Abstract: A trailer door fastener includes a T-nut and a bolt. The T-nut includes a large washer face with a hollow cylinder extending coaxially from and perpendicular to the washer face. The hollow cylinder contains internal threads running the entire length of the hollow cylinder. The bolt includes a large head with a shank extending coaxially from and perpendicular to the head. On the shank adjacent the head is a knurled portion with grooves running parallel to the axis of the shank. The remainder of the shank has external threads running from the end of the knurled portion opposite the head to the end of the shank opposite the head. The bolt is inserted through aligned holes in the hinge plate and the door panel from the outside of the trailer such that the knurled portion traverses the interface between the hinge plate and door panel. This provides a greater surface area on the bolt to withstand shear forces at the interface.

Abstract: A self-tapping screw fastener includes a shank having first and second ends and a head disposed at the second end of the shank. The shank has a tapered portion of a predetermined axial length adjacent the first end, and the tapered portion terminates at the first end in a substantially circular end surface having a first diameter. The shank also has a substantially cylindrical portion having a second diameter extending from the second end to the tapered portion. A thread extends helically along a circumferential outer surface of the shank from a location near the head substantially to the first end such that the thread at least partially covers the cylindrical and tapered portions of the shank. The ratio of the axial length of the tapered portion to the diameter of the end surface exceeds substantially 1.5, and the diameter of the end surface is less than but substantially equal to the diameter of the cylindrical portion of the shank.