Caterpillar Inc.

Timothy L Cooper

Kenneth J Chlad

Ronald W Clutter

Charles A Robinson

James Ivan Portscheller

Xiaojun Zhang

Naga Raja Rao Mosam

Michael Lee Ferguson, Jr

A method for operating an electromagnetic lift that includes a generator-driven electromagnet comprises adjusting a position of the electromagnet, in response to a first position command. Upon receiving a lift command, an output power level of a generator is established at a predetermined level above a predefined normal power level. In response to an excess release command, the output power level is set to a first predetermined level below the normal power level. In response to a transport command, the output power level is established as approximately the normal power level. Upon receiving a release command, the output power level is established at a second predetermined level below the normal power level.

System and method for controlling electromagnet lift power for material handlers

A method for protecting against current overload conditions associated with an electromagnetic lift system comprises receiving current data from a current monitoring device associated with an electromagnetic lift system. The method also includes determining a current level based on the collected current data, and identifying a predetermined overload range corresponding to the current level if the current level exceeds an overload current threshold. The method also includes monitoring a time that the current level is within the predetermined overload range, and providing a command signal to an actuator associated with the electromagnetic lift system if the time that the current level is within the predetermined overload range exceeds a predetermined time limit. The command signal causes the actuator to substantially limit mechanical power provided to a generator associated with the electromagnetic lift system.

Overload protection system for an electromagnetic lift

A wheeled carrier adaptable for use with material handling equipment comprises a main body and first and second frames adjustably connected to the main body portion. Wheel assemblies are connected to the frames. The width of the carrier is adjustable so the carrier can be easily transported yet provide sufficient stability when used in material handling applications.

Rubber tired carrier

An apparatus and method for controlling a lifting magnet (12) of a materials handling machine (10) to eliminate arcing between contacts (70-80) within the magnet controller (26) as is well as is large voltage spikes. The controller (26) selectively excites the shunt field windings (66,68) of a direct current generator (22). The magnitude and direction of the current passing through the shunt field windings (66,68) is varied by the magnet controller (26) to control the magnitude and polarity of the voltage at the generator output (23). The armature (60) of the generator (22) is rotatably driven by a hydraulic motor at an essentially constant speed to minimize voltage variations at the output (23) of the generator (22). At least the drop cycle is controlled through use of a current transducer (200) that senses current flowing to the lifting magnet so that the electronic controller is able to control the flow of current to the lifting magnet based upon the sensed current in the magnet circuit.

Method and apparatus for controlling a lifting magnet of a materials

A hydraulic circuit (124) is defined in a manifold (130) which may be aluminum, steel, or any other suitable material. The circuit (124) regulates the flow of hydraulic fluid to the hydraulic motor (120) and thus ensures that the motor rotates at an essentially constant speed, independent of the speed of the hydraulic pump (122) supplying the circuit. The circuit includes a pressure compensated flow control valve assembly (140) with an adjustable flow control valve (142) that regulates the flow of hydraulic fluid to the motor (120). The assembly (140) also includes a balanced piston-type pressure compensator (144) that ensures a select pressure differential across the flow control valve (142) such that the flow through the valve (142) remains at least essentially constant. This constant flow through the pressure compensated flow control valve assembly (140) ensures an essentially constant rotational speed of the motor (120). A surge suppression/protection normally closed solenoid operated valve (180) is provided to prevent undesirable surges of hydraulic fluid during start-up of the motor.

Method and apparatus for controlling the flow of hydraulic fluid

An apparatus and method for controlling a lifting magnet (12) of a materials handling machine (10) to eliminate arcing between contacts (70-80) within the magnet controller (26) as well as large voltage spikes. The controller (26) selectively excites the shunt field windings (66,68) of a direct current generator (22). The magnitude and direction of the current passing through the shunt field windings (66,68) is varied by the magnet controller (26) to control the magnitude and polarity of the voltage at the generator output (23). The armature (60) of the generator (22) is rotatably driven by a hydraulic motor at an essentially constant speed to minimize voltage variations at the output (23) of the generator (22). The magnet controller (26) includes a programmable logic controller (40) which selectively opens and closes the contactors (70-80) within the controller (26). The programmable logic controller 40 is also connected to indicator lamps (L1-L5) within the operator's cab (14) of the materials handling machine (10), and selectively illuminates the lamps (L1-L5) to provide an operator of the apparatus with information regarding the status of the magnet control system (27) including the controller (26). A drop time adjustment control (81) is also positioned in the operator's cab (14) and operable to vary the drop time of the magnet controller (26).

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Marion, OH, United States of America

Timothy L Cooper