Abstract: The present invention describes a filter screen for removing debris from the hydraulic actuating fluid in an internal combustion engine having a hydraulic pump for supplying hydraulic actuating fluid to hydraulically-actuated unit fuel injectors. An upper portion of a priming reservoir is mounted on a front cover of the engine. The front cover forms a lower reservoir portion. A screen assembly is positioned adjacent to an interface defining an entrance from the upper reservoir portion to the lower reservoir portion. The screen assembly includes a filter screen enclosing the entrance to force the actuating fluid to pass through the filter screen, thus retaining debris that exceed the mesh size of the filter screen.

Abstract: The present invention describes a filter gasket (50) for removing debris from the hydraulic fluid in an internal combustion engine (10). An upper reservoir structure (30) is mounted on a front cover (14) of the engine (10) at interface (46). The front cover forms a lower reservoir (16). The upper reservoir structure (30) forms an upper reservoir (35). A gasket (42) is disposed along the interface (46) to seal the upper reservoir structure (30) to the front cover (14). A screen assembly (70) is positioned adjacent to the interface (46). The screen assembly (70) includes a filter screen (76) connected to a plate member (56). The plate member (56) operatively engages the gasket (42). The plate member (56) forces hydraulic fluid to pass through the filter screen (76), thus retaining debris that exceed the mesh size of the filter screen (76).