Abstract: A pull out step assembly is provided to assist in climbing into or out of a cab of a crane, excavator or similar vehicle. The step assembly includes a pair of brackets carrying forward and rearward rollers and a step having support guides for embracing the rollers to prevent the step from shifting laterally during use. A locking mechanism positively secures the step in place in both the extended and retracted positions. The locking mechanism includes an operating shaft having a pivotal handle positioned below the step for easy access and a dual crank. The crank receives the ends of a pair of reciprocal locking rods that extend transversely to engage corresponding pairs of forward and rearward slots formed in the brackets. A compression spring supplies a biasing force to keep the rods engaged in the slots. To shift the step, the handle is manually rotated either clockwise or counterclockwise to overcome the biasing force and disengage the rods from the respective slots.