Where an on/off valve gives you two speeds — stopped and full — a proportional valve gives you every speed in between. Spool position follows an electrical command signal, so acceleration, deceleration and holding are all controllable. That is what makes smooth press cycles, controlled crane slewing and repeatable injection moulding possible.
Twin Hydraulics Engineering supplies the full Rexroth proportional range across Malaysia, with support from engineers who work on these systems daily. We also supply proportional and servo valves from Parker, Eaton, Danfoss, Yuken and Atos — useful when a machine's control card is matched to a particular make and changing the valve alone is not an option.
Which family do you need?
— 4WRA / 4WRAE — direct operated, no positional feedback. Economical, for less demanding control.
— 4WRE / 4WREE — direct operated with electrical spool feedback, far better repeatability. The extra E carries on-board electronics.
— 4WRZ / 4WRH — pilot operated for higher flows, where a small proportional valve shifts a large main spool.
— 4WRKE — high response, pilot operated with on-board electronics, for closed-loop position and force control.
— 4WRTE — high response in the larger sizes.
— 4WRPH / 4WRPEH — direct operated servo-solenoid valves, fastest response in small sizes.
On-board electronics or external amplifier?
Valves with OBE contain their own amplifier: you supply power and a ±10 V or 4–20 mA command, and the valve closes its own position loop. Without OBE you need a matching amplifier card, and the pairing has to be right. If you are replacing an older valve plus card with a modern OBE unit the wiring changes — tell us the existing setup and we will specify the whole change-over.
Proportional and servo valve repair — with a warranty
A failed proportional or servo valve does not always need replacing. We repair them in our own workshop, and every repair carries a written warranty of 6 to 12 months depending on the level of repair — a seal and clean carries a shorter term than a full strip, spool and sleeve rework with test-bench recalibration. You are told which level your valve needs, and what warranty comes with it, before any work starts.
Each valve is tested on our own Bosch Rexroth hydraulics test bench and its characteristic verified before it goes back to you, so what you refit performs to specification rather than merely working. You can see the bench and what it measures here.
We have launched this service on Bosch Rexroth valves, and we will extend it to other manufacturers. If you have a valve from another make that you would rather repair than replace, tell us — the demand we see is what decides which brand we add next.
Amplifier cards — installation, commissioning and retrofit on site
A proportional valve is only half the system. The amplifier card that drives it has to be correctly matched, correctly wired and correctly set up, and that is where most commissioning problems actually happen.
Struggling with an obsolete amplifier card, or a valve that will not set up properly after installation? Our engineers come to site. We handle:
— Retrofitting a modern amplifier, or an OBE valve, where the original card is discontinued and no longer available
— Wiring, ramp, gain and dither set-up against your machine's actual duty cycle
— Commissioning a new proportional or servo valve into an existing control system
— Fault-finding when a replacement valve and card will not behave like the original
Contact us with the existing valve and card details and we will tell you whether it is a straight swap or a retrofit before you buy anything.
Cleanliness decides service life
Proportional valves are sensitive to contamination, and most premature failures we see are contamination-related rather than electrical. Pair a new valve with the correct filter element and confirm your system cleanliness class before commissioning. Where the fluid is already contaminated we can bring in a filtration unit before the new valve goes in — see our filtration system design and rental service.
Frequently asked
Can a proportional valve replace my servo valve? Often yes, for position and speed control. True servo valves still win where bandwidth demands are extreme — we can assess your loop and advise honestly.
Do you supply amplifier cards? Yes, including VT-VSPA and related series, matched to the valve.
What command signal do these take? Commonly ±10 V or 4–20 mA, depending on the electronics version in the type code.
Do you repair proportional and servo valves? Yes, with a 6 to 12 month warranty depending on the level of repair. Currently Bosch Rexroth valves, with other brands to follow.
My amplifier card is obsolete and I cannot buy a replacement — what are my options? Usually a retrofit: a current amplifier, or an OBE valve that carries its own electronics. We specify the change-over and commission it on site.
Can you come to site to commission the valve? Yes — installation, set-up and commissioning of proportional and servo valves and their amplifier cards, anywhere in Malaysia.
See also Directional On/Off Valve and hydraulic pump and motor repair.
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