US Patent 7721904 Hydraulic tank access cover with self-centering and anti-rotation device

A hydraulic access cover assembly for a hydraulic reservoir tank that provides a self-centering and anti-rotation feature for quick and positive sealing of the tank. Tabs located on the inner cover interlock with tabs incorporated into the tank access hole to provide the self-centering and anti-rotation features. This system eliminates the need to weld anything to the tank, which eliminates a potential contamination source of the hydraulics.