Patent ID: 8127890

Claim:
A step unit comprising a top step, a bottom step, right and left step frames arranged to lie in spaced-apart relation to one another to locate the top and bottom steps therebetween and mounted to each of the top and bottom steps for movement between a flat-fold shipping position and an unfolded use position, the right step frame includes a front riser pivotably coupled to each of the top and bottom steps and a step-support linkage including a rear step mount pivotably coupled to each of the top and bottom steps, a rear riser pivotably coupled to the rear step mount, and a horizontal expander pivotably coupled to the rear step mount, wherein the horizontal expander includes a horizontal leg that is pivotably coupled to the front riser, matingly connected to the rear riser, and pivotably coupled to the rear step mount and is arranged to extend between the front and rear risers upon movement of the right step frame to assume the unfolded use position and the rear step mount is positioned to lie between the front step mount and the horizontal leg of the horizontal expander upon movement of the right step frame to assume the flat-fold shipping position, and wherein the horizontal expander further includes a hinge unit mounted on the horizontal leg to move therewith and is pivotably coupled directly to the rear step mount.