US Patent 7628047 Compound lock

A compound lock has a common housing, a latch assembly, a supplementary lock and a combination lock. The latch assembly is rotatably attached to and protrudes from the common housing. The combination lock and supplementary lock are mounted in the common housing and engage the latch assembly, and either may rotate the latch assembly. Thus, in general, people may unlock the compound lock using either the combination lock or the supplementary lock with a key when the combination is forgotten without breaking the compound lock.