Abstract:
A lift truck is provided comprising: a power unit assembly comprising a power unit base, a wheel coupled to the base, and a system for driving the wheel; and a main frame assembly detachably connected to the power unit assembly. The main frame assembly comprises a main frame base, a mast assembly coupled to the main frame base, a carriage assembly coupled to the mast assembly, and hydraulic drive apparatus coupled to the mast assembly. Preferably, substantially the entirety of the hydraulic drive apparatus is provided on the main frame assembly such that the main frame assembly is detachable from the power unit assembly without requiring disconnecting hydraulic connections to the power unit assembly.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to a fork lift truck comprising a power unit assembly detachably connected to a main frame assembly, wherein substantially all hydraulic components are mounted on the main frame assembly.  
       BACKGROUND OF THE INVENTION  
       [0002]     Fork lift trucks, such as turret stockpicker trucks, comprising a power unit assembly detachably connected to a main frame assembly are known in the prior art. In such a truck, the power unit assembly comprises a power unit base, at least one wheel coupled to the base and being driven by one or more traction motors, a battery for providing power to the traction motor(s), and a traction motor control module(s) for controlling the operation of the traction motor(s). A first hydraulic motor/pump assembly and at least one manifold valve block are also mounted on the power unit base. The main frame assembly comprises a main frame base, a mast assembly comprising a fixed first mast and a second mast movable relative to the first mast, a piston/cylinder unit for effecting movement of the second mast relative to the first mast, a second hydraulic motor/pump assembly for providing pressurized fluid to the piston/cylinder unit for effecting movement of the second mast, and a carriage assembly coupled to said second mast for movement with the second mast. Further provided on the main frame base is a hydraulic fluid reservoir and at least one manifold valve block.  
         [0003]     Because the first hydraulic motor/pump assembly and at least one manifold valve block are mounted on the power unit base and the fluid reservoir is mounted on the main frame assembly, hydraulic tubes/lines extend between the power unit and main frame assemblies. Hence, in order to separate those assemblies, such as for shipping the truck, one or more of the hydraulic tubes/lines extending between the power unit assembly and the main frame assembly must be disconnected. Such a disassembly operation is disadvantageous due to its complexity. Also, disconnecting one or more hydraulic lines/tubes increases the risk that those lines/tubes may become contaminated with moisture, dirt, air, etc. A further disadvantage to having the first hydraulic motor/pump assembly mounted on the power unit is that it is located in close proximity to many of the electronic and electrical components. As a result, there is an increased risk that those electronic and electrical components may be contaminated with hydraulic fluid or dirt accumulated on the first hydraulic motor/pump assembly mounted to the power unit base.  
       SUMMARY OF THE INVENTION  
       [0004]     In accordance with the present invention, a fork lift truck, such as a turret stockpicker truck, is provided comprising a power unit assembly detachably connected to a main frame assembly, wherein substantially all hydraulic components are mounted on the main frame assembly. Consequently, when the truck is separated, such as for shipping, no hydraulic tubes/lines extending between the power unit and main frame assemblies need be disconnected. Hence, the disassembly operation is simplified. Further, risk of moisture, dirt, air, etc. contaminating open hydraulic tubes/lines is reduced. Also, the length of hydraulic tubes/lines required on the truck is reduced since tubes/lines extending between the power unit and main frame assemblies are not required. This reduces costs as well as pressure drops within the hydraulic system.  
         [0005]     In accordance with a first aspect of the present invention, a lift truck is provided comprising: a power unit assembly comprising a power unit base, at least one wheel coupled to the base, and a system for driving the wheel; and a main frame assembly detachably connected to the power unit assembly. The main frame assembly comprises a main frame base, a mast assembly coupled to the main frame base, a carriage assembly coupled to the mast assembly, and hydraulic drive apparatus, preferably coupled to the mast and carriage assemblies. Preferably, substantially the entirety of the hydraulic drive apparatus is provided on the main frame assembly such that the main frame assembly is detachable from the power unit assembly without requiring disconnecting hydraulic connections to the power unit assembly. A control structure, such as a control module, for controlling the operation of the hydraulic drive apparatus is provided and, preferably, is located on the power unit assembly.  
         [0006]     The hydraulic drive apparatus may comprises a hydraulic fluid reservoir, a hydraulic motor/pump assembly, and a manifold system. Preferably, the reservoir is spaced from the motor/pump assembly and the manifold system.  
         [0007]     The main frame base may comprise front and rear portions. The mast assembly, the hydraulic fluid reservoir and the hydraulic motor/pump assembly are preferably located at the rear portion of the main frame base, with the reservoir being positioned on a first side of the mast assembly and the motor/pump assembly being positioned on a second side of the mast assembly.  
         [0008]     The power unit system for driving the at least one wheel may comprise at least one traction motor, a battery for providing power to the motor, and a control module for controlling the operation of the traction motor.  
         [0009]     As noted above, the main frame base may comprise front and rear portions. Similarly, the power unit base may comprise front and rear portions. The rear portion of the main frame base may be positioned adjacent to the front portion of the power unit base, and the traction motor and the traction motor control module may be located in the rear portion of the power unit base.  
         [0010]     The power unit assembly may further comprise a steer motor for effecting steering movement of the wheel and a steer motor control module for controlling the operation of the steer motor. The steer motor and the steer motor control module are preferably located in the rear portion of the power unit base.  
         [0011]     The mast assembly may comprise a fixed first mast, a second mast movable relative to the first mast and a mast piston/cylinder unit for effecting movement of the second mast relative to the first mast. The carriage assembly may comprise a platform assembly coupled to the second mast so as to move with the second mast. The platform assembly may be movably coupled to the second mast so as to move relative to the second mast as well as with the second mast.  
         [0012]     The carriage assembly may further comprise a load handler assembly movably coupled to the platform assembly and a fork carriage assembly movably coupled to the load handler assembly.  
         [0013]     In accordance with a second aspect of the present invention, a lift truck is provided comprising: a power unit assembly comprising a power unit base having front and rear portions, at least one wheel, at least one traction motor for driving the at least one wheel, a battery for providing power to the at least one traction motor, and at least one traction motor control module for controlling the operation of the at least one traction motor. The at least one wheel, traction motor and traction motor control module are preferably mounted in the rear portion of the power unit base. The lift truck further comprises a main frame assembly comprising a main frame base having front and rear portions, a mast assembly, a carriage assembly coupled to the mast assembly, and hydraulic drive apparatus coupled to the mast assembly. The front portion of the power unit base may be coupled to the rear portion of the main frame base. The power unit assembly may further comprise a hydraulic drive apparatus control module, which, preferably, is mounted in the rear portion of the power unit base for controlling the operation of the hydraulic drive apparatus.  
         [0014]     The hydraulic drive apparatus may comprise a hydraulic fluid reservoir, a hydraulic motor/pump assembly and a manifold system. The reservoir is preferably spaced from the motor/pump assembly and the manifold system.  
         [0015]     The mast assembly, the hydraulic fluid reservoir and the hydraulic motor/pump assembly are preferably located at the rear portion of the main frame base, with the reservoir being positioned on a first side of the mast assembly and the motor/pump assembly being positioned on a second side of the mast assembly.  
         [0016]     The power unit assembly may further comprise at least one steer motor for effecting steering movement of the at least one wheel and a steer motor control module for controlling the operation of the steer motor. The steer motor and the steer motor control module are located in the rear of the power unit base.  
         [0017]     In accordance with a third aspect of the present invention, a fork lift truck is provided comprising a power unit assembly detachably connected to a main frame assembly, wherein substantially all truck hydraulic components are mounted on the main frame assembly while substantially all truck electronic control modules are mounted on the power unit assembly.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0018]      FIGS. 1 and 2  are perspective views, from opposite sides, of a materials handling vehicle constructed in accordance with the present invention with outer covers on the power unit and main frame assemblies removed;  
         [0019]      FIG. 1A  is a schematic view illustrating the first and second masts, and a piston/cylinder unit of the main mast assembly of the vehicle illustrated in  FIG. 1 ;  
         [0020]      FIG. 1B  is a schematic view illustrating a piston/cylinder unit of the auxiliary mast of the vehicle illustrated in  FIG. 1 ;  
         [0021]      FIG. 3  is a perspective view of the hydraulic motor/pump assembly and first manifold of the vehicle illustrated in  FIG. 1 ;  
         [0022]      FIG. 4  is a perspective view of the power unit assembly with outer covers removed and shown disconnected from the main frame assembly;  
         [0023]      FIG. 5  is a perspective view of the main frame assembly with outer covers removed and shown disconnected from the power unit assembly; and  
         [0024]      FIG. 6  is a perspective view of a portion of the main frame assembly and illustrating a rear portion of the main frame base. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     Referring now to the drawings, and particularly to  FIGS. 1 and 2 , which illustrate a materials handling truck or vehicle  10  constructed in accordance with the present invention. In the illustrated embodiment, the vehicle  10  comprises a turret stockpicker. The vehicle  10  includes a power unit assembly  20  and a main frame assembly  30 , which assemblies  20  and  30  are releasably coupled together, as will be discussed more explicitly below. The power unit assembly  20  includes a power unit base  21  having front and rear portions  21   a  and  21   b , respectively, a power source, such as a battery unit  22 , positioned on the base  21 , a steered wheel  23  rotatably coupled to the base rear portion  21   b , a traction motor  23   a  for driving the wheel  23  and a traction motor control module  25  for controlling the operation of the traction motor  23   a , i.e., its speed and direction, in response to operator generated commands, see  FIGS. 1, 2  and  4 . The main frame assembly  30  comprises a main frame base  31  having front and rear portions  31   a  and  31   b , respectively, a mast assembly  32  coupled to the base  31 , a carriage assembly  34  coupled to the mast assembly  32 , a hydraulic drive apparatus  80  coupled to the base  31 , the mast assembly  32  and the carriage assembly  34 , and a pair of load wheels  37  coupled to the main frame base  31 . The carriage assembly  34  comprises, in the illustrated embodiment, a platform assembly  130  adapted to carry an operator and coupled to the mast assembly  32 , a load handling assembly  132  coupled to the platform assembly  130 , and a fork carriage assembly  136  coupled to the load handling assembly  132 .  
         [0026]     The mast assembly  32  comprises a first mast  32   a  fixedly coupled to the main frame base  31 , a second mast  32   b  movable coupled to the first mast  32   a , and a main mast piston/cylinder unit  50 , see  FIG. 1A . In the illustrated embodiment, the platform assembly  130  is movably coupled to the second mast  32   b  so as to move relative to the second mast  32   b  and with the second mast  32   b . The load handling assembly  132  is coupled to the platform assembly  130  and, hence, moves vertically with the platform assembly  130 .  
         [0027]     The mast piston/cylinder unit  50  is provided in the first mast  32   a  for effecting movement of the second mast  32   b  relative to the first mast  32   a  and the base  31 , see  FIG. 1A . The cylinder  50   a  forming part of the piston/cylinder unit  50  is fixedly coupled to the base  31 . The piston  50   b  forming part of the unit  50  is fixedly coupled to the second mast  32   b  such that movement of the piston  50   b  effects movement of the second mast  32   b  relative to the first mast  32   a . The piston  50   b  comprises a roller  50   c  on its distal end which engages a pair of chains  52  and  54 . Each chain  52 ,  54  is fixedly coupled at a first end  52   a ,  54   a  to the first mast  32   a  and coupled at a second end  52   b ,  54   b  to the platform assembly  130 . Hence, movement of the piston  50   b  relative to the cylinder  50   a  effects movement of the platform assembly  130  relative to the base  31  via the roller  50   c  acting against the chains  52 ,  54  and the piston  50   b  acting against the second mast  32   b . One unit of vertical movement of the piston  50   b  results in two units of vertical movement of the platform assembly  130 . Hence, in the illustrated embodiment, the platform assembly  130  moves with the second mast  32   b  as the second mast  32   b  moves relative to the base  31  and further moves relative to the second mast  32   b.    
         [0028]     The load handling assembly  132  comprises a first structure  42  which is movable back and forth transversely relative to the platform assembly  130 , as designated by an arrow  200  in  FIG. 2 , via a hydraulic motor (not shown). The load handling assembly  132  further comprises a second structure  44  (also referred to as an auxiliary mast) which moves transversely with the first structure  42  and is also capable of rotating relative to the first structure  42 . In the illustrated embodiment, the second structure  44  is rotated back and forth relative to the first structure  42  through an angle of about 180° via first and second piston/cylinder units (not shown) provided in an upper portion  42   a  of the first structure  42 . A similar arrangement for pivoting a second structure is disclosed in U.S. Pat. No. 5,011,363, the disclosure of which is incorporated herein by reference.  
         [0029]     Coupled to the second structure  44  is the fork carriage assembly  136  comprising a pair of forks  62  and a fork support  64 . The fork carriage assembly  136  is capable of moving vertically relative to the second structure  44 , as designated by an arrow  201  in  FIG. 1 . While not shown in the figures, a piston/cylinder unit may be provided in each fork  62  for causing a corresponding sliding fork member (not shown), comprising part of the fork  62 , to extend and retract relative to a corresponding fixed fork member (not shown), see again U.S. Pat. No. 5,011,363. Rotation of the second structure  44  relative to the first structure  42  permits an operator to position the forks  62  in one of at least a first position and a second position, wherein the second position may be located about 180 ° from the first position.  
         [0030]     A second structure or auxiliary mast piston/cylinder unit  70  is provided in the second structure  44  for effecting vertical movement of the fork carriage assembly  136  relative to the second structure  44 , see  FIG. 1B . The cylinder  70   a  forming part of the piston/cylinder unit  70  is fixedly coupled to the second structure  44 . The piston  70   b  forming part of the unit  70  comprises a roller  70   c  on its distal end which engages a chain  72 . One unit of vertical movement of the piston  70   b  results in two units of vertical movement of the fork carriage assembly  136 . The chain  72  is fixedly coupled at a first end  72   a  to the cylinder  70   a  and fixedly coupled at a second end  72   b  to the fork support  64 . The chain  72  extends from the cylinder  70   a , over the roller  70   c  and down to the fork support  64 . Upward movement of the piston  70   b  effects upward movement of the fork carriage assembly  136  relative to the second structure  44 , while downward movement of the piston  70   b  effects downward movement of the fork carriage assembly  136  relative to the second structure  44 .  
         [0031]     The hydraulic drive apparatus  80  supplies pressurized fluid to the mast piston/cylinder unit  50  and the second structure piston/cylinder unit  70 . The hydraulic apparatus  80  may also provide pressurized fluid to the hydraulic motor for effecting transverse movement of the first structure  42 , the first and second piston/cylinder units for effecting rotation of the second structure  44  and the first and second piston/cylinder units for causing the sliding fork members to extend and retract. The apparatus  80  comprises, in the illustrated embodiment, a hydraulic motor/pump assembly  82 , a first manifold  90 , and a hydraulic fluid reservoir  84 , all of which are mounted on the main frame base  31 , see  FIGS. 1-3 ,  5  and  6 . The hydraulic apparatus  80  further comprises a second manifold  190 , shown in phantom only in  FIG. 1 , mounted in the upper portion  42   a  of the first structure  42 , see  FIG. 1 . The motor/pump assembly  82  supplies hydraulic fluid from the reservoir  84  under pressure to the manifolds  90  and  190 . In response to appropriate operator-generated commands, a hydraulic drive apparatus control module  400 , see  FIGS. 2 and 4 , causes the first manifold  90  to provide pressurized fluid to the piston/cylinder unit  50  and further causes the first and second manifolds  90  and  190  to provide pressurized fluid to the piston/cylinder unit  70 , the hydraulic motor for effecting transverse movement of the first structure  42 , the first and second piston/cylinder units for effecting rotation of the second structure  44 , and the first and second piston/cylinder units for causing the sliding fork members to extend and retract. Example first and second manifolds  90  and  190  are disclosed in patent application U.S. Ser. No. ______, entitled “ELECTRONICALLY CONTROLLED VALVE FOR A MATERIALS HANDLING VEHICLE,” filed concurrently with this application, by Dammeyer et al., Attorney Docket No. CRN 339 PA, the disclosure of which is incorporated by reference herein.  
         [0032]     As noted above, the power unit assembly  20  and the main frame assembly  30  are releasably coupled to one another. The power unit base  21  comprises a front plate member  210  provided with three openings in a first lower comer  210   a , three opening in a second lower corner  210   b  and a pair of openings along an upper edge  210   c , see  FIG. 4 . Bolts  300  extend through those openings such that head portions (not shown) of the bolts  300  engage a first side  210   d  of the front plate member  210  while threaded portions  300   a  of the bolts  300  extend through the openings in the plate member  210 . A first horizontal member  310  and first and second vertical members  312  and  314 , respectively, of the main frame base  31  are provided with openings  310   a ,  312   a , and  314   b , see  FIGS. 5 and 6 . The bolt threaded portions  300   a  extend through the openings  310   a ,  312   a  and  314   b  and nuts  315  are secured to the bolts  300  so as to releasably couple the power unit base  21  and the main frame base  31  to one another, see  FIG. 3 .  
         [0033]     All hydraulic fluid lines extending from the reservoir  84  to the motor/pump assembly  82 , from the motor/pump assembly  82  to the first and second manifolds  90  and  190  and from the first and second manifolds  90  and  190  to the mast piston/cylinder unit  50 , the second structure piston/cylinder unit  70 , the hydraulic motor for effecting transverse movement of the first structure  42 , the first and second piston/cylinder units for effecting rotation of the second structure  44 , and the first and second piston/cylinder units for causing the sliding fork members to extend and retract are contained within the main frame assembly  30 . Hence, all vehicle hydraulic components including the hydraulic apparatus  80 , the mast piston/cylinder unit  50  and the second structure piston/cylinder unit  70  are contained within the main frame assembly  30 . This is advantageous as there is no need to disconnect any hydraulic tubes/lines extending between the power unit and main frame assemblies  20  and  30  when the vehicle  10  is to be separated. Hence, the vehicle disassembly operation is simplified. Further, risk of moisture, dirt, air, etc. contaminating open hydraulic tubes/lines is reduced. Also, the length of hydraulic tubes/lines required on the vehicle  10  is reduced since tubes/lines extending between the power unit and main frame assemblies  20  and  30  are not required. This reduces costs as well as pressure drops within the hydraulic apparatus  80 .  
         [0034]     The vehicle  10  comprises three substantial heat sources, which are: 1) the hydraulic fluid reservoir  84 ; 2) the motor/pump assembly  82  and the first manifold  90 ; and 3) the traction motor  23   a , a gear box (not shown) coupled to and mounted below the motor  23   a  and the control modules  25 ,  27 ,  130  and  400 . So as to allow the heat generated by those sources to be efficiently transferred from the vehicle  10 , those elements are spaced apart from one another on the vehicle  10 . In particular, the hydraulic fluid reservoir  84  is positioned to a first side  32   c  of the mast assembly  32  so as to be spaced from the motor/pump assembly  82  and the first manifold  90 , which are positioned to a second side  38   d  of the mast assembly  38 , see  FIGS. 1 and 2 . The control modules  25 ,  27 ,  130  and  400 , the traction motor  23   a , and the traction motor gear box (not shown) are mounted in a rear section  26  of the power unit assembly  20 .  
         [0035]     The power unit base  21  comprises first, second and third compartments  100 ,  110  and  120  located in the rear section  26  of the power unit assembly  20 , see  FIGS. 1 and 2 . The traction motor  23   a  for driving the wheel  23  and a steer motor  24  for effecting steering movement of the wheel  23  are mounted in the second compartment  110 , see  FIG. 1 . Mounted in the first compartment  100  is the traction motor control module  25  for controlling the operation of the traction motor  23   a , i.e., its speed and direction of rotation, in response to operator generated commands. Also mounted in the first compartment  100  is a steer motor control module  27  for controlling the operation of the steer motor  24  in response to operator generated commands. Mounted in the third compartment  120  is the control module  400  for controlling the operation of the motor/pump assembly  82  and the first and second manifolds  90  and  190  in response to operator generated commands. Also mounted in the third compartment  120  is a guidance control module  130 . The vehicle  10  may be provided with front and back sensors (not shown) for sensing a guide wire provided in the floor on which the vehicle  10  is operated. The control module  130  receives signals generated by those sensors and generates appropriate control commands to the steer motor control module  27  to ensure that the vehicle  10  is positioned correctly relative to the guide wire. The control module  130  may also include an end-of-aisle feature such that the vehicle  10  is slowed to a stop before leaving an aisle, i.e., a predefined area, in response to the control module  130  receiving signals from end-of-aisle sensors on the vehicle which sense end-of-aisle markers in or on the floor.  
         [0036]     Each of the traction motor  23   a , the steer motor  24  and the control modules  25 ,  27 ,  130  and  400  generate significant amounts of heat energy, which energy must be efficiently transferred from the vehicle. By placing the traction motor  23   a  and the steer motor  24  a spaced distance away from the control modules  25 ,  27 ,  130  and  400 , efficient transfer of the heat generated by those elements from the vehicle  10  occurs. Furthermore, by locating the traction motor  23   a , the steer motor  24  and the control modules  25 ,  27 ,  130  and  400  in the rear section  26  of the power unit assembly  20 , those elements are spaced a substantial distance from the hydraulic fluid reservoir  84 , the motor/pump assembly  82  and the first manifold  90 , so as to improve thermal balance on the vehicle  10  and to facilitate dissipation of heat from those elements.  
         [0037]     The power unit assembly  20  can be detached from the main frame assembly  30  by removing the nuts  315  from the bolts  300 . Prior to separating the assemblies  20  and  30 , power supply cables  405  extending from the power unit assembly  20  to the hydraulic motor/pump assembly  82  and wiring harnesses  410 , three in the illustrated embodiment, extending from the power unit assembly  20  to the main frame assembly  30  need to be disconnected.  
         [0038]     Having described the invention in detail and by reference to preferred embodiments thereof, it will be apparent that modifications and variations are possible without departing from the scope of the invention defined in the appended claims.