The search for a better pitch led ProBatter Sports engineers to the sales department of Cranston, R.I.-based Mearthane Products Corp. ProBatter of Milford, Conn., wanted to add durability to its batting cages. With a video pitcher throwing in consort with a curveball pitching machine, the cage already offered plenty of realism.

According to ProBatter's president, Greg Battersby, many pitching machines use two counter-rotating wheels to throw a ball. His company's machine adds a third wheel, by which the machine can throw fast balls and every pitch tossed in the Major Leagues, save the knuckleball. To do so, the machine varies individual wheel speed from 1,500 to 2,500 rpm.

Just when star pitcher Vid Eo is about to release the ball, a throwing machine backing him up tosses one out a screen opening.

Rubber-coated wheels gripped each ball in the original machines. But they wore prematurely—in as few as 30,000 cycles—because of the demands placed on the rubber as it accelerated the balls to speeds near 100 mph. Once the cycle of wear began, wild pitches increased, until replacement wheels had to be brought in to relieve the pitchers 10,000 throws later.

Downtime to replace the wheels bothered commercial users, who expected the equipment to throw 10 pitches a minute 16 hours a day.

In seeking a better material, Mear-thane engineers cast several urethane prototypes before selecting one in the 40-45 Shore A durometer range. The material needed to grip and wear well on both the urethane covering amusement-park balls and the stitched-cowhide outers the pros handle.

The new wheels throw quite a few innings before needing relief.

A blender handling bulk powder or slurry might turn a 5-inch-diameter main shaft at 50 rpm. Flights welded to the shaft over its typical 8- to 12-foot length can create a high degree of runout, making shaft sealing difficult with mechanical packings. Such dry sealing applications also don't share the same beneficial lubrication that wet seals enjoy, said David Pitchko, president of Damar Inc. of Cherry Hill, N.J.

By moving the sealing area away from the shaft, a cartridge seal avoids touching the surface.

Damar makes cartridge seals specifically for dry applications. The cartridges move the sealing surfaces off the shafts. A sliding seal develops between a pair of stationary stainless steel plates and the cartridge's plastic rotor cups. Several of Damar's OEM customers asked the company if it could solve another sealing headache. The manufacturers were building smaller, high-speed choppers, called intensifiers, to augment the mixing that takes place inside the main blender chambers. Each chopper unit turned a small shaft at 3,600 rpm that protruded through the blender sidewall.

According to Pitchko, sealing a 50 rpm shaft using a Cinchseal cartridge is no problem, but sealing higher-speed shafts generates more heat. PTFE braided packing, if it tightens even slightly under the same conditions, will plasticize and burn, Pitchko said.

After trying a number of seal materials in the chopper cartridges, Damar engineers opted for a polyaryletherketone polymer manufactured by Victrex USA Inc. of Greenville, S.C. In addition to withstanding high heat, the polymer resists attack by most of the chemicals that Cinchseals routinely meet. FDA approval of the polymer for food contact was another plus.

According to Pitchko, the cartridge seal can be pressurized to further enhance sealing.

Like a mirror reflecting the sun's rays back upon itself, a solar attic ventilator runs fastest in the middle of the day. Mornings, it ramps up from a standstill. Evenings, it slows before resting for the night.

Targeting homeowners who'd rather not wire a conventional unit or hire an electrician to do it, the fan requires only that a 12-inch circular hole be cut through a roof. Installation takes about a half-hour, according to maker Sun Tunnel Systems Inc. of San Jose, Calif.

In picking a motor to drive the solar ventilator, Sun Tunnel turned to Pittman of Harleysville, Pa. Graeme Blackburn, Sun Tunnel's president, said the fan's solar panel produces up to 17.4 volts, about half the motor's rated voltage.

Most direct current motors require 2 to 3 amps to get them started, Blackburn said. But Pittman provided special windings on the motors it shipped to Sun Tunnel, letting them operate on as little as 3/4 amp.

A thermostat is available for those of its customers who would prefer that the fan not run in the winter. But the manufacturer said that venting a cold attic helps reduce condensation.

Mississauga, Ont.-based Nordic Systems Inc. builds winding reels for both fixed and mobile applications. Some of its OEM customers—makers of propane delivery trucks, for instance—require winders that can be operated remotely.

That's because certain DOT requirements specify remote shutoff for propane trucks when there isn't a second person at the vehicle.

Gas delivery vehicle makers, meeting transportation regulations, open a market for auto-winders.

To assist the hose or cable onto the drum, Nordic uses a traversing guide that rides a ball reverser from Norco Inc. of Ridgefield, Conn. According to Norco's director of power transmission, John Boscia, the reverser uses a single shaft with a pair of right- and left-hand threads cut over its length.

A sprocket driven off the main reel drive turns the shaft in one direction only. A cage on the shaft houses three balls, one fixed and two in slots. The balls follow the spinning thread, until they come to a turnaround curve at either shaft end. There, they continue riding the thread, but the balls in slots slide to reverse the hand of the cage.

Rewind speed usually matches that of walking, so an operator can wind in a hose while he holds its nozzle off the ground.

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© 2002 by The American Society of Mechanical Engineers