US Patent 9340969 Crush zone dowel tube

A slip dowel tube and elongate dowel are disclosed herein which allow for transverse and longitudinal movement of two adjacent concrete slabs and also limit vertical movement of the two concrete slabs. The slip dowel tube is housed within a sheath that provides a void to allow for transverse movement of the slip dowel tube when the first and second slabs move transversely with respect to each other. The elongate dowel is slidably disposed within the main tube to allow for longitudinal movement or movement which brings the two slabs closer to or further away from each other. This system also limits vertical movement between the two adjacent slabs.