Locking device for shopping carts

Claim 1

IN A SHOPPING CART OF THE NESTING TYPE INCLUDING A WHEELED FRAME AND A BASKET SUPPORTED BY SAID FRAME, A DEVICE FOR READY ATTACHMENT TO THE UNDERSIDE OF SAID CART, SAID DEVICE COMPRISING: AN AUXILIARY WHEEL PIVOTABLY SUPPORTED BY SAID DEVICE, SAID AUXILIARY WHEEL BEING PIVOTALLY MOVABLE IN RESPONSE TO ITS OWN WEIGHT FROM A FIRST POSITION IN WHICH THE LOWERMOST SURFACE OF SAID AUXILIARY WHEEL LIES SUBSTANTIALLY WITHIN THE PLANE TANGENT TO THE LOWERMOST SURFACES OF THE CART WHEELS TO A SECOND POSITION A PREDETERMINED DISTANCE BELOW SAID FIRST POSITION; AND A LOCKMOUNTING SAID AUXILIARY WHEEL FOR ROTATION; AND A LOCKING MECHANISM ASSOCIATED WITH SAID AUXILIARY WHEEL FOR SELECTIVELY LOCKING SAID AUXILIARY WHEEL AGAINST ROTATION WHEN SAID AUXILIARY WHEEL IS IN SAID SECOND POSITION, SAID LOCKING MECHANISM INCLUDING A DISC MOUNTED ON THE MEANS MOUNTING SAID AUXILIARY WHEEL, SAID DISC DEFINING A PLURALITY OF PERIPHERAL SLOTS THEREIN, A SPRING BIASED LEVER ARM PIVOTALLY MOUNTED TO SAID DEVICE AND NORMALLY URGED TOWARD SAID DISC FOR ENGAGEMENT IN ONE OF THE END SLOTS, AND MEANS FOR PREVENTING SAID LEVER ARM FROM ENTERING ONE OF SAID SLOT UNLESS SAID AUXILIARY WHEEL IS IN SAID SECOND POSITION.