United States Patent 3554541

An exercise treadmill with an endless belt disposed on rollers to present a walking surface in an inclined plane, the belt having an inwardly projecting ridge at its longitudinal center line; which ridge provides an upwardly convex walking surface between the upstream and downstream ends of said treadmill, and also retains the endless belt in longitudinal alignment by virtue of annular aligning grooves in the rollers located at the upstream and downstream ends of the walking surface.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
198/837, 474/167
International Classes:
A63B22/02; A63B21/22; (IPC1-7): A63B23/06
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US Patent References:

Foreign References:
Primary Examiner:
Oechsle, Anton O.
Assistant Examiner:
Shapiro, Paul E.
I claim

1. A treadmill which includes:

2. A treadmill as described in claim 1 in which said frame comprises side members which are each provided with a series of spaced notches corresponding to the ends of each roller axis, and adapted to provide bearing accommodations of a shaft end of one of said rollers, all of said notches being upwardly open; and a pair of retaining plates, one for each of said side members, each of said retaining plates being disposed longitudinally on said side members above said notches, and adapted to retain said roller shafts in said notches.

3. A treadmill as described in claim 1 in which a flywheel is mounted on the end of the shaft of said upstream end roller, outboard of one side of said frame, said flywheel having sufficient mass to impart a substantially smooth continuous movement to said endless belt when it is being driven by the walking action of a user.

4. A treadmill as described in claim 1 which includes a handrail support disposed in a vertical plane at the longitudinal center line of said frame, said support being anchored to the upstream end of said frame, and extending upwardly downstream the upstream end of said walking plane; and a handrail supported at handrail elevation by said handrail support, said handrail being parallel with the transverse dimension of said frame, and at a handrail elevation above the upstream end of said walking surface.

This invention relates generally to exercise treadmills of the type used in gymnasiums, health clubs, and sanitaria to provide a controlled form of exercise within a confined indoor space. More particularly, the invention relates to such a treadmill in which a novel combination of internally ridged endless belt with two different types of supporting rollers serve to provide both an upwardly convex walking surface and retension of longitudinal alignment of the belt during movement.

Exercise treadmills are well known, but heretofore, all those available on the market have been of relatively expensive and complex construction. Cheaply constructed treadmills have heretofore failed to perform the desired controlled exercise function, have frequently developed certain failures of structure within the short period used, and have proven both unreliable and sometimes unsafe.

Typically, exercise treadmills comprise an endless belt movably supported on rollers in some type of frame, with an upper belt surface, herein referred to as the walking surface, disposed in an inclined plane. The person exercising on the treadmill steps into the walking surface and walks uphill causing the upper side of the endless belt to move from an elevated "upstream" end of the treadmill to a relatively lower "downstream" end of the treadmill, the latter being rearward of the walking person.

It is important that the treadmill present some frictional resistance which must be overcome by the exercising person, but at the same time, the moving system of the treadmill must store sufficient kinetic energy so that, once started, it has some tendency to persist in movement. The latter feature is necessary in order that the exercising person may experience a continuous walking action, instead of a series of jerks and fresh starts with each step. In short, an exercise treadmill must strike a medium between being so easily movable as to be dangerous, and so resistant to movement that continuous walking on it cannot be achieved.

Unfortunately, the balance between resistance to movement, and continuity of movement under treading action, has proven difficult to incorporate in a low cost treadmill. Simple and inexpensive exercise treadmills of the past have tended to become unusable after relatively short periods of use. Most of the difficulties have been traceable to wear of the belt system. Such wear is inevitable in any treadmill.

The treadmill of the present invention has overcome the difficulties encountered in the past with small treadmills by introducing a belt and roller design which insures a long period of satisfactory operations, despite continuing wear of the parts. Whereas similarly constructed treadmills of the past have radically altered after a short period of wear, the treadmill of the present invention may be used for a long period of time, and may experience extensive wear, while continuing to maintain substantially the same performance as when it was new.

Small exercise treadmills of the past have tended to develop wear of the moving endless belt, so that this belt fairly soon began to exhibit upturning edges along the sides, and a worn depressed area in the center. At the same time, wear and imbalance of the endless belt cause it to develop a tendency to wander to one side or the other, introducing a new element of wear and friction because of belt misalignment. In the treadmill of the present invention, the endless belt is provided with an internally projecting ridge at the longitudinal center line. In the system of supporting rollers, the two end rollers, the upstream end roller and the downstream end roller, are provided with annular grooves, at the longitudinal center line of the walking surface, so as to keep the belt in longitudinal alignment. Obviously, not much walking occurs over these two rollers. None of the intermediate rollers, which carry most of the walking, have any grooves; instead, these rollers carry the ridged center part of the belt in a manner which produces a slightly convex walking surface. The latter feature insures that despite continuing wear, the right and left edges of the belt always fit flat and close to the rollers on which they are moving.

The foregoing and other preferred novel features will be understood from the following description of a preferred specific embodiment, which description should be read with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an exercise treadmill constructed according to the invention;

FIG. 2 is a plan view of the treadmill of FIG. 1, with part of the treadmill belt broken away to reveal roller construction;

FIG. 3 is a left side elevational view of the treadmill of FIGS. 1 and 2; FIG. 4 is a sectional view through the forward part of the treadmill of FIG. 1, taken at a vertical longitudinal central plane, as indicated by and in the direction indicated by the arrows 4-4 in FIG. 1; and

FIGS. 5 and 5A are transverse sectional views taken, respectively, at the transverse planes normal to the inclined plane of the treadmill, indicated by the numbers 5-5 and 5a-5a in FIG. 4.

In FIG. 1, a treadmill constructed according to the invention is indicated generally by the numeral 10. The basic structure of treadmill 10 is a rectangular wood frame 11, which is comprised principally of right and left side members, 12 and 13, respectively, and upstream and downstream end members 14 and 15, respectively. The upper surfaces of frame 11 are disposed in an inclined plane, indicated in FIG. 4 by the numeral 16, hereinafter referred to as "walking plane" 16.

FIGS. 1 and 2 show that frame 11, in the preferred form illustrated, is substantially longer than it is wide; frame 11 may be described as having a longitudinal dimension parallel with side members 12 and 13, and longitudinal center line 17 (seen in FIG. 2), and a transverse dimension at right angles in a horizontal plane, to said longitudinal dimension.

Frame 11 encloses a rectangular opening 20 in the walking plane 16. An endless belt 21 is supported in opening 20 by a relatively large number of rollers 22, which are disposed transversely in frame 11, substantially at walking plane 16.

Each of the rollers 22 is carried on a shaft 23, each roller and shaft being rotatable as a unit, shaft 23 being rotatably mounted, at its ends, in right and left frame side members 12 and 13. Preferably, each shaft end, 23a is received in an upwardly open notch 24 in the upper edge of one of side members 12 and 13, as seen in transverse cross section in FIG. 5A. Notches 24, in transversely opposite pairs, are provided for each of the shafts 23, at a spacing which disposes rollers 22 in parallel position across opening 20 as illustrated in plan view of FIG. 2. Preferably, all of the shaft ends 23a at one side of frame 11, are retained in their notches 24 by a single cover plate 25, which may be the side parts of a rectangular angle iron frame 26 (see FIG. 1) attached to the upper edges of wooden frame 11 by means of screws 27. The use of angle iron frame 26 as a unitary retaining cover for all of the shaft ends 23a greatly simplifies manufacturing assembly and also repair of treadmill 10.

FIGS. 2 and 4 show that belt 21 forms a longitudinally disposed loop extending from upstream end roller 22a to downstream end roller 22b. Belt 21 is seen to have an upper reach 21a, lying substantially in the walking plane 16, and a lower reach 21b, located below walking plane 16 by a distance approximately that of the diameter of rollers 22. Belt 21 has an outer walking surface 31, and an inner roller-contacting surface 32 (FIGS. 5 and 5A). Inner surface 32 is provided down its longitudinal center line with en endless alignment ridge 33. Upstream and downstream end rollers, 22a and 22b, respectively, have annular grooves 34 and 35, located in the vertical plane at longitudinal center line 17. Ridge 33 mates with groove 34 and 35, and by this means, belt 21 is retained in substantially perfect longitudinal alignment on rollers 22, despite long periods of usage and accompanying wear.

It will be seen from FIGS. 2 and 4, however, and also from the transverse sectional views FIGS. 5 and 5A, that all the rollers 22 which lie intermediate the upstream and downstream end rollers 22a and 22b, are uniform cylinders, and do not have any central groove corresponding to annular grooves 34 and 35. The consequence of this is that belt 21 presents an upwardly convex surface is illustrated in FIG. 5A, along upper reach 31, which surface may be designated as walking surface 36.

A person wishing to use treadmill 10 for exercise, steps onto walking surface 36 and begins walking in an uphill direction at inclined walking plane 16. The person's walking action causes the upper reach 31 of belt 21 to move backward and downstream in the direction of the arrow 40. The walking surface 36 should be at a convenient step-height elevation above the floor upon which treadmill 10 is resting, and from which the person using the treadmill must step. No precise height or inclination of walking plane 16 is required, provided the treadmill 10 be convenient for the person using it to mount. Upstream end member 14 may be set to be at some unspecified step-height, meaning that a person can readily step onto surface 36 in a single step. The inclination of walking plane 16 is a few degrees only, so that a person may stand on walking surface 36 at rest, with comfort.

Preferably, the longitudinal dimension of frame 11 is substantially greater than the longitudinal dimension of walking surface 36, in order to impart stability to treadmill 10. Rubber feet 41 may be employed under the four corners of frame 11 to prevent movement of treadmill 10 over the floor during use.

At the upstream and downstream ends of the frame opening 20, it is desirable to provide upstream and downstream platform members 42 and 43, which serve not only to provide structural rigidity to frame 11, but also to provide a secure stationary platform at each end of movable belt 21, upon which a person may step if he finds himself stumbling or insecure, during use of treadmill 10. A flywheel 44 is carried on a projecting end 45 of the shaft 23 of upstream roller 22a, being keyed to said shaft, and adapted to rotate outboard of left side member 13, when belt 21 and rollers 22 are placed in motion by a person walking on walking surface 36. Flywheel 44 makes the movement of belt 21 substantially continuous, so that the person using treadmill 10 will feel walking surface 36 continuously moving smoothly downstream, without jerky stops and interruptions. Also, flywheel 44 has sufficient mass to present some resistance to the starting movement of belt 21. Without it, there would be a danger that a person using treadmill 10 might step on the walking surface 36, and might fall because of immediate backward, unresisted, movement. The presence of flywheel 44 gives the person an opportunity to step on walking surface 36 with less danger of falling.

An additional safety feature is a handrail 46 disposed at approximately waist height or any convenient handrail height, above the upstream end of walking surface 36. Handrail 46 is preferably supported at the top of rigid steel pipe column, which is securely anchored near upstream end of member 14, at a point on longitudinal center line 17 of frame 11. In the preferred form illustrated, pipe column 47 extends vertically upward from a point forward of the walking surface 36, and backwards as indicated by bend 48, to present handrail 46 at a point safely downstream from the extreme upstream end of treadmill 10. In the cross-sectional view of FIG. 4, the column 47 is seen to be anchored by means of a plate 49 on upstream platform member 42, and said column being anchored at its lower end to upstream end member 14 by means of a bolt 50.

Treadmill 10 is seen to have a number of advantageous features for manufacture, adjustment, and repair. Flywheel 44 is placed outboard of the frame 11 so that the best weight can be experimentally determined and the flywheel easily changed. Also, it will be apparent from the cross-sectional view of FIG. 4 that the elevation of handrail 46 can be changed readily by shifting the vertical location of bolt 50.

Angle iron frame 27 may be quickly unscrewed from frame 11 exposing all the shaft ends 23a of roller shafts 23. This facilitates replacement of belt 21, when necessary, or the selective replacement of individual rollers 22.

The most advantageous novel feature of the invention, however, is the upwardly convex walking surface 36, best seen in the transverse cross-sectional view of FIG. 5A.

There is a tendency in exercise treadmills for wear to occur at the central area of the treadmill belt, with two undesirable consequences: First, the operation of the treadmill begins to deteriorate rapidly with wear of the belt, since the characteristics of contact and friction between the inner surface of the belt and the surface of the rollers begins to undergo continuous radical change. In the design of the invention, this is avoided, since throughout almost all the wearing life of belt 21, the contact with rollers 22 is always essentially the same; it is a contact between the side edges of belt 21 and ridge 33 with the surfaces of rollers 22. Secondly, conventional treadmill belts, as they become worn in the center area, tend to have side edges which are loose, so that an opening appears at the sides of the treadmill belt between the inner surface of the belt and the adjacent surface of the rollers. There is a danger that a person trying to mount the treadmill will catch the toe of his foot under the uplifted edge of the belt, and thereby trip and fall. In treadmill 10 however, the side edges of belt 21 are pressed closely against the surfaces of rollers 22, at all stages of wear; longitudinal central ridge 33 thus insures against the development of loose side edges on belt 21.

Finally, it has been found that the upwardly convex shape of walking surface 36 makes it easier for the person using treadmill 10 to keep his path of travel along longitudinal center line 17, with his right and left foot continuously seeking the right and left half of the walking surface 36. As soon as a person strays to one side of the center line 17, he experiences a warning discontinuity of treading action, as one foot encounters the uplifted center portion of walking surface 36.

It will be seen from the foregoing, that the treadmill of the invention, as disclosed by a typical embodiment, provides a treadmill of great stability and adjustability, which retains its original design characteristics of operation after long periods of wear.