Hydraulicspneumatics Com Sites Hydraulicspneumatics com Files Uploads Custom Inline Archive Www hydraulicspneumatics com Content Site200 Articles 10 01 2007 73296hydraulics 00000047506

Hydraulics needs a better mousetrap

Oct. 18, 2007
When I first became a staff member of Hydraulics & Pneumatics, I was quickly indoctrinated on what the hot topics were at the time. One of the hottest topics then, 20 years ago, was the ...

Alan Hitchcox editor [email protected]

When I first became a staff member of Hydraulics & Pneumatics, I was quickly indoctrinated on what the hot topics were at the time. One of the hottest topics then, 20 years ago, was the integration of electronics into hydraulics — which I came to know as electrohydraulics.

Since then, we have published hundreds of articles about electrohydraulics in this magazine. Of course, back then, electrohydraulics meant analog electronics. More recently, we’ve written about digital electrohydraulics. And even more recently, it’s been digital electrohydraulics in fieldbus systems — both in stationary and mobile equipment.

One thing hasn’t changed, though: the need for a universal linear displacement transducer (LDT) that can easily and inexpensively be integrated into most hydraulic cylinders.

Don’t get me wrong, several different designs of acceptable LDTs already exist, each with characteristics that suit them to specific types of applications. At the low end are resistive sensors, at the high end are magnetostrictive transducers, and in between are various other designs that have gained limited acceptance. The problem is, resistive sensors have physical limitations that will likely prevent them from ever gaining widespread use in hydraulic cylinders. Magnetostrictive transducers have become the favored technology for high-performance applications. Magnetostrictive transducers have been a real success story for electrohydraulics. They have allowed incorporating electrohydraulic cylinders into countless applications that would not have been possible otherwise. However, their relatively high cost prevents them from being used in most applications. Furthermore, the extensive machining required to accommodate in-cylinder installation only adds to their initial cost.

Therefore, a key to more widespread use of electrohydraulic cylinders is development of an LDT with the performance on par with magnetostrictive transducers but with a lower cost and that does not require extensive machining of the cylinder. What’s encouraging is that some new designs of LDTs are emerging that hold potential to provide low-cost position sensing in pneumatic cylinders. For example, Motion Controls, LLC, Hartford, Wis, is developing a sensor that fits in the cap end of an air cylinder and uses (non-laser) light and a light sensor to determine piston position. Another, from Astyx, Chicago, uses microwave technology to measure piston position.

The question is, can these or other technologies migrate over to hydraulic cylinders? Probably not — at least not without substantial redevelopment. The inside of a hydraulic cylinder is a vastly different environment from that of an air cylinder.

Eventually, though, someone will develop a low cost, high-performance LDT for use in hydraulic cylinders. When they do, you can bet that the hydraulics world will beat a path to their door.

Continue Reading

Handbook Simplifies Advanced Aspects of Mobile Hydraulic Controls

May 10, 2017
Author Brendan Casey lays out his hydraulics know-how that he acquired over 27 years in a simple handbook made for people that want to improve their skills in troubleshooting ...

The Impacts of Electrification on Fluid Power Systems

May 15, 2023
Electrification presents challenges as well as opportunities to re-evaluate and improve upon the design of hydraulics and pneumatics.

Sponsored Recommendations

MONITORING RELAYS — TYPES AND APPLICATIONS

May 15, 2024
Production equipment is expensive and needs to be protected against input abnormalities such as voltage, current, frequency, and phase to stay online and in operation for the ...

Circuit Protection Devices & Busbars

March 13, 2024
With experienced Product Engineers and Customer Service personnel, Altech provides solutions to your most pressing application challenges. All with one thought in mind - to ensure...

All-In-One DC-UPS Power Solutions

March 13, 2024
Introducing the All-In-One DC-UPS, a versatile solution combining multiple functionalities in a single device. Serving as a power supply, battery charger, battery care module,...

Motor Disconnect Switches

March 13, 2024
With experienced Product Engineers and Customer Service personnel, Altech provides solutions to your most pressing application challenges. All with one thought in mind - to ensure...