Assignee: Master Lock Company, Milwaukee, WI
https://patents.google.com/patent/US4730467A/
I've been curious about Master Lock's higher-end version of the ubiquitous 1500 combination lock. (Gordon, did you ever get yours open?)
Master Lock models 2001/2002/2010 have combination mechanisms that are essentially safe locks, where the fence stays in contact with the wheel pack. For strength, ball bearings secure the shackle, and to open, the combination mechanism slides a piece with a cutout the center bearing slips into, allowing the shackle to be pulled out. The patent presumably most closely resembles the 2010 model, which has a key override. I believe the 2010 may be the only model still being produced?
I couldn't find much about this lock in open locksport circles, but there is a fun early '00s promotional video
(mechanism shown briefly at 1:57,) and a short training video, where you can see how the dialing procedure differs based on the safe-like construction and upset spring.------------
Excerpts from the patent documents:
