Designer's Corner 425

Cleanable keypad

Despite its tactile man-machine interface, the Abbott ambulatory infusion pump is easily cleaned. That's because the keypad features a laminate of liquid silicone rubber adhesively bonded to a membrane switch assembly.

Manufactured by liquid injection molding, the 2-part rubber catalyzes in the mold barrel, exposing itself to the environment in a cured state only. Labeling ink vulcanizes directly into the rubber so it won't rub off and can withstand ethylene oxide sterilization.

Tactile response comes from a conductive polydome layer, thermoformed in a contiguous sheet and die cut to shape. The upper surface of each dome cavity contains a silver switch contact, which snaps down onto the interdigitated fingers of the screened circuit.
FDA approved, the entire Elastikey(TM) assembly weighs less than one ounce.

Abbott Ambulatory Infusion Systems, 15330 Ave. of Science, Suite 100, San Diego, CA 92128, (619) 485 7474.
Lucas Control Systems Products, 1000 Lucas Way, Hampton, VA 23666, (804) 766-4286.

Hybrid helicopter

Combining the speed of an airplane with the land-anywhere convenience of a helicopter, the CarterCopter could have an enormous impact on the general aviation market. The design uses a massive rotary wing made of depleted uranium. Once up to speed, the energy stored in the rotor allows the craft to practically leap into the air and build the speed necessary for its stubby fixed wings to gain lift. In flight, the rotor's mass keeps its tip speed down, permitting higher forward speeds than conventional helicopters. Now under development, plans call for a five-passenger, pusher-prop model capable of 300-mph cruise and trans-continental range.

Jay Carter, Cartercopters, Inc., 5720 Seymour Hwy., Wichita Falls, TX 76310, (817) 691-0819.

360 Degrees of gripping power

Keyways are not necessary with this 3-part bushing. Instead, mechanical friction joins hub and shaft. Components include a tightening ring with captive set screws, and opposing tapered sleeves.

The tightening ring threads to the inner sleeve, positioned at any point along the shaft. Its set screws act against the outer sleeve, which climbs the tapered threads of the inner sleeve for a uniform radial expansion.
Good for applications where there is significant vibration or reversing action, 'SH' bushings fit all shafts--even those that are worn or exhibit corroded key joints.

Daniel Statler, SKF USA Inc., 1100 First Ave., P.O. Box 1507, King of Prussia, PA 19406-0907, (610) 962-4735.