U.S. patent number 3,909,028 [Application Number 05/502,728] was granted by the patent office on 1975-09-30 for knee twist sensing ski binding.
This patent grant is currently assigned to F. Salomon & Fils. Invention is credited to Gerard Chevrolet, Pierre Comte, Guy Courvoisier.
United States Patent |
3,909,028 |
Courvoisier , et
al. |
September 30, 1975 |
Knee twist sensing ski binding
Abstract
A ski binding for preventing twist-type fractures of the lower
leg has an elongated sensor element extending between the knee
region of the skier and the ski boot and responsive to angular
displacement of the knee relative to the foot so as to release a
locking mechanism interconnecting the boot to the ski when
excessive twist between the foot and the knee is detected. This
sensor element can comprise a Bowden-type cable whose core projects
more or less from the sheath as the leg is twisted. Alternately a
nontwistable but otherwise flexible element extending from the knee
to the latch in the boot is provided which operates the locking
mechanism securing the boot to the ski.
Inventors: |
Courvoisier; Guy (Geneva,
CH), Comte; Pierre (Troinex, CH),
Chevrolet; Gerard (Damphreux, Bern, CH) |
Assignee: |
F. Salomon & Fils (Annecy,
FR)
|
Family
ID: |
27175193 |
Appl.
No.: |
05/502,728 |
Filed: |
September 3, 1974 |
Foreign Application Priority Data
|
|
|
|
|
Sep 3, 1973 [CH] |
|
|
12583/73 |
|
Current U.S.
Class: |
280/613 |
Current CPC
Class: |
A61B
5/224 (20130101); A43B 5/0417 (20130101); A63C
9/0846 (20130101); A63C 9/086 (20130101); A43B
5/0415 (20130101); A63C 9/00 (20130101); A63C
9/0844 (20130101); A63C 9/0845 (20130101); A61B
5/4528 (20130101); A63C 9/08 (20130101); A63C
9/0805 (20130101) |
Current International
Class: |
A43B
5/04 (20060101); A61B 5/22 (20060101); A63C
9/00 (20060101); A63C 9/086 (20060101); A63C
9/08 (20060101); A63C 009/08 () |
Field of
Search: |
;280/11.35R,11.35D,11.35M,11.35K,11.35T,11.36 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Schonberg; David
Assistant Examiner: Mitchell; David M.
Attorney, Agent or Firm: Ross; Karl F. Dubno; Herbert
Claims
We claim:
1. A safety ski binding comprising:
a ski boot adapted to receive the foot of a skier;
latch means for releasably securing said boot to a ski;
a sensor means having one portion carried at the knee region of
said skier and another portion carried at the foot region of said
skier adapted to sense relative movement of the two said portions;
and
operating means connected between said sensor means and said latch
means for operating same and releasing said boot from said ski when
said knee and foot regions are angularly offset to each other about
an axis passing through said regions to an extent exceeding a
predetermined limit.
2. The ski binding defined in claim 1 wherein said sensor means
including an elongated flexible element having one end constituting
said one portion and another end constituting said other portion
and connected to said operating means.
3. The ski binding defined in claim 2, further comprising means for
securing said one end to said knee region and for securing said
other end to said foot region.
4. The ski binding defined in claim 2, further comprising a second
such sensor element having its one end secured to one side of said
knee region and its other end passing over to the other side of
said foot region, the first-mentioned sensor element having its one
end secured to the other side of said knee region and its other end
passing over to the one side of said foot region.
5. The ski binding defined in claim 4 wherein said elements each
include a tubular and flexible extensible sheath and an
inextensible and flexible core received within said sheath, said
cores being fixed at said one ends at said knee region and being
secured at said other ends to said operating means.
6. The ski binding defined in claim 5 wherein said operating means
includes a pivotal lever assembly having one lever arm secured to
said cores.
7. The ski binding defined in claim 3 wherein said element is
flexible and said ends are angularly fixed relative to each other,
said one end of said element being angularly fixed at said knee
region and said other end being angularly displaceable relative to
said binding at said foot region, whereby the angular orientation
of said other end relative to said binding at said foot region
corresponds to the angular position of said knee region relative to
said foot region.
8. The ski binding defined in claim 7 wherein said operating means
includes a pivotal lever assembly having one lever arm formed with
a cam engageable with said other end.
9. The ski binding defined in claim 8 wherein said other end
carries a radially projecting arm and a roller on said arm engaging
said cam.
10. The ski binding defined in claim 3 wherein said latch means
includes a slidable body formed with a notch and said operating
means includes a pivotal lever assembly connected to said element
and having a nose engageable in said notch for preventing sliding
thereof.
Description
FIELD OF THE INVENTION
The present invention relates to a ski binding. More particularly,
this invention concerns a safety ski binding of the type adapted to
release the ski when subjected to a predetermined force.
BACKGROUND OF THE INVENTION
Safety ski bindings are known which automatically uncouple the
skier from the ski when his leg or foot is subjected to a
predetermined stress relative to the ski. Such a binding is
provided in order to prevent the relatively long lever arm
constituted by the ski from breaking the user's leg, a very common
incident prior to usage of such safety ski bindings.
A ski boot is usually secured to a ski in such a manner that it can
be disengaged from the ski by forces acting in opposite directions.
Thus if a toe or heel of the skier pulls away from the ski with a
force exceeding a predetermined limit it is usual for such bindings
to release the ski boot. Similarly it is desirable for the ski boot
to be released if it is twisted about an axis generally
perpendicular to the upper surface of the ski so as to prevent
so-called spiral fractures of the leg.
Although it has been found relatively simple by use of springs,
small hydraulic dashpots, and the like to provide means for
releasing the heel or toe of the ski boot when raised from the
surface of the ski, it has been found extremely difficult to
provide means which can hold the ski boot securely to the ski
during strenuous skiing, but which will release the ski boot when
it exerts a twist against the ski binding. This difficulty is
principally caused by the fact that the amount of twist which a
particular skier's leg can withstand without fracture of any of the
lower-leg bones or damage to the ankle or knee joint, is dependent
on a great many factors such as the age of the skier, the strength
of his joints, and the like. It has, however, been found generally
to be the case that the foot of a person cannot rotate relative to
the knee of a person about an axis passing upwardly through the
lower leg by an angle of more than 25.degree. without some degree
of injury to the leg.
This fact has been used in ski bindings wherein locking means
securing the ski boot to the ski can be operated by a mechanism
actuated through a cable connected to the hips of the skier, thus
he wears a sensor at his hips which is connected via a cable to his
ski boots so that when his hips assume a predetermined angle
relative to the ski boot, the ski boot will be released.
Such arrangements have the considerable disadvantage that the cable
follows the leg, thereby passing over the ankle and knee joints, so
that when the cable is deformed by bending at the ankles or knees
the apparatus becomes almost totally ineffective. Thus it is
possible for the skier to bend at the knees and suddenly find that
his ski boots have been released from the binding, or similarly for
him to be subjected to a sufficient strain to break his leg without
his ski bindings releasing. This danger is particularly present
when the cable is able to form a loop instead of transmitting a
signal to the ski binding. Similarly when the cable is bent over on
itself or otherwise kinked, as is the case when the skier is
squatting on his skis, displacement of the body in twisting one leg
will be read as a dangerous torsion for the other leg and will not
be responded to by the correct ski binding. As a rule such
cable-type sensors are almost totally ineffective when the upper
and lower legs form an angle of approximately 90.degree., with one
leg twisted relative to the other leg. In this case it is possible
for excessive strains to be applied to one or both legs without the
apparatus functioning.
OBJECTS OF THE INVENTION
It is therefore an object of the present invention to provide an
improved safety ski binding.
Another object is the provision of such an apparatus which will
rapidly respond to a torsional stress applied to a skier's leg and
cause the corresponding ski boot to be released from the ski.
Yet another object is the provision of such a safety ski binding
which is inexpensive to manufacture and simple to adjust.
SUMMARY OF THE INVENTION
These objects are attained according to the present invention in a
ski binding comprising releasable locking means for securing a ski
boot to a ski, sensor means including a knee-position detector
adapted to be secured approximately to the knee of the skier and a
foot-position detector adapted to be secured approximately at the
foot or ankle of the skier and operating so as to generate an
output when the knee and foot regions are twisted relative to each
other beyond a predetermined limit, and means interconnecting the
sensor means and the locking means for releasing the ski boot from
the ski when the sensor produces the output indicating excessive
twisting of the foot relative to the knee.
In accordance with the present invention the sensor means includes
a flexible and elongated element having one end attached
approximately at the skier's knee and another end at the skier's
foot or ankle to the ski boot. This latter lower end is connected
to the locking mechanism which secures the boot to the ski so that
when the foot and knee are twisted excessively relative to each
other the boot is released and is freed from the ski.
Thus according to the present invention the sensor comprises a pair
of like Bowden cables each having a sheath fixed to one side of the
skier's knee and to the other side of the skier's foot so that
these two sheaths cross over each other, preferably in front of the
skier's ankle. The core wires of these Bowden cables are secured at
their upper ends to the knee region of the skier and are connected
at their lower ends to the locking mechanism of the ski boot. Thus
if the knee twists relative to the foot or vice versa the one cable
core or the other, depending on the direction of twist, will move
within its sheath and operate the locking mechanism once a
predetermined twist has been exceeded.
According to a further feature of this invention the elongated
sensor elements have a pair of ends which are always at the same
angular orientation relative to each other so that when one end is
attached to the knee the other end located at the foot will have an
orientation exactly corresponding to the angular position of the
knee relative to the foot. Once again this lower end is connected
to the lock-operating mechanism so as to trip it and open the
latch, thereby freeing the ski boot from the ski.
The arrangement in accordance with the present invention is built
into a conventional ski boot and a legging which surrounds the
lower leg, that is the calf and ankle region of the skier, and
encloses the knee of the skier.
In accordance with this invention the legging is provided with a
pocket at the knee which is adapted to be filled with a hardening
synthetic-resin foam so as to permit a custom fit of this knee
portion to the individual skier. The boot is similarly provided
with fillable pockets so as to allow to be custom-fitted to the
skier's foot.
BRIEF DESCRIPTION OF THE DRAWING
The above and other objects, features, and advantages will become
more readily apparent from the following, reference being made to
the accompanying drawing in which:
FIG. 1 is a schematic view illustrating the operation principles of
the apparatus according to the present invention;
FIG. 2 is a perspective diagrammatic view illustrating the
apparatus in accordance with this invention;
FIG. 3 is a vertical section through the arrangement according to
the present invention;
FIG. 4 is a perspective view illustrating features of the apparatus
according to the present invention;
FIG. 5 is a vertical section through another arrangement according
to this invention;
FIG. 6 is a section taken along line VI--VI of FIG. 5;
FIG. 7 is a view similar to FIG. 6 illustrating the apparatus in
another operative position;
FIG. 8 is a view similar to FIG. 6 illustrating a further
arrangement in accordance with the present invention;
FIG. 9 is a section taken along line IX--IX of FIG. 8;
FIG. 10 is a schematic view illustrating the operation principle of
yet another arrangement in accordance with this invention;
FIGS. 11a and 11b are further schematic views illustrating the
operation of the apparatus illustrated schematically in FIG.
10;
FIG. 12 is a vertical section through an apparatus embodying the
principles shown in FIG. 10;
FIG. 13 is a large-scale perspective view of a detail of the
apparatus of FIG. 12; and
FIGS. 14 and 15 are views corresponding to FIGS. 12 and 13,
respectively.
SPECIFIC DESCRIPTION
FIG. 1 shows a cylinder s serving schematically to illustrate the
lower leg of a skier. This cylinder s has an upper end b
corresponding to the knee region of the leg and a lower end c
corresponding to the foot and ankle region thereof. A limitedly
extensible and compressible tube g extends generally helically from
one end of this cylinder s to the other, being attached at a point
p at the end c and at a point q at the end b. A flexible but
axially inextensible core wire f is received within the sleeve g
and has an upper end attached at a point q to the upper end b of
the cylinder and a lower end which extends from the tube g at p by
distance equal to l.sub.1. Another tube g* is attached at the upper
end b of the cylinder s at a point P.sub.1 and has a core f*
extending below the lower end c of the cylinder s. The cores g and
g* are of opposite helical hand and have their ends spaced
angularly apart by an angle .gamma. equal to approximately
160.degree., drawn to the central axis a of cylinder s.
When the upper end b of the cylinder s is twisted in a direction T
relative to the lower end c the core f will retract within sleeve g
by a distance equal to .DELTA.l. Thus the sleeve g will assume the
position indicated by dashed line g' and the point q will move
through a distance d to position q' on the end b. Similar twisting
in the opposite direction as illustrated by arrow T' will move the
other core f* similarly. Thus twisting of the ends b and c of the
cylinder s relative to each other will retract one or the other of
the cores f or f* within its respective sleeve.
FIGS. 2, 3 and 4 show a ski boot 1 and a legging 2 which are
interconnected in an accordion-pleated ankle region 3 by a hinged
member 4 on boot 1. The legging 2 is of flexible material and is
provided in the back with a slit 2a which is closable by means of a
slide fastener 7. The boot 1 is formed with a plurality of pockets
adapted to be filled with a synthetic-resin foam 5 and the knee
region of the legging 2 is adapted to be filled with a semi-rigid
synthetic-resin body 6 similarly so as to custom fit the apparatus
according to the present invention both to the foot and the knee of
the user.
A pair of like Bowden-type cables 8 and 9 each extend from the
respective side of the knee insert 6 across the shin and to the
back of the boot 1. The insert 6 is split in back at 6a so as to
permit the shoe to be fitted around the calf and the knee of the
skier. Each of the sleeves 8 and 9 is provided with a respective
inextensible core wire 13 connected via a bracket 10 to the knee
insert 6 and the core 13 is connected to a riveted plate 14'
carried on this insert. The lower ends of the tubes 8 and 9 are
anchored at 11 on the boot 1.
Both of these cores 13 are connected to a common pin 14 slidable in
a plate 15 in boot 1 and pushed downwardly from this plate 15 by a
compression spring 16. The lower end of the pin 14 is engaged in
one arm 17 of a two-arm lever L pivoted at 18 in boot 1 and having
another arm 20 formed with a nose 20a engageable in a notch 21 of
an actuating rod 22 of the locking mechanism for the boot 1. The
boot 1 is formed with a generally square recess 12 in which the
upper end of the rod 14 and the ends of the cores 13 are received
so as to permit the operation thereof.
One end of the rod 22 is provided with a flexible cable 25 threaded
through an eye 33 carried on the ski 32 and having an end received
in a lever 35 pivoted at 35* on the back of the boot d at 37. This
lever 35 allows the rod 22 to be pulled back so that the nose 20a
can engage in the notch 21. At the same time this cable 25 serves
to secure the boot 1 to the ski 32, so as to eliminate the
conventional lanyard that prevents the ski from escaping from the
skier should he have a fall. A lever 19 is provided on the lever
arrangement L so as to permit manual actuation of this lever
arrangement L and freeing of the rod 22.
The sole 24 of the boot 1 is formed with a parallelepipedal chamber
28 terminating near the toe region 29 of the boot 1. The forward
end 31 of the rod 22 carries a piston-like mechanism 30 received in
a chamber 27a in a parallel epipedal body 27 in the chamber 28. The
chamber 27a is provided with a spring 31a to one side of the piston
30 and a spring 31 to the other side thereof. The end 27b of the
body 27 engages under the head 34a of a locking element 34 carried
on a shaft 36 extending between two ears 37 on the ski 32. To the
other side of this element 34 there is provided another block 36 so
that this element 34 may be captured and securely held between
these two elements 26, 27 so as to secure the boot 1 to the ski 32.
When the nose 20a engages in notch 21 as shown in FIGS. 2 and 3 the
spring 31 forces the end 27b with considerable force against the
element 34. When, however, the nose 20 a does not engage the notch
21 it is possible for the block 27 to slide in the chamber 28
toward toe 29 and therefore free the elements 34, allowing the boot
1 to pull off the ski 32.
Thus it should be clear that in use, if the knee section 6 is
twisted beyond a predetermined extent to either side relative to
the foot 1, one of the core wires 13 will pull pin 14 up, thereby
pivoting the lever arrangement L about its transverse axis 18 and
freeing the rod 22. This will have the immediate effect of
unlatching the locking element 34 from between the end 27b of the
element 27 and the nose 26a of the element 26, thereby allowing the
boot to slip off the ski 32. As the skier dons the ski he threads
the cable 35 through the eye 33 and connects the ends of the cable
25 to the lever 35. Then he fits boot 1 over the locking member 34
and pulls up lever 35 so as to press the block 27 against the
latching element 34 and to engage the nose 20a in the latch 21.
The arrangement shown in FIGS. 5-7 is similar in principle to that
of FIGS. 1-4, except that here a heel or toe clamp of conventional
design is operated by a pair of Bowden-type cables 8* and 9* each
having a core 13* connected at the knee much as shown in FIGS. 1-4.
The ski 41 is provided with a plate 40 carrying a rod 42 having a
spherical head 42a with a center 0 and formed with a semispherical
recess 42b. A clamping body 44 is formed with a pair of
circular-section boards 44a and 44b which meet at a common point
and have a semispherical base whose center of curvature can
correspond as shown in FIGS. 5 and 7 to the center 0 of head
42a.
This clamping body 44 is provided with a lower pedal jaw 45 and an
upper latching jaw 45b so that the skier need merely step on the
lower jaw 45a so as to pivot the entire body 44 down and lock his
heel or toe in place with the upper jaw 45b.
A piston 43 slidable in bore 44a has a head snugly receivable in
the recess 42b and is urged by a spring 46 bearing against a cup 47
in bore 44a. This piston 43 therefore defines a stable position of
the body 44 relative to the ski 41 so as to lock it in place in
this position. Of course as is known the force of spring 46 can be
overcome by an upward force against the jaw 45b so as to release
the skier's boot, should his toe or heel exert excessive upward
force on this jaw 45b.
The cup 47 is slidable piston-fashion in the bore 44a and is formed
with a ridge 47a which can engage a lever 48 pivoted at 49 in a
recess 50 formed in the body 44. This lever 48 has another arm
formed with a pair of bores 48a and 48b which, as shown in IFG. 6,
receive the cores 13*. Balls 13a on the end of core 13* assure that
displacement of the core 13* in direction F.sub.1 against the force
of respective springs 51a and 51b will tip the lever, thereby
pulling it into the position shown in FIG. 17. A loading lever 52
has a first arm 52a lying atop the body 44 and a second arm 52b
provided with an end 52c that can engage against the upper end of
the cup 47 as shown in dot-dash lines in FIG. 5 so as to displace
cup 47 down into the illustrated position. A tension spring 54
engaged between a pivot 54a on the body 44 and the end 52c of the
lever 52 serves to pivot this lever about its axis 53 into the
solid-line position of FIGS. 5 and 7.
Thus once the mechanism has been operated as shown in FIG. 7 to
free the toe of the ski boot, the skier can reset it simply by
pulling up the lever 52.
The arrangement of FIGS. 8 and 9 is similar in concept to that of
FIGS. 5-7. The ski 41 is again provided with a stem 42* having a
head 42*a with a center 0* and formed with a recess 42*b. This head
42*a is received in a hole 44*b in the mechanism and a piston 58
has a head adapted to be received in the recess 42*c.
This piston 58 is slidable into bore 44a and is pressed by a spring
57 against the head 42*a. A tension screw 56 threaded into the end
of the bore 44a varies the spring pressure and therefore the
resistance to displacement from the illustrated position of the
mechanism.
Piston 58 is formed with a throughgoing hole 58a through which
engages a lever 59 pivoted to one side of the piston at 60 and
having a boss 59a engageable with one side of bore 58a so as to
displace the piston 58 on pivoting backwardly away from the ball
head 52*a as shown by dot-dash line. The two Bowdens 8* and 9* have
their cores 13* passing through holes 59b and 59c in the lever 59
and provided at the opposite side thereof with lead balls 13*d so
that displacement of these two cores 13* in the direction of arrows
F.sub.2 will move the piston 58 and the ballhead 52*a out of
contact with each other and thereby allow the ski boot to be lifted
away from the ski 41.
FIGS. 10, 11a and 11b illustrate another arrangement according to
the present invention using the same cylinder s employed in the
description of FIG. 1. In this arrangement, however an elongated
sensor element d is provided which has an upper element e.sub.1
secured at the upper end b of the cylinder s and a lower end
e.sub.2 secured at the lower end c of the cylinder s.
The element d is flexible. However its ends d.sub.1 and d.sub.2
cannot be twisted or deflected angularly relative to each other so
that even when the element d is bent the angular orientation of,
for instance, an imaginary line on one end e.sub.1 bears the same
relationship to a similar line on the other end e.sub.2.
The upper end e.sub.1 is rigidly fixed to the upper end b of
cylinder s. End e.sub.2 however, can rotate about its own axis
relative to cylinder s. In this manner, as will be described below,
the orientation of the lower end e.sub.2 to the lower end c of the
cylinder s is the same as the orientation of the upper end b of the
cylinder to the lower end c thereof.
As shown in FIG. 11a, if the upper end b is displaced through an
angle of .sup.-.gamma. so that the end e.sub.1 lies in a position
e.sub.1 .degree. or is displaced through an angle of .sup.+.gamma.
so that it lies in a position corresponding to e.sub.1 * the lower
end e will be displaced so that an imaginary arrow i.sub.d fixed
radially on this end will move into positions i.sub.d .degree. or
i.sub.d *, respectively. These positions at the lower end e.sub.2
correspond exactly to the positions of the upper end b.
When, as shown in FIG. 11b, the lower end c is twisted relative to
the upper end through angle .sup.+.gamma. or .sup.-.gamma. an
imaginary arrow i.sub.c fixed radially at lower end c moves between
a position of i.sub.c * and i.sub.c .degree., respectively, the
imaginary line i.sub.d of the lower end d.sub.2 is not displaced
angularly on this lower end. This is true even though the lower end
e.sub.2 is moved around the central axis of the cylinder s.
This is carried out in practice as shown in FIGS. 12 and 13 in an
arrangement substantially identical to that of FIGS. 1-4, but
wherein the elongated sensor element is attached at its upper end
near the knee of the skier by a plate 126 secured by rivets 127.
This element comprises an upper part 125 formed with a
polygonal-section core 124 in which a lower element 116 telescopes.
Both of these parts 125 and 116 are flexible but have ends which
cannot be twisted readily angularly relative to one another so that
a twist at the upper end of element 125 is transmitted directly to
the lower end of element 116.
In this arrangement an operating rod 100 is connected via a cable
101 to a lever 102 pivoted at 103 on a fulcrum 104 on the boot
which serves to operate via spring 113 a clamping element 114
similar to that described in the abovd-mentioned embodiment.
The rod 100 is formed with a notch 105 in which fits a tooth or
nose 106 of a lever 109 pivoted in the booth at 110 and urged down
to the notch 105 by means of a tension spring 111 secured in the
boot at 111a and received in a hole 112.
FIG. 13 shows in more detail the lower end of the element 116 shown
to have a radially projecting collar 116a adapted to prevent the
element 116 from being pushed up in the boot and from which extends
a pair of like arms 123 and 123a carrying respective rollers 122
and 122a. These rollers normally lie on respective planar surfaces
117 and 117a of a semicircular cam 115 provided on the upper side
of lever 109. When rotated as shown by arrow F the roller can ride
from surfaces 117 and 117a up over inclines 120 and 121a onto
surfaces 118 and 119a. This presses the end of lever 109 down so as
to lift the nose 106 from the notch 105. Similarly displacement in
the opposite direction will displace the rollers 122 and 122a up
inclined surfaces 121 and 120a onto surfaces 119 and 118a,
respectively. No matter which way the element 116 is twisted this
will effect a disengagement of nose 106 from notch 105. This
releases the rod 100 and allows the ski boot to pull free from the
ski.
The arrangement of FIGS. 14 and 15 is very similar except that here
the lever 135 of the unlatching arrangement 133 has a nose 131
which engages in a notch 130 of an actating rod 129. In addition
this lever is formed at its rear end with an upper arm 137 having
an eye 137a allowing the lever 135 to have its front arm 132 lifted
and the nose 131 disengaged from the notch 130 manually.
The sensor element here has an upper part 149 secured to a plate
150 held via rivets 151 to the knee region of the legging and is
formed with a telescoping portion 148 and receives a lower section
144 having a collar 145 to prevent its upward or downward
displacement in the boot. In addition the lever 133 has a cam arm
136 carrying a cam 138 normally urged downwardly by a compression
spring 128 and formed as shown in FIG. 15 of semicircular
shape.
As also shown in FIG. 15 the lower end 144 of the sensor rod has a
hub 144a carrying a pair of arms 146 and 146a carrying respective
rollers 147 and 147a which normally rest on raised coplanar
surfaces 139 and 139a, respectively. Between these surfaces are
provided coplanar camming surfaces 140, 140a and 141. Inclined
regions 142, 143, 143a and 142a interconnect the lower planar
regions. Thus when the lower end 144 is rotated as shown by arrow
F.sub.1 the rollers 147 and 147a are displaced from the regions 130
and 139a and ride over the inclined region 142 and 143a onto the
other regions 140 and 141 so as to allow the cam 138 to drop,
thereby lifting the nose 131 from notch 130 allowing the boot to be
freed from the ski.
The arrangement according to the present invention therefore
insures that the boot will be released from the ski whenever the
skier's leg is stressed torsionally, that is when the foot is
twisted relative to the knee to an extent which would result in
injury. It provides a safety feature which, in addition to the
normally known release-type ski binding, almost completely avoids
the possibility of a leg fracture in skiing.
* * * * *