Abstract:
An exercise treadmill in which the slope of an endless belt is varied by changing the height of one end of a base frame by means of a swing frame having a vertically adjustable pivot axis. The swing frame is movable from an active treadmill supporting position to an inactive condition where the pivot axis can be changed.

Description:
DESCRIPTION 
     1. Technical Field 
     The present invention relates to portable exercise treadmills of the type having an endless motor-driven belt with an upper run on which the exerciser walks, jogs or runs, and more particularly relates to such a treadmill in which the endless belt may be given an adjustable slope. 
     2. Background Art 
     The support frames of portable exercise treadmills have commonly had short ground engaging legs of adjustable height for leveling the frame, but these have not been intended for use in intentionally sloping the frame to responsively slope the endless belt and thereby simulate an uphill condition. Some treadmills have had slope adjustment by simultaneously vertically extending a pair of legs by various mechanisms operated, for example, by hand crank or power driver. 
     3. Disclosure of the Invention 
     The present invention aims to provide an adjusting mechanism whereby the height of the forward end of a treadmill can be easily adjusted without loss of stability to slope the endless belt within a range of several slope settings not involving the extension or retraction of legs. 
     In carrying out the invention there is provided a front swing frame having a pair of horizontally aligned trunnions which have several height settings by way of groups complementing vertically-spaced fulcrums provided in a pair of side plates mounted on the support frame of the treadmill. These fulcrums consist of downwardly facing gullets formed at the front of a forwardly and downwardly sloped slot or recess in the side plates serving as a transferway between the gullets. The swing frame has wheels at the bottom which roll rearwardly alongside the treadmill frame responsive to pivoting of the swing frame induced by manually pulling forwardly on the swing frame above the level of the side plates until the wheels are rearward of the transferways so that they can be manipulated into another pair of gullets to provide the desired treadmill slope. Then the swing frame is pushed rearwardly at the top thereby causing the wheels to roll forwardly beyond the transferways and causing the top of the swing frame to engage stops located rearwardly of the transferways. The weight of the treadmill then keeps the trunnions engaged within the selected gullets. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a treadmill embodying the present invention. 
     FIG. 2 is a detailed fragmentary side elevational view of a forward portion of the treadmill as viewed from the left side. 
     FIG. 3 is a fragmentary bottom view beneath the portion shown in FIG. 2. 
     FIG. 4 is a fragmentary front view of the portion shown in FIG. 2. 
     FIGS. 5-7 are schematic views illustrating the procedure for adjusting the treadmill from a level condition (minimum slope) to a maximum slope condition. 
    
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     Referring to the drawings, the present invention is illustrated applied, for example, to an exercise treadmill having a base frame 20 with longitudinal side rails 21 between which an endless belt 22 is mounted on cross-rollers 23. The belt 22 is driven at the front by a cog-belt drive from a variable speed electric motor covered by a front housing 24. Upstanding rigidly from the side rails 21 is a bar frame unit 26 which includes a pair of sloped legs 26a between which is mounted a top cross-bar 26b and a control panel 27. This control panel typically has a speed control switch for the motor, an on/off switch, and a timer. Depending from the side rails 21 are front feet 28 and rear adjustable leveling feet 29. 
     In accordance with the present invention, a pair of side fulcrum plates 30, 31 are mounted at the ends of the front housing 24 outboard of the legs 26a and side rails 21. These side plates are rigidly connected to the base frame 20, as by lateral flanges 33 and 33a straddling and bolted to the side rails 21, and may gain lateral support from the bar unit 26. Near the front, the side plates 30, 31 have an outwardly exposed, elongated cutout or recess 32 which has a back ramp edge 32a sloping generally like the adjacent legs 26a of the bar unit 26, and has a wavy front edge generally sloping in parallel relation to the back edge 32a. This wavy front edge has a series of fulcrum gullets 32b separated by a series of dowwnardly hooked retaining teeth 32c which are spaced forwardly of the back edge 32a by a sloped guideway 32d closed top and bottom. The gullets 32b are rounded at the under side of the teeth 32c, and the guideway 32 d is slightly wider between the teeth 32c and the back ramp edge 32a than the diameter of the curvature of the upper portions of the gullets 32b. 
     For operation with the fulcrum plates 30, 31, there is provided a front swing frame 34 which comprises an inverted U-shaped tubular member providing an upper crossmember 34a and a pair of depending legs 34b which are connected to a bottom transverse tubular axle 35. This axle projects laterally at each end to receive a pair of wheels 36. The legs 34b have a pair of opposed trunnions 38 which project into the cutouts 32 in the side plates 30, 31 to selectively occupy the gullets 32b. The distance from the trunnions 38 to the axle 35 is sufficient compared to the distance from the top gullets 32b to the underside of the front end of the base frame 20 to permit the axle 35 to clear the front end of the base frame 20 when the trunnions occupy the top gullets and the lower end of the frame 34 is swung past the forward end of the side rails 21. The swing frame 34 is preferably provided with a pair of U-shaped spring clips 40 positioned to grip the legs 26a of the front bar frame 26 when the desired height adjustment has been obtained. 
     It will be noted that the bar frame legs 26a and the side plate cutouts 32 slope forwardly in the down direction. This arrangement positions the gullets 32b forwardly of the portions of the frame legs 26a which are higher than the side plates 30, 31. Hence, locking engagement of the spring clips 40 with the front bar legs 26a can occur only when the axle 34b is positioned forwardly of the particular gullets 32b occupied by the trunnions 38. In other words, the axis of the wheels 36 will always be &#34;over center&#34;, forwardly of the selected swing axis of the swing frame 34, when the swing frame is in locked position with its wheels in floor engagement supporting the forward part of the treadmill. It will be apparent that the weight of the treadmill and the person exercising will act to keep the swing frame in locked position while the treadmill is in operation. 
     As indicated in FIG. 5, when, for example, it is desired to raise the elevation of the front of the treadmill to thereby change the slope of the belt 22, the exerciser takes a position in front of the machine, grips the cross-bar 34a, and pulls forwardly to disengage the spring clips 40 and swing the swing frame 34 about its trunnions 38. This swinging movement causes the wheels 36 to roll rearwardly on the floor. The forward pulling on the cross-bar 34a is continued until the axle 35 passes beneath the forward end of the base frame 20 and swings rearwardly sufficiently for the load of the forward part of the treadmill to transfer from the wheels 36 to the forward feet 28. At that point, as indicated in FIG. 6, the swing frame 34 can be easily manipulated to move the trunions 38 up or down in the guideway portion 32d of the recesses 32 in the side plates until the trunnions 38 reach the mouth of the two gullets 32b at opposite sides corresponding to the desired slope of the belt 22. The operator then pushes upwardly and rearwardly on the cross-bar 34a, thereby causing the wheels to roll forwardly, take the load back from the forward feet 28, and continue to pass &#34;over center&#34; forwardly beyond the base frame 20 until the spring clips engage the bar frame legs 26a so that the bar-frame unit 26 then functions as a stop unit with respect to the swing frame 34. FIG. 5 illustrates the position at minimum belt slope (level) and FIG. 7 shows the position of maximum belt slope. 
     The wheels 36 not only assist in ease of operation of the swing frame 34, but also make it easier to move the treadmill, if desired, since the treadmill can be wheeled about when the rear end is lifted sufficiently to take the weight off the rear feet 29. 
     From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims.