Double spring bolt re-keyable padlock

Claim 1

In a lock construction, the combination comprising: a. a lock body having a pair of spaced apart longitudinal bores extended into the top end of said body; b. a shackle member having a pair of shackle legs slidably mounted in said bores; c. said body being provided with a transverse slot communicating at its ends with said bores and in which is slidably mounted a pair of latch members; d. each of said shackle legs being provided with recesses on either end thereof for the reception of one of said latch members; e. means for normally biasing said latch members outwardly into locking engagement with the recesses in said shackle legs for holding the shackle in a locked position; f. an elongated chamber formed in the lower end of the body and being open at the outer end thereof; g. a key plug rotatably mounted in said chamber and being rotatable between locked, unlocked, and removal positions, and being provided with a longitudinal keyway and a transverse peripheral slot on the inner end thereof which communicates at one end with the longitudinal keyway; h. said key plug having an inner cam end engageable with said latch members for camming them to an unlocked position free of said shackle legs against the action of said biasing means when the key plug is turned to the unlocked position; i. a plurality of longitudinally aligned, spring biased outer tumbler pins mounted in said body in spaced bores communicating with said chamber; j. a plurality of inner tumbler pins mounted in said key plug in spaced bores which are aligned with the bores in said body when the key plug is rotated to the locked position; k. a fixed retainer pin mounted in said body and having the inner end thereof extended into the peripheral slot in said key plug to prevent longitudinal movement of the key plug to normally retain the same in the body, and to limit the normal rotative movement of the key plug between the locked position and the unlocked position by engagement with a key in the key plug keyway when the key plug is turned to the unlocked position and by engagement with the other end of the peripheral slot when the key plug is turned to the locked position; l. a longitudinal slot in said key plug which is open at the inner end thereof and which communicates with said keyway and peripheral slot for passage therethrough of said retainer pin from said peripheral slot to permit longitudinal movement of the key plug and removal of the key plug from said chamber when said key plug is turned by a key in said keyway which has the inner end notched to permit the retainer pin to pass into the longitudinal slot, to permit replacing said inner tumbler pins to change the key combination of the lock construction; m. passageway means in said lock construction, and including said latch members, for the reception of means capable of retaining the outer tumbler pins in their respective bores in the body when the key plug has been removed and for retaining said latch members in the unlocked position; and, n. the passageway means in the latch members comprises a semicircular recess in each of said latch members which are moved to an aligned position to form a cylindrical passage when the latch members are cammed to the unlocked position.