Fluid Power – Ceramic Air Motors Put A New Spin On MRI Imaging!

When surgeons need to see inside a patient during a surgery, they often have to send the patient outside the operating room because the metal in a MRI system can interfere with critical equipment needed for surgery. Tasked with this challenge, the designers at Deprag Schulz GmbH & Co., Amberg, Germany, custom-designed an air motor to power the shield in open MRI machines. The result: a modular design that uses only ceramics and plastics, runs on oil-free compressed air, and is almost noiseless.
Photo courtesy of Doral Medical Imaging,
Open-MRI machines, like the one pictured, can use customized, metal-free air motors to allow them to be used in operating rooms without disrupting critical surgical equipment.


Using an MRI (magnetic resonance imaging) machine in an operating room would be ideal for clinical monitoring of minimally invasive procedures (keyhole surgery), during tumor operations on the brain or liver, and procedures involving the heart. However, ferrous metal in traditional motors that drive the MRI’s rotating shield causes interference fields in the operating room. The patient, therefore, has to be moved to an adjacent room accompanied by an anesthetist in the middle of an operation to be examined using operative magnetic resonance imaging. Such brain tumor examination procedures have been successfully carried out at the Neuro-surgical University Clinic in Heidelberg, Germany, for 13 years.

In an effort to reduce the need to move patients, research has been conducted to provide an accompanying MRI exam inside operating rooms. Instead of the usual MRI tunnel system, new open MRI exam systems enable doctors to access the target area of the patient during image scanning. The need then, was to develop a rotating MRI-imaging shield driven by a completely metal free-system, including the motor.

Going metal-free

A custom designed air motor from Deprag uses ceramic and engineered plastics instead of metal, thereby preventing it from producing stray electromagnetic fields.


Because they must contain metals to generate magnetic fields to convert electrical power into mechanical rotational power, any electric motor was ruled out. Therefore, an air motor became the most likely solution. The challenge to develop a completely non-metal air vane motor was presented to the Development Department at Deprag Schulz GmbH & Co., Amberg, Germany. Gerd Zinn , the head of Serial Machine Development remembers: “This motor was needed for diagnostics in an MRI system where the use of metal would cause interference with the operating system. Therefore, it was not a suitable material for the application.”

Product Manager Dagmar Hierl added, “Our ferrite-free air motors were designed and developed especially for such an application. These Deprag air motors can play an important role in the development of medical equipment.” This motor is suitable for other applications where the use of metal is out of the question.

Modular designs make for easy customization

Deprag specializes in air motors. Hierl said that 85 % of all the company’s projects are special solutions. “We individually adapt the air motors from our catalog to fit our clients’ specific requests. We are able to develop cost-effective special motors because of our modular system,” Hierl said. “The spectrum ranges from single air motors to fully automatic production systems. Creativity and customer focus are therefore very important to us.”

The team set to work, drawing on their knowledge from decades of developmental projects involving air motors. The result: an air motor made of ceramic and synthetic materials that does not contain a single piece of metal.

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The prototype of the ceramic motor has a diameter of 40 mm and is only 78 mm long. Operating from compressed air at 2 bar, the motor transmits 150 W of power at a speed of 14,000 rpm. At its idle speed of 9000 rpm, it achieves 36 W power.

Because the entire motor system had to be metal-free, the pneumatic hose end fittings are also made of an engineered plastic. Three ports on the motor produce clockwise rotation, counter-clockwise rotation, and exhaust. In addition, valve circuitry is designed based on needs. For example, if one directional hookup is used (either CW or CCW only), a 2-position, 3-port valve is used. If bidirectional rotation is needed, a 3-position, 4-port valve will be used.

Zinn says the motor runs on oil-free compressed air. And although the research team did not require it, Deprag designers worked to reduce noise as well. To reduce noise from the motor assembly, a hose system was designed consisting of a combined inlet and exhaust hose.


For more details, contact Dagmar Hierl at d.hierl@deprag.de or Gerd Zinn at g.zinn@deprag.de, call +49 09621 371-343 begin_of_the_skype_highlighting +49 09621 371-343 end_of_the_skype_highlighting, or visit www.deprag.com.

In the U.S., contact Lori Logan at Deprag Inc., at (972) 221- 8731, ext. 3806 or visit www.depragusa.com.

Fluid Power – Web Based, “Repair Estimator” for Cylinders!


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Hydraulic Cylinder Repair Program

San Marcos, CA — The new “Hydraulic Repair Estimator”TM for Cylinders program from Rupe Corporation, gives consistent, “Best Price” estimates for hydraulic cylinder repairs from a basic resealing to a complete rebuilding. This comprehensive web based program will work on any desktop, laptop, netbook, tablet with internet access. Web based, there is no software to install, however labor rates, material costs, and cost of supporting services (i.e. Chrome plating) can be personalized for each subscribing company.

The “Hydraulic Repair Estimator”TM for Cylinders program lets a sales person in the field quote with confidence and provide potential customers a consistent, accurate quote on-the-spot in minutes and immediately e-mail the estimate with detailed pricing right from their laptop.

To set up or individualize the program, “shop rates” (labor, material, and overhead) of the subscriber’s company and “shop rates” of vendors, such as chrome platers, are entered and stored. Already in the data base are all the tasks and the time and materials to complete each task, related to the repair of a hydraulic cylinder. To fine tune the program based on experience, an efficiency adjustment can be made to refine the quote process even further for a particular subscriber’s company.

Using “Hydraulic Repair Estimator”TM for Cylinders program is easy. Using a preprinted cylinder evaluation sheet a sales person, or shop personnel takes basic measurements of the cylinder, notes the condition, checks off the appropriate repairs needed, logs on and enters the information into the program, and in seconds has a accurate, detailed quote. The work sheet can be attached to the cylinder and is the identifier and guide for shop personnel.

Who should be using “Hydraulic Repair Estimator”TM for Cylinders program? Hydraulic cylinder repair facilities, with this program can offer more accurate quotes and improved service. Companies that lease or rent equipment with hydraulic cylinders, and companies with large numbers of trucks and off road equipment equipped with hydraulic cylinders can use this program to control costs, make timely decisions such as repair or replace, and analyze quotes from repair facilities.

The low cost of the program is based on the number of new quotes created each month by a subscriber company. A Return-On-Investment calculator highlights the real value of using this program compared to working up a quote from scratch using a pencil and paper. Features also include: A “ToolBox” including a calculator, metric converter, and a data base of Cat® cylinders by part number, recommended vendors, and rebuild instructions.

The benefits of using “Hydraulic Repair Estimator”TM for Cylinders program are: Easy to use, customers will view estimates with confidence, reduce time in getting estimates to potential customers, reduces overhead by reducing time needed to produce quotes, ability to offers quotes On-the-Spot 24/7/365, no over or under quoting, and have greater insight into costs and efficiency.

The Rupe Corporation has been in the hydraulic repair industry since 1976 developing one of the largest repair facilities in the western United States. In 2005 Rupe Corporation took on the task of developing and researching innovative projects that would benefit the hydraulic industry and their customers. One of those projects was a program to bring a pricing standard to the repair of hydraulic cylinders and other components. Drawing on many years of experience rebuilding hydraulic cylinders Rupe Corporation was able to develop a program that is simple to use, quick, accurate, consistent, and sets an honest standard for repair facilities and consumers.

For additional information contact Jack Rupe at: Rupe Corporation, 585 N Twin Oaks Valley Rd; Suite C; San Marcos CA; 760-815-1620 or E-Mail: rupecorp@gmail.com or visit the website at http://www.hydraulicsrepairestimator.com

And say, “I saw it on FluidShop.com, “The Fluid Power Home Page.”