Manitowoc Crane Companies, Inc.

Vacon Oyj

Todd Snider

John Fremont Benton

David R Peiffer

Mark A Harbold

Andreas Doktar

William Giewont

A hydraulic circuit for use on a construction machine includes a first valve, a second valve, and at least a third valve. The second and third valve each includes at least one inlet port connected to a first outlet port of the first valve. The first outlet port of each of the second and third valves are configured to reduce a first pressure to a second pressure and/or a third pressure downstream of the second valve and the third valve, respectively. The second valve and the third valve also include at least a second outlet port connected to a reservoir tank. A hydraulic motor is connected to the first outlet port of the second valve, which operates the hydraulic motor in a first direction. The hydraulic motor also is connected to the first outlet port of the third valve, which operates the hydraulic motor in a second direction.

Electronically controlled hydraulic swing system

A piston type compressor wherein the position of the piston highest pressure point is indicated and the rotor of the motor at the optimal starting angle aligned prior to the actual compression operation by providing a pre-pulse to rotate the rotor of the motor at least one full rotation at a certain frequency, during rotation measuring the load torque by the frequency converter as well as indicating the maximum load torque point and at the end aligning the rotor of the motor at the optimal starting angle of about 180&#xb0; from the maximum pressure angle, and at the beginning of the actual compression operation setting the rotor position opposite to the maximum torque angle by feeding direct current to the stator winding and starting the motor by supplying maximum motor current to the motor to give the maximum torque and acceleration.

Compressor starting method and apparatus

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Fort Loudon, PA, United States of America

Todd Snider