Abstract:
A seat platform for industrial and agricultural vehicles capable of supporting a seat for forward and rearward movement characterized by low cost and ease of assembly of a seat mount plate with a base plate wherein linear tracks defined on the seat mount plate cooperate with linear guides formed on the base plate.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention pertains to vehicle seat supports permitting adjustment in forward and rear directions wherein the seat may be locked in a predetermined position. 
     2. Description of the Related Art 
     Industrial and agricultural vehicles such as lift trucks, tractors, garden tractors, mowers, and the like, include a seat for the operator that is often pivotally mounted to the vehicle adjacent the seat front end whereby the seat may be pivoted in a partially inverted relationship, usually for the purpose of protecting the seat from weather conditions. Further, such vehicle seats are sometimes adjustable in forward and rearward directions to provide maximum comfort for the operator to accommodate longer and shorter limbs. Forward and rearward seat adjustment movement is often accomplished through track and guide arrangements existing between components mounted upon the vehicle, and those affixed to the vehicle seat. 
     In known vehicle seat constructions of this type, assembly of the vehicle mounted portions of the seat structure with the seat mounted portions often are difficult to accomplish because of clearance and access limitations. Also, the assembly of the seat to its vehicle mounted structure is often difficult and care must be taken to insure that the assembly is proper so that limited movement of the seat adjustment is maintained for safety purposes. 
     Additionally, vehicles seats of the above type capable of forward and rearward adjustment usually utilize relatively expensive components to achieve adjustment difficult to manufacture and assemble. 
     OBJECTS OF THE INVENTION 
     It is an object of the invention to provide a vehicle seat platform support which is of economical construction, permits forward and rearward adjustment of the seat, and permits the seat to be easily assembled to its platform in a locked condition between its operable limits of adjustment. 
     Another object of the invention is to provide a seat platform for vehicles which permits the platform to be pivotally mounted adjacent its forward region, and yet permits the seat to be adjusted in forward and rearward directions between limits, and a detent is employed to lock the position of the seat supporting platform at a location intermediate its maximum limits of adjustment. 
     Yet a further object of the invention is to provide an adjustable seat platform for vehicles capable of adjustable movement in forward and rearward directions wherein the components are of low cost but of high strength, and wherein those components directly associated with the seat may be easily mounted upon the vehicle supported components which will automatically be locked upon the vehicle component upon assembly therewith. 
     SUMMARY OF THE INVENTION 
     Preferably, the seat structure platform described below is mounted for pivotal movement at its front edge so that the vehicle seat may be tilted forwardly to a partially inverted orientation to protect the seat from weather conditions or for access purposes. However, it will be appreciated that the seat platform of the invention may be directly mounted on the vehicle in a non-pivotal manner. 
     The primary component of the adjustable seat platform is a flat base plate formed of stamped steel having front and rear ends, a central region between the front and rear ends, upper and lower sides and parallel lateral edges extending between the front and rear ends. The base plate is preferably formed by a stamping operation of steel, and the lateral edges are formed as flanges including a riser extending above the central region, and the riser terminates in lips which extend away from the base plate central region and each have a linear edge, the lips of the base plate are parallel and form guides or ways. 
     The base plate central region is lanced to provide an upstanding detent shoulder which functions as a stop, and a plurality of spaced detent shoulders, which may be defined by holes, are formed in one of the lateral edge risers intermediate the base plate front and rear ends. 
     A pair of tabs lanced from the central region extend downwardly from the base plate at the lateral edges adjacent the front end, and these tabs may be pivotally connected to a pivot bracket mounted upon the vehicle by pivot pins wherein the base plate is capable of pivotal movement adjacent its front end. 
     The vehicle seat, not shown in the drawings for purposes of clarity, is mounted upon a seat mount plate of flat configuration which also includes front and rear ends, a central region, upper and lower sides and lateral edges. The lateral edges of the seat mount plate are parallel to each other, and are, preferably, formed in a downward manner and shaped to define U-shaped tracks adapted to extend over the base plate lips. Preferably, a non-metallic bearing material, preferably of a thermoplastic nature, is mounted upon the base plate lips and is located between the base plate lips and the seat mount plate tracks whereby the seat mount plate will be movable upon the base plate in forward and rear directions in a smooth, relatively noiseless manner. 
     The seat mount plate includes a spring engageable shoulder lanced from the seat mount plate central region extending from the lower side thereof forming a shoulder stop surface spaced from and parallel to the seat mount plate rear end. A leaf spring affixed to the base plate adjacent the base plate rear end includes a free front end extending above the base plate upper surface an extent higher than the vertical dimension of the base plate risers wherein, upon inserting the seat mount plate tracks upon the base plate lips at the rear end of the base plate, movement of the seat mount plate toward the base plate front end will cause the spring engageable shoulder of the seat mount plate to engage and depress the leaf spring permitting the shoulder to ride over the leaf spring to assemble the seat mount plate to the base plate as desired. Once the leaf spring passes the spring engageable shoulder, the leaf spring will move upwardly into an abutting relationship with the shoulder to limit rearward movement of the seat mount plate on the base plate. 
     Also, the spring engageable shoulder extends downwardly toward the base plate upper surface sufficiently to permit engagement of the shoulder with the base plate stop abutment, which will limit forward movement of the seat mount plate on the base plate. Of course, the spring engageable shoulder and the stop abutment will be spaced sufficiently from the rear edge of the seat mount plate and the front edge of the base plate, respectively, to permit a liberal extent of forward and rearward movement of the seat mount plate on the base plate to adjust the seat location for a particular operator, yet maintain sufficient engagement between the seat mount plate and the base plate to adequately support the seat mount plate and vehicle seat for safety purposes. 
     Adjustment of the seat mount plate intermediate its maximum forward and rearward positions is achieved by a detent lever pivotally mounted to the underside of the seat mount plate. The detent lever includes a handle portion extending beyond the front end of the seat mount plate as to be accessible to the operator, and the lever also includes a detent selectively engageable with a detent shoulder defined upon the base plate lateral edge riser. An extension spring biases the detent lever in a direction tending to engage the detent with a detent shoulder. 
     Because the seat mount plate may be easily mounted to the underside of the seat structure, and because the seat mount plate may be easily assembled to the base plate merely by sliding the seat mount plate over the rear end of the base plate, the adjustable seat platform of the invention permits the seat structure to be readily mounted upon the vehicle, the stop structure provides important safety features as it limits movement of the seat mount plate on the base plate, and the stamped configuration of the components permits the components to be manufactured at a relatively low cost. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The aforementioned objects and advantages of the invention will be appreciated from the following description and accompanying drawings wherein: 
     FIG. 1 is a perspective view of an adjustable seat platform in accord with the invention, the seat mount plate being assembled to the base plate and illustrated in an intermediate position thereon, 
     FIG. 2 is a top plan view of the base plate, per se, prior to assembly of the seat mount plate thereon, 
     FIG. 3 is a perspective view of the base plate, per se, and the pivot bracket, 
     FIG. 4 is a side elevational view of the structure shown in FIG. 3 as taken from the right of FIG. 3, 
     FIG. 5 is a top plan view of the seat mount plate, per se, the dotted lines illustrating seat mount plate structure located on the underside of the seat mount plate, and 
     FIG. 6 is an elevational sectional view of the spring engageable shoulder as taken along Section  6 — 6  of FIG.  1 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The assembled adjustable seat platform generally indicated at  10  is shown in FIG. 1, and the basic components of the seat platform include a base plate  12 , a seat mount plate  14 , and a pivot bracket  16 . These components are described in detail below. 
     The base plate  12  is of a stamped steel construction and includes a front end edge  18  and a rear end edge  20  located between a flat central region  22  having an upper side  24  and a lower side  26 . The base plate  12  central region includes parallel lateral edges in the form of flanges  28  extending upwardly with respect to the upper side  24 , and the flanges  28  extend between ends  18  and  20 . Each flange includes a riser  30  from which a lip  32  extends. The lips  32  formed on the two risers  30  extend away from each other and away from the central region  22 . Each lip  32  terminates in a linear edge  34 . 
     Preferably, a thermoplastic bearing material  36 , such as U-shaped extrusion of nylon or the like, is mounted over the lips  32  and the edges  34 , FIG. 3, for a purpose later described. 
     A stop abutment  38  is lanced from the base plate central region  22  in an upward direction extending above upper side  24  and the stop abutment  38 , as will be appreciated from FIG. 3, has a length extending parallel to the flanges  28 . 
     Further, a plurality of evenly spaced detent holes  40  are defined in one of the flange&#39;s riser  30 , FIGS. 3 and 4, forming shoulders at right angles to the length of the associated flange. 
     A pair of pivot tabs  42  are defined adjacent the base plate front edge  18  from the material of the central region  22  as will be appreciated from FIGS. 2 and 3. The pivot tabs  42  are in alignment with a flange riser  30  and extend below the central region lower side  26 . A pivot pin hole is defined in each pivot tabs  42 . 
     A leaf spring  44  is attached to the base plate upper side  24  intermediate the base plate flanges  28  by fasteners  46 . The leaf spring  44  includes a cantilevered free end  48  normally located spaced above the central region upper side  24 , FIGS. 3 and 6, having a downwardly extending portion which serves to abut a stop shoulder as later described. 
     The seat mount plate  14  is best shown in FIGS. 1 and 5, and consists of a flat stamped steel member adapted to be attached to the bottom of a seat, not shown. The seat mount plate  14  includes a front end edge  50 , a rear end edge  52 , and a flat central region  54  having an upper side  56  to which the seat, not shown, is affixed by fasteners extending through the central region  54 . 
     The lower side of the central region  54  is represented at  58 , and each lateral edge of the central region  54  consists of a U-shaped track  60  which extends below the lower side  58 . The tracks  60  each define a U-configuration void which encompasses the lips  32  of the flanges  28  of the base plate  12 , and the bearing material  36  mounted upon the lips as will be apparent from FIG.  1 . In this manner, the seat mount plate  14  is reciprocally mounted upon the base  12  for movement in a linear forward and rear direction, and the presence of the bearing material  36  makes this movement smooth and relatively noiseless in view of the self-lubricating aspect of the bearing material  36 . 
     A spring shoulder  62  is lanced from the base plate central region  54  and extends downwardly from the lower side  58 . The spring shoulder  62 , as apparent in FIGS. 1 and 5, is spaced from the seat mount plate rear end edge  52  and is substantially parallel thereto. 
     A detent lever  64  is pivotally mounted upon the seat mount plate lower side  58  by a pivot  66 , FIG.  5 . The lever  64  includes a handle  68  which extends beyond the front end edge  50 , FIG. 5, and is thereby accessible to the vehicle operator mounted upon the seat. The lever  64  also includes a pair of detents  70 , and a tension spring  72  biases the lever  64  in the clockwise direction, FIG. 5, to bias the detents  70  toward the adjacent base plate flange  28  in which the detent holes  40  are formed. The spacing between the detents  70  and the detent holes  40  are equal wherein the two detents  70  will be received within two holes  40  when aligned, and thereby lock the seat mount plate  14  with respect to the base plate  12 . 
     In most instances, it is desirable that the vehicle seat mounted upon the platform  10  be pivotal in a forward direction in order to protect the seat from weather, or to provide clearance during maintenance of the vehicle, as is commonly known. In such instance, the pivot tabs  42  are mounted on the pivot bracket  16  by the pivot bracket columns  74  having holes therein for receiving the pivot pins  76 . The base of the bracket  16  includes mounting holes wherein the bracket may be bolted to the vehicle seat supporting surface, not shown, such as a transmission casing, housing, or the like. 
     In use, the pivot bracket  16  will be mounted to the base plate  12  to produce the assembly shown in FIG.  3 . At this time, the seat mount plate  14  is not mounted upon the base plate  12  but bracket  16  may be bolted to the vehicle, not shown. 
     The seat mount plate  14  is then bolted to the bottom of the vehicle seat, not shown, by fasteners extending through the seat mount plate central region  54  so that the seat will be engaging upper side  56 . Once the seat is mounted upon the seat mount plate  14  and side  56 , the front end  50  of seat mount plate  14  can be aligned with the base plate rear end edge  20  so that the tracks  60  will receive the base plate lips  32  having the bearing material  36  mounted thereon. Once the tracks  60  are properly aligned with the lips  32 , the seat mount plate  14  may be moved forwardly over the base plate  12 . Such forward movement causes the spring shoulder  62  to engage the upstanding free end  48  of the leaf spring  44  depressing the spring end  48  so that the spring shoulder  62  will pass over the spring end  48 . Once the shoulder  62  has cleared the spring end  48 , the spring will be resiliently biased upwardly to be on a horizontal orientation with the shoulder  62  as will be appreciated from FIG.  6 . Accordingly, rearward movement of the seat mount plate  14  on base plate  12  is limited by engagement of the spring free end  48  with the spring shoulder  62 . 
     The spring shoulder  62  will also engage the stop abutment  38  to limit forward movement of the seat mount plate  14  on base plate  12 , and the spring shoulder  62  and stop abutment  38  are spaced apart a distance sufficient to permit the desired movement of the seat mount plate  14  on base plate  12  between its maximum forward and rearward positions. 
     During adjustment of the seat mount plate  14  on base plate  12 , the lever  64  will be pivoted in a counterclockwise direction, FIG. 5, to remove the detents  70  from the detent holes  40 , and once the desired seat position is achieved, the handle  68  may be released to permit the detents  70  to enter detent holes  40  and thereby lock the relative position of the plates  12  and  14 . 
     As the primary components of an adjustable seat platform in accord with the invention can be economically formed of sheet steel by known stamping and forming procedures, an economical platform is achieved capable of forward and rear adjustment, and wherein significant interconnection exists between the base plate  12  and seat mount plate  14  to meet safety requirements. As the seat mount plate  14  only needs to be slipped onto the base plate  12  from the rear of the base plate, it is possible to quickly assemble the seat structure to the base plate  12 , for shipping purposes or the like. If it is desired to remove the seat mount plate  14  from base plate  12 , a tool, such as a screwdriver, may be inserted between the plates  12  and  14  over the base plate rear end  20  to depress the leaf spring front end  48  sufficiently to permit the spring shoulder  62  to pass over the spring end  48 . 
     It is appreciated that various modifications to the inventive concepts may be apparent to those skilled in the art without departing from the spirit and scope of the invention.