Caterpillar Inc.

David R Orr

Scott F Shafer

Steven Francis Meister

Thomas S Carroll

J Roger Weber

The present invention is an apparatus 10 for hydraulically slowing a member (12), preferably an engine poppet valve, to an acceptable impact seating velocity as the valve (12) is moved from open to closed. The poppet valve (12) has a stem (16) having a first portion (18) connected through a stepped portion (20) to a second portion (22) having a greater cross-sectional area than the first portion (18). The valve (12) rides within a guide body (28) having an opening (34) in an end wall (32) thereof through which the first portion (18) of the stem (16) extends. A hydraulic fluid space (50) is formed by the guide body (28) and the valve (12). As the valve (12) closes, fluid is forced out of the space (50) through a first fluid exit opening (66). As the valve (12) nears its seat (44), the fluid still in the space (50) is forced out through a second fluid exit opening (68) through which the rate of flow is less than the rate of flow through the first fluid exit opening (66). As the valve (12) continues closing, fluid still in the space (50) is compressed, increasing its hydraulic pressure and creating a resistive force to further movement of the poppet valve (12), thereby slowing it to an acceptable impact velocity.

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Pekin, IL, United States of America

David R Orr