Compact utility loader with synchronized lift and extension of working tool attachment

Abstract

A utility loader incorporating a boom of adjustable length. The boom includes either or both of a left and right arm assembly, with each lift arm assembly including a rear lift arm telescopingly engaged with a front lift arm. Each lift arm assembly also includes an extension actuator adapted to variably extend and retract the front lift arm relative to the rear lift arm. The lift arm assembly includes a connection point to, e.g., receive a tool assembly, and the motion of the lift arm assembly is synchronized to move the connection point along a predetermined path. In one or more embodiments, the predetermined path includes moving along a direction that is normal to the ground surface.

1 . A compact utility loader comprising:
 a chassis carrying a prime mover;   ground engaging members operatively attached to the chassis, wherein at least one of the ground engaging members is powered by the prime mover to propel the chassis over a ground surface;   a control console located at or near a rear end of the chassis, the control console carrying controls adapted to be manipulated by an operator either: standing on a platform mounted near the rear end of the chassis; or walking behind the chassis;   a lift arm assembly movably attached to the chassis, wherein the lift arm assembly is adapted to move at least between a first position and a second position different than the first position, wherein the lift arm assembly comprises:
 an elongate rear lift arm including a front end and a rear end, wherein the rear end of the rear lift arm is pivotally attached to the chassis at a transverse lift arm pivot axis; and 
 an elongate front lift arm also including a front end and a rear end, wherein the rear end of the front lift arm is telescopingly engaged with the front end of the rear lift arm such that a distance between the rear end of the rear lift arm and the front end of the front lift arm is variable, wherein the elongate front lift arm comprises a connection point adapted to receive a tool assembly; and 
   a controller adapted to move the lift arm assembly such that the connection point moves in only a direction normal to the ground surface when moving between the first and second positions.   
     
     
         2 . The compact utility loader of  claim 1 , wherein the lift arm assembly further comprises an extension actuator adapted to extend or retract the front lift arm relative to the rear lift arm, wherein the extension actuator extends outward to the first position and then the connection point moves vertically to the second position. 
     
     
         3 . The compact utility loader of  claim 1 , wherein the lift arm assembly further comprises:
 an extension actuator adapted to extend or retract the front lift arm relative to the rear lift arm, and   a lift actuator attached between the elongate rear lift arm and the chassis, wherein the lift actuator is adapted to extend or retract to pivot the elongate rear lift arm relative to the chassis,   wherein the extension actuator extends or retracts at the same time as the lift actuator extends or retracts to move the connection point along a direction normal to the ground surface between the first and second positions.   
     
     
         4 . The compact utility loader of  claim 3 , wherein the controller is adapted to restrict operator extension of the extension actuator. 
     
     
         5 . The compact utility loader of  claim 1 , wherein the lift arm assembly is configurable in a synchronized mode and a manual mode, wherein the controller is adapted to move the lift arm assembly from the first position to the second position when in the synchronized mode. 
     
     
         6 . The compact utility loader of  claim 1 , wherein the prime mover is positioned on the chassis at a location lateral to the lift arm assembly. 
     
     
         7 . A compact utility loader comprising:
 a chassis carrying a prime mover;   ground engaging members operatively attached to the chassis, wherein at least one of the ground engaging members is powered by the prime mover to propel the chassis over a ground surface;   a control console located at or near a rear end of the chassis, the control console carrying controls adapted to be manipulated by an operator either: standing on a platform mounted near the rear end of the chassis; or walking behind the chassis;   a lift arm assembly attached to the chassis, wherein the lift arm assembly comprises:
 an elongate rear lift arm including a front end and a rear end, wherein the rear end of the rear lift arm is pivotally attached to the chassis at a transverse lift arm pivot axis; 
 a lift actuator attached between the elongate rear lift arm and the chassis, wherein the lift actuator is adapted to extend or retract to pivot the elongate rear lift arm relative to the chassis; 
 an elongate front lift arm also including a front end and a rear end, wherein the rear end of the front lift arm is telescopingly engaged with the front end of the rear lift arm such that a distance between the rear end of the rear lift arm and the front end of the front lift arm is variable, wherein the elongate front lift arm comprises a connection point adapted to receive a tool assembly; and 
 an extension actuator adapted to extend or retract the front lift arm relative to the rear lift arm; and 
   a controller adapted to extend or retract the extension actuator in concert with movement of the lift actuator to maintain movement of the connection point along a predetermined path.   
     
     
         8 . The compact utility loader of  claim 7 , wherein extension actuator extends when the lift actuator extends to maintain movement of the connection point along a direction normal to the ground surface. 
     
     
         9 . The compact utility loader of  claim 7 , wherein extension actuator retracts when the lift actuator retracts to maintain movement of the connection point along a direction normal to the ground surface. 
     
     
         10 . The compact utility loader of  claim 7 , wherein extension actuator extends when the lift actuator retracts to maintain movement of the connection point along a direction normal to the ground surface. 
     
     
         11 . The compact utility loader of  claim 7 , wherein extension actuator retracts when the lift actuator extends to maintain movement of the connection point along a direction normal to the ground surface. 
     
     
         12 . The compact utility loader of  claim 7 , wherein the extension actuator extends prior to maintaining movement of the connection point along the predetermined path. 
     
     
         13 . The compact utility loader of  claim 7 , wherein the lift arm assembly is configurable in a synchronized mode and a manual mode, wherein the controller is adapted to move each of the lift actuator and the extension actuator such that the connection point maintains movement along the predetermined path when in the synchronized mode. 
     
     
         14 . The compact utility loader of  claim 7 , wherein the prime mover is positioned on the chassis at a location lateral to the lift arm assembly. 
     
     
         15 . The compact utility loader of  claim 7 , wherein the controller is adapted to restrict operator extension of the extension actuator. 
     
     
         16 . A method of moving a lift arm assembly of a compact utility loader, the method comprising:
 providing the compact utility loader, wherein the compact utility loader comprises:
 a chassis carrying a prime mover; 
 ground engaging members operatively attached to the chassis, wherein at least one of the ground engaging members is powered by the prime mover to propel the chassis over a ground surface; 
 a control console located at or near a rear end of the chassis, the control console carrying controls adapted to be manipulated by an operator either: standing on a platform mounted near the rear end of the chassis; or walking behind the chassis; and 
 a lift arm assembly attached to the chassis, wherein the lift arm assembly comprises:
 an elongate rear lift arm including a front end and a rear end, wherein the rear end of the rear lift arm is pivotally attached to the chassis at a transverse lift arm pivot axis; 
 a lift actuator attached between the elongate rear lift arm and the chassis, wherein the lift actuator is adapted to extend or retract to pivot the elongate rear lift arm relative to the chassis; 
 an elongate front lift arm also including a front end and a rear end, wherein the rear end of the front lift arm is telescopingly engaged with the front end of the rear lift arm such that a distance between the rear end of the rear lift arm and the front end of the front lift arm is variable, wherein the elongate front lift arm comprises a connection point adapted to receive a tool assembly; and 
 an extension actuator adapted to extend or retract the front lift arm relative to the rear lift arm; 
 
   extending or retracting the lift actuator to move the elongate rear lift arm relative to the chassis; and   automatically extending or retracting the extension actuator in concert with extending or retracting the lift actuator to maintain the connection point in a vertical plane.   
     
     
         17 . The method of  claim 16 , further comprising positioning the connection point in the vertical plane prior to automatically extending or retracting the lift actuator and the extension actuator. 
     
     
         18 . The method of  claim 17 , wherein positioning the connection point in the vertical plane comprises manually extending or retracting one or both of the lift actuator and the extension actuator. 
     
     
         19 . The method of  claim 17 , further comprising positioning the lift arm assembly along a generally horizontal plane relative to the ground surface prior to automatically extending or retracting the lift actuator and the extension actuator. 
     
     
         20 . The method of  claim 16 , further comprising restricting operator extension of the extension actuator.