Lift Truck With Mast

Abstract

A lift truck includes an operator compartment having a center operating position providing an operator with a first field of view and an off center operator position providing the operator with a second field of view. A pair of forks extend away from the operator compartment. Each of the forks include a distal end. A pair of base legs extend away from the operator compartment and space laterally outwardly from the pair of forks away from a central axis of the truck. Each of the base legs include a distal end. A pair of mast columns is interposed between the operator compartment and the forks. A portion of the first field of view is blocked by the mast columns and a portion of the second field of view is blocked by the mast columns. The distal ends of the forks and the distal ends of the base legs are visible in the first field of view and the second field of view.

We claim: 
     
         1 . A lift truck comprising:
 an operator compartment providing an operator with a center operating position, in which the operator takes a center forward stance, and an off center operator position, in which the operator takes an offset forward position, said center operator position providing said operator with a first field of view emanating from a point located near a central axis of said truck, and said off center operator position providing said operator with a second field of view emanating from a point located proximal a side of said truck far from the central axis within the operator compartment;   a pair of forks extending away from said operator compartment, each of said forks of said pair of forks including a distal end;   a pair of base legs extending away from said operator compartment, each of said base legs of said pair of base legs being spaced laterally outwardly from said pair of forks away from said central axis of said truck and including a distal end;   a pair of mast columns interposed between said operator compartment and said forks; and   wherein a portion of said first field of view is blocked by said mast columns and a portion of said second field of view is blocked by said mast columns, said distal ends of said forks and said distal ends of said base legs being visible in said first field of view and said second field of view.   
     
     
         2 . The lift truck as recited in  claim 1 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck;   said lift truck further including:   a base section having a pair of spaced, upright base rail members attached to the lift truck;   said mid rail members slidably attached to the pair of base rail members and disposed laterally inward therefrom;   a pair of lift chain pulleys, one mounted to the upper end of each mid rail member and each being interposed between the top rail members of the inner telescopic section and said forks;   a pair of lift chains, one disposed over each of the lift chain pulleys and having one end connected to the base rail member and a second end connected to the top rail member; and   a pair of main lift cylinders connected between the base section and the outer telescopic section and being operable to extend the mast upward by sliding the outer telescopic section with respect to the base section.   
     
     
         3 . The lift truck as recited in  claim 1 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck;   said lift truck further including:   a carriage slidably mounted to the inner telescopic section; and   a pair of free lift cylinders mounted to the inner telescopic section and being operable to slide the carriage up and down the inner telescopic section, said free lift cylinders being disposed adjacent the inner telescopic section.   
     
     
         4 . The lift truck as recited in  claim 3 , in which one of said free lift cylinders is connected to one of said top rail members and substantially laterally aligned therewith, and the other free lift cylinder is connected to the other top rail member and laterally aligned inboard of said other top rail member. 
     
     
         5 . The lift truck as recited in  claim 3 , in which a hose pulley is mounted to the upper end of the outer telescopic section, the hose pulley being aligned laterally between one of said main lift cylinders and the other of said free lift cylinders and being disposed adjacent the mid rail member of said outer telescopic section. 
     
     
         6 . The lift truck as recited in  claim 1 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck and each lift chain pulley extends through a web portion of the mid rail member to which it mounts.   
     
     
         7 . The lift truck as recited in  claim 1 , in which said off center operator position provides said operator with the second field of view emanating from a point between one fork of said pair of forks and an adjacent base leg of said pair of base legs. 
     
     
         8 . A lift truck comprising:
 an operator compartment providing an operator with a center operating position, in which the operator takes a center forward stance, and an off center operator position, in which the operator takes an offset forward position;   a pair of forks extending away from said operator compartment, each of said forks including a distal end;   a pair of base legs extending away from said operator compartment, each of said base legs of said pair of base legs being spaced laterally outwardly from said pair of forks away from said central axis of said truck and including a distal end;   a pair of mast columns interposed between said operator compartment and said forks; and   wherein said center operator position providing said operator with a first field of view emanating from a point located near said central axis of said truck, and said off center operator position providing said operator with a second field of view emanating from a point between one fork of said pair of forks and an adjacent base leg of said pair of base legs, a portion of said first field of view is blocked by said mast columns and a portion of said second field of view is blocked by said mast columns, said distal ends of said forks and said distal ends of said base legs being visible in said first field of view and said second field of view.   
     
     
         9 . The lift truck as recited in  claim 8 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck;   said lift truck further including:   a base section having a pair of spaced, upright base rail members attached to the lift truck;   said mid rail members slidably attached to the pair of base rail members and disposed laterally inward therefrom;   a pair of lift chain pulleys, one mounted to the upper end of each mid rail member and each being interposed between the top rail members of the inner telescopic section and said forks;   a pair of lift chains, one disposed over each of the lift chain pulleys and having one end connected to the base rail member and a second end connected to the top rail member; and   a pair of main lift cylinders connected between the base section and the outer telescopic section and being operable to extend the mast upward by sliding the outer telescopic section with respect to the base section.   
     
     
         10 . The lift truck as recited in  claim 8 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck;   said lift truck further including:   a carriage slidably mounted to the inner telescopic section; and   a pair of free lift cylinders mounted to the inner telescopic section and being operable to slide the carriage up and down the inner telescopic section, said free lift cylinders being disposed adjacent the inner telescopic section.   
     
     
         11 . The lift truck as recited in  claim 10 , in which one of said free lift cylinders is connected to one of said top rail members and substantially laterally aligned therewith, and the other free lift cylinder is connected to the other top rail member and laterally aligned inboard of said other top rail member. 
     
     
         12 . The lift truck as recited in  claim 10 , in which a hose pulley is mounted to the upper end of the outer telescopic section, the hose pulley being aligned laterally between one of said main lift cylinders and the other of said free lift cylinders and being disposed adjacent the mid rail member of said outer telescopic section. 
     
     
         13 . The lift truck as recited in  claim 8 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck, and each lift chain pulley extends through a web portion of the mid rail member to which it mounts.   
     
     
         14 . The lift truck as recited in  claim 8 , in which said off center operator position providing said operator with the second field of view emanating from a point located proximal a side of said truck far from the central axis within the operator compartment. 
     
     
         15 . A lift truck comprising:
 an operator compartment providing an operator with a center operating position, in which the operator takes a center forward stance, and an off center operator position, in which the operator takes an offset forward position, said center operator position providing said operator with a first field of view emanating from a point located near a central axis of said truck, and said off center operator position providing said operator with a second field of view emanating from a point located proximal a side of said truck far from the central axis within the operator compartment;   a pair of forks extending away from said operator compartment, each of said forks including a distal end;   a pair of base legs extending away from said operator compartment, each of said base legs of said pair of base legs being spaced laterally outwardly from said pair of forks away from said central axis of said truck and including a distal end;   a pair of mast columns interposed between said operator compartment and said forks; and   wherein said center operator position providing said operator with a first field of view emanating from a point located near said central axis of said truck, and said off center operator position providing said operator with a second field of view emanating from a point between one fork of said pair of forks and an adjacent base leg of said pair of base legs, a portion of said first field of view is blocked by said mast columns and a portion of said second field of view is blocked by said mast columns, said distal ends of said forks and said distal ends of said base legs being visible in said first field of view and said second field of view.   
     
     
         16 . The lift truck as recited in  claim 15 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck;   said lift truck further including:   a base section having a pair of spaced, upright base rail members attached to the lift truck;   said mid rail members slidably attached to the pair of base rail members and disposed laterally inward therefrom;   a pair of lift chain pulleys, one mounted to the upper end of each mid rail member and each being interposed between the top rail members of the inner telescopic section and said forks;   a pair of lift chains, one disposed over each of the lift chain pulleys and having one end connected to the base rail member and a second end connected to the top rail member; and   a pair of main lift cylinders connected between the base section and the outer telescopic section and being operable to extend the mast upward by sliding the outer telescopic section with respect to the base section.   
     
     
         17 . The lift truck as recited in  claim 15 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck;   said lift truck further including:   a carriage slidably mounted to the inner telescopic section; and   a pair of free lift cylinders mounted to the inner telescopic section and being operable to slide the carriage up and down the inner telescopic section, said free lift cylinders being disposed adjacent the inner telescopic section.   
     
     
         18 . The lift truck as recited in  claim 17 , in which one of said free lift cylinders is connected to one of said top rail members and substantially laterally aligned therewith, and the other free lift cylinder is connected to the other top rail member and laterally aligned inboard of said other top rail member. 
     
     
         19 . The lift truck as recited in  claim 17 , in which a hose pulley is mounted to the upper end of the outer telescopic section, the hose pulley being aligned laterally between one of said main lift cylinders and the other of said free lift cylinders and being disposed adjacent the mid rail member of said outer telescopic section. 
     
     
         20 . The lift truck as recited in  claim 15 , in which each of said mast columns comprising:
 an outer telescopic section having an upright mid rail member, and   an inner telescopic section having an upright top rail members slidably attached to the mid rail member and disposed laterally inward therefrom toward said central axis of said truck, each lift chain pulley extends through a web portion of the mid rail member to which it mounts.