Crown Equipment Corporation

Eric D Holbrook

Lucas B Waltz

Karl L Dammeyer

Darrin R Ihle

Marc A McClain

Marc A Mcclain

Lucas B Walt

A materials handling vehicle is provided comprising: a support structure including a first member; a movable assembly coupled to the support structure; a hydraulic system; and a control system. The support structure further comprises lift apparatus to effect movement of the movable assembly relative to the support structure first member. The lift apparatus includes at least one ram/cylinder assembly. The hydraulic system includes a motor, a pump coupled to the motor to supply a pressurized fluid to the at least one ram/cylinder assembly, and at least one electronically controlled valve associated with the ram/cylinder assembly. The control structure may estimate a speed of the movable assembly from a speed of the motor and may control the operation of the at least one valve using a comparison involving the estimated movable assembly speed and a determined speed, and the comparison may not involve use of an operator commanded speed.

Materials handling vehicle estimating a speed of a movable assembly from a lift motor speed

A materials handling vehicle is provided comprising: a support structure including a fixed member; a movable assembly coupled to the support structure; a hydraulic system; and a control system. The support structure further comprises lift apparatus to effect movement of the movable assembly relative to the support structure fixed member. The lift apparatus includes at least one ram/cylinder assembly. The hydraulic system includes a motor, a pump coupled to the motor to supply a pressurized fluid to the at least one ram/cylinder assembly, and at least one electronically controlled valve associated with the at least one ram/cylinder assembly. The control structure may estimate a speed of the movable assembly from a speed of the motor and control the operation of the at least one valve using the estimated movable assembly speed.

Materials handling vehicle monitoring a pressure of hydraulic fluid within a hydraulic structure

A materials handling vehicle is provided comprising: a support structure including a fixed member; a movable assembly coupled to the support structure; a hydraulic system; and a control system. The support structure further comprises lift apparatus to effect movement of the movable assembly relative to the support structure fixed member. The lift apparatus includes at least one ram/cylinder assembly. The hydraulic system includes a motor, a pump coupled to the motor to supply a pressurized fluid to the at least one ram/cylinder assembly, and at least one electronically controlled valve associated with the at least one ram/cylinder assembly. The control structure may measure an electric current flow into and/or out of the hydraulic system motor and reduce an operating speed of the hydraulic system motor if the electric current flow into and/or out of the hydraulic system motor is greater than or equal to a predetermined threshold value.

Materials handling vehicle measuring electric current flow into/out of a hydraulic system motor

A materials handling vehicle is provided including: a support structure including a fixed member; a movable assembly coupled to the support structure; a hydraulic system; and a control system. The support structure further includes lift apparatus to effect movement of the movable assembly relative to the support structure fixed member. The lift apparatus includes at least one ram/cylinder assembly. The hydraulic system includes a motor, a pump coupled to the motor to supply a pressurized fluid to the at least one ram/cylinder assembly, and at least one electronically controlled valve associated with the at least one ram/cylinder assembly. The control structure may estimate a speed of the movable assembly from a speed of the motor and calculate an updated pump volumetric efficiency using the estimated movable assembly speed and a determined movable assembly speed.

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Findlay, OH, United States of America

Eric D Holbrook