Bucyrus International Inc.

Michael Haws

Carl Delbert Gilmore

Michael G Onsager

Matthew Brueck

Jeanne M Yaunke

Timothy R Kerrigan

A crowd control mechanism for a power shovel includes an extendible dipper handle having an extended position and a retracted position. A double acting hydraulic cylinder having a an extendible ram has one of the cylinder and the ram fixed to the dipper handle and the other of the cylinder and the ram is stationary relative to the dipper handle. At least one of the cylinder and the ram have at least one of a blind end port and a rod end port, and at least one of the cylinder and the ram have the other of the blind end port and the rod end port, wherein hydraulic fluid flowing into the cylinder through the blind end port urges the ram toward an extended position to extend the dipper handle, and hydraulic fluid flowing into the rod end port urges the ram toward a retracted position to retract the dipper handle. Hydraulic fluid flowing into and out of the cylinder is controlled by one or more pilot operated poppet valves. A spool valve is disposed in a pilot line controlling at least one of the pilot operated poppet valves, and the spool valve controls the flow of fluid into the pilot line to control the at least one pilot operated poppet valve as opposed to a spool valve directly controlling the flow of hydraulic fluid into and out of the cylinder.

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Racine, WI, United States of America

Michael Haws