Engineering News

By Design News Staff -- Design News, December 6, 1999

Smart toys at your command line

By Jean Young Gonzalez

Sunnyvale, CA-What do this unlikely trio--a cuddly teddy bear, a steely robot, and a purple password diary--have in common?

Other than the fact that they are the hottest new Christmas toys, all three use embedded chip technology to respond to the sound of your voice.

Koby may look like your average bear. But don't be fooled. This new-age electronic teddy from MCA Entertainment (North Hills, CA) speaks over 400 words and 125 phrases, recognizes your voice, asks questions and listens to your answers. Not only that--he winks, blinks, walks, can solve math problems, play games, and wiggle around, and interact with other Kobys.

The ultimate boy toy, Commandobot responds to 11 action commands, including "Fire Gun," "Laser," and "Release Missiles." Commandobot has a 50-ft range of movement, can fire 10 missiles with 4 different commands, light and sound effects, a "tank tread" design, and an articulated body and arms for maximum movement against the enemy. But beware--the enemy may be you.

Shopping for the sugar and spice side of the family? Consider Password Journal by Radica. Built to be a girl's best friend, this lockable diary uses your voice as the key to keep secrets safe and snoops out. Simply record a password into the journal and it automatically locks and will only unlock at the sound of your voice and no other!

Koby, Commandobot, and Password Journal contain Sensory Inc.'s (Sunnyvale, CA) RSC-164 8-bit microprocessor. The chip and its embedded software can provide any combination of speech recognition, speech synthesis, music synthesis, record/playback and speaker verification, and general purpose product control.

Applications include cordless phones and Sony's new voice command car stereo system.

In Sensory's toy chips, neural networks with several hundred processing units and several thousand interconnections are used for sound classification. With a spoken word as input, the network classifies the sound as one of the possible words within a set of words. The network is trained by a supervised learning paradigm. For every answer Koby the talking teddy bear wants to hear, for example, linguists at Sensory record the voices of several hundred children from all parts of the United States to accommodate different accents and speaking styles, and to establish a baseline for recognition and comparison. All the data resides on an ice cream sandwich-sized board, which Sensory sells as is or as a development tool. Sensory's neural network approach eliminates the need for expensive signal processing of extensive RAM storage and reduces parts count.

Sensory's RSC series chips find most use in home security, environmental controls, and consumer electronics, but will be used in space to record sound on Mars when the Mars Polar Lander touches down December 3rd. Thanks to the low-powered record and playback features of the RSC-164 speech recognition chip, a new dimension in space exploration--sound--will be captured on this mission.

Jammin' with flash memory

Sunnyvale, CA-MP3, compressed music that you can record directly from your PC and the Internet, is one of the hottest topics in computer commerce today. But for this trend to become mainstream, flash memory storage must continue to improve. SanDisk Corp. intends to make sure it happens. Even in time for Christmas!

The company has introduced a patented 256-megabit double density flash chip. Made with a new memory technology, the chip doubles the capacity of the company's MultiMedia Cards, CompactFlash^TM cards, PC cards, and their new Secure Digital memory cards. "The actual memory chip size is only 5% larger than our 128-megabit technology, but offers double the capacity," says SanDisk's Jeff Ellerbruch, product manager. This means engineers can design higher capacity digital cameras, handheld PCs, and the popular new portable MP3 Internet music players.

Penman Corp., a Korean consumer electronics company, will use the MultiMedia Card for its NETTIiPN-2000 MP3 portable Internet player. In addition to playing music, the NETTi offers a large LCD to display lyrics for Karaoke and text for voice lectures.

The U.S. Army is also interested in SanDisk for the company's personal information carrier (PIC), a solid-state, wearable data storage device equipped with the new flash memory chip. Seeing the PIC as a benefit to military personnel, the Army awarded a multi-million dollar contract to Kaneb Services Inc. (Dallas, TX) to buy more than 2,000,000 SanDisk personal information carriers to store medical data for soldiers. Smaller than a match-book, the devices are designed to be worn about the neck along with traditional dog tags and will store medical records and identification information, including MRIs and x-rays.For more information about flash memory products from SanDisk

Palm PCs proliferate

The installed base of Palm OS devices is about four million units today and is expected to grow to an estimated seven million units by 2001. Market analysts forecast that the information appliance, cellular, and handheld markets are set for explosive growth over the next several years.

Animation key to winning contract

Eberhardstrasse, Germany-Engineers at WMF Aktiengesellschaft, a hotel and catering equipment manufacturer, finished a new design for a computer controlled bistro-model coffee machine. They were excited. This $10,000 java maker even identifies the user through an infrared security system.

But when the WMF salesperson presented the 2D drawings to the prospective client, the customer showed him the door, literally. The reason: the client didn't understand technical drawings.

So Patrick Rodrigues, manager for WMF, quickly turned the 2D drawings into 3D solid models with Solid Edge from Unigraphic Solutions (St. Louis, MO) and rendered the model. Rodrigues then downloaded a free trial package of IPA animation software from Immersive Design (Acton, MA). By following the online tutorial, he put the solid model into a short movie sequence.

In less than 18 hours, Rodrigues turned the 2D drawings into a full-blown 29 sec. animation, complete with ray tracing and photo realistic drawings on a Pentium II, 450 MHz computer.

When the salesperson went back this time, equipped with Rodrigues' film, he won the contract not only for the industrial coffee machines, but also for the complete cafeteria.

And Rodrigues won the 1^st annual Immersive Design animation contest at the Solid Edge User's Conference in October. Not bad from a free download. WMF bought three licenses of IPA to supplement its 57 licenses of Solid Edge for the generation of animation for sales, maintenance personnel education as well as design intent presentation.

Self-aligning bearing accommodates hole misalignment

Northbrook, IL-Sometimes the simplest solution is best. That was certainly the case for Quickset International engineer Tom Rakowski, who recently selected a self-aligning bearing from Spyraflo (Peachtree City, GA) to accommodate several alignment issues associated with the mounting holes on a pair of 0.25-inch-diameter worm gear shafts. The worm gears achieve a wide range of speed-reduction ratios in a small space on the company's compact pan-and-tilt devices. They move a 20-lb load through 435 degrees of rotation with a ±90-degree tilt.

"In the prototype, we were using press-in brass bushings that have no flotation capabilities. You couldn't turn the shaft with your fingers, that's how tight it was," recalls Rakowski, a mechanical engineer who designed the new pan-and-tilt device. "As a result, the shaft had to work harder, which meant lower mechanical efficiency and the potential for premature gear wear."

Because the diameter of the steel retainer of Spyraflo’s self-aligning bearing has a 45-degree taper from the large diameter to the small diameter, the bronze insert it holds can swivel ±5 degrees to accommodate any slight misalignment of rotational mounting holes.

One alternative open to engineers was to machine precision holes. But achieving the required tolerance of 0.0001 inch would have increased machining costs by a factor of five. "In contrast, our self-aligning journal bearings, which are designed to pivot ±5 degrees in a radial direction, can accept a significantly greater offset on the mounting," explains Peter Allen, a mechanical engineer and chief operating officer of Spyraflo.

A variation on the company's popular line of self-clinching, self-aligning bearings, the bronze journal bearing features an outer steel retainer with a slightly tapered outer diameter that holds a lubricated bronze spherical insert. Assembly of the press-fit bearing is easy. After dropping the bearing into place, tooling is used to keep the hole located through the center of the retainer. The top lip of the retainer is rolled over on assembly, trapping a nylon washer which in turn retains the bearing insert inside.

Allen explains that the tapered diameter is the key. "The diameter is tapered about 45 degrees from the large diameter to the small diameter. This geometry allows the insert to swivel, accommodating any misalignment of the rotational alignment holes."

Put a keyboard in your pocket

Solana Beach, CA-Currently, all handheld devices, information appliances, smart phones and other new-generation computing and communications devices share a common problem: No practical input solution that allows people to quickly and comfortably enter text, without resorting to a full-size keyboard that's bigger than the product itself. A start-up company recently solved this mobile-technology challenge. The Stowaway^TM portable keyboard from Think Outside, LLC, offers the same key size, key spacing, key travel, and tactile response of a full-size keyboard, but folds easily to fit in a pocket or purse.

Initially designed to work with Palm Computing^®'s connected organizers, and the Handspring handheld, the Stowaway is an essential add-on for any user, enabling these devices to live up to their full potential--on the road, at home, or away from the office. A built-in dock provides a cordless connection to popular handheld computers that provide the keyboard power. Drawing power only when the user depresses a key, a custom integrated circuit reduces battery drain. Key mechanisms have a minimum life of seven million cycles, and use the finest scissors action keylift mechanisms, such as those used in the best notebook computers.

"The burgeoning market for handheld computers and information appliances has been stymied by the lack of a full-sized, practical keyboard that can be carried in a pocket, allowing people to do real work--like writing e-mail, sending faxes, jotting memos, or taking notes," says Bob Olodort, founder and CEO of Think Outside and the inventor of the keyboard. "With the Stowaway keyboard, we've come up with the magic combination of size, weight and ergonomic design that enhances the whole handheld and information appliance markets for millions of current and future users. Like the missing piece of a puzzle, the Stowaway takes a handheld device that's now mostly an information retrieval product, and turns it into a powerful information creation device. With the Stowaway keyboard, all these devices are more practical, more powerful, and more productive."

Different models of the Stowaway keyboard will be available for the Palm III^TM family of connected organizers and Palm V^TM model with appropriate connectors for each device, as well as for the Handspring handheld device.

Key features of the Stowaway keyboard, for which Think Outside has a number of mechanical and electronic patents pending, include the following:

100% full-size keyboard when opened; when closed measures 3.6 x 5.1 x 0.8 inches (93 x 130 x 20 mm) or about the size of a Palm III^TM connected organizer

• Weighs only 7.9 ounces (224 gm)

• Full 19mm pitch (space between keys), both horizontally and vertically (the same as desktop keyboards)

• Full 3-mm key travel (the distance the key travels downward when it is pressed)--the same as the best laptop keyboards, with superb tactile feedback

• Standard QWERTY layout with 69 keys; includes special keys for computer functions such as Calendar, Address Book, To Do List, Memo, and many command buttons, such as Done, New, Details, Cancel

• User-programmable keys

• Built-in docking station for the handheld device

• Ultra-low profile design makes wrist supports unnecessary

• Made of glass-filled polycarbonate and aluminum for high durability

• No batteries or cables required

"Think Outside has developed an innovative data input solution for Palm users seeking optional text entry methods," says Gabriel Acosta-Lopez, director of platform development services for Palm Computing Inc., a 3Com company. "Also, the Stowaway keyboard's fold-out design and standard layout extend the Palm Computing platform ideals of portability and ease-of-use."

"The Stowaway keyboard meets an interesting challenge in the industry today--giving people the option to have the comfort and accuracy of a full-size keyboard in a package that doesn't defeat the purpose of the handheld computer," said Ed Colligan, vice president of marketing and development for Handspring, Inc. "Think Outside has created a no-compromise keyboard that is a great companion to our products."

When expanded for use, the Stowaway includes a built-in docking station for the handheld device, enabling the handheld computer to "sit up" for easy viewing. Connection is automatic, and the keyboard is compatible with all the popular software that works with the handheld products.

The Stowaway keyboard is available for a suggested retail price of $99.95. In addition, Think Outside is collaborating with a number of hardware and Internet companies that will incorporate this keyboard technology into new mobile computers, smart phones, information appliances, and space-saving desktop keyboards.

Computer chip simplifies router design

Charles J. Murray, Senior Regional Technical Editor

Irvine, CA-As more audio and video files stream across the Internet, engineers have sought a way to build a network router more capable of handling the additional traffic.

Now, they may have a key component. A new integrated circuit helps solve the traffic problem by offering higher speed and greater bandwidth in a solid state design. Known as the Wisper (Wire Speed Edge Router) chip, it is said to be the first fully integrated Internet Protocol router chip of its type. It works by assisting the router's main processor as it moves packets of voice, video, and data onto and off of the Internet.

Designed by engineers at Entridia Corp., the Wisper chip could help meet the greater demands now facing network routers. In the past ten years, computer processing speeds and bandwidth have increased dramatically. At the same time, users are sending more audio and video files. "If it's a data-only file, it doesn't matter if there's a five-second delay in the system," notes Ram Krishnan, founder and chief technology officer of Entridia Corp. "But if you're sending a fragment of speech over the internet, you can't afford to have a five-second delay."

Wisper helps solve the problem because it offers 6.4 Gbit per second of network bandwidth and 8 microsecond ingress and egress latencies. That means shorter delays for users.

The new design could also be an important step forward for the engineers who develop routing hardware. The reason: The Wisper chip performs tasks that used to require anywhere from three to ten programmable gate arrays and application specific integrated circuits (ASICs). As a result, engineers no longer have to be experts at designing systems around field programmable gate arrays. Nor do they have to create their own ASICs.

"We've reduced all the routing functions into one piece of silicon," says Terry Holdt, president and CEO of Entridia. "So we have a high performance product that's out there for any hardware designer who chooses to use it."

Hot Spots in Cyberspace

Got a job? Want a job?

The economy is hot and so is the job market. Want the best places on the Internet to look for engineering jobs? The editors of Design News got together and came up with a comprehensive list of websites that cater to engineers. Check it out in our new Careers section at http://www.designnews.com and click on the Careers button on the left. You can also find archived stories from the Design News' annual careers' issues, as well as useful links to preparing a resume and cover letter, hints for interviewing, and a salary calculator.

Getting that perfect fit

Fit Finder is a new tool that specifies hole and shaft tolerances offered on http://www.cadfly.com. The program takes users through a graphical interface and shows how different dimensional choices affect the final fit. Fit Finder also offers a Fit Calculator, Fit Explore, ANSI Preferred Fit, and an insertion tool for AutoCAD 13/14. If this doesn't fit your needs, (sorry, we could not resist!), Cadfly also offers a collection of dimensional charts outlining standard fasteners and hardware and other items.

Open a virtual door and see 3D

3Dmodelserver.com offers a web-based service to flow 3D model data through a manufacturing enterprise. Engineers can request an open beta test and should be using Netscape 4.x or above, or Internet Explorer 3.x or above. Just register for an account and fill out the log-in information. Then upload a model. Users can track models through a status page on the website, then download the file when complete. The site was developed by Spatial, Inc., a provider of 3D solid modeling software.

Box 'em up

Need a custom-designed electronic enclosure? Then head on over to http://www.ochs-ind.com and see their enclosures, read about their design capabilities, and take a cyber-walk through their product and service areas. Animations on the site show how two products--the ATX chassis and the Vault Device Bay--are assembled and disassembled.

Get the power

Xantrex Technology Inc., a designer of programmable dc power supplies, offers an online technical library with users' manuals, interface cards, and drivers. Also online is information with delivery date projections for your purchases, product inventory supplies and a list of sales reps. Or if you do things the old-fashioned way, you can order a free catalog at their site http://www.xantrex.com.    

Cyberspace Invention Convention open all day, every day

Have an idea, product, or other invention you're trying to market? Then head to Invention Connection and its Cyberspace Convention. Just like a "live" trade show, you can check out product photos, read descriptions and benefits, review target markets, and download contact information. The convention links pre-qualified venture capitalists, manufacturers, distributors, etc. with new product ideas. Just head over to the exhibit hall at http://www.inventionconnection.com.   

Dress up your desktop

Okay, we admit, the regular old browser can get a little old. So how about dressing up your desktop browser with a "skin" from Neoplanet (http://www.neoplanet.com). Download the software and then use the "personalize" part to add news from your favorite sports team, the weather, or your horoscope. You can also set up favorite links to help you get to where you are going even faster. The fun part is adding "skins" to your browser page--from sports pages, to TV characters like the Simpsons, to dressing up the browser for the holidays. Best of all, it's free.

Adroit meter assures steel tempering

Omaha, NE-Tempering steel is a tricky process. Just ask Michael Smith, maintenance supervisor at G&G Manufacturing, a maker of power transmission parts for heavy-duty agricultural and off-road equipment.

To perform effectively, a machined part requires a carefully controlled heat treatment that produces high hardness with good wear, abrasion, and impact characteristics. The temperature of the ovens involved has to be controlled to within a critical range of only ±5F--if too hot, the metal becomes too brittle; too cool, the tempering fails.

To make sure his various ovens are set properly after every two-year overhaul, and are performing correctly every three months, Smith uses the digital multimeter (DMM) of the ScopeMeter^® 123 test tool from Fluke (Everett, WA). The unit also features oscilloscope and recorder functions. Smith says the company previously used a chart recorder of "suspect accuracy."

"Quality is our highest priority," says Smith. "We can't take chances--our customers expect nothing less. But the ovens are only a small part of our overall testing. Responsibility for high-power solid state devices, magnetic probes, and temperature immersions is also part of my job and the jobs of the eight other technicians." The ScopeMeters monitor these and other machines.

When initially trouble shooting a problem, a technician usually does not know its cause. It could be a glitch, or a broken wire. Identifying the source may involve looking at signals anywhere from a microsecond to days or weeks. Obviously, the technician needs to find the cause as quickly as possible to keep equipment up and running. According to Smith, the ScopeMeter can actually capture a disturbance as it happens. Add to that feature the meter's flexibility in temperature monitoring and tracking, and it has become the tool of choice for G&G.

With such integration of tools, G&G's ScopeMeters feature fast--up to 40 nanosecond per channel--transient detectors to catch spikes, glitches, and contact bounce. The unit's TrendPlot "paperless" recording capability isolates intermittents and problems that occur only once in a day or a week. The recording capability also comes in handy when monitoring oven temperature. The ScopeMeter stores two screen images in non-volatile memory and up to 10 instrument setups.

During equipment testing, the Scope-Meter gives a technician a stable waveform on the display, regardless of what the signal looks like--spikes, noise, even complex waveforms used in motor drives, are shown. Proprietary circuitry continuously analyzes input signals while the microprocessor uses the information to control the instrument's settings. In addition, the ScopeMeter 123 speeds up the process by allowing the technician to check test points without changing test leads.

To sum up, Smith says, "The Fluke ScopeMeter does all this well with a DMM that cuts right to the problem--whether we're monitoring furnace temperatures or chasing an evasive electronic glitch in sensitive equipment."

Engineering plastics go for a walk in the snow

Joseph Ogando

Grand Junction, CO-Forget about those rawhide-and-wood contraptions your grandfather wore. Snowshoes, like much of today's outdoor gear, have gone high-tech.

The newest twist on the engineered snowshoe combines a thermoplastic platform with a patent-pending binding design to meet aggressive pricing and performance goals. Called the "Winter Walker," the snowshoe represents a joint design effort by Spring Brook Manufacturing Inc. (Boulder, CO) and the catalog retailing giant, L.L.Bean (Freeport, ME). "Our goal was to produce a technically advanced yet affordable snowshoe," explains Jim Watson, Spring Brook's president and design engineer.

For a high-tech winter stroll, these new snowshoes combine engineering thermoplastics with a patent-pending binding design.

Unlike many of today's high-end snowshoes, which are most often built around an aircraft aluminum frame or from commodity plastics, the Winter Walkers feature a platform, or deck, injection molded from Lexan polycarbonate (GE Plastics). Watson explains that the engineering plastic, with its tensile strength in the neighborhood of 10,000 psi, resulted in a deck strong enough to support almost 200 lb of gear-laden snowshoer. And he adds that the material provides enough impact strength and cold weather resistance to survive the unconditional lifetime warranties offered by Spring Brook and L.L. Bean. "It's a tough material," he says.

While more expensive than commodity resins, polycarbonate also helped Spring Brook meet aesthetic objectives. "For the outdoor market, we had to couple function with a good appearance to heighten the shelf appeal," Watson says, noting that sales take place in the store not out in the field. To give the snowshoes a distinctive look, they come in a variety of semi-translucent colors--a look that Watson says would be difficult to achieve in other plastics. Polycarbonate will also support a move to in-mold-decorating on upcoming models, Watson adds.

Because the snowshoe targets a recreational user who will likely spend some time on hard-packed or icy trails, the Winter Walker's deck also integrates features designed to enhance traction. Its underside incorporates both molded-in ribs and press-fit stainless steel studs, which together add gripping capabilities beyond those provided by the claw-like snowshoe's crampon. "If you take the crampon of an aluminum snowshoe, what you have is a ski," Watson notes.

Unique binding. For the Winter Walker's rotating binding, which attaches the deck to the user's boot, Watson set out to provide a mechanism that fits securely and goes on easily under finger-numbing conditions. "The binding is really the most important part," says Watson. "If it's not working, you're not going to have a good time on the snowshoe."

The binding he came up with combines two different grades of thermoplastic polyurethane, which are injection molded together in a two-shot process. The outer component, a Shore D 70 urethane, forms the binding's skeleton. The more pliant inner component, a Shore A 80 urethane, "provides a high friction surface to grip the user's boots," Watson says. The entire binding assembly, which also includes a lacing system that tightens with one pull, can be color coordinated with the deck.

One unique--and patent pending--aspect of the binding assembly is how it forms part of an integrated hinge, which enables the user's foot to rotate forward relative to the deck to mimic normal walking and also to engage the crampon teeth in the snow. According to Watson, many snowshoes have to attach a metal hinge to facilitate this motion. The Winter Walker, by contrast, has a multi-section "hinge-pin" molded into its plastic deck. A corresponding u-channel in the bottom of the binding engages the molded-in pin from above. And the flat plate of the snowshoe's aluminum (6061 T6) crampon, encloses the hinge on the bottom.

Fewer parts. With its one-piece deck, two-shot binding, and integrated hinge, the Winter Walker has fewer parts than many snowshoes on the market. Watson contrasts his three main components to models that have in excess of 40 parts. "We intentionally kept the number of parts down to keep our manufacturing costs low," he says. In fact, the Winter Walker's design is modular, in that one deck can be paired with different bindings to get different performance levels from the fewest number of parts.

Coming up with such a simple design, however, required "lots of upfront engineering work," Watson reports. First, L.L. Bean purchased a seat of SolidWorks 3D solid modeling package for this paperless project. Spring Brook created SLA and cast-urethane prototypes based on the CAD designs and then spent "a lot of time on the snow with them," Watson says. Finally, the companies tooled up--a long expensive process given the complexity of the three tools needed to make the snowshoe. "Our tooling costs a lot, so that our individual pieces do not," says Watson.

All the upfront engineering seems poised to pay off. At $99, the Winter Walkers will sell for what Watson says is a one-third to one-half the price of competitive models.

Gearbox designs exhibit out-of-the-box thinking

Charles J. Murray, Senior Regional Technical Editor

Manufacturers of power transmission equipment continue to exhibit ingenuity and creativity in their product development efforts. Consider, for example, these two gearbox designs recently introduced.

Bison's MultiTech^TM gear reducer accommodates steppers and servos in precision applications and slashes power transmission costs. The new line of servo-duty gear reducers mounts directly to brushless dc motors and steppers, at a fraction of the cost of competing gearboxes.

The reducer is designed for motion applications that don't require extreme positioning accuracy. Inherent backlash of the system is approximately 60 arc-minutes. By comparison, many such gearboxes offer 20 arc-minutes or less, but do so at more than twice the cost of the MultiTech system.

Engineers from Bison Gear and Engineering, designers of the system, say that the cost-positioning tradeoff is ideal for some users--particularly those with existing systems that don't require ultra-high precision. "If you have a sophisticated drive, but you already have that much backlash built into the rest of your system, this gives you the opportunity to cut your costs," says Matt Hanson, vice president of marketing for Bison Gear and Engineering.

The new Bison gear reducers are designed for use with NEMA 23 and NEMA 34 mounts. A precision one-piece pinion mounts onto the motor shaft within two minutes. The gearcases are permanently lubricated.

The company offers eight ratios in each frame size, ranging from 3:1 to 100:1. Torque ratings range from 45 to 399 in-lb, with peak torque capacities up to 798 in-lb.

Hanson says that the lower price of the MultiTech product could encourage users of permanent magnet DC motors to opt for steppers in some applications. Potential applications include conveyor ovens, circuit board processing conveyors, medical pumps, plasma cutters, and agricultural feeding systems, among others. Says Hanson: "It's an enabler to bring steppers and servos into a whole new line of applications."

Helical-bevel gear. Also new to the market is Lenze's GKR04 gearbox, which employs a helical-bevel gear set instead of a worm gear for greater efficiency and more compactness.

Designed by engineers at Lenze Power Transmission, the new GKR04 gearbox departs from the conventional in its use of the helical-bevel concept. Until now, the vast majority of gearboxes rated under 1 hp and 750 in-lb of torque have employed worm gears. And while worm gears cost less, their efficiency is less, particularly at higher gear ratios. But by employing proprietary production methods, Lenze engineers say they were able to reduce the cost of a helical-bevel gear set, while maintaining its efficiency.

As a result, they believe that helical-bevel gears can replace worm gears in a variety of applications, particularly those involving modular machinery. There, they say, several smaller drives can replace one big one, and offer greater mechanical efficiency in the process.

The GKR04 consistently offers 95% efficiency at ratios ranging from 6:1 to 60:1, they say. In contrast, worm gears typically offer efficiencies of around 90% at 6:1 and slowly drop off to about 65% as they approach 60:1.

As a result of the GKR04's greater efficiency, users can select smaller motors and still achieve the same output torque while promoting compactness in the design.

Lenze engineers acknowledge that the helical-bevel concept is still more costly than worm gears, but they note that users can recoup the cost over time. "The helical-bevel gearbox has higher initial cost," notes Karim El-Rikabi, division manager for Lenze's motion products. "But the user is compensated for those higher initial costs through energy savings."

The company says that the GKR04 is ideally suited for material handling, turning machines, and milling machines, as well as any applications requiring large numbers of conveyors. Says Rikabi: "The higher the gear ratios and the larger the number of drives, the more benefit this technology offers." 

Hydrophobic materials make flashlights safer

John Lewis, Northeast Technical Editor

Torrance, CA-People don't normally consider flashlights unsafe, but under certain conditions some underwater diving lights have actually exploded!

The problem is not with the flashlights, but with the alkaline batteries that power them. A damaged or defective alkaline battery is a potential source of explosive hydrogen gas--something every designer of sealed battery-powered devices needs to consider. If enough gas accumulates and the pressure builds within a sealed chamber, exposure to a single spark from the switch contact could ignite the gas, causing an explosion.

That's why to meet safety standards Pelican Products Inc. designs purge vents into all of its underwater-diving, industrial-safety, and hazardous-location flashlights. Pallflex^® hydrophobic materials from Pall Corp. (Port Washington, NY) allow the purge vent to repel water while venting potentially explosive gases.

Hydrophobic membranes repel low-surface-tension fluids while venting gases, and present an effective barrier to airborne microbial contaminants and particulate matter.

By choosing the right composition from the Pallflex family of hydrophobic materials in venting applications, engineers can customize airflow, water-intrusion pressure, and aerosol reduction capability. "Working with Pallflex was actually very simple," says Pelican Engineering Services Manager Kevin Deighton. "Pall Corp. sent us a bunch of samples. We tested them under various conditions of rain or light submersion, and made the selection based on our test results."

Pallflex media, available in customer-defined widths, lengths and various shapes, sheets, rolls, and discs weld easily (sonically or thermally) into medical and industrial devices, and can be sterilized by gamma irradiation, EtO, and autoclaving methods. All Pallflex media meet the USP Class VI test criteria.