A modular gearbox design integrates gearing into a timing pulley for dynamic linear motion systems, including gantry robots, high-speed packaging machinery, and assembly automaton. These precision pulleys offer ratios up to 90:1 and provide high torsional stiffness and smooth, quiet operation.
Key to the design are two angular contact ball bearings located on either side of the pulley. Instead of supporting the belt in a cantilevered fashion, as in traditional designs, the balanced bearings provide even support from underneath. The Power Pulley reducer balances forces to the middle of the belt, so the moment load associated with traditional gearbox designs is eliminated, and only pure radial load is applied. Because they are located right beneath the belt, the bearings support up to three times more load than those on traditional pulleys, and resist shock and vibration. As a result, the bearings last longer.
With internal, hardened, ground gears, the Power Pulley provides low backlash, reduces inertia and saves space too, because the gearbox does not protrude from the machine as in systems with separate pulleys and gearboxes.
Vital stats
On display: Power Pulley reducers
Key feature: Two angular contact bearings centered in the pulley extend life and boost load capacity to three times that of traditional pulleys. Gears inside the pulley exceed traditional reduction ratios (on average, about 3:1) to hit 4:1 to 90:1.
What it means to you: Fewer components and smaller package size result in higher reliability and lower costs.
What else: Allow input speeds to 6,000 rpm; 12 arc/min. backlash; sealed to IP67 for washdown applications.
Innovator: Onvio LLC, Salem, N.H.
For more information: onviollc.com or (866) 685-0404.
Flexing their muscles
Pulleys can be provided for almost any pitch style. In addition, sprockets or wheel hubs are available upon request. Single or two-stage designs are easily interchangeable on linear actuators and gantry systems, and their universal servo interface allows quick connection to any servo or stepper motor.
Streamlining design
In designing its automated tray handling systems, Distech Systems Inc., Rochester, N.Y., needed two things — a simplified design and a compact package. Stacks of trays with components on them are moved on conveyors into its machine, where a robotic arm picks components out and feeds them to a machine tool, automation cell, or conveyor palletizing system. Distech's six-axis articulated robot has a small reach of just 650 mm. To extend this reach, it is mounted to yet another linear axis to drive it forward to the machine or conveyor area. This seventh axis was driven with a shaft-to-shaft inline planetary gear reducer. To maintain the compact design required of the machine, Distech had to sacrifice simplicity in its design — another belt and pulley gear train was added to move the drive system above the seventh axis.
According to Justin Heckert, mechanical engineer, “With the old design, we had to machine seven parts of the system ourselves, and then purchase another five.”
So to simplify the machine, the company switched to Onvio's Power Pulley reducer. Instead of machining extra parts and installing them, the Pulley reducer simply bolts onto the seventh axis. “This eliminates about four purchased parts and five machined details,” said Heckert. “The pulley reducer let us regain design simplicity, while maintaining a compact design.”
