelligent manufacturing, sales and technical services.
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PRODUCTSMain business includes high-end hydraulic components such as electro-hydraulic servo valves, proportional valves, proportional multi-way valves, high-performance threaded cartridge valves, balancing valves, and hydraulic integrated valve groups.
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APPLICATIONIn the future, Norma Hydraulics will continue to strive forward, aiming to become a significant manufacturer in the high-end hydraulic components segment of the global hydraulic industry.
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RT7625M（D761）（G761）
Maximum Working Pressure: 210bar
Rated Flow: 4~63L/min (measured at △P=70bar)
- Product Description
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Twin flapper-nozzle electrohydraulic servo valve
Features and Benefits
Suitable for closed-loop control of position, force and speed
Frictionless double nozzle-baffle control stage
High dynamic response
High resolution, low hysteresis
Dry torque motor and two stages of hydraulic power amplification.Optional external control for the Pre-amplifier
Available with LVDT position electrical feedback and built-in amplifier
Can be used as a 3-way valve
Strong structure and long service life
All adjustments are made at the factoryThe output flow rate of the valve is related to the input command electrical signal and the pressure drop at the throttle of the valve. For a given valve
pressure drop, the output flow rate of the valve can be calculated by the following equationWorking Principle
Can be used as three-way and four-way throttle type flow control valve, four-way when the best control performance, this valve is suitable for closed-loop control of position, force and speed.
Structure：
The valve consists of the following parts
-Pilot stage:
An electro-mechanical converter (torque motor)（1）
One hydraulic amplifier (consisting of nozzle (5), baffle (6))
-Power level:
spool (8), valve sleeve (9) and other components
-The spool is connected to the torque motor through mechanical
feedback
Working principle：
In the torque motor coil (2) input - electrical signal, will produce
elec tromagnetic force on the armature (3) ends to form an
electromagnetic torque, then the armature deflection drive pipe spring
(4) and baffle (6) deflection, baffle deviation from the middle will reduce
the flow of a nozzle (5), and then change the pressure of the spool (8) -
side of the nozzle, resulting in pressure difference to push the spool to
one side. The displacement of the spool opens the oil circuit between
the supply port (P port) and a control port (A or B). At the same time, the
displacement of the spool generates a force through the feedback lever
(7) connected to the baffle, forming a return torque to the armature.
When the return torque is balanced with the electromagnetic torque,
the baffle returns to the neutral position, and the pressure on both
sides of the spool is equal. The spool displacement is proportional
to the size of the input electrical signal, and the load flow rate is
proportional to the spool displacement at a constant pressure drop.
These valves are mechanically controlled by a feedback lever tube
spring, but also by a feedback and control of the electrical signal
of the spool position. The spool position is obtained by an LVDT
displacement sensor (11) and compared with a given signal value by
a built-in amplifier (10). The built-in amplifier amplifies this control
deviation and transmits it as a control signal to the pilot stage torque
motor. With this additional electrical feedback, the closed-loop
amplification of the electrical signal increases the loop gain, making
it possible to achieve higher dynamic values in the small signal range
than with the mechanical type. The mechanical feedback ensures that
the spool can be located at the factory-set zero point in the event of a
power supply failure.
The zero point of these valves can be adjusted by means of an open
potentiometer adjustment port at the top cover or by a mechanical
zeroing lever on the valve side.
Product Description
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Service Hotline：
+86 400 997 5058
Telephone：+86-21-54832120
Address：3229 Jindu Road, Minhang District, Shanghai
WeChat ID：RADK-TECH
Email： info@radk-tech.com
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