They save the best for last, eh? Anyway the motors...
They're 12VDC, size 550 Duratrax Starter Motors (they're meant for starting internal-combustion engines in radio-controlled vehicles). 55o is the standard size used in electronic radio-controlled vehicles, so why not use them in a remotely-operated vehicle?
Anyway the motors draw up to 148 amps when stalled, and produce about .55 horsepower (this is roughly equivalent to the power output of the motors that the ROV originally came with-- ~380 watts each. Also, the Duratrax motors were the only ones small enough and with enough power to meet the requirements of our project [hence the outrageous stall current]).
Now, all motors have different face-patterns (the arrangement of the tapped holes in the front of the motor for mounting). To adapt the new face pattern to that machined into the motor housing--with tight tolerance to reduce vibration--I commissioned a quick-turn prototyping machine shop (emachineshop.com) to fabricate adapter plates from ~1/8 inch, 6061-T6 multipurpose aluminum alloy (for strength, weight, and--to some extent--cost).
That's about all there is to the motors (the physical bit at least).
Cheerio~
