Designer's Corner

DN Staff

June 23, 1997

4 Min Read
Designer's Corner

In-line rotary transmission

Gear-based speed-conversion devices can be relatively bulky and cumbersome because most of the gear's working volume is unused during operation. SYNKdrive(R) rotary technology uses in-line flat plates and rolling balls to do the work of side-by-side spur gears. Drive and driven disks, called cam-gears, sandwich a slotted reaction disk that has rolling balls installed in each slot. As the drive cam-gear rotates, it displaces the balls radially in or out in the reaction disk's slots. The balls roll on the driven cam-gear's flanks, giving rotary output.

SYNKdrive employs in-line flat plate gears and rolling balls to do the work of side-by-side spur gears, achieving volume and weight advantages in speed conversion applications.

Cam-gears are disks with at least one, and perhaps many cycles or "teeth" milled into their surfaces. The number of teeth on the driven cam-gear compared to the number of teeth on the drive cam-gear determines the speed-conversion ratio. Any variety of speed reductions and some speed increases are possible. All teeth and balls work simultaneously to transmit torque, resulting in volume and weight reductions.

The system can handle high-torque power transmission applications, yet is accurate enough for low backlash, precision-positioning devices. SYNKdrive can be produced in metal, specialty plastic, or ceramic construction, making it suitable for many applications.

James Maslow, Synkinetics Inc., 2 Industrial Ave, Lowell, MA 01851, (508)453-4900.


Water damps cylinder bounce

Powered by deionized water, elevator assembly's two S.S. cylinders, lift waters in and out of polypropylene DI rinse tank.

To eliminate bouncy cylinder operation, Strausbaugh Inc. converted its existing pneumatic elevator assembly to operate with deionized water (DI) instead of air. Two 12-inch-long 5/8-inch-bore Aipel(R) cylinders lift a 20-lb load that is canted 4 degrees from vertical.

.The setup caused side-loading and resulted in a pause at the bottom of the stroke, followed by several bounces before reaching the top.

Taking advantage of DI's non-compressibility in an air cylinder required replacing the nickel-plated aluminum cylinder head, piston/rod coupling, and seal retainer with stainless steel parts to ensure DI tolerance.

Mark Gaberman, Airpot Corp., 35 Lois St. Norwalk, CT 06851. (800) 848-7681.


High-flow pinch valve

When the user-supplied, spring-returned, four-way control valve is in its closed position, the pinching surface of the air-operated piston prevents flow by collapsing the pinch valve's tube. A patented pinch-stop adjusting mechanism limits pinch, and by doing so also limits stress on the tube. Self-compensating anvil automatically adjusts to accommodate variations in tubing wall thickness.In the four-way valve's open position on the right, air moves the pinch valve's piston back to the adjustable stop, which controls the amount of the tube opening.

Generally, pinch valves must employ elastomeric materials as the pinch element when tubing bores exceed 1/8 inch ID. But in this new valve, a patented "Overpinch Control" limits stress in the tubing, while a pinch anvil automatically adjusts for variations in tube-wall thickness. These design innovations allow the use of pinch tubes made from Teflon(R), polyethylene, polypropylene and similar materials in bore sizes to 7/16 inch.

Tracy Curran, Tridak Division of Indicon Inc., 1120 Federal Rd., Brookfield, CT 06804, 203-774-1287.

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