Roller skate including at least two rollers aligned along a median plane

The skate includes an under-frame (3) equipped with two or several rollers aligned one behind the other in a common median plane. Each roller (4, 5) has a shape of a narrow-bobbin, with two circular flanges provided with bands and a central hollowed hub, fixed inside a ball-bearing. This bearing is put in an orifice of a central plate (24) of the under-frame, this plate holding also a front buffer-stop (6) and a back buffer-stop (7). An instrument absorbing the shocks in the radial direction is intercalated between the bearing and the plate (24). Preferably, the under-frame (3) of the skate is equipped with a support for a leg (1) which is articulated in relation to a transverse axis (Y) at the level of the ankle. A braking mechanism of the rollers (4, 5) can be fixed on the central plate (24) of the under-frame. Thanks to the special shape of the rollers, bearings and the under-frame are lightened.

The present invention relates to a roller skate including an under-frame, 
at least two rollers fixed on a lower part of this under-frame and aligned 
one behind the other, along a common median plane perpendicular to their 
axes of rotation, and support means to fix the under-frame to a foot and 
to the corresponding leg of a user. 
The French certificate of utility A-2 312 174 and the corresponding U.S. 
Pat. No. 4,072,317 describe a skate of the same kind, including two 
aligned and relatively large rollers. Each roller is fixed under the 
under-frame between two parallel arms holding the extremities of its axle. 
In order to have the desired rigidity, this known setting requires at 
least four very rigid arms, as well as axles of rollers, which are 
relatively large and long enough to hold each roller by two parallel 
bearings. Thus, this construction presents a rather significant weight. 
Moreover, the arms form, on each side of the rollers, projecting elements 
which can hit against the ground or against various obstacles when one 
rollerskates, which is a source of dangers and damages. 
The U.S. Pat. No. 4,418,929 also shows a skate of the same kind, but 
equipped with two narrow rollers fixed between two vertical plates of the 
under-frame. This structure should also be rather heavy in order to have 
the desired rigidity, especially regarding the transverse deformations, 
and the axles of the rollers are also laterally protuberant. 
The purpose of the present invention is to supply a skate of the type 
indicated in the preamble, arranged so as to avoid the above mentioned 
disadvantages, in order to allow a great freedom of evolution thanks to 
its lightness, to its stability and to the absence of protuberant lateral 
elements. 
For this purpose, the roller-skate in accordance with the invention, is 
characterized by the fact that each roller includes two circular flanges, 
substantially parallel and with the same diameter, and by the fact that 
these two flanges are joined to a central tubular portion of lesser 
diameter, which is fixed inside a rolling bearing or pillow-block fixed on 
the under-frame and located in the median plane. 
In this manner, the wheels have the general shape of a very narrow bobbin 
that can rest on the ground by its two flanges when the bobbin is 
perpendicular to the ground, or just by one flange when it is inclined. 
Moreover, this bobbin can be supported only at the proximity of its median 
plane, which allows avoidance of any protuberant frame at the extremities 
of the bobbin, i.e., on the faces of the skate. To be lightened, each 
roller can be hollowed out by a central hole axially traversing the entire 
roller. 
Preferably, the said lower part of the under-frame includes a longitudinal 
central plate located in the median plane and in which are mounted the 
bearings of the two rollers, this plate being joined to a support plate, 
stretching out under the foot of the user. 
In a form of a special embodiment, an elastic element is placed between 
each rolling bearing and the under-frame. For that purpose, each rolling 
bearing can include an external ring, externally equipped with a radial 
border fixed with a radial clearance in a groove of the under-frame, an 
elastic material being inserted between this border and the bottom of the 
groove to absorb the shocks. The rolling Plummer-block can be a 
ball-bearing the internal ring (race) of which is formed by the central 
tubular portion of the roller. On the other hand, the external border of 
each flange of the rollers can be provided with a band of elastomer. 
In a special embodiment, a braking mechanism of the rollers is put on the 
central plate of the under-frame and includes braking means fixed in a 
sliding manner along the plate to be in contact with the rollers, and a 
central control mechanism. Such braking means can include at least a 
sliding frame comprising a wheel pressed upon the central plate of the 
under-frame and arranged to roll on the border of the flange or the 
corresponding roller. On the other hand, at least one of the rollers can 
be equipped with a mechanism of rotation in one way only in order to avoid 
a backward rotation. 
In a form of an advantageous embodiment, the support means include a collar 
arranged to be fixed around the leg of the user, and connected to the 
under-frame transversely by a rigid mechanism, but articulated in relation 
to a transverse axis at the level of the ankle of the user.

FIG. 1 shows a roller-skate in accordance with the invention, fixed to a 
leg 1 and to the corresponding foot or to the shoe 2 of a user. The skate 
includes a rigid under-frame 3 supporting the sole of the shoe 2 and 
equipped, in its lower part, with a front roller 4, a back roller 5, a 
front buffer-stop 6 and back buffer-stop 7. The under-frame 3 is attached 
to the shoe 2 with the help of a conventional adjustable collar 8. Also, 
the skate includes a leg holder 10 having a collar 11 adapted to be fixed 
around the leg 1 of the user and connected to the under-frame 3, on each 
side of the ankle 12 of the user, by a pair of rigid metallic blades 13 
and 14, articulated to themselves at 15 at the level of the ankle 12 to 
allow the collar 11 to swing with the leg 7 to the front or to the back, 
by executing a turn w.sub.y in relation to a transverse axis Y as shown in 
FIG. 3. In return, a relative lateral swing of the under-frame 3 in 
relation to the leg 1, by a rotation w.sub.z around the longitudinal axis 
Z, is prevented by the rigidity of the leg holder 10. However, the leg 1 
can nevertheless execute a certain turn w.sub.x around its longitudinal 
axis X inside the collar 11, so that the skater can direct the axis X of 
his foot as he desires. 
The transverse rigidity of the leg holder 10 considerably relieves the 
efforts to be provided by the skater at the level of the ankle. It has 
also the function to maintain the common median plane of the two rollers 4 
and 5, practically in coincidence with the longitudinal axis X of the leg 
1, and to incline it laterally with the leg in relation to the ground 19 
as is shown in FIG. 2. The angle A between the extreme positions 1' and 1" 
of inclination of the leg is very important, thanks to the narrowness of 
the rollers, and to the absence of protuberant lateral elements, at the 
level of the rollers. 
FIG. 4 shows in perspective schematically the bobbin shape of the rollers 4 
and 5, with the two flanges 20 which are parallel and symmetrical in 
relation to the median plane, and which are rigidly connected by a central 
tubular portion on hub 21, the external diameter of which is smaller than 
the rollers. The roller includes a central hole 22 that allows lightening 
it. 
FIGS. 5 and 6 show more specifically the shape of the under-frame 3, 
essentially formed by a horizontal plate 23 supporting the sole of the 
shoe and by a vertical plate 24 pierced by two large circular orifices 25 
and 26 for the setting of the tubular portions 21 of the rollers 4 and 5, 
the sides 20 of each roller being respectively on one side and the other 
side of this plate 24. Of course, one could provide a similar skate having 
more than two consecutive rollers, mounted in alignment or following a 
curved longitudinal profile. Also, the plate 24 is pierced with holes 27 
and 28 for the fixation of the front 6 and back 7 buffer-stops with 
screws, and with holes 29 and 30 for the setting of a braking mechanism 
that will be described later. 
FIG. 7 shows more in detail a form of advantageous embodiment of a roller 
4, 5 and its mounting in the plate 24 of the under-frame. The tubular 
portion 21 and the flanges 20 of the roller are made of a single rigid 
piece, preferably metallic, the periphery of the flanges being provided 
with a band 32 of relatively rigid elastomer which has a quarter round 
cross-section. Near the tubular portion 21 an enlarged space 33 is 
provided between the two flanges 20 which encloses a ball-bearing 34 
having an external ring (race) 35, the tubular portion 21 working directly 
as an internal ring of the ball-bearing. The ring 35 presents externally a 
flat border 35a that is fit into a rectangular profiled groove, formed in 
the thickness of the plate 24 and including a relatively soft elastomer 36 
which absorbs the shocks suffered by the roller, the ring 35 then sliding 
radially in the groove. In this example, the plate 24 must obviously have 
a removable part 24a around the lower half of each bearing 34, to allow 
the setting of the rollers. 
In the variation shown in the FIG. 8, one succeeds in reducing to a few 
millimeters the distance between the two bands 32 of the roller, by giving 
to the flanges 20, a cross section in a shape of a vice and by providing 
in each side of the plate 24, a groove 38 in an arcuate shape for the 
passage of the band 24. As the thin part 39 of the plate 24 is arcuate, it 
does not result in a significant weakening of the plate. In return, one of 
the sides 20 must be removable to allow the mounting and the unmounting of 
the roller. 
Further, the bobbin-shaped rollers allow advantageously the setting of a 
mechanism of rotation in one direction (not shown) set between the 
internal surface of one side 20 and a lateral surface of the plate 24 or 
of the ring 35. It can be, for example, a metallic oblique bladed stop 
washer, co-operating with thin radial grooves formed in the said surfaces, 
or a ball-bearing in a "free wheel" style, which jams automatically as 
soon as it primes a backward rotation. In this way, the roller can only 
turn forward and it allows the skater to propel himself easily, especially 
on a slope. 
FIGS. 9 to 11 show an adjustable braking mechanism 40 that is fixed on the 
plate 24 of the under-frame between the two rollers 4 and 5. For each 
roller, the braking mechanism includes a sliding frame 41 having one pair 
of metallic plates 42 each equipped with a head 43 and connected to one 
another by two axles 44 and 45 that can slide in the oblong holes 29 (FIG. 
6) of the under-frame. Each axle 44 and 45 supports a pair of braking 
wheels 46 and 47 made of a compressible material, these wheels being 
disposed on both sides of the plate 24 and being pressed against it, for 
example by means of plastic stop washers, in order to assure a braking by 
friction against this plate. The heads 43 of the two sliding frames bear 
against a central cam 48 rotation of which is effected by a rack 49 which 
slides lengthwise in a groove of the under-frame, under the power of a 
back trigger 50 (FIG. 1) and of a release spring. Also, the rack 49 is 
maintained in position by a locking pawl mechanism (not shown) that one 
can unlock by raising the trigger. In the present case, it is noted that 
the cam 48 includes, on each side of the under-frame, cam surfaces 51 and 
52 distinct for the back and front braking mechanisms, but which are 
similar and jut out angularly one from the other to produce simultaneously 
the same effect of braking in the two mechanisms. 
The operation of the braking mechanism will also be described in reference 
to FIG. 11 which shows the profile of one of the peripheral surfaces 51 of 
the cam 48, this cam being rotatable around its axis 53. The head 43 of 
the sliding frame 41 is pressed against the surface 51 only by the 
elasticity of the material composing the braking wheels 46 and 47. Various 
positions of the support of the head 43 against the surface 51 during the 
rotation of the cam are marked by a gradation from 0 to 4. In position 0, 
the frame 41 is stepped back enough in relation to the corresponding 
roller 4, 5 so that the wheel 46 does not touch the band 32 and so the 
roller will not be braked. In position 1, the wheel 46 rests lightly 
against the band 32 and slips on it, because its friction against the 
plate 24 is strong enough to prevent it from turning at this stage. In 
position 2, on the contrary, the friction of the wheel 46 on the band 32 
becomes stronger and makes the wheel 46 turn, the braking then taking 
place against the plate 24. In position 3, the push exercised by the 
roller is strong enough for the wheel 46 to move back until it touches the 
second braking wheel 47, thanks to its deformation by elasticity or, in 
that case, thanks to an elastic structure sliding from its axis 44 in the 
frame 41. The braking is then reinforced by the friction of the wheel 47 
against the plate 24. Finally, in position 4, an even stronger braking is 
obtained that allows to completely stop the wheel, by application of the 
head 43 against the wheel 47 thanks to the elasticity of this wheel 47 
around the axle 45. The rack 49 is held by a stop so that the cam 48 
cannot turn beyond the position 4. 
This structure allows resolving in a simple manner the problem of the 
proportioned and simultaneous braking of all the rollers of a skate to 
allow the roller-skater to run over, without danger, relatively steep 
downward slopes. The roller skater can increase at any time the effort of 
braking of a skate by hitting on the control trigger 50 by means of the 
front buffer-stop 6 of the other skate. The releasing can be done by 
raising the trigger by means of the same buffer-stop or by hand. 
FIG. 12 shows more specifically the use of the front and back buffer-stops 
6 and 7. The roller-skater can use the front buffer-stop 6 to propel 
himself. He then bends his foot to the front, under an angle greater than 
the angle B that equals 41.degree. in the example, and he presses the 
buffer-stop 6 against the ground 19 to propel himself forward. The 
buffer-stop 7 serves for braking by friction against the ground. For this, 
the skater bends his foot to the back, at an angle higher than the angle C 
that equals here, preferably, 29.degree.. One notices that the sum of the 
angles B+C, that is to say 70.degree., is high enough to give the skater a 
great freedom to bend his foot to the front or to the back, without the 
buffer-stops touching the ground while he roller skates. 
The present invention is not limited to the example of embodiments above 
described, but on the contrary extends to any kind of modifications or 
variations obvious to a man skilled in the art. In particular, one will be 
able to use any appropriate materials for the building of different 
elements, for example steel, light metal or a rigid synthetic material for 
the under-frame and for the bobbin-shaped rollers. The articulated leg 
holder 10 can also be the subject of multiple variations from the 
standpoint of the building, the stuffing and the instruments of fixation 
to the leg, especially as shown in the already cited publications. In that 
case, it can include a half of a shell, applied on a certain height along 
the leg, or even be replaced by a complete articulated or lengthwise 
flexible shoe, on which is fixed the under-frame 3. The publications 
German-A-2 745 040 and Swiss-A- 580'976 show different ways to fix the 
sole of the shoe on an under-frame of a skate formed principally by a 
central longitudinal plate. 
With regard to conventional roller-skates with two wheels, the 
roller-skates in accordance with the invention, have the advantage of a 
central under-frame that can be very rigid while being simple and light. 
The central plate of the under-frame holds at the same time, the 2 wheels, 
the buffer-stops and, if such should be the case, the braking mechanism. 
Combined with the bobbin-shaped wheels, this simple structure allows 
realization of a lighter and less expensive skate than the conventional 
skates. Thanks to their hollowed hub and high diameter, the bobbin-shaped 
rollers are light and have an aesthetic aspect, and moreover, are mounted 
in high diameter bearings that are not very encumbering while being very 
resistant to shocks thanks to the great number of balls that they can 
hold. Because the two bands of each roller are close to the median plane, 
the bearing points on the ground are always very close to this median 
plane. It allows the user to roller-skate in a more precise, easier and 
more secure way. The skates, in accordance with the invention, allow the 
skater the same evolutions as an ice-skater. The user, wearing these 
skates, can also travel easily in the street or in a building, on 
longitudinal or transverse slopes and on stairs. 
The invention applies to skates intended to perform evolutions on a track 
or for artistic skating, as well as to skates suited to trips in the 
street or in buildings.