Patent Publication Number: US-8991843-B2

Title: Movable step for a materials handling vehicle

Description:
REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 11/556,318, filed Nov. 3, 2006, and entitled “A MOVABLE STEP FOR A MATERIALS HANDLING VEHICLE,” which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/765,230, filed Feb. 3, 2006, and entitled “A MOVABLE STEP FOR A MATERIALS HANDLING VEHICLE,” the entire disclosures of each of which are incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Materials handling vehicles comprising low level order pickers are known. Such a vehicle comprises a power unit, a battery compartment housing a battery, a load backrest, and a set of forks extending in a direction away from the load backrest. A walk-through operator compartment or platform is positioned between the battery compartment and the load backrest. An operator, when positioned within the operator compartment, may control the speed, braking and direction of the vehicle via a control handle structure. 
     It is known to place a fixed step on the backrest facing toward the operator compartment. It is also known to place a pivotable step on a wall of the battery compartment defining an inner wall of the operator compartment. The pivotable step is not positioned adjacent, i.e., at or very near, an outer peripheral edge of the vehicle. Nor does it extend to and engage the vehicle backrest. 
     An improved step arrangement is desired so as to allow an operator to more easily gain access to an elevated storage location. 
     SUMMARY OF THE INVENTION 
     In accordance with a first aspect of the present invention, a materials handling vehicle is provided comprising a frame including an operator compartment having at least one entrance and a floorboard. The vehicle further comprises at least one step capable of being positioned across the entrance a spaced distance from the floorboard such that an operator may stand on the step when the step is positioned across the entrance to gain access to an elevated storage location. 
     The step may be movable between a deployed position where the step is positioned across the entrance and a stowed position where the step is positioned in a location so as not to block the entrance into and exit from the operator compartment. 
     The step may be pivotable between the deployed and stowed positions. 
     The step may be in a down position when deployed and in an up position when stowed. A biasing element may be associated with the step for assisting an operator in moving the step from the down position to the up position. 
     The vehicle may further comprise a drive wheel coupled to the frame, a motor coupled to the drive wheel for effecting rotation of the drive wheel, a controller for controlling the operation of the drive motor, and a sensor associated with the step. The sensor may generate a signal to the controller when the step is in a travel state. Preferably, the controller provides a drive signal to the motor only when a travel state signal is being generated by the sensor. 
     The step may be positioned above the floorboard a distance of from about 250 mm to about 450 mm. 
     The operator compartment may comprise a walk-through operator compartment having first and second entrances. A first step may be positioned across the first entrance a spaced distance from the floorboard. A second step may be positioned across the second entrance a spaced distance from the floorboard. An operator may stand on one of the first and second steps when the one step is positioned across a corresponding one of the first and second entrances to gain access to the elevated storage location. 
     The first step may be movable between a deployed position where the first step is positioned across the first entrance and a stowed position where the first step is positioned in a location so as not to block the first entrance into the operator compartment. The second step may be movable between a deployed position where the second step is positioned across the second entrance and a stowed position where the second step is positioned in a location so as not to block the second entrance into the operator compartment. 
     In accordance with a second aspect of the present invention, a materials handling vehicle is provided comprising a frame including an operator compartment having at least one entrance and a floorboard, a drive wheel coupled to the frame, a motor coupled to the drive wheel for effecting rotation of the drive wheel, a controller for controlling the operation of the motor, at least one step associated with the frame, and at least one sensor associated with the step. The step is capable of being moved between a deployed position to allow an operator to stand on the step and gain access to an elevated storage location and a stowed position where the step is stored in an out-of-the-way location. The at least one sensor is preferably associated with the step so as to generate a signal to the controller when the step is in a travel state. The controller preferably provides a drive signal to the motor only when a travel state signal is being generated by the at least one sensor. 
     The step may slide between deployed and stowed positions. It is also contemplated that the step may be pivotable between the deployed and stowed positions. 
     The step may be in a down position when deployed and an up position when stowed. A biasing element may be provided for assisting an operator in moving the step from the down position to the up position. 
     The operator compartment may further comprise first and second walls. A stop may be coupled to the first wall. The step may be pivotably coupled at a first end to the second wall. A second end of the step may engage the stop when the step is moved to the down position. The first wall may comprise a backrest and the second wall may comprise a battery compartment wall. Alternatively, the first wall may comprise a battery compartment wall and the second wall may comprise a backrest. 
     A locking mechanism may be associated with the second wall for releasably locking the step in position when the step has been moved to the up position. 
     The step may comprise a camming surface. The sensor may comprise a microswitch which is actuated by the camming surface. 
     In another embodiment, the step comprises a flag and the sensor may comprise a proximity sensor which is actuated by the flag. 
     First and second steps may be provided. The first step may be moved between a deployed position to allow an operator to stand on the first step and gain access to an elevated storage location and a stowed position where the first step is stored in an out-of-the-way location. The second step may be moved between a deployed position to allow an operator to stand on the second step and gain access to an elevated storage location and a stowed position where the second step is stored in an out-of-the-way location. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a materials handling vehicle and including first and second step assemblies (a stop for the second step assembly is not illustrated) constructed in accordance with a first embodiment of the present invention; 
         FIGS. 2 and 3  are perspective views of the materials handling vehicle of  FIG. 1  with its forks removed and including the first and second step assemblies constructed in accordance with the first embodiment of the present invention; 
         FIG. 4  is a top view of the vehicle illustrated in  FIGS. 2 and 3 ; 
         FIG. 5  is a side view of the vehicle illustrated in  FIGS. 2 and 3  with the first and second steps in their stowed positions; 
         FIG. 6  is a side view of the vehicle illustrated in  FIGS. 2 and 3  with the first step in its deployed position; 
         FIGS. 7 and 8  are side views of the first step assembly and its corresponding stop; 
         FIG. 9  is a top view of the first and second step assemblies and corresponding stops with the first and second steps in their deployed positions; 
         FIG. 10  is a top view of the first and second step assemblies and corresponding stops with the first and second steps in their stowed positions; 
         FIG. 11  is a front view of the first step assembly; 
         FIG. 11A  is a view taken along view line  11 A- 11 A in  FIG. 11 ; 
         FIG. 11B  is a view taken along view line  11 B- 11 B in  FIG. 11 ; 
         FIG. 12  is a perspective view of a first locking mechanism; 
         FIG. 13  is a side view of the first locking mechanism illustrated in  FIG. 12 ; 
         FIG. 13A  is a view taken along view line  13 A- 13 A in  FIG. 13 ; 
         FIG. 14  is a perspective view of an upper portion of a second wall of the vehicle including a female portion of the first locking mechanism; 
         FIG. 15  is a perspective view of a portion of the first step including a male portion of the first locking mechanism; 
         FIG. 16  is a view of the second wall of the vehicle illustrating upper and base portions of the second wall, wherein the upper portion pivots relative to the base portion; 
         FIGS. 17 and 18  are perspective views of a first hinge mechanism of the first step assembly; 
         FIG. 19  is a rear view of the first hinge mechanism illustrated in  FIGS. 17 and 18 ; 
         FIG. 20  is a side view of the first hinge mechanism illustrated in  FIGS. 17 and 18 ; 
         FIGS. 21 and 22  are perspective views of the first step assembly and a first microswitch; 
         FIGS. 21A and 22A  are perspective views of the second step assembly and a second microswitch; 
         FIGS. 23 and 24  are perspective views illustrating a camming surface of a first arm and the first microswitch; 
         FIGS. 25 and 26  are front and side views respectively of the camming surface and the first microswitch illustrated in  FIGS. 23 and 24 ; 
         FIG. 27  is a schematic view of a vehicle drive wheel, a traction motor/brake assembly, a processor and the first and second microswitches, all assembled in accordance with a first embodiment of the present invention; 
         FIG. 27A  is a schematic view of a vehicle drive wheel, a traction motor/brake assembly, a processor and first and second proximity sensors, all assembled in accordance with a second embodiment of the present invention; 
         FIG. 28  is a perspective view of first and second step assemblies constructed in accordance with a second embodiment of the present invention; 
         FIGS. 28A and 28B  are exploded views of the second step assembly illustrated in  FIG. 28 ; 
         FIGS. 29 and 30  are perspective views of the first step assembly illustrated in  FIG. 28 ; 
         FIG. 31  is a view of the first step assembly coupled to a second wall of a materials handling vehicle; 
         FIG. 32  is a view taken along view line  32 - 32  in  FIG. 31 ; 
         FIG. 33  is a view taken along view line  33  in  FIG. 31  with the first step in its stowed position and without the second wall illustrated; 
         FIG. 33A  is a view similar to  FIG. 33  but with the first step in its deployed position; and 
         FIG. 34  is a view of the first and second step assemblies of  FIG. 28  coupled to the second wall. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to  FIG. 1 , a materials handling vehicle comprising a low level order picker  10  is illustrated. The vehicle  10  comprises a frame  12  including a power unit  20  containing a traction motor/brake assembly  300  coupled to a drive wheel  22 , see  FIGS. 5 ,  6  and  27 , for driving and braking the drive wheel  22 . The drive wheel  22  is positioned below the power unit  20 . A non-driven caster wheel (not shown) is also positioned below the power unit  20 . A power steering motor (not shown) is provided in the power unit  20  for turning the drive wheel  22 , i.e., to allow the vehicle  10  to be steered. A hydraulic pump/motor (not shown) is also housed within the power unit  20  for providing pressurized hydraulic fluid to a piston/cylinder unit (not shown) for raising and lowering first and second forks  30  and  32  relative to a load backrest  40 . The load backrest  40  comprises part of the vehicle frame  12 . The forks  30  and  32  are illustrated in  FIG. 1  only. A load wheel assembly  30 A,  32 B is coupled to each fork  30 ,  32 . The frame  12  further comprises a battery compartment  50  housing a battery  52 . The battery compartment  50  is provided adjacent the power unit  20 . The battery  52  provides power to the traction motor/brake assembly, the power steering motor, and the hydraulic pump/motor. The frame  12  also includes a walk-through operator compartment  60 , which is positioned between the battery compartment  50  and the load backrest  40 . An operator, when positioned within the operator compartment  60 , may control the speed, braking and direction of the vehicle  10  and the height of the forks  30  via a control handle structure  70 . 
     The walk-through operator compartment  60  may comprise opposing first and second walls  62  and  64  and a floorboard  66 , see  FIGS. 1-6 . The walk-through operator compartment  60  further comprises first and second entrances  68 A and  68 B through which an operator can enter and exit the operator compartment  60 , see  FIGS. 2-6 . 
     The vehicle  10  further comprises, in accordance with a first embodiment of the present invention, first and second step assemblies  80  and  90  and first and second stops  100  and  102  (the stops are not illustrated in  FIG. 1 ), see  FIGS. 2-10 . The first step assembly  80  comprises a first step  82  capable of being pivoted between a deployed positioned where the step  82  is positioned across the first entrance  68 A, see  FIGS. 2-4  and  6 , and a stowed position, where the first step  82  is positioned in a location so as not to block the first entrance  68 A into the operator compartment  60 , see  FIG. 5 . When in the deployed position, a second end  82 B of the step  82 , opposite a first end  82 A of the step  82 , engages or rests upon the stop  100 . The stop  100  is bolted to or otherwise coupled to the first wall  62  at a location on the first wall  62  such that the step  82  is located in a generally horizontal plane. The second step assembly  90  comprises a second step  92  capable of being pivoted between a deployed positioned where the step  92  is positioned across the second entrance  68 B, see  FIGS. 2-4 , and a stowed position, where the second step  92  is positioned in a location so as not to block the second entrance  68 B into the operator compartment  60 , see  FIG. 5 . When in the deployed position, a second end  92 B of the step  92 , opposite a first end  92 A of the step  92 , engages or rests upon the stop  102 . The stop  102  is bolted to or otherwise coupled to the first wall  62  at a location on the first wall  62  such that the step  92  is located in a generally horizontal plane. When the first and second steps  82  and  92  are positioned in their down or deployed positions, they may be positioned above the floorboard  66  a distance of from about 250 mm to about 450 mm. As best viewed in  FIG. 4 , outer edges  82 C and  92 C of the first and second steps  82  and  92  are positioned just adjacent to an outer peripheral edge  10 A of the vehicle  10 . When the first step  82  is in its deployed position, an operator may stand on the step  82  to gain access to an elevated storage location. Likewise, when the second step  92  is in its deployed position, an operator may stand on the step  92  to gain access to an elevated storage location. 
     The first step assembly  80  further comprises a first hinge mechanism  110  for coupling the step  82  to a base portion  64 A of the second wall  64 , see  FIGS. 16 and 17 . The second step assembly  90  further comprises a second hinge mechanism  120  for coupling the step  92  to the base portion  64 A of the second wall  64 , see  FIG. 16 . The second wall  64  defines one wall of the battery compartment  50 . In the illustrated embodiment, the hinge mechanisms  110  and  120  are not coupled to an upper portion  64 B of the second wall. It is also contemplated that the second wall  64  may comprise a single portion; hence, the wall  64  would not include separate base and upper portions  64 A and  64 B but instead would include only a single portion. 
     The first step  82  comprises an outer channel  130  and an inner step plate  132  coupled together via one or more welds  133  located along outer edges  132 A of the step plate  132  and inner edges  130 A of the outer channel  130 , see  FIG. 11A . A polymeric sheet or mat  134  formed, for example, from synthetic rubber, is positioned over the inner step plate  132 , see  FIGS. 11 ,  11 A,  17  and  22 . The mat  134  is coupled to the inner plate  132  via adhesive, bolts or other like fastening mechanisms. A pair of connector arms  182 , each provided with a bore  182 A, see  FIG. 11B , are weldably connected to the outer channel  130 , see  FIG. 22 . The outer channel  130  is not shown in  FIGS. 18 ,  19  and  20 . 
     The first hinge mechanism  110  comprises a main attachment block  112  welded or otherwise coupled to an inner surface  164 A of the second wall base portion  64 A near a first outer edge section  364 A of the second wall base portion  64 A, see  FIGS. 16 and 17 . The inner surface  164 A is opposite an outer surface  264 A, which faces the operator compartment  60 , see  FIG. 16 . A pivot shaft  114  extends through the bores  182 A in the step connector arms  182  and a bore  112 A provided in the main attachment block  112 , see  FIG. 11B . Pins (not shown) may be provided in bores  114 A in the shaft  114  to maintain the shaft  114  in position relative to the connector arms  182  and the main block  112 . First and second of bushings  116  are positioned on the shaft  114  and extend through the bores  182 A in the connector arms  182 . A spring-engagement bracket  118  is coupled to the main attachment block  112  via a pair of bolts  118 A which are threadedly received in openings  112 B in the attachment block  112 , see FIGS.  11  and  17 - 22 . A torsion spring  119  is positioned about the shaft  114 , see  FIGS. 11 ,  11 B and  17 - 22 . The spring  119  is not illustrated in  FIGS. 23-26 . A first end  119 A of the torsion spring  119  engages the bracket  118 , while a second end  119 B of the torsion spring  119  engages the step  82 ; more specifically, an inner surface  132 B of the step plate  132 , see FIGS.  11 A and  17 - 20 . The first hinge mechanism  110  allows the first step  82  to pivot between its down or deployed position where the step  82  is positioned across the first entrance  68 A, see  FIGS. 2-4  and  6 , and its up or stowed position, where the first step  82  is positioned in a location so as not to block the first entrance  68 A into the operator compartment  60 , see  FIG. 5 . The spring  119  defines a biasing element for assisting an operator in moving the step  82  from its down or deployed position to its up or stowed position. 
     The second step  92  comprises an outer channel  140  and an inner step plate  142 , see  FIGS. 21A and 22A , coupled together via one or more welds located along outer edges of the step plate  142  and inner edges of the outer channel  140 . A polymeric sheet or mat  144  formed, for example, from synthetic rubber, is positioned over the inner step plate  142 . The mat  144  is coupled to the inner plate  142  via adhesive, bolts or other like fastening mechanisms. A pair of connector arms  192 , each provided with a bore, are weldably connected to the outer channel  140 . 
     The second hinge mechanism  120  comprises a main attachment block  122  welded or otherwise coupled to the inner surface  164 A of the second wall base portion  64 A near a second outer edge section  364 B of the second wall base portion  64 A, see  FIG. 16 . A pivot shaft  124  extends through the bores in the step connector arms  192  and a bore provided in the main attachment block  122 , see  FIGS. 21A and 22A . Pins (not shown) may be provided in bores  124 A in the shaft  124  to maintain the shaft  124  in position relative to the connector arms  192  and the main block  122 . A pair of bushings (not shown) is positioned on the shaft  124  and extend through the bores in the connector arms  192 . A spring-engagement bracket  128  is coupled to the main attachment block  122  via a pair of bolts  128 A which are threadedly received in openings  122 B in the attachment block  122 . A torsion spring  129  is positioned about the shaft  124 . A first end  129 A of the torsion spring  129  engages the bracket  128 , while a second end  129 B of the torsion spring  129  engages the step  92 ; more specifically, an inner surface of the step plate  142 . The second hinge mechanism  120  allows the second step  92  to pivot between its down or deployed position where the step  92  is positioned across the second entrance  68 B, see  FIGS. 2-4 , and its up or stowed position, where the second step  92  is positioned in a location so as not to block the second entrance  68 B into the operator compartment  60 , see  FIG. 5 . The spring  129  defines a biasing element for assisting an operator in moving the step  92  from its down or deployed position to its up or stowed position. 
     A first locking mechanism  200  is provided for releasably locking the first step  82  in its up or stowed position, see  FIGS. 12 ,  13  and  13 A. A second locking mechanism  230  is provided for releasably locking the second step  92  in its up or stowed position, see  FIG. 21A . The second locking mechanism  230  is constructed in the same manner as the first locking mechanism  200 . Hence, only the first locking mechanism  200  will be described herein in detail. However, one skilled in the art will understand that the second locking mechanism  230  may be constructed in accordance with the description herein of the first locking mechanism  200 . 
     The first locking mechanism  200  comprises a female portion  202  having an inner cavity  204  with a spring  206  mounted in a recess  208  at an entrance  204 A into the inner cavity  204 , see  FIGS. 12 ,  13  and  13 A. The female portion  202  is coupled to the upper portion  64 B of the second wall  64  via a bolt  210  passing through a bore in the second wall upper portion  64 B and threadedly engaging a bore  202 A in the female portion  202 , see  FIGS. 13A and 14 . The first locking mechanism  200  further comprises a male portion  220  coupled to the outer channel  130  of the step  82 , see  FIGS. 11A ,  12 ,  13 ,  13 A and  15 . A nut  222  is threaded onto a shaft  220 A of the male portion  220 , see  FIG. 13A . The nut  222 , in turn, is welded to the outer channel  130  of the step  82 , see  FIG. 11A . When the first step  82  is moved to a nearly vertically position, an operator may apply a force against the step  82  in a direction toward the female portion  202  sufficient to move the step  82  to a generally vertical position and also causing the male portion  220  of the first locking mechanism  200  to pass through the spring  206  and enter into the inner cavity  204  of the female portion  202 , see  FIG. 13A . The spring  206  retains the male portion  220  in the inner cavity  204  until an operator applies a force against the step  82  in a direction away from the female portion  202  sufficient to cause the male portion  220  to exit the inner cavity  204  and, hence, allow the step  82  to be manually pivoted downward to its deployed positioned, see  FIG. 2 . 
     In place of the female and male portions  202  and  220 , it is contemplated that other releasable locking mechanisms such as one or more magnets may be used. 
     As noted above, a traction motor/brake assembly  300  is coupled to the vehicle drive wheel  22  for driving and braking the drive wheel  22 . A controller  302  controls the operation of the fraction motor/brake assembly  300 , see  FIG. 27 . First and second sensors associated with the first and second steps  82  and  92 , respectively, comprising first and second microswitches  304  and  306  in this illustrated embodiment, are coupled to the controller  302 , see  FIG. 27 . The first microswitch  304  is also coupled to the spring-engagement bracket  118 , see  FIGS. 21-23  and  25 , while the second microswitch  306  is also coupled to the spring-engagement bracket  128 , see  FIGS. 21A and 22A . In  FIGS. 24 and 26 , the first microswitch  304  is illustrated but the bracket  118  is not. 
     A first arm  182 ′ of the first step connector arms  182  is provided with a camming surface  382 , see  FIGS. 23-26 . When the first step  82  is located in its stowed position, see  FIG. 5 , the camming surface  382  engages a spring-biased control arm  304 A, forming part of the first microswitch  304 , causing the microswitch  304  to be actuated. When actuated, the microswitch  304  generates a signal to the controller  302  indicating that the first step  82  is in a travel state, i.e., the step  82  is in its stowed position in this illustrated embodiment. However, when the step  82  is rotated counter-clockwise approximately 1 degree from vertical, the camming surface  382  releases the control arm  304 A a sufficient amount to cause the microswitch  304  to be deactuated. When the microswitch  304  is deactuated, it generates a signal to the controller  302  that the first step  82  is no longer in a travel state. 
     A second arm  192 ′ of the second step connector arms  192  is provided with a camming surface  392 , see  FIGS. 21A and 22A . When the second step  92  is located in its stowed position, the camming surface  392  engages a spring-biased control arm  306 A, forming part of the second microswitch  306 , causing the microswitch  306  to be actuated. When actuated, the microswitch  306  generates a signal to the controller  302  indicating that the second step  92  is in a travel state, i.e., the step  92  is in its stowed position in this illustrated embodiment. However, when the step  92  is rotated counter-clockwise approximately 1 degree from vertical, the camming surface  392  releases the control arm  306 A a sufficient amount to cause the microswitch  306  to be deactuated. When the microswitch  306  is deactuated, it generates a signal to the controller  302  that the second step  92  is no longer in a travel state. 
     The controller  302 , in response to operator commands, generates drive signals to the traction motor/brake assembly  300  to drive or effect rotation of the wheel  22  only when it receives signals from both the first and second microswitches  304  and  306  indicating that the steps  82  and  92  are in their travel states, i.e., are in their stowed positions in this illustrated embodiment. However, if the controller  302  receives a signal from the first microswitch  304  that the first step  82  is no longer in a travel state or a signal from the second microswitch  306  that the second step  92  is no longer in a travel state, the controller  302  does not generate a drive signal to the traction motor/brake assembly  300 , i.e., the controller  302  will only permit the traction motor/brake assembly  300  to brake the wheel  22  but will not permit the traction motor/brake assembly  300  to effect rotation of the wheel  22 . When the controller  302  receives a signal from the first microswitch  304  that the first step  82  is no longer in a travel state or a signal from the second microswitch  306  that the second step  92  is no longer in a travel state, it may be preferred for the controller  302  to cause the traction motor/brake assembly  300  to brake the wheel  22 . 
     While the microswitches  304  and  306  have been used as the first and second sensors of the illustrated embodiment, it will be apparent to those skilled in the art from this description that Hall Effect devices, other proximity sensors and/or other devices positioned at other locations relative to the steps  82  and  92 , such as near the second ends  82 B and  92 B of the steps  82  and  92 , may be used as the first and second sensors for the present invention. 
     While not shown in the drawings, it is contemplated that the first and second steps  82  and  92  may slide between deployed and stowed positions. It is also contemplated, that the first and second steps  82  and  92  may be rotated from a horizontal position to a vertical position before being moved into a storage pocket so as to be stowed in a vertical position. After being pulled out of the storage pocket to be deployed, each step  82 ,  92  is rotated from its vertical position to its horizontal position. 
     Alternate control arrangements may be preferred in given applications. For example, it may be desirable to enable an operator to travel with a step  82 ,  92  in its lowered, deployed position if a series of picks were to be performed from a series of elevated storage locations. To accomplish such operation, a sensor can be placed in the step, placed in the stop that supports the step or otherwise be associated with the step so that when the step is deployed the sensor would be activated. Thus, the truck would be enabled to travel when the step is stowed or deployed but not when the step is any position between its stowed and deployed positions. 
     For this mode of operation, it may also be desirable to prevent travel if an operator is using the step. Thus, while the sensor would indicate that the step is deployed, that sensor or another sensor would also indicate if the step is in use, i.e., an operator is standing or otherwise engaging the step with a predefined force, for example by resting a foot on the step, sitting on the step, resting a package or other object on the step and the like. If the step is indicated as being in use, truck travel is not allowed. 
     A single sensor can be used to provide a first signal when the step is deployed, i.e., a force is generated by the weight of the step but no other force is applied to the step, and to provide a second signal if the step is deployed and in use as indicated by a force above a given threshold force, i.e., some force above the weight of the step alone, is being applied to the sensor. For example, the sensor could comprise a three position switch that closes (or opens) on contact in response to the weight of a deployed step to generate the first signal and closes (or opens) a second contact in response to an increased weight to generate the second signal. 
     In this embodiment, a “travel state” is generated when the step is in its deployed position as indicated by the first signal but not when the step is in use as indicated by the second signal. For this embodiment, the step stowed sensor can also be used so that the “travel state” is also generated when the step is stowed. 
     Alternately, a sensor can be positioned in the step, for example, a device such as a weight sensing piezoelectric element or the like can be incorporated into the step to sense deflection of the step with deflection created by deployment of the step generating the first signal and further deflection created by additional weight being applied to the step beyond a given point corresponding to a predetermined force applied to the step such as a force that would be created by an operator resting a foot or standing on the step, generating the second signal. A pressure sensor mounted on the upward facing surface of the step under the step mat can be used to generate the second signal in response to pressure applied to the upward surface of the step, for example by an operator standing on the step mat. 
     Here again, a “travel state” is generated when the step is in its deployed position as indicated by the first signal but not when the step is in use as indicated by the second signal. For this embodiment, the step stowed sensor can also be used so that the “travel state” is also generated when the step is stowed. 
     Also, one or more sensors sensitive to weight can be positioned at a hinge mechanism  110 ,  120  of a step  82 ,  92 . 
     First and second step assemblies  480  and  490  and first and second stops  500  and  502  constructed in accordance with a second embodiment of the present invention are illustrated in  FIG. 28 . The first step assembly  480  comprises a first step  482 , see  FIGS. 28-30 , capable of being pivoted between a deployed position where the step  482  is positioned across a first entrance of an operator compartment (not shown in  FIGS. 28-30 ) and a stowed position where the first step  482  is positioned in a location so as not to block the first entrance into the operator compartment. The operator compartment may be defined by opposing first and second walls, such as the first and second opposing walls  62  and  64  illustrated in  FIGS. 1-6 . When in the deployed position, a second end  482 B of the step  482 , opposite a first end  482 A of the step  482 , engages or rests upon the stop  500 . The stop  500  is bolted to or otherwise coupled to the first wall of the operator compartment at a location on the first wall such that the step  482  is located in a generally horizontal plane when deployed. When the first step  482  is in its deployed position, an operator may stand on the step  482  to gain access to an elevated storage location. 
     The second step assembly  490  comprises a second step  492 , see  FIG. 28 , capable of being pivoted between a deployed positioned where the step  492  is positioned across a second entrance of the operator compartment and a stowed position where the second step  492  is positioned in a location so as not to block the second entrance into the operator compartment. When in the deployed position, a second end  492 B of the step  492 , opposite a first end  492 A of the step  492 , engages or rests upon the stop  502 . The stop  502  is bolted to or otherwise coupled to the first wall of the operator compartment at a location on the first wall such that the step  492  is located in a generally horizontal plane. When the second step  492  is in its deployed position, an operator may stand on the step  492  to gain access to an elevated storage location. 
     The first step assembly  480  further comprises a first hinge mechanism  510  for coupling the step  482  to a base portion  664 A of the second wall  664  of the operator compartment, see  FIGS. 31 ,  32  and  34 . The second step assembly  490  further comprises a second hinge mechanism  520  for coupling the step  492  to the base portion  664 A of the second wall  664 , see  FIG. 34 . The second wall  664  defines one wall of a battery compartment  650 . 
     The first step  482  comprises an outer channel  530  and an inner step plate  532 , see  FIG. 28 , coupled together via one or more welds (not shown) located along outer edges of the step plate  532  and inner edges of the outer channel  530 . A polymeric sheet or mat  534  formed, for example, from synthetic rubber, is positioned over the inner step plate  532  and comprises a gripping portion  534 A extending over a tab  482 C defined by ends of the outer channel  530  and the inner step plate  532 , see  FIGS. 28 and 32 . The tab  482 C and the gripping portion  534 A define the second end  482 B of the step  482 . The gripping portion  534 A, because it is formed from a sound absorbing polymeric material, functions to reduce sound which may be generated when the step  482  makes contact with the stop  500 . The mat  534  may be coupled to the inner plate  532  and the tab  482 C via adhesive, bolts or other like fastening mechanisms. 
     The first step  482  further comprises first and second connector arms  582  and  584 , each provided with a bore  582 A,  584 A, see  FIG. 28 . The first and second connector arms  582  and  584  are coupled to the outer channel  530 . 
     The first hinge mechanism  510  comprises a main attachment block  512  coupled via bolts  512 A to an outer surface  664 B of the base portion  664 A of the second wall  664 , see  FIGS. 31 ,  32  and  34 . The main attachment block  512  is provided with a pair of arms  513 , each provided with a bore  513 A, see  FIG. 28 . A pivot shaft  514  extends through the bores  582 A,  584 A in the first and second connector arms  582  and  584  of the first step  482  and the bores  513 A in the arms  513  provided as part of the main attachment block  512 , see  FIGS. 28 and 33 . A pin or a set screw  514 A extends through the shaft  514  and is coupled to one of the main attachment block arms  513  so as to maintain the shaft  514  in position relative to the main attachment block  512 . 
     First and second of bushings  516 A and  516 B are positioned on the shaft  514  and extend through the bores  582 A,  584 A in the first and second connector arms  582 ,  584 , see  FIGS. 28 and 33 . The bushings  516 A,  516 B permit the first and second connector arms  582 ,  584  and, hence, the step  482 , to rotate relative to the shaft  514  and the main attachment block  512 . A tube  519 A is fitted over the shaft  514  and positioned between the first and second bushings  516 A and  516 B. A torsion spring  519  is positioned about the shaft  514  and the tube  519 A, see  FIGS. 28 and 33 . A first end  519 B of the torsion spring  519  is received in an opening  512 B in the attachment block  512 , while a second end  519 C of the torsion spring  519  engages the step  482 , see  FIGS. 28  and  33 A. 
     The first hinge mechanism  510  allows the first step  482  to pivot back and forth between its down or deployed position where the step  482  is positioned across the first entrance into the operator compartment and its up or stowed position, where the first step  482  is positioned in a location so as not to block the first entrance into the operator compartment. The spring  519  defines a biasing element for assisting an operator in moving the step  482  from its down or deployed position to its up or stowed position. 
     The second step  492  comprises an outer channel  540  and an inner step plate  542 , see  FIGS. 28 and 28A , coupled together via one or more welds located along outer edges of the step plate  542  and inner edges of the outer channel  540 . A polymeric sheet or mat  544  formed, for example, from synthetic rubber, is positioned over the inner step plate  542  and comprises a gripping portion  544 A extending over a tab  492 C defined by ends of the outer channel  540  and the inner step plate  542 , see  FIGS. 28 ,  28 A and  28 B. The tab  492 C and the gripping portion  544 A define the second end  492 B of the step  492 . The gripping portion  544 A functions to reduce sound which may be generated when the step  492  makes contact with the stop  502 . The mat  544  may be coupled to the inner plate  542  and the tab  492 C via adhesive, bolts or other like fastening mechanisms. 
     The second step  492  further comprises first and second connector arms  592  and  594 , each provided with a bore  592 A,  594 A, see  FIG. 28A . The first and second connector arms  592  and  594  are coupled to the outer channel  540 . 
     The second hinge mechanism  520  comprises a main attachment block  522  bolted via bolts  522 A to the outer surface  664 B of the base portion  664 A of the second wall  664 , see  FIG. 34 . The main attachment block  522  is provided with a pair of arms  523 , each provided with a bore  523 A, see  FIGS. 28A and 28B . A pivot shaft  524  extends through the bores  592 A,  594 A in the first and second connector arms  592  and  594  of the second step  492  and the bores  523 A in the arms  523  provided as part of the main attachment block  522 . A pin or a set screw  524 A extends through the shaft  524  and is coupled to one of the main attachment block arms  523  so as to maintain the shaft  524  in position relative to the main attachment block  522 . 
     First and second of bushings  526 A and  526 B are positioned on the shaft  524  and extend through the bores  592 A,  594 A in the first and second connector arms  592 ,  594 . The bushings  526 A,  526 B permit the first and second connector arms  592 ,  594  and, hence, the step  492 , to rotate relative to the shaft  524  and the main attachment block  522 . A tube  529 A is fitted over the shaft  524  and positioned between the first and second bushings  526 A and  526 B. A torsion spring  529  is positioned about the shaft  524  and the tube  529 A. A first end  529 B of the torsion spring  529  is received in an opening  522 B in the attachment block  522 , while a second end  529 C of the torsion spring  529  engages the step  492 . 
     The second hinge mechanism  520  allows the second step  492  to pivot between its down or deployed position where the step  492  is positioned across the second entrance into the operator compartment and its up or stowed position, where the second step  492  is positioned in a location so as not to block the second entrance into the operator compartment. The spring  529  defines a biasing element for assisting an operator in moving the step  492  from its down or deployed position to its up or stowed position. 
     A first locking mechanism  600  is provided for releasably locking the first step  482  in its up or stowed position or its down or deployed position, see  FIGS. 28 and 32 . A second locking mechanism  630  is provided for releasably locking the second step  492  in its up or stowed position or is down or deployed position. The second locking mechanism  630  is constructed in the same manner as the first locking mechanism  600 . Hence, only the first locking mechanism  600  will be described herein in detail. However, one skilled in the art will understand that the second locking mechanism  630  may be constructed in accordance with the description herein of the first locking mechanism  600 . 
     The first locking mechanism  600  comprises a magnet  602  coupled via a bolt  604  to an extension  531  of the outer channel  530 , see  FIG. 32 , and is positioned within an opening  532 A in the inner step plate  532 , see  FIG. 28 . The mat  534  covers the magnet  602 . When the step  482  is positioned in its up or stowed position, the magnet  602  attracts to an opposing protruding section  664 C of the second wall  664  so as to releasably hold the step  482  in its stowed position, see  FIG. 32 . 
     The stop  500  comprises a block  500 A and a rubber stop element  501  secured to the block  500 A via bolts  501 A, see  FIG. 28 . When the step  482  is moved to its deployed position, the stop element  501  cushions a final impact of the step  482  with the stop  500 . The stop  502  comprises a block  502 A and a rubber stop element  503  secured to the block  502 A via bolts  503 A, see  FIG. 28A . When the step  492  is moved to its deployed position, the stop element  503  cushions a final impact of the step  492  with the stop  502 . 
     As noted above, a traction motor/brake assembly  300  is coupled to the vehicle drive wheel  22  for driving and braking the drive wheel  22 . A controller  302  controls the operation of the fraction motor/brake assembly  300 , see  FIG. 27A . In the second embodiment, the first and second sensors associated with the first and second steps  482  and  492 , respectively, comprise first and second proximity sensors  804  and  806 , see  FIG. 27A . The sensors  804  and  806  are coupled to the controller  302 . The first proximity sensor  804  is also coupled to a first holding bracket  805  via bolts  804 A and the second proximity sensor  806  is coupled to a second holding bracket  807  via bolts  806 A, see  FIG. 28 . The first holding bracket  805  is coupled to inner surface of the second wall  664  via bolts  805 A and the second holding bracket  807  is coupled to the inner surface of the second wall  664  via bolts  807 A, see  FIG. 34 . The inner surface of the second wall  664  is opposite the outer surface  664 B, shown in  FIG. 34 . 
     The second connector arm  584  of the first step  482  comprises a flag  584 B, see  FIGS. 30 ,  33 ,  33 A. When the first step  482  is located in its stowed position, see  FIGS. 31 ,  32  and  33 , the flag  584 B is positioned directly across from the proximity sensor  804 , causing the proximity sensor  804  to be actuated. When actuated, the proximity sensor  804  generates a signal to the controller  302  indicating that the first step  482  is in a travel state, i.e., the step  482  is in its stowed position in this illustrated embodiment. However, when the step  482  is rotated between about 1 and 10 degrees and preferably about 5 degrees from vertical, the flag  584 B is rotated a sufficient amount to cause the proximity sensor  804  to be deactuated. When the proximity sensor  804  is deactuated, it generates a signal to the controller  302  that the first step  482  is no longer in a travel state. In  FIG. 33A , the step  482  is shown in its deployed position where the flag  584 B is positioned a sufficient distance away from the proximity sensor  804  such that the proximity sensor  804  is deactuated. 
     The second connector arm  594  of the second step  492  comprises a flag  594 B, see  FIGS. 28A and 28B . When the second step  492  is located in its stowed position, the flag  594 B is positioned directly across from the proximity sensor  806 , causing the proximity sensor  806  to be actuated. When actuated, the proximity sensor  806  generates a signal to the controller  302  indicating that the second step  492  is in a travel state, i.e., the step  492  is in its stowed position in this illustrated embodiment. However, when the step  492  is rotated between about 1 and 10 degrees and preferably about 5 degrees from vertical, the flag  594 B is rotated a sufficient amount to cause the proximity sensor  806  to be deactuated. When the proximity sensor  806  is deactuated, it generates a signal to the controller  302  that the second step  492  is no longer in a travel state. 
     The controller  302 , in response to operator commands, generates drive signals to the traction motor/brake assembly  300  to drive or effect rotation of the wheel  22  only when it receives signals from both the first and second proximity sensors  804  and  806  indicating that the steps  482  and  492  are in their travel states, i.e., are in their stowed positions in this illustrated embodiment. However, if the controller  302  receives a signal from the first proximity sensor  804  that the first step  482  is no longer in a travel state or a signal from the second proximity sensor  806  that the second step  492  is no longer in a travel state, the controller  302  does not generate a drive signal to the traction motor/brake assembly  300 , i.e., the controller  302  will only permit the traction motor/brake assembly  300  to brake the wheel  22  but will not permit the traction motor/brake assembly  300  to effect rotation of the wheel  22 . When the controller  302  receives a signal from the first proximity sensor  804  that the first step  482  is no longer in a travel state or a signal from the second proximity sensor  806  that the second step  492  is no longer in a travel state, it may be preferred for the controller  302  to cause the traction motor/brake assembly  300  to brake the wheel  22 . 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.