US2055757A - Ski - Google Patents

Description

N. F. TOLMAN Sept. 29, 1936.

' I SKI Filed Aug. 16, 1935 INVENTOR. NEWTON F fi/WAN ATTORNEY Patented Sept. 29, 1 936 UNITED STATES PATENT OFFICE 5 Claims.

The present invention relates to improvements in skis and has for an object to provide a device of this character which will reduce friction when coasting or racing down-hill.

I-Ieretofore, racing skis have been made narrow so as to reduce running friction. It is an object of my invention to effect a reduction of running friction without sacrificing lateral stability of the skis.

Another object of the invention is to provide a ski which will resist backward slipping and thereby facilitate walking along a level surface or climbing a hill.

A further object of the invention is to provide a ski with a running surface composed of lands separated by shallow recesses, the latter being merely deep enough to collect friction pads of snow when climbing or travelling along a level, the shape of the recesses being such that they will clear themselves of snow when the ski is sliding down-hill.

Other objects and advantages of the invention will appear in the following description of a preferred embodiment and thereafter the novelty and scope of the invention will be pointed out in the claims.

In the accompanying drawing;

Figure 1 is a top plan view of a ski embodying my invention;

Fig. 2 is a view in side elevation showing the ski in its normal arched position with snow packed in the recesses;

Fig. 3 is a similar View showing the ski flattened by the weight of the wearer;

Fig. 4 is a View in cross-section taken on the line 4-4 of Fig. 2;

Fig. 5 is a bottom plan view of the ski; and

Fig. 6 is a view in side elevation similar to Fig. 3 but with no snow packed in the recesses.

The ski shown in the drawing resembles the standard form of ski differing therefrom in the form of its running surface. It comprises a toe portion l I with an upwardly curved tip l2, a body portion l3 on which the foot M of the wearer is supported and secured by straps or other means (not shown), and an after or heel portion 15. As in the standard form of ski there is a slight arch of the bottom of the ski between the toe portion and the heel portion. This is clearly shown in Fig. 2. When, however, the ski is in use the weight of the wearer flattens out the ski to the position shown in Fig. 3.

The bottom of the ski is formed with three separated lands or flats. 16, ll and I8, disposed at the toe, body and heel portions, respectively.

It will be understood that these lands lie in the same plane only when the ski is supporting the weight of the wearer, as shown in Figs. 3 and 6. The rear end of the land I6 terminates in a shoulder l9 and the rear end of the land I! in a shoul- 5 der 28. A wall 2| connects the shoulder I9 with the forward end 22 of the land ll, thus forming a shallow recess 36 which tapers from its greatest depth at the shoulder E9 to zero at the junction line 22. Another Wall 23 extends from the shoull0 der 20 to the forward end 24 of the land I8, forming a similar tapering shallow recess 3|.

In accordance with common practice the running surface of the ski is formed with a central groove 25 which is interrupted by the two recesses 15 and thereby divided into three parts running through the lands I6, ii, and I8. If desired the side edges of the land ll may be reinforced with metal strips 26.

In use when racing down-hill the weight of 0 the wearer is supported on the three surfaces It,

II, and 58 which are widely separated by the recesses formed therebetween. It will be observed from an inspection of Fig. 3 that the running surface is about half of that in a normal ski which 25 has a bearing surface extending substantially throughout its length. By reducing the running surface I reduce friction and hence promote the attainment of higher speeds.

The central land ll which is directly under the 30 foot of the skier has a length at least equal to and preferably greater than the combined length of the other two lands. I find it desirable to make this central land at least two feet long. Thus, the ski has a smooth bottomed mid-portion for 35 a length of two feet or more which corresponds in section to that of the conventional ski and provides a smooth sliding surface. This center portion receives the major part of the pressure from above on sinking into soft snow and because 40 this center portion is of smooth conventional design on the bottom, little slowing of the ski takes place on a sudden downward plunge into the snow.

It is essential that the ski respond to the technic necessary in executing the accepted methods of 45 turning a corner. It is well established that a short body can turn sideways or be pushed sideways more easily in direct proportion to the reduction of its length. Hence, a short ski is much easier to steer than a long one. Applicants ski achieves to a marked degree the effect of steering a shorter ski because the major portion of the weight is carried by a short section comprising the mid-portion of the ski. If this smooth bottomed mid-portion is too short the sustaining force is too small to maintain buoyancy efficiently, that is, without excess friction. Any irregularity disturbing the smoothness of this central bearing surface unavoidably presents friction in turning and hence I provide a smooth central land under the foot the skier, such land being a plane surface interrupted only by the central groove 25 running longitudinally.

It is customary for racing purposes to wax the bottom of a ski, but heretofore there has been a limit to the nature of the wax that could be applied because if a very fast wax were used the ski would become so slippery that it would be impossible to walk with it on a level surface. With my improved construction the amount of surface to be waxed is much less than thatof the ordinary ski, thus resulting in an economy of wax. Fur thermore, the fastest wax can be used without danger of back slipping.

The shallow recesses between the lands fill with snow when walking on a level surface or when climbing a hill, and pads of snow indicated at 28 in Fig. 3 offer considerable resistance to sliding of the ski. The shoulders l9 and 2t serve merely to confine the snow so that it will not slide forward with respect to the ski and permit the ski to slip backward. I find that with a ski of the design illustrated it is possible to walk with case on a level surface with no danger of backward slipping no matter how highly polished the running faces of the ski may be. The snow filled recesses give a firm anchorage for one foot while thrusting the other forward and by precluding back slipping enable one to walk faster. It is also possible to climb steep surfaces without danger of slipping because the snow pads offer high resistance to slippage on snow. When walking or climbing the snow pads 28 are packed tightly in the recesses by the alternate rearward thrust of each foot while the other foot is being moved forward. During such forward movement of the foot the weight is lifted off the ski on said foot, permittingsaid ski to arch and raise the friction pads 28 off the surface 29 of the snow on which the wearer of the ski is travelling. Of course, in practice the pads may not be actually lifted clear of the snow surface because the latter is soft and plastic. However, since the pads are not pressed into the snow surface during the forward movement of the ski there is no tendency to drag the snow pads out of the recesses. This reduction of friction on the forward stroke is due not only to relieving the ski of the weight of the wearer, but also to the arching of the ski when it is relieved of such weight.

While this condition prevails when walking or climbing, the conditions are entirely different when coasting or sliding down-hill, because the weight is then maintained constantly on both skis and the skis are pressed down into the snow surface during the forward movement so that the snow pads are dragged out of the recesses. It will be obvious, therefore, that it is necessary to provide the recesses with an abrupt end wall at the forward end against which the snow can pack during the rearward thrust of the ski and to have each recess taper to zero depth at its rear end so that the snow pads will slide out of the skis when coasting down-hill. Since the recesses are kept constantly clear of snow when sliding down-hill, the actual running surface of the ski during coasting is represented only by the lands i6, H and I8, and the sliding friction is materially less than it would be with a continuous running surface extending substantially the full length of the ski.

Another advantage of my invention lies in the fact that less metal edging 26 need be used. Heretofore, it has been considered necessary to use such metal edging along substantially the entire length of the ski but I find that the ed ing is requisite only on the body portion of the ski and may be confined to the central land I! thus effecting a material economy. With the ordinary continuous bottomed ski the metal edging is usualy put on in short strips so as not to interfere with the flexibility of the ski. This calls for very carefully butting the strips to one another to prevent them from slowing up the ski, or ripping off in service. In my ski these difiiculties are avoid-ed. A continuous strip is countersunk in each side edge of the land ll and the forward end of the metal strip is curved upward from the junction line 22 into the forward recess, as shown at 2i, so that should it become slightly loosened it could not dig into the snow to retard the ski or be ripped off.

The metal edging is used to prevent slide slipping and facilitates turning on icy surfaces and has nothing to do with forward movement of the ski. The same is true of the shallow groove 25 which is kept clear of snow when coasting because each section of it is open at each end and there is no chance of packing snow in the groove to form a friction pad.

While I have described a preferred embodiment of my invention, I wish it to be understood that this is to be taken as illustrative and not limitative and that I reserve the right to make various changes in form, construction and arrangement of parts, without departing from the spirit and scope of the following claims.

I claim:

1. A ski formed on its running surface with three lands disposed respectively at the rear, at the center and at the forward part thereof with a pair of transverse recesses extending completely across the face of the ski and separating said lands, each recess tapering from the maximum depth at its forward end to mergence with the land immediately to the rear thereof, the three lands providing a combined bearing surface equal to about half the length of the ski with the central land of considerably greater length than the other two lands.

2. A ski comprising a strip of resilient material having an arched bottom surface adapted to be flattened by the weight of a wearer of the ski, said bottom surface being formed with three lands disposed respectively at the rear, the center, and forward part thereof, the lands being separated by shallow transverse recesses extending completely across the face of the ski, said lands lying on the same plane when the ski is flattened by the weight of the wearer, each recess tapering from maximum depth at its forward end to mergence with the land immediately to the rear thereof, the central land providing a smooth bearing surface of at least two feet in length.

3. A ski comprising a strip of resilient material having .an arched bottom surface adapted to be flattened by the weight of a wearer of the ski, said bottom surface being formed with three lands lying in the same plane when the ski is flattened, the lands being disposed respectively at the rear, the center, and the forward part of the ski and being separated by shallow transverse recesses extending completely across the" face of the ski, each recess tapering from maximum depth at its forward end to mergence with the land immediately to the rear thereof, and a continuous metallic strip countersunk in each side edge of the central land, each strip curving upwardly at its forward end into the adjacent recess.

4. A ski comprising a strip of wood having an arched bottom surface adapted to be flattened by the weight of a wearer of the ski, said bottom surface being formed with three lands lying in the same plane when the ski is flattened, the lands being disposed respectively at the rear, at the center, and at the forward part of the ski and being separated by shallow transverse recesses extending completely across the face of the ski, each recess tapering from maximum depth at its forward end to mergence with the land immediately to the rear thereof, each land being formed with a central groove extending lengthwise thereof and open at each end, and a continuous metallic strip countersunk in each side edge of the central land, each strip curving upwardly at its forward end into the adjacent recess.

5. A ski formed on its running surface with three lands disposed respectively at the rear, at the center, and at the forward part thereof with a pair of transverse recesses extending completely across the face of the ski and separating said lands, the central land being at least two feet long and the two recesses being each of approximately the same length as that of the central land, each recess tapering from maximum depth at its forward end to mergence with the land immediately to the rear thereof.

NEWTON F. TOLMAN.

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