Abstract:
A lift truck cab having front, side, and rear faces, and a roof, mounting structure attached to the roof for suspending the cab from a mast of the lift truck in a manner that permits the front and side faces when installed on the truck to be hung in the manner of curtains without the necessity of direct fastening of lower portions of the front and side faces to the chassis/body of the truck. The cab construction affords generous operator space, high visibility, a convenient electrical raceway and ready access to truck control circuitry.

Description:
BACKGROUND OF THE INVENTION 
   The invention relates to lift truck cabs and, in particular, to cabs for lift trucks designed for rear ingress and egress by the operator. 
   PRIOR ART 
   Lift trucks designed for general utility are often used in freezer environments. For operator comfort and increased productivity, it is desirable that the lift truck be fitted with a heated cab so that the operator can more readily endure the cold environment. It is axiomatic that productivity can be improved when a heated cab is available since the need for warm-up periods for the operator during a work shift can be reduced or eliminated. 
   Lift trucks are largely designed primarily for use in moderate environments and climates and consideration of cab integration can be limited so that later cab design can be complicated and/or difficult. Current chassis/body design of material handling trucks frequently emphasizes a “soft” look that avoids angular shapes and favors generous curves on the exterior of the chassis/body. 
   In large warehouse applications and, particularly, in commercial freezer buildings, floor space for goods is maximized and paths or aisles for material handling trucks are minimized. This translates into truck designs that must be compact to fit the allotted aisle clearances. It can be difficult to construct a cab for a compact truck because the area allotted to the operator is deliberately minimized and add-on cab structure seemingly must encroach on the operator&#39;s space. A continuing factor in the design of a lift truck cab is that the safety requirements for protecting the operator from falling objects must be met. 
   SUMMARY OF THE INVENTION 
   The invention involves a cab for a lift truck that is especially suited for compact or narrow aisle units where the operator stands or leans on a seat of limited size. The disclosed cab has its sides constructed as curtains suspended from an overhead guard which, in turn, is suspended from the truck mast. The curtain-like construction of the cab where the weight of the side panels is largely supported from above, greatly reduces the time and complexity of installation of the cab. For the most part, modification of the chassis/body upon installation of the cab is largely eliminated and only a limited number of bolts are required to accomplish the assembly procedure. 
   The cab follows the convention of a walk-on rear entry to the operator station typically used in narrow isle truck designs. A full height door closes the entry to the operator station. The door is framed by a unique door jamb that can strengthen the overhead guard structure by vertically supporting the guard from a plane spaced considerably rearwardly of the mast. A threshold, forming part of the door jamb, is conveniently attached to a lower rear face of the truck chassis/body. The threshold is configured with a cantilevered geometry that advantageously adds space to the cab interior. The side panels, for the most part, comprise steel sheet stock to which is mounted transparent window material. The side panels are wrapped about generally vertical lines to avoid angular corners and to stiffen the panels so that space robbing heavy structural posts and horizontal box-like frame members can be avoided. A front windshield panel, bolted directly to the front face of the cab leaves the operator with generous space while allowing ready replaceability of this important component. The overhead or curtain suspension of the cab leaves the lower front panel free of fasteners or direct support from the chassis/body. This structural separation allows a panel that closes the lower front of the cab to be flipped up out of its closed position for immediate access to the circuitry that controls the truck functions for diagnosis, service and/or repair. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a left rear perspective view of a cab constructed in accordance with the invention mounted on a lift truck; 
       FIG. 2  is a right rear perspective view of the cab and lift truck; 
       FIG. 3  illustrates the main mounting structure of the cab on the lift truck; 
       FIG. 4  illustrates secondary mounting structure for mounting the cab on the lift truck; 
       FIG. 5  is a cross-sectional view of the secondary mounting structure taken in the plane  5 - 5  indicated in  FIG. 4 ; 
       FIG. 6  is a fragmentary perspective view of a portion of the front of the cab; 
       FIG. 7  is a top view of the cab; 
       FIG. 8  is a fragmentary perspective view of the lower portion of the front of the cab as viewed from the interior; 
       FIG. 9  is a fragmentary cross-sectional view of the lower portion of the cab taken along the lines  9 - 9  in  FIG. 8 ; 
       FIG. 10  is a perspective view of a portion of the inside upper front part of the cab; and 
       FIG. 11  is a schematic plan view illustrating the relative locations of the truck mast, front window divider, and operator station. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to the drawings, a cab  10  encloses an operator station  15  on a lift truck  11 . The illustrated lift truck  11  is generally conventional in construction being particularly suited for narrow aisle use and being driven by electric motors powered by on-board batteries. The principles of the invention are applicable to other types of lift trucks. The truck  10  has rear, steerable propulsion wheels  12  and front wheels  13 , and a mast  14  on which the lift forks are supported for vertical movement and, when a reach truck, for horizontal movement. 
   The cab  10  has four generally vertical faces  16 - 19 , and a top  20 . The illustrated cab is fabricated primarily of hot-rolled steel sheet stock. The front and side faces  16 ,  17  and  18  extend downwardly from the top or roof  20 , roughly ½ of the height or elevation of the cab to a chassis/body  26  of the lift truck  11 . The rear face  19  of the cab  10  has a left portion extending downwardly from the top  20  to the level of the bottom of the left face  17  and a right portion that extends downwardly to the level of the floor  27  of the truck ( FIG. 5 ). 
   The top or roof  20  is a welded assembly of an overhead guard  28  and a roof panel  29  of sheet steel. The guard  28  comprises a set of parallel spaced bars  31  aligned front to back of the cab, i.e. aligned with the longitudinal axis of the truck  11 , held within a perimeter frame  32  of steel bar stock. The guard  28 , which can be an original equipment part, overlies the operator station  15  to protect the operator from falling objects. The roof panel  29  is fixed to the guard  28  by welding inverted U-shaped brackets  33  between the guard and the panel. The vertical flanges of the U-shaped brackets  33  spread the weight of the cab  10  over a relatively large area of the roof panel  29 . This serves to resist premature fatigue failure that might otherwise occur in this welded-up area. 
   The roof panel  29  is cut out to provide three lights or windows  35  which are individually glazed with transparent sheet material  34 , preferably polycarbonate, a plastic. The transparent panels or panes  34  are mounted in conventional extruded elastomeric molding. 
   The sides  16 - 19  of the cab  10  are welded to and extend downwardly, in the manner of a curtain, off the periphery of the top panel  29 . The contours of the side faces  17 ,  18  and rear face  19  follow the profile of the top panel  20 . The forward portions of the side faces  16 ,  17  are generally planar, while the rearward portions are curved about vertical axii in the manner of a column. The rear face  19  of the cab is curved at the left and right to merge with the corresponding cab faces  17  and  18 . The front face  16  of the cab  10  is generally flat or planar and is formed of sheet metal strips arranged in a rectangular border and in an off center strip  36  dividing the front face into two main window openings or lights  37 ,  38 . A single sheet  39  of transparent material, such as polycarbonate, covers both of the lights  37 ,  38 . The glazing sheet is fixed to the outside of the sheet metal forming the cab front face  16  by screws  41 . The front side or face  16  is configured so that the glazing sheet  39  is closely adjacent to the mast  14  to maximize the space afforded to the operator. The bolts or screws  41  enable the sheet to be removed and replaced with less effort than would be needed with traditional extruded rubber molding set into the window cut outs as is conventional. 
     FIG. 11  is a diagrammatic plan view of the lift truck  11  with the front face  16  of the cab  10  shown just behind the mast  14  which has left and right portions  14   a  and  14   b .  FIG. 11  schematically illustrates how the location of the off center or asymmetric front window dividing strip  36  is advantageously located in the line of sight  90  from the operator&#39;s station  15  to the left hand mast assembly or column  14   a . As shown, the operator station  15  is asymmetric relative to the longitudinal centerline of the truck  11 . When an operator, diagrammatically shown at  91 , looks in the direction of the left mast portion or assembly  14   a  the image of the dividing strip  36  is superimposed on the image of the left mast portion so that the dividing strip avoids a reduction in the field of view forward of the mast  14 . 
   A narrow light  42  at an inclination of about 45° from the horizontal is formed by a cut-out in the roof panel  29  and by bending the surrounding part of the panel downwardly out of the horizontal plane of the main part of the panel. The light or window  42  is glazed with a transparent sheet  45 , preferably polycarbonate, attached to the outer surface of the roof panel  29  by screws. The side faces  17 ,  18 , front face  16 , and portions of the rear face  19 , are fabricated of steel sheet stock welded together and are largely devoid of any heavy angle, channel, or box-type reinforcement. The sides  17 ,  18  are provided with generous side windows or lights  43 ,  44  glazed with a transparent sheet material such as polycarbonate. The illustrated windows  43 ,  44  are fitted with elastomeric moldings for attaching the transparent sheets at the window openings  43 ,  44 . Lower edges  46 ,  47  of the cab sides or faces  17 ,  18 , are complementary in shape to the upper surfaces of the truck chassis/body and are fitted with suitable weatherstrip material (not shown) to seal against drafts. The rear side or face  19  is asymmetrical with the right portion including a full length door  48 , and a left portion descending from the roof panel  29  to an elevation of the adjacent part of the left face  17 . 
   Rounded or wrap-around corners between the sides  17 ,  18  and rear  19  generally conform to the configuration of the chassis/body in plan view, thus carrying out is “soft” shape. This configuration avoids sharp corners and reduces the risk of injury to personnel or property in the event a corner is accidentally struck. Horizontal strips  51  of sheet metal, widely spaced vertically from one another, wrap around the corners between the side faces  17 ,  18  and rear face  19 . The corners are glazed with transparent flexible sheet stock  52 ,  53  bent to conform to the respective corner curve. The horizontal strips  51  constrain the transparent window sheets  52 ,  53 , and permit them to be cold formed in place on the inside of the strips  51  to the desired curved shape by constraining this flexible sheet material to the rigid form of the strips  51 . This technique avoids the risk of distortion and diminished clarity attendant with hot forming the window material. These rear corner window sheets  52 ,  53  are held in place by screws or bolts secured to the side and rear sheet metal cab faces. 
   The door  48  is preferably a weldment of sheet steel with suitable channel or angle along its periphery and/or double wall construction to achieve adequate strength. A vertical piano hinge  56  at the right of the door  48  mounts the door to a door jamb  57 . Suitable weatherstripping is provided to seal the door  48  to the jamb  57 . A door handle/latch mechanism  58  releasably holds the door  48  against the door jamb  57 . A large window  59  glazed with a transparent medium, preferably polycarbonate, takes up most of the upper half of the door to provide generous rear vision for the operator. 
   The guard  28  and, as disclosed, the remaining part of the cab, is rigidly fixed and thereby suspended from the mast  14  by bolts  61  that pass through a front plate  62  of the guard and a bracket  63  welded to the rear of the mast. Note that the front plate  62  is directly abutted against the mast bracket  63 . This connection between the guard  28 , integrally welded with the remainder of the cab  10 , and the mast bracket  63  is sufficiently strong and rigid to support the entire cab  10  enabling the cab faces  16 - 19  to hang as curtain walls from the top panel or roof  29  and be free of other structural attachments to the truck apart from the auxiliary connection adjacent the bottom of the door jamb  57 . With reference to  FIGS. 4 and 5 , the cab  10  includes a threshold assembly  66  contoured to fit the shape of the truck chassis/body at the foot step entrance to the operator station  15 . The threshold assembly  66  is a weldment of steel sheet stock comprising a horizontal step plate  67  and a generally vertical mounting plate  68  braced by gussets  69 ,  70 . Bolts  76  are assembled through holes in the threshold mounting plate  67  into threaded holes in the chassis/body of the truck  11  for fixing the assembly  66  to the chassis/body. The connection of the threshold assembly  66  afforded by the bolts  76  stabilizes the lower end of the cab  10  distal from the mast  14  and preferably is the sole connection between the cab  10  and truck  11  apart from the described mounting of the guard  28  to the mast  14 . The box-like structure of the cab walls or faces  16 - 19  obviates a necessity for otherwise attaching or fixing parts of the cab such as the side faces to adjacent parts of the truck  11 . The mast  14  supplies the primary support for the cab  10  and is only supplementarily supported at the threshold assembly  66  remote from the mast attachment. The cab  10  is conveniently assembled onto the truck  11  by temporarily supporting it from above with straps, cables, or the like, coupled to lifting eyes  78 , welded on the channels or brackets  33  at the longitudinal center of gravity of the cab  10 . With the cab temporarily supported by the lifting eyes  78  so that it hangs in a vertical orientation, the bolts  61  can be assembled in the mast bracket  63  and the bolts  76  in the threshold support plate  68  can be assembled in respective holes thereby accomplishing the mechanical installation of the cab  10  on the truck  11 . 
   Referring to  FIG. 8 , a lower part of the front  16  is a hinged sheet metal panel  79  having a plurality of horizontally arrayed cut-outs  81  glazed with a single sheet  80  of transparent material, preferably polycarbonate, screwed to its outer face. The cut-outs or windows  81  provide for visibility towards the floor in front of the lift truck  11 . The panel  79  is hinged with a horizontal piano hinge  82 , which permits the panel to flip inward towards the interior of the cab and then upward through an arc of approximately 180° to a retracted position, shown in phantom, thereby permitting access to a service area of the lift truck control system. This pivotal retraction of the lower panel  79  is accomplished without tools in a quick flip-up motion, thereby facilitating inspection, diagnosis, and/or repair of underlying parts of the lift truck. 
     FIG. 10  illustrates the relationship of the front window off-center dividing strip  36  and its integration with an electrical raceway  86  that runs along the roof panel  29  between two of the roof lights. As shown in the broken-away area of the raceway  86 , the raceway cross-section is J-shaped with a gap  87  at one side to permit assembly of control wires for fans and heaters, for example. It will be seen that the raceway  86  is conveniently in vertical alignment with the off-center strip  36 , thereby allowing the control wires to conveniently be contained in a vertical raceway  88  attached to the inside surface of the off-center strip. 
   It should be evident that this disclosure is by way of example and that various changes may be made by adding, modifying or eliminating details without departing from the fair scope of the teaching contained in this disclosure. The invention is therefore not limited to particular details of this disclosure except to the extent that the following claims are necessarily so limited.