Retractable and extendable hand truck base plate assembly with a securing and releasing mechanism

A hand truck comprising:

• a hand truck frame that is supported by a set of wheels that are mounted at least indirectly to the lower end of the hand truck frame for rotation about a wheel axis, the hand truck frame including members which are arranged in a plane to present a flat structure for supporting loads,
• a frame bracket mounted at the lower end of the frame that presents a flat surface that is parallel to the plane of the hand truck frame,
• a base plate having an upper surface and a lower surface, the base plate being mounted to the lower end of the hand truck frame so that it is able to rotate with respect to the hand truck frame between a retracted position and an extended position suitable for supporting loads, such rotation of the base plate being about an axis that is parallel to the wheel axis,
• at least one base plate bracket that is fixed to the base plate, the base plate bracket presenting an upwardly extending finger portion which presents a distal end, the finger portion being arranged to come into arresting contact with the flat surface of the frame bracket when the base plate is in the extended position, and,
• a lock and release member that is mounted at least indirectly to the hand truck frame for rotation about an axis that is at least parallel to the wheel axis, the lock and release member being arranged to rotate between an open position and a closed position, the lock and release member also being biased to rotate toward the closed position, the lock and release member having an exterior surface that is shaped so that upper end of the upwardly extending finger portion of the at least one base plate bracket is secured between the exterior surface of the lock and release member and the flat surface of the frame bracket when the base plate is in the extended position and the lock and release member is in the closed position, the exterior surface of the lock and release member also being arranged such that if the base plate bracket is secured between the exterior surface of the lock and release member and the flat surface of the frame bracket, the lock and release member being able to be rotated against its bias toward the open position in order to permit rotation of the base plate from the extended position to the retracted position, and such that when the base plate is in the retracted position, rotation of the base plate toward the closed position will cause the distal end of the finger portion of base plate bracket to press upon the exterior surface of the lock and release member thereby urging the lock and release member to rotate away from the closed position such that the finger portion of the base plate bracket is able to swing into contact with the frame bracket as the lock and release member being biased toward the closed position rotates into the closed position thus capturing the finger portion of the base plate bracket thereby securing the base plate bracket and thus also the base plate in the extended position suitable for carrying loads.