Attention robotics boffins: Here's a nice, powerful 12-24VDC Mabuchi brush motor with a gearbox and pulley attached. At its nominal 24DC, it spins 45rpm, draws 280mA no load, and stalls a 750mA. 7.5 in-lbs of torque and is rated for continuous duty. Has a 3/4" long x 5/16" flattened shaft with a 4-5/8" dia x 5/16" wide (3/16" ID) single-sheave pulley attached, with a matching O-ring. The gearbox measures 2-3/4" x 3" x 9-1/16". The motor measures 1-1/16"dia x 1-5/8" long and comes with 7" leads and a 2-pin Molex connector.

This torquey take-out 6-24VDC (12VDC nominal) motor draws approx 250mA no load, stalls at 7.2A and spins approx 5700 rpm. Measures 2" x 1-13/32" with a 3/4" x 1/8" flattened shaft and may have a setscrew-mounted coupler that resembles a router bit. Has prewired leads. Mabuchi part no. RS-545SH.

Our motorman, CJ, called this reversible 12-24VDC motor strange, mostly because it has the power contacts mounted on the face, bracketing the 11/16" x 1/8" mostly striated shaft, and has no mounting brackets. But that shouldn't stop a clever person like you. (Hint: it was probably made to fit into a sleeve of some sort.) At 12VDC, draws 100mA no load, stalls 850mA and spins approx 900 rpm; at 24VDC, draws 150mA, stalls 2.2A and spins approx 1800 rpm.  Measures 2-1/4" x 1-13/32" dia.

Great little 6-12VDC reversible motor draws 1.6A, spins approx 6000 rpm no load and stalls at over 10A. Measures 2-1/4" long x 1-7/16" dia with a 5/16" long x 1/8" dia shaft, 5/32" power terminals and 3/32" mounting holes on the shaft side.

This beefy little gear motor from Ametek® is nominally rated for 24VDC, draws 160mA no load and stalls at 5.7A. Measures 3-7/8" long x 2" dia at the gearbox and has a 9" long actuator shaft with a ACME 3/8" - 8  (Right Angle) thread. (Nuts available here) Spins approx 1325 rpm. Also operates on 12VDC for 130mA/2.25A/450rpm. Plenty of torque: motor is rated for 5.165 oz/in, not counting the gearbox. Has 17" leads.