Patents Assigned to Liebherr Mining Equipment Company
  • Patent number: 9151304
    Abstract: A cushion arrangement for smoothing stage changes in an hydraulic cylinder and including at least one compression chamber of variable volume with a movable and/or deformable chamber wall element displaceable by at least one of the pistons when approaching the transition zone between first and second stages of displacement. The compression chamber is operatively connected to a gas volume to be compressed upon displacement of the chamber wall element.
    Type: Grant
    Filed: March 14, 2012
    Date of Patent: October 6, 2015
    Assignee: Liebherr-Mining Equipment Company
    Inventors: Bryan Michael Harper, James Arthur Whitfield, Jr.
  • Patent number: 8930052
    Abstract: The present invention relates to a method and an apparatus for controlling the drive system for mobile equipment, when the operator's drive commander is kept constant, electric traction motors are controlled by a torque controller to provide uniform torque, deviations in speeds of the electric traction motors are determined and electric motor power of at least one is varied relatively to the electric motor power of the other in response to a determined deviation in speed to keep the torques uniform. The power control balancing compensates for the torque differences previously encountered when the speeds of the traction motors differ at equal power supplied to the traction motors.
    Type: Grant
    Filed: November 22, 2011
    Date of Patent: January 6, 2015
    Assignee: Liebherr Mining Equipment Company
    Inventor: James A. Whitfield
  • Publication number: 20120255432
    Abstract: A cushion arrangement for smoothing stage changes in an hydraulic cylinder and including at least one compression chamber of variable volume with a movable and/or deformable chamber wall element displaceable by at least one of the pistons when approaching the transition zone between first and second stages of displacement. The compression chamber is operatively connected to a gas volume to be compressed upon displacement of the chamber wall element.
    Type: Application
    Filed: March 14, 2012
    Publication date: October 11, 2012
    Applicant: Liebherr-Mining Equipment Company
    Inventors: Bryan Michael Harper, James Arthur Whitfield, JR.
  • Publication number: 20120130578
    Abstract: The present invention relates to a method and an apparatus for controlling the drive system for mobile equipment, when the operator's drive commander is kept constant, electric traction motors are controlled by a torque controller to provide uniform torque, deviations in speeds of the electric traction motors are determined and electric motor power of at least one is varied relatively to the electric motor power of the other in response to a determined deviation in speed to keep the torques uniform. The power control balancing compensates for the torque differences previously encountered when the speeds of the traction motors differ at equal power supplied to the traction motors.
    Type: Application
    Filed: November 22, 2011
    Publication date: May 24, 2012
    Applicant: Liebherr Mining Equipment Company
    Inventor: James A. Whitfield