DESCRIPTION Ski-boot with parallelogram clamping The characteristic of this ski-boot consists in the fact that its hack part is fixed to the boot-vamp by means of four links which form - together with the ski-boot (the fixed and the moving part) - two side- -parallelograms. Such parallelograms allow the back part to near the front part whenever their links make half-rotation movement. This movement makes the final clamping push the foot forward by means of a slanting pressure caused by the palm of the hand.
At present, ski-boots are fastened in various ways, generally by means of levers. The main drawback to such levers consists in the fact that, as they stick out of the boot-vamp, they are subject to shocks which could open or even break such levers. Another drawback to such levers is represented by the time and the effort necessary to close such levers in order to clamp the foot as wished. Finally, they are not nice from an aesthetic viewpoint because they stick out of the boot and hardly match with the design of the boot. Such remark is confirmed by the present tendency to reduce the number of levers as much as possible.
The clamping device described in this document offers one main advantage: the possibility of clamping the ski-boot with one single - and simple - pressing movement. In fact, once the link's length is adjusted, every subsequent clamping will be as precise and accurate as the first one. This type of clamping can be fixed not only on ski-boots, but also on ice-skates or roller-skates or on whatever type of boot or shoe.
Table I shows a ski-boot equipped with the type of clamping - this document presents - in the position "clamped". Table II shows the same type of ski-boot in position "unclamped". Table III shows a ski-boot in section and in the position of maximum unclamping, which allows for a more precise description of the invention. No 1 shows the back moving-part of the boot in its farthest position from the leg (that is in its unclamped position). You can also notice the padded shoe 2 and the gasket 3 which, wnen tne boot is clamped, is press.ed against part 4 of the boot. This must happen when the two pairs of links 6 have accomplished a 180° rotation towards right from the position shown in the figure. The precise fitting of the gasket 3 into the part of the boot 4 depends on the length of the links 6.
Such links are made of a central cylinder in which two screws are tightened respectively with right and left pitch. In this way, by operating the central cylinder, it is possible to increase or decrease the distance between A and B (or between C and D): the greater such length is, the tighter is the clamping, because the distance between the back padding 2 and the front padding 8 and 10 is shorter. With the clamping operation, described above, the foot is pushed forward inside the boot until it gets under the padding shoe 10. A special loose sole 11 that can move freely inside the boot, could make such sliding movement of the foot easier. The links used could be of different type . They could
be simple and small plates with various holes so as to have a link length that can adjust the tightening of the clamping. Or also, such links could consist of screws 16 fixed on the moving pin (A,C) fig.3 and screwed in the fixed pin (B, D) so as to allow the back part to near the front part still further when the boot is clamped. In this case, there would be. four screws on each boot. Such screws could be tightened by means of a special wing nut put on them; or they could be screwed with a screwdriver or a coin inserted in a special slot, and so on. In this case, the degree of tightenening of the boot could be adjusted when the foot is inside the boot by screwing the four screws. Besides, when the boot is unclamped, a further tightening of the four screws could lead to tighter clamping, though continuing to be as Taalanced as during the previous tightening operation when the foot is inside the boot. This elastic pressure - shown in table III and used only when putting on or taking off the ski-boot - does not occur when links (6) are located on the left of the pin B; but it occurs when links are located obliquely and upwards on the right side of the pin. In order to clamp the ski-boot, it is necessary to rotate such links of about 45°. This rotating movement is caused by pushing down the back part 1. The tightening or horizontal movement is caused by a vertical lowering movement, in a circular area where ever bigger vertical movements are associated with ever smaller horizontal movements. The result of this situation is that to an ever tighter clamping corresponds a progressively reduced physical effort. This is possible if we
consider part 8 as part of the boot-shoe, which is possible either designing the two parts as a single part, or by linking one part to the other by means of device 9. Such a device may be a link like link 6 having the function of creating a certain angle between the shoe and the boot-leg, according to the skier's needs, by tightening the screws of the corrisponding double lead screw (9A).
Device 9 can also work as elastic bind and be made in different ways, which does not mean that the main chracteristies of the invention are affected.
In any case, with the clamping operation (with horizontal links on the right of B and D) , the backwards reaction-push give by the elastic parts of the ski- boot, does not virtually lead to the unclamping of the boot. However, in order to be sure - that is in order to be sure that the device does not allow for undesired unclamping (when skiing) - the links not only must be horizontal, but also tilted downwards. In this way, the horizontal reaction pushes cause a further lowering movement of the back moving-part (1, 2) until the foot touches the insile part of the vamp. (5). Another device apt to prevent the boot from unclamping casually could consist in some sort of bolt. In this case, the ski-boot could be unclamped with links located in any angular position. We can take fig. 2 of tableIII as an example. This figure shows one of the fixed pins (i.e. hinges ) round the axes of which the links rotate. Such a pin must be attached to one of the four links: it would be better if the pin could be located outside and on the boot-vamp: in fact in
this position, operating the the pin would be easier. Besides, the pin is not subject to shocks. This pin is tooth-headed 12. Such tooth-headed pin is in connection with the end 13 of the lever 14 hinged in 15. The possible unclamping movement of the ski-boot causes rotation of the tooth-headed pin 12 in the direction shown by arrow f. This causes pushes against end 13 of the lever 14 which would rotate such lever round its axis 15. As the radii's sum of the point where the contact occurs is higher than the distance between the two centers, such rotation does not occur, while the tooth-headed pin stands still: in this way, it prevents the links 6 from rotating and consequently, it prevents the ski-boot from unclamping. On the contrary, if one wants to unclamp the ski-boot, one only has to push in the direction of arrow a. Such device is a ratchet gear, actually, whose end is kept in touch with tooth-headed pin 23 elasbically by an elastic return device - extension spring round axis 16 or extention spring or compression spring oe also flexure spring if the lever is placed somewhere else. - Just remark that the release of this ratchet gear is easy because the opening moment is very little or unexisting because the elastic push against the foot should be aligned to the link.