US 3923316 A
A ski structure is provided including a frame which includes a pair of rigid side plates, a plurality of reinforcing strut members extending between said side plates, and a support platform extending between said side plates, and a plurality of wheel assemblies secured to and extending between said side plates and longitudinally spaced therealong.
Description (OCR text may contain errors)
United States Patent [1 1 Birnbaum et al.
[ 1 Dec. 2, 1975 I 1 GRASS-SKI [76} Inventors: Richard S. Birnbaum, 111 E. 64th Ave., Philadelphia, Pa. 19120; Bruce H. Birnbaum, 13540 Youngwood Turn, Bowie, Md. 20715  Filed: Dec. 27, 1973  Appl. No.: 428,711
 US. Cl. 280/11.22
 Int. Cl. A63C 17/04  Field of Search..... 280/11.22, 11.1 BT, 11.1 R,
 References Cited UNITED STATES PATENTS 880,519 3/1908 Graffenberger 280/7.l3 954,993 4/1910 Peters 280/11.22 X 1,428,210 9/1922 Boche 280/1 1.22
1,801,205 4/1931 Miriclc 280/1122 X 2,644,692 7/1953 Kahlert 280/11.22 3,282,598 ll/1966 Goodwin 280/11.22 X 3,722,900 3/1973 Dickert 280/11.1 BT X FOREIGN PATENTS OR APPLICATIONS 453,425 9/1936 United Kingdom 280/l1.22 247,346 10/1963 Australia 280/11.1 BT
Primary ExaminerRobert R. Song Attorney, Agent, or FirmFidelman, Wolffe & Leitner  ABSTRACT A ski structure is provided including a frame which includes a pair of rigid side plates, a plurality of reinforcing strut members extending between said side plates, and a support platform extending between said side plates, and a plurality of wheel assemblies secured to and extending between said side plates and longitudinally spaced therealong.
6 Claims, 6 Drawing Figures US. Patent Dec. 2, 1975 Sheet 1 of2 3,923,316
I :0 F103 A v ZL////// US. Patent Dec.2, 1975 Sheet 2 of2 3,923,316
SAMPLE 1 SAMPLE 2 8m U. U
GRASS-SKI BACKGROUND OF THE INVENTION It is another object of the invention to provide a means to permit ski resorts to operate throughout the entire year.
It is a further object to enable the beginner to learn to ski more easily because the skier automatically develops the technique of parallel skiing.
It is still another object to provide means for skiing on grass using conventional ski equipment such as ski boots and bindings.
It is another object of the invention to make possible the enjoyment of the sport of skiing in areas never before possible because cold weather and snow are not necessary in the practice of the instant invention.
These, together with other objects and advantages which will become apparent in the details of construction and operation are more fully described and claimed hereina ter.
For a more detailed description of the invention, reference is made to the following specification and drawings in which:
FIG. 1 is a side elevational view of the ski;
FIG. 2 represents a bottom plan view of the ski shown without wheels;
FIG. 3 represents a partial bottom plan view showing the placement of wheels and spacers on the individual axles;
FIG. 4 is an enlarged partial plan view of the wheel and axle assembly;
FIG. 5 is a perspective view of one embodiment of the ski showing sample support struts and axle mountings; and
FIG. 6 shows a few modified wheel diameter and wheel assembly profile variations without spacers.
DESCRIPTION OF THE PREFERRED EMBODIMENTS The grass-ski unit includes a frame member 1, a plurality of wheel assemblies 2 and a ski boot holder 3.
The frame 1 is constructed with side plates 4, struts 5 and a ski boot holder platform 6. The struts S are located at various points along the ski to give the frame rigidity. The lower most struts, as seen in FIG. 5, add this rigidity and substantiallyprevent cambering of the lower edge of the side plates. The over-all length of the ski may be varied to provide the proper stability to keep the user from tipping over and falling.
For a more detailed description of the wheel assemblies 2, reference is made to the view of FIG. 4. An axle shaft 7 extends between aligned apertures in the side plates 4 perpendicular to the longitudinal axes of the ski. A fastener 8 and locking pin 9 serve to secure the axles 7 in position. A plurality of cylindrical sectional wheels 10 are mounted on the axle 7 and are separated from each other and the side plates 4 by spacer rings 1 1 FIG. 4) are located longitudinally along the length of the ski. The multiple wheel assemblies 2, provided with the spacers 11 allow for slippage or different relative velocities between the individual wheels 10 to allow the operator to turn and provide minimum friction while in operation. The multiple wheel assemblies serve to provide low friction movable support points that allow an operator to move downhill at a high rate of speed unaffected by uneven surfaces in the terrain.
The multiple wheel assemblies may be resiliently mounted between said side plates through aligned elongated apertures in said side plates using a resilient fastener and locking device. This mounting means provides for a slight vertical movement of the entire assembly, thereby further minimizing the effects of rough terrain.
The preferred number of wheel assemblies is generally less than 20; the most preferred number of wheel assemblies being between 8 and 16 inclusive.
In the preferred embodiment, steel was chosen for strength and low cost in construction of the frame and axles while nylon was chosen for the wheels and spacers to provide a tough abrasion and cut resisting surface while at the same time being self-lubricating to enhance the low-fiction characteristics and requirements.
Alternate materials could be utilized in the construction of the frame. A few examples include reinforced plastic, cast or injection molded plastic, aluminum alloys, mangesium alloys, copper alloys, and brass and stainless steel alloys. The wheels and spacers could also be made of wood, steel or plastic and may not have separate sleeve bearings, ball bearings, or self-lubricating cast-in bearings.
The structural shape may be modified in length, width, number of axles and wheels to provide different operating characteristics. In addition, as shown in FIG. 6, the diameters and end profiles of the wheels may be varied along the axles to change the operating characteristics of the skis. The axles may be resiliently mounted in the side plates to minimize the effects of rough terrain, and may be uniformly spaced or grouped along the length of the ski. The boot holder may be moved forward or back along the ski or sunken into the frame to provide modified operational characteristics.
The foregoing is considered as illustrative only of the principles of the invention. Thus, it is to be understood that changes and modifications to the embodiments as illustrated and described may be made without departing from the spirit of the invention or the scope of the appended claims.
What is claimed is:
l. A ski structure comprising a frame including a pair of rigid side plates, a plurality of reinforcing strut members extending between said side plates, and a support platform extending between said side plates, and a plurality of wheel assemblies secured to and extending between said side plates and longitudinally spaced therealong, at least one of said strut members located below the axis of rotation of said wheel assemblies and adjacent the lower edge of the side plates to substantially lindrical section and having a diameter less than the diameter of said wheels.
4. A ski structure of claim 2 wherein the diameters of the individual wheels may vary along the axles.
5. A ski structure of claim 2 wherein said axles are secured between said side plates perpendicular to the longitudinal axis of said ski by means of a fastener and locking pin.
6. A ski structure of claim 1 wherein the plurality of wheel assemblies comprises at least three of said wheel assemblies.