Patents Assigned to NPK Construction Equipment, Inc.
  • Slow start control for a hydraulic hammer
    Patent number: 6491114
    Abstract: A control system for a heavy duty hydraulic hammer reduces blank firing of the hammer. The control system provides a reduced flow of hydraulic fluid to the hammer for a selected period of time upon actuation of the hammer and then provides full hydraulic flow increasing the frequency of impacts to full rated values.
    Type: Grant
    Filed: October 3, 2000
    Date of Patent: December 10, 2002
    Assignee: NPK Construction Equipment, Inc.
    Inventor: Roger A. Webel
  • Control system for an excavator thumb and a method of controlling an excavator thumb
    Patent number: 6385870
    Abstract: A control system and method of using a control system for a thumb on an excavator allows the thumb to follow a workpiece held in a bucket when the bucket moves. The thumb control circuit is activated by the press of a button and thereafter maintains a constant reduced close fluid pressure of the extend port of the thumb cylinder until the open control is actuated.
    Type: Grant
    Filed: July 6, 2001
    Date of Patent: May 14, 2002
    Assignee: NPK Construction Equipment, Inc.
    Inventors: Roger A. Webel, Salvatore L. Zingales, Sr.
  • Heavy duty shear with anti-jam feature
    Patent number: 5542180
    Abstract: A heavy duty shear attachable to the boom of an excavator comprises a fixed lower jaw and a movable upper jaw driven by a hydraulic cylinder. To overcome jams, the cylinder is provided with hydraulic fluid at a higher pressure in the open direction than in the close direction.
    Type: Grant
    Filed: February 3, 1994
    Date of Patent: August 6, 1996
    Assignee: NPK Construction Equipment, Inc.
    Inventor: Ron R. Karani