Servo - December 2013

SERVO 12.2013 27

light enough for use in a 12 lb robot. The 8 mm shaft may be somewhat awkward to deal with; with that small of a shaft, it would be wise to either protect the wheel from shock or add an outer support bushing/bearing to distribute the load.

PDXNN Gearmotor/BaneBots P60 Gearbox

Dimensions: 1.5 inches square, 4. 16 inches long

Nominal Voltage: 12V

RPM: 1,500 for 16:1;

900 for 26:1

Stall Torque: 91 in-lbs for 16:1; 145 in-lbs for

26:1

Stall Current: 148A

Shaft: 1/2 inch diameter with keyway, 1.5 inch long Weight: 15. 9-16.05 oz

Cost: $79.99-$84.99

Comments: Robot Marketplace sells an assembled version of the BaneBots P60 gearbox called the PDXNN, with NN being the ratio. Of the options, 16:1 and 26:1 are the most practical. BaneBots offers quite a few more ratios through their website. These gearmotors are a staple of the 12 lb class. They're not particularly expensive, are easy to use, and are reasonably durable. Three versions of the gearbox exist with each designed for a different common size brushed DC motor. If you take care to protect the shaft and wheels, these gearmotors are a solid option for the 12 lb class; if four or more are used, they’re at least an option for the 30 lb class, though in that situation extra effort must be put into shaft protection. The addition of a shaft support is recommended.

Robot Power Magnum 775

Dimensions:

1.75 inches square,

4.92 inches long

Nominal Voltage:

14.4V

RPM: 720

Stall Torque:

156.25 in-lbs

Stall Current: 140A

Shaft: 1/2 inch diameter with keyway, three inches long Weight: 28 oz

Cost: $89.99

Comments: The Magnum 775 is the next step up from the P60. This gearbox is designed to work with an RS775 motor which is the largest option for the P60 gearbox.

With a larger planetary gearbox and shaft supported by a dual bearing arrangement, this gearbox is a solid option for the 30 lb class. In a high shock environment, a motor support plate like the one shown in the photo is recommended; however, it may not be needed for all applications. This is the largest currently available gearmotor solution that could reasonably be wedged into a 12 lb robot.

Equals Zero Designs DeWut?!

Dimensions:

2. 5 inches square,

6.1 inches long

Nominal Voltage: 18V

RPM: 450, 1,450,

2,000 selectable

Stall Torque:

162.4 in-lbs estimated, middle gearing

Stall Current: 155A

Shaft: 1/2 inches diameter with keyway, three inches long

Weight: 2. 9 lbs with three inch shaft

Cost: $190 (assembled)

Comments: The De Wut?! from Equals Zero Designs is an attempt to create a replacement for the no longer available Team Delta power drive kit. Due to the size and weight, the De Wut?! is primarily an option for the 30 lb class. The three selectable gear ratios ( 51.2:1, 17.1:1, and 12.8:1) mean you have a solid range of speed options for most practical wheel sizes. These gearmotors are well designed, durable, and easy to use. Two De Wut?!s will provide plenty of power for a 30 lb robot, though if you want even more there have been competitive 30 lb robots made using four DeWut?!s.

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Product Spectrum:

Wheels for Bots 30 lbs and Under

When building a robot, there is a wide range of wheel options to choose from. All of the wheels presented here are meant to be ready or nearly ready to go solutions that are practical to use on robots weighing