Locking structure for a truck of a switchgear drawout circuit breaker

A method of locking a truck, carrying a circuit breaker, into a switchgear frame, the method comprising the steps of:

• providing the switchgear frame including rails, and at least one lock receiving opening in the frame,
• providing the truck carrying the circuit breaker, the truck having wheels;
• a racking screw;
• a racking screw nut in threaded engagement with the racking screw, the racking screw nut being constructed and arranged to float linearly with respect to the truck;
• a spring between a portion of the truck and the racking screw nut;
• and a locking structure coupled to the racking screw nut,
• rotating the racking screw to cause linear movement of the nut, with the nut pushing against the spring, with the spring pushing the truck to move the truck linearly along the wheels that roll on the rails, and
• stopping movement of the truck while continuing to rotate the racking screw so that the nut will move to compress the spring, causing the locking structure to move from an unlocked position, disengaged with the at least one lock receiving opening in the frame, to a locked position, engaged with the at least one lock receiving opening in the frame.