Patent ID: 6389952
Filing Date: 2002-05-21
Classification: B66C,F15B

Abstract:
An apparatus for operating a fluid cylinder of a work machine, said fluid cylinder (i) having a rod and a housing and (ii) being operable in (1) an extend mode in which said rod is urged outwardly from said housing by fluid being advanced by an operational pressure source and (2) a retract mode in which said rod is urged inwardly into said housing by fluid being advanced by said operational pressure source, comprising:a cylinder actuator operatively coupled to said fluid cylinder, said cylinder actuator being positionable between (i) an extend position in which said fluid cylinder is placed in said extend mode, (ii) a retract position in which said fluid cylinder is placed in said retract mode, and (iii) an isolate position in which said fluid cylinder is isolated from said operational pressure source; a sensing arrangement operatively coupled to said cylinder actuator and said fluid cylinder so that (i) said sensing arrangement detects when said cylinder actuator is in said isolate position and (ii) said sensing arrangement generates a signal in response to detecting that said cylinder actuator is in said isolate position so as to cause said fluid cylinder to be placed in a float mode of operation in which said rod is substantially free to move outwardly from said housing or move inwardly into said housing and; a control valve operatively coupled to said actuator and said fluid cylinder so that when (i) said cylinder actuator is in said extend position or said retract position fluid is advanced through said control valve by said operational pressure source and (ii) said cylinder actuator is in said isolate position fluid is prevented from being advanced through said control valve by said operational pressure source, wherein said sensing arrangement includes (i) a pilot line fluidly coupled to said control valve, (ii) a pilot pressure source fluidly coupled to said pilot line, and (iii) a pressure sensor fluidly coupled to said pilot line, fluid is allowed to advance out of said pilot line and through said control valve when said cylinder actuator is in said isolate position, fluid is prevented from being advanced out of said pilot line and through said control valve when said cylinder actuator is positioned in said retract position or said extend position so as to cause an increase in pressure in said pilot line, and said pressure sensor detects said increase in pressure of said pilot line an generates a signal in response thereto.