Robot Power GB42 mounted to Mini-EV motor The Robot Power GB42 is a robust low-cost planetary gearbox kit which includes the gearbox, mounting screws and motor pinion for a series of DC motors. The first motor supported (pictured here) is the 400-700W surplus Johnson "Mini-EV" motor. Gearbox Features Size: 42mm dia. x 50.5mm (1.66" x 1.97") Gear Ratio: 16:1 2-stage planetary Gears: machined steel Motor Pinion: 5mm bore - 15 tooth Output Shaft: 0.50" dia. x 3.0" long with standard 1/8" keyway Output Bearings: dual ball bearings Weight: 380g (13.4oz) without motor Kit Contents GB42 gearbox 5mm bore pinion gear Four M5 x 12mm gearbox to motor mounting bolts Printed assembly instructions Performance with Johnson "Mini-EV" motor (motor not included in kit) Motor Speed: 18000 RPM no load at 12V Output Speed: at 16:1 ~900 RPM at 12V No Load Current: 6A at 12V Stall current: 140A at 12V Peak Ouput Power: 400W at 12V (880W at 18V) motor spec Peak Efficiency: ~65% motor spec not including gearbox Motor Information: May be found here and here (see Tools, Torque/AH Calculator and Mini-EV motor) Motor Purchase: The Mini-EV motor may be purchased here and here GB42 Kit Details The GB42 includes a planetary gearbox with a 16:1. A massive steel ring gear supports the steel planet gears riding on hardened steel pins. The 3" long 0.5" diameter output shaft is supported by dual high-quality ball bearings. GB42 disassembled view The GB42 is mounted to the motor by four M5 x 12mm hex head bolts. GB42 mounting ring and motor pinion pressed onto motor shaft Assembly to the Mini-EV motor is very simple and requires only trimming 3mm off the motor shaft and pressing the provided pinion onto the motor. The gearbox to motor mounting ring then bolts right onto the motor face for a strong secure mount. The GB42 Mini-EV assembly guide is available for download. Shaft end view of the GB42 showing M4 mounting holes The GB42 may be mounted to the target application via 4 - M4 mounting bolts to the face of the gearbox. These are located in a 36mm bolt circle. A clamp style mount may also be used around the gearbox and/or the motor can. If the gearbox is mounted securely it is not necessary to support the motor can but for high-vibration or shock applications supporting the motor along with the gearbox is recommended. Robot Power offers the the GB42 kit with all the parts needed to mount the gearbox to the motor. Check the Web store for details on prices and special offers. Back to top