Legality of purchasing Planetary Gearboxes from alternative sources.

[GeeTwo]

Originally Posted by pilleya

For teams wanting to do this or something similiar, make sure you only use the low-power RS775-125 that Andymark sells. If you try to hook up a 775pro or 775-18 it is not going to end well for you. Andymark says on their website that if the pg27 with a 9015 is stalled then the gearbox will break. So even a reduction as low as probably 10-15ish:1 with a decent 775 will cause failure of the gearbox. In comparison the Versa-Planetary is rated up to 210:1 for the 775pro. So the gearbox can only handle 1/20th of the torque.

Check that again:

Originally Posted by PG27 web page on AndyMark

Performance Specs:

• Gearbox Reduction: 26.9:1
• Voltage: 12 volt DC
• Dyno Tested No Load Free Speed: 512.4 rpm
• No Load Current: 1.2 amps
• Gearbox Output Power: XX Watts
• Dyno Tested Stall Torque: 3.55 ft-lbf
• Stall Current: 63 amps
• Minimum torque needed to back drive a non-powered PG27: 0.3ft-lbs
• Maximum torque applied at shaft which breaks gearbox: 39 ft-lbs (breakage point is shearing of shaft)

There's another factor of ten in torque before breakage. Using the PG-188 with a higher torque motor is certainly subject to a sheared shaft, as stall torque with the 9015 motor is listed as 33 ft-lb, on the same output shaft.