Cushion hitch for motor grader

Abstract

A cushion hitch having a hydraulic cylinder coupled to a vertical link and an extendable rod coupled to the front of a motor-grader type machine. The cushion hitch allows for both articulation and vertical movement. The cushion hitch helps reduce bounce and pitch in the motor-grader type machine—having a front frame and a rear frame—by controlling the supply of hydraulic fluid to the hydraulic cylinder.

1 . A cushion hitch, comprising:
 a vertical link coupled to a rear frame of a machine;   an upper pivotable link coupled to the vertical link and to a front frame of the machine;   a lower pivotable link coupled to the vertical link and to the front frame of the machine; and   a hydraulic cylinder coupled to the vertical link, the hydraulic cylinder having a rod coupled to the front frame of the machine   at least one articulation cylinder having an extendable rod, wherein the at least one articulation cylinder is coupled to the rear frame and the extendable rod is coupled to the vertical link.   
     
     
         2 . The cushion hitch of  claim 1 , further comprising a control valve operatively associated with the hydraulic cylinder for controlling fluid into and out of the hydraulic cylinder. 
     
     
         3 . The cushion hitch of  claim 2 , wherein the control valve is operably associated with a variable orifice assembly. 
     
     
         4 . The cushion hitch of  claim 3 , wherein the variable orifice assembly comprises a variable orifice and a check valve assembly in series. 
     
     
         5 . (canceled) 
     
     
         6 . The cushion hitch of  claim 4 , further comprising a control valve for controlling fluid into and out of the at least one articulation cylinder. 
     
     
         7 . The cushion hitch of  claim 1 , wherein the vertical link is coupled to the rear frame of the machine using one or more vertical pivot pins. 
     
     
         8 . A motor-grader machine, comprising:
 a front frame attached to an operator station;   a rear frame having a power system, the rear frame being coupled to a vertical link;   an upper pivotable link coupled to the vertical link and to the front frame;   a lower pivotable link coupled to the vertical link and to the front frame; and   a hydraulic cylinder assembly having an extendable rod, wherein the hydraulic cylinder assembly is coupled to the vertical link and the extendable rod is coupled to the front frame   at least one articulation cylinder having an extendable rod, wherein the at least one articulation cylinder is coupled to the rear frame and the extendable rod is coupled to the vertical link.   
     
     
         9 . The motor-grader machine of  claim 8 , further comprising a control valve fluidly coupled to the hydraulic cylinder assembly, wherein the control valve is configured to adjust an extension length of the extendable rod. 
     
     
         10 . The motor-grader machine of  claim 9 , further comprising a variable orifice fluidly coupled to the control valve, wherein the variable orifice is configured to adjust resistance to extension and retraction of the extendable rod. 
     
     
         11 . The motor-grader machine of  claim 10 , wherein a size of the variable orifice is electrically controlled. 
     
     
         12 . The motor-grader machine of  claim 10 , further comprising a check valve assembly in series with the variable orifice. 
     
     
         13 . (canceled) 
     
     
         14 . The motor-grader machine of  claim 12 , further comprising a control valve for controlling fluid into and out of the at least one articulation cylinder. 
     
     
         15 . The motor-grader machine of  claim 1 , wherein the vertical link is coupled to the rear frame of the machine using one or more vertical pivot pins. 
     
     
         16 . A method for reducing bounce in a motor-grader machine having a front frame and a rear frame, comprising:
 controlling a supply of hydraulic fluid to a hydraulic cylinder coupled to a vertical link that is coupled to the rear frame of the motor-grader machine, the hydraulic cylinder having an extendable rod coupled to the front frame of the motor-grader machine   at least one articulation cylinder having an extendable rod, wherein the at least one articulation cylinder is coupled to the rear frame and the extendable rod is coupled to the vertical link.   
     
     
         17 . The method of  claim 16 , wherein controlling a supply of hydraulic fluid comprises adjusting a resistance to extension and retraction of the extendable rod with a variable orifice. 
     
     
         18 . The method of  claim 17 , wherein adjusting the resistance with the variable orifice is performed electronically. 
     
     
         19 . The method of  claim 16 , wherein controlling a supply of hydraulic fluid comprises adjusting a resistance to extension and retraction of the extendable rod with a variable orifice in series with a check valve assembly. 
     
     
         20 . The method of  claim 19 , wherein adjusting the resistance with the variable orifice in series with the check valve assembly is performed electronically.