Before the late 1960s or early 1970s, the Master pin tumbler laminated padlocks (“Secret Service” padlocks) only had one locking lever and locked only the toe of the shackle. In fact, the only Master padlocks before then that locked both the heel and toe of the shackle may have been the “Super” warded padlocks (nos. 905 through 908) made in the 1920s and ’30s (though the original box of this c. 1940s Master #510 padlock I have here interestingly says “A Convenient and Powerful Lock with Double Brass Lever Locking Both Sides of Adjustable Shackle”, even though the lock clearly locks only one side).
The patent for the double locking levers (no. 3,475,930) was filed Jan. 30, 1968, and issued Nov. 4, 1969. The first patent Dicey posted was filed Nov. 7, 1967, and issued Jan. 21, 1969. The second patent is a “division” of the first one, with an application date of Sep. 27, 1968 and issue date of Dec. 22, 1970; its drawing page is simply a redrawn version of the first one’s page. It’s not at all unlikely that the patent drawings simply matched the actual padlocks of the time with regard to having only one locking lever.
