Regarding the RS-555SH-2670, I searched Google with
RS-555SH-2670 filetype:pdf, and got four useful results, including three that referred to that exact part number. The fourth was the one linked above, but it doesn't specify that it's the -2670.
- From Ignis: 24 V, 8 200 rev/min free, 0.14 N·m stall, 7.00 A stall, 0.16 A free => 7.56 W max. at 12 V.
- From Kinmore: 12 V, 4 500 rev/min free, 0.11 N·m stall, 4.40 A stall, 0.19 A free => 13.29 W max. at 12 V.
- From Globalsources: 12 V, 4 500 rev/min free, 0.11 N·m stall, 4.40 A stall, 0.19 A free => 13.29 W max. at 12 V.
- From Compucanjes (cited above): 24 V, 8 500 rev/min free, 0.23 N·m stall, 9.00 A stall, 0.18 A free => 12.52 W max. at 12 V.
The last ones are quite similar (once you convert them to 12 V), but the first is way off. (I don't think it has anything to do with the gearbox, since the torque values are not scaled as you'd expect if the gearbox were included.) I can't find a good reason to ignore the first set of data—which refers to this motor by number.
Maybe I'm missing something (so feel free to check my math). Either way, it appears that this isn't a very powerful motor.