Systems, methods and apparatuses for wireless power transfer are disclosed. In one aspect, a wireless power transfer apparatus is provided comprising a casing with at least one projecting member projecting from an inner side of the surface of the casing that is subject to external compression forces. An induction coil and other components such as insulating layers and magnetically permeable members are positioned around at least one of the projecting members and maintained in position by the projecting members. The wireless power transfer apparatus is able to withstand large compressive forces, such as those imparted by heavy vehicles and the like passing over the apparatus when positioned on the ground in a wireless power transfer system.