Combination spring/dead bolt lock

Abstract From the Canadian patent

One part of a key-in-knob lock set functions in a normal manner such that when the lock set is unlocked either the outside or inside knob can be manipulated to open the door by withdrawing the latch bolt from a normal spring latch extended position. When, instead the lock set is locked, the latch bolt is extended an exceptionally long distance into the frame to a dead bolt position. Extension and retraction of the latch bolt to and from dead bolt position is accomplished by manipulation of a main cam through the agency of a key in the outside operating member or an inside operating member.