Motion System Design
Better by Design: Planetary gear unit packs a punch

Better by Design: Planetary gear unit packs a punch

For applications with inflexible torque demand, sometimes designers specify oversized and less efficient gearsets. Other times, manufacturing engineers sacrifice torque in their designs to minimize gearhead size.

To eliminate both of these compromises and make efficient gearboxes with higher torque density, STOBER Drives Inc., Maysville, Ky., recently introduced the PHQ planetary gear unit. It features helical-cut gears (to carry higher loads than spur gears) and four planet gears for output of up to 88,500 in.-lb. from the largest version.

Because the PHQ is part of the company's ServoFit line, it is supplied with a TriAdapt motor coupling, which features a triple-split collet connection. This coupling fits all motor shafts (including IEC, NEMA, and customized geometries) without requiring a key; it allows motor installation in minutes (without special tools) and thermal expansion of the motor shaft, to prevent thrust load on the motor bearings — and extend motor life. The PHQ also includes a motor plate to fit specific motors, toleranced to improve concentricity.


On display: PHQ planetary gear unit

Key features: Boosts torque up to 35% while extending life and maintaining up to 93% efficiency.

What it means to you: Compact gear unit allows for smaller and more efficient designs

What else: PHQ backlash is less than or equal to 3 arc/min. and a PHQA version reduces backlash to less than 1 arc/min. The design increases torsional rigidity up to 80% for fewer positioning errors under load and better vibration behavior. Ratios range from 18:1 to 600:1; peak input speed is up to 7,000 rpm; noise with a 3,000-rpm input is as low as 62 dB(A). The unit is suitable for machine tool manufacturing, material handling, robotics, injection molding, and tube bending.

Innovator: STOBER Drives Inc.
(606) 759-5090

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