Abstract:
A backboard arm is pivotally mounted to a mast member rearwardly offset from the ground supported mast member in which a jack is internally positioned for extending upwardly out of the upper end for engagement with the backboard arm extending over and outwardly thereof. The jack operates in compression and is substantially concealed from sight.

Description:
BACKGROUND OF THE INVENTION 
     The regulation height for a basketball backboard and rim is too high for small children interested in playing the game. A backboard that is readily adjustable from lower heights to the regulation height is desirable. Backboards that are adjustable in heights are known but involve complicated, unattractive adjustment mechanisms mounted on the outside of the support mast. What is needed is an easily operated, internally mounted adjustment mechanism integrated into the mast of an adjustable basketball goal. 
     SUMMARY OF THE INVENTION 
     The mast is hollow and contains a screw jack adjustment mechanism which extends out the top and engages the backboard arms for raising and lowering the backboard. The backboard arms are pivotally connected to a mast member horizontally offset from the ground engaging mast member thereby giving the jack leverage when raising and lowering the lift arms. The jack operates in compression when raising the backboard lift arms and thereby minimizes any risk of injury by the lifting mechanism failing as would be the case in a cable-type operated lifting mechanism. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary perspective view of the adjustable basketball goal. 
     FIG. 2 is a side elevation view thereof showing the adjustable basketball goal in several positions at different heights. 
     FIG. 3 is a fragmentary side elevational view taken along line 3--3 in FIG. 1 showing the mast pivotal connection to the ground anchor base for erecting the adjustable basketball goal. 
     FIG. 4 is a cross-sectional view taken along line 4--4 in FIG. 3. 
     FIG. 5 is a fragmentary side elevational view taken along line 5--5 in FIG. 4. 
     FIG. 6 is a fragmentary side elevational view of the jack inside the mast member. 
     FIG. 7 is a side elevational view taken along line 7--7 in FIG. 6. 
     FIG. 8 is a cross-sectional view taken along line 8--8 in FIG. 6. 
     FIG. 9 is a fragmentary side elevational view showing a peep hole in the mast for viewing the height measurement scale carried on the extendable rod of the jack. 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     The adjustable basketball goal of this invention is referred to generally in FIG. 1 by the reference numeral 10 and includes a first hollow mast member 12 to which a horizontal second mast member 14 is connected. A third mast member 16 parallel to the first mast member 12 extends upwardly from the rear end of the second mast member 12 and pivotally supports a pair of vertically spaced apart upper and lower basketball goal yoke arms 18 and 20. The yoke arms 18 and 20 are vertically spaced apart in a parallelogram relationship. The backboard pivot arms are connected to the backboard 22 which includes a basket rim 24. 
     A screw jack 26 of conventional design is positioned in the hollow first mast member 12 and includes an extendable rod 28 received in a stationery base 30 pivotally connected by a bracket 32 to a pivot pin 34 mounted by screws 35 to the sidewall 36 of the first mast member 12. As seen in FIG. 8 the jack 26 will pivot about an axis 40. The upper end of the extendable rod 28 is connected to the lower backboard arm 20 which extends over and beyond the first mast member 12. It is seen that the hollow first mast member 12 is sufficiently large in cross sectional area to allow the pivoting of the jack 26. A crank handle 42 on the outside of the first mast member 12 is operatably connected to the screw jack 26 by the handle 42 extending through the sidewall 36 of the hollow first mast member 12 and engaging a stem 44. 
     A U-shaped display plate 46 is seen in FIGS. 6 and 7 connected by legs 48 to the extendable rod 28 and thus moves with it as it moves up and down as the jack 26 is operated. A peep hole 49 in the sidewall of the first mast member 12 as seen in FIG. 9 exposes for viewing a height measurement scale 50 on the plate 46 and thus visually indicates the relative height of the basket rim 24 which is seen in FIG. 2 in its lowered six foot height position, midway eight foot position and in its upper ten foot height position. 
     A spacer support post 60 is positioned under the jack 26 as seen in FIG. 1 and extends to the ground and includes plates 62 on opposite ends. It is thus seen that should the jack mounting bracket 32 fail the backboard 22 would not crash down on the users since the jack could not fall within the first mast member 12 as it would be positively supported by the support post 60. 
     A fourth mast member 64 is pivotally connected by a hinge 66 to the first mast member 12. The mast member 64 is buried in the ground 67 as seen in FIG. 2 and with the adjustable basketball goal 10 being laid out on the ground horizontally as fragmentally shown in FIG. 3, it can be readily raised to its operable vertical position by pivoting it upwardly from the horizontal dash line position to the vertical raised solid line position. When fully raised bolts 68 are used to connect hinge plates 70 and 72 on the bottom of the first mast member 12 and on the top of the fourth member 64. 
     As seen in FIG. 5, a drain weep hole 74 is located in the sidewall of the first mast member 12. 
     Thus in operation it is seen that a streamlined in appearance adjustable basketball goal has been provided which is foolproof in operation and includes an internally mounted jack 26 which operates in compression in raising the backboard 22. Through operation of the crank 42 the rim 24 can be positioned as seen in FIG. 2 at any one of an infinite number of height positions. When not in use the crank handle 42 can be removed to further improve the appearance of the structure and avoid unauthorized operation of the jack. Ease of erecting the basketball goal is made possible through the provision of the hinge 66 connecting the bottom base plate 70 of the first mast member 12 to the top base plate 72 of the fourth mast member 64 anchored in the ground.