Note: Descriptions are shown in the official language in which they were submitted.
3~
~ 'his invention relates to a skid attachment for a shopping
cart. More particularly, it relates to a device Eor attachment to a
supermarket shopplng cart, which allows the use of such a cart under
normal weather conditions with four operative wheels and allows
ready positioning of skids or skiis under the front wheels of the
cart for use when the cart is to be pushed over snowy or icy areas,
as in supermarket parking lots.
It is well known that shopping carts are utili~ed not only
in supermarkets and other stores for carrying materials selected to
a check-out counter, but are also employed to transport the
purchased items to the customer's vehicle in the store's parking
lot. In good weather pushing the cart through the lot is an easy
task but when the lot is covered with ice and snow, as is the case
during winter conditions in many areas, moving the cartr especially
by pushing it in the normal manner, becomes difficult. In such
circumstances customers may refuse to attempt to use the cart in the
parking lot and may try to carry their parcels to their vehicles.
Under conditions of poor footing this can lead to slipping, and
accidents. Sometimes, when the customer is accompanied by another
person, he or she may have that other person drive the vehicle to
the store exit because it is too difficult to move the cart to the
car, which can cause congestion at that location. When it is
attempted to move the cart through a snowy parking lot it has been
found that it is easier to pull it than to push it but this is
awkward and is sometimes dangerous because the customer then often
walks backward and cannot be as aware of vehicle movements in the
lot as is desirable. For these reasons and others there has been a
need to make supermarket shopping carts readily movable through
supermarket parking lots despite adverse weather conditions under
which the ground or pavement is covered with snow and/or ice.
2 -
In a search conducted in the United States Patent and
I`rademarks Office in subclasses 280-7.12; 280-8; 280-9; 280-10;
280-11; 280-33.99A; 280-33.99C; 280-33.99R; and 280-47.26, the only
patent found that shows a shopping cart including a ski attachment
is U.S. Patent 4,163,564. Mone showed a skid attachment like that
of this invention. Other patents found in the search which are
considered to be of interest include U.S. ~atents 1,234,200;
1,343,046; 1,450,924; 2,518,561; 2,823,042; and 3,719,370. O~ these
it is considered that ~he most relevant are U.S. pa-tents 1,234,200
and 1,450,924, both of which show full length sled runners which may
be retracted to positions under a baby carriage so as to allow use
of the carriage as a wheeled vehicle or a sled. However, none of
the patents, either alone or in combination with others, describes
or suggests the present invention, wherein an attachment for a
supermarket shopping cart, readily installable thereon, includes
skid members which are readily moved between operative and
inoperative positions so as to allow use of the cart as a wheeled
vehicle in the store, as a wheeled vehicle in the store parking lot
under normal weather conditions and as a combination wheeled and
skid-equipped vehicle, to facilitate movement of the cart through
the parking lot under snowy and/or icy conditions.
In accordance with the present invention a skid attachment
for a shopping cart incorporating a removable attachment to
facilitate use of such cart in snow, which comprises a nestable
supermarket shopping cart, nestable with other such carts by
relative horizontal motion thereof, which cart includes a pair of
front wheels, each of which is rotatable about a horizontal axis
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3~:i
which is transverse to the longituclinal axis of the shopping cart
when the cart is being moved forwardly, and which wheels are movable
about a vertical axis, and a pair of rear wheels, each of which is
rotatable only about a horizontal transverse axis in a vertical
plane parallel to the longitudinal axis of the cart, a removable
skid, runner or ski attachment which includes a pair of cart
supporting skids, runners or skiis, which are simultaneously movable
into inoperative and into operative positions, as desired, with
respect to the shopping cart, so that when such cart supporting
members are in operative positions they are below the shopping cart
front wheels and alongside and outside of such wheels, bearing the
weiyht of the cart instead of the Eront wheels bearing such weight,
and so that when such members are in inoperative positions, which
are retracted or storage positions, they are above the bottoms of
the shopping cart front wheels, inside such wheels and substantially
horizontal, and combinatin mounting and positioning means for
selectively holding the pair of cart supporting members in operative
or inoperative positions on the shopping cart and near the front
wheels thereof and away from the back wheels thereof and for moving
the pair of such members between operative and inoperative
positions, during which movements the members pass under the
shopping cart front wheels, which shopping cart attachment
combination is nestable with other such combinations when the
attachments thereof are in inoperative positions.
The invention will be readily understood from the
description herein, especially when taken in conjunction with the
accompanying drawing, in which:
,~
~. ~,J~
~ I .t ~
Fig. 1 is a side elevational view of a shoppiny cart with
an attachment of the present invention instal:led thereon, which
attachment is shown in operative position;
Fig. 2 is a partial, enlarged front elevational view of the
shopping cart of Fig. 1 with a skid attachment of this invention in
position thereon, in operative mode;
Fig. 3 is an enlarged perspective view of a skid attachment
of -this invention, seen from the bottom, considering installed
position, with a portion thereof omitted and with holding or
fastening means thereof being shown partially disassembled;
Fig. 4 is an end elevational view of the attachment of this
invention shown in Fig's. 1-3, viewed from the front thereof, with
the attachment being shown in installed and inoperative position;
Fig. 5 is an enlarged partial, sectional view of a locking
mechanism, shown on a smaller scale in Fig. 3, for selectively
holding the skid members of the skid attachment in operative
position, as shown, or in inoperative position;
3~:;
FIG. 6 is a partially sectional side elevational
view of a lower front part of a supermarket shopping cart,
with the apparatus of this invention affixed thereto, in
raised position, with the cart front wheels raised above the
ground, by use of a lifting mechanism, to facilitate move-
ment of the s~id members of the attachment past the wheels
and into operative position; and
FIGr 7 is a front elevational view of a different
cart lifting device, included as a part of the skid apparatus.
In FIG. 1 numeral 11 designates a supermarket cart
on which there has been installed skid attachment 37 Of the
present invention. Cart 11, whi¢h is shown in U.S. patents
3,052,319; 3,245,~98; 3,517,773; 3,813,111; 3,815,932; and
Reissue patent 25,616~ is of a type which presently is
becoming among the most popular of the supermarket shopping
carts. Such a shopping cart is self-storing and nesting,
with a basket compartment 13 including an optional baby
seat, not shown and a wall 1~, foldable down when desired,
optionally separating it from main compartment 15. At the
front of the main compartment of the shopping cart basket is
openable wall 17, which is rotatable forwardly and downwardly
to facilitate transfer to the check-out counter of items
selected by the shopper. The various basket parts are
supported on upper horizontal tubular framing portion 18,
which is a part of a unitary frame 20, which also includes
vertical tubular framing portions lg, 29 and 29a (see FIG. 2).
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3~
There is also a shorter framing member, like 29a, corresponding
to frame 19, but not illustrated in the present drawing.
Both framing portion 29a and the other such shorter framing
portion extend upwardly from lower tubular framing part 27
to about the height of the top of auxiliary basket 25 and
may have further horizontal extensions, not illus-trated, to
help support such basket. A bottom shelf 45 not shown in
FIG. 1 except for a part 28 thereof, acts as a floor between
lower framing parts 27. Forward part 31 of frame 20 is
downwardly inclined, which facilitates multiple unit storage
and nes-ting, in known manner. For such storage, in the
cart illustrated in FIG. 1, basket section 15 is rotated 90
clockwise so as to assume a position above basekt section
13. Affixed to lower portion 27 of frame 20 are back wheels
21, in mounts 22r and front casters 24 and 26, including
wheels 23 and 39, respectively. A handle 38 is provided so
that the cart may be conveniently pushed and steer~!d.
Although the illustrated cart is one which is highly prefer-
ably improved by installation thereon of the skid attachment
of this invention, it should be unders-tood that the invention
is applicable to carts of various designs and types, nesting
and non-nesting, self-storing and non-self-storing~ metal
wire and tubular construction or plastic construction, etc.
The skid attachment of this invention, shown in
operating or skid position in FIGo 1 (on a slanting supporting
surface, not illustrated), includes skid members 33 and 41
(FIG~ 2) and a handle 35 for making it easier for a customer
to place the skids in operative position when leaving the
store to travel to her or his ~ehicle over a snow filled or
ice covered parking lot. Because of the smaller scale of
S the illustration of FIG~ 1 the means for positioning the
present skid attachment on the shopping cart will be described
with respect to FIGo 2 and details of attachment of the skid
member wlll be described with respect to FIG~ 2-4~
In FIG. 2 casters 24 and 26 are shown held to
transverse bar or strap member 49,which is fastened to the
under side of lower framing portion 27 at a location just to
the rear of the downwardly inclined forward part 31 thereof.
Bottom cart shelf 45, with longitudinal rods or wires 47r to
which skid attachment 37 is held, has the skid assembly
bolted to it so that the attachment is desirably mounted and
positioned on the shopping cart, with a spacing and positioning
member 50, not shown in FIG~ 2, extending transversely with
respect to the cart longitudinal axis and being positioned
behind and adjacent to cart cross member 49~ on which the
casters are mounted. Mounting bracket 51, together with
bolts 55 and 71, which pass through holes 73, and nuts 53
and 69 (also see FIG~ 3) hold the attachment in place on the
cart. Lockwashers are also preferably utilized to prevent
loosening of the attachment, but -they are not illustrated.
25 Accommodating bend 68 in bracket 51 fits over shelf edge 45
and between longitudinal rods 47 so as to tightly hold skid
-- 8 --
~:~9~,~3~
attachment 37 in place. Yet the shelf is liftable for good
nesting (it pivots about edge 45) and the skid attachment
does not in-terfere with such lifting and nesting. In FIG.
2 front cart wheels 23 and 39 are shown, which are rotatable
about horizontal axes and pivotable abou-t vertical axes.
The various other parts of the skid attachment are well
illustrated in FIG~S. 3-5 and now will be described with
respect to them.
In FIG. 3 skid attachment 37 is seen viewed from the
bottom, or inverted, so that the various parts thereof may be
better illustratedO It will be noted that the skid attachment
assembly includes removable bracket 51 and plate 57, which
is welded or otherwise suitably jointed to spacing or positioning
cross-member 50. ~uch combination tightly holds the attachment
to the bottom of the supermarket cart in the manner previously
describedO At the ends of member 50 longitudinally oriented
flat plates 82, welded to the spacing member 50, provide
mounts or bearings 83 in which generally C~shaped skid
members 33 and 41, with the openings of the C's facing
upwardly (as installed)~ are mounted by means of end or
journal portions 84 thereoE. The skid members have offset
ends 42 and skid surfaces 43, which, as shown, are continuous
portions of the rod materials from which the skid members
are made, but in some aspects of the invention such surfaces
may be larger, like skiis, or may include runners or portions
of specially hardened steels or other materials so as to provide
wear resistance and prevent premature thinning of the material at
_ g
such wear surfaceO Skid members 41 are turnable via journal
members 84 ln bearings 83 so as to be selectively placeable
in storage or inoperative position and in operative positionr
as desired. The skid members are moved in concert by means
5 oE linkages 63 and 65, held -to the skid members by pins 79,
which linkages are joined to partially rotatable plate 6I at
pins 75. Plate 61 has mounted in it bearing member 67,
preferably a ball or roller bearing, which turns about
longitudinally oriented ~ournal member ~8, which is mounted
on post 85, fastened to mounting plate 57O Thus, when
handle 35 is moved from indicated position inwardly -the skid
members of the skid attachment are moved to storage or
inoperative position. Instead of employing the handle means
shown, various other types of mechanisms may be utilized to
effect movements of the linkage parts and the skid members.
For example, a flexible cable may be mounted so as to
accomplish this from the handle or back portion of the
shopping cart so that the user may merely tilt the front
wheels of the cart upwardly and operate the activating means
to place the skid members in operative position. Alternative~
ly, threaded rod means may be connected to linkage plate 61
so that upon rotation of the rod the skid members will be
moved. If desired, no such operating mechanism may be
included and hand pressure applied to one of the skid members
may be the means for shifting positions thereof, preferably
while the cart front is being lifted.
-- 10 --
J I~Il> ~ ~
To preverlt undue strain on the linkage mechanism
stops 81 are provided to prevent movement to open or operative
positions beyond the desired extent. Similarly, stop member
59 limits the movement of the linkage and the skid members
-to inoperative position. Desirably, such stop members are
so located as to facilitate positioning of locking members
for holding the skids selectively in either operative or
inoperative position and for preventing unintentional
movements out of such positions. They also preven~ the linkage
par-ts from being moved too far so that returns thereof are
inhibited. One such locking mechanism is illustrated in
FIG. 5 (and is also shown, on a smaller scale, in FIG. 3)O
In FIG. 5 a part of skid member 33 is shown having trans-
verse openings or bores 91 and 117 therein, for positioning
the skid members in operative position when pin 89 is in
bore 117 and in inoperative position when such pin is in
hole 91. Pin 89, in the mechanism illustratedr is held by
spring plate 87, surrounding pin groove 119, and passes
through clearance 121 in plate 82. Thus, in normal position
the pin is urged downwardly (considering the orientation of
the skid member on the shopping car-t) but may be moved
upwardly and out of engagement with ei-ther of holes 91 and
117 by moving spring plate 87 accordlngly. Thus, to release
the locking member and change positions of the skid members,
one need only release pin 89 by movement of spring member
87 and rotate handle 35, as desired. When the skid is in
? v~ ~
desired position the pirl will automatically lock by moving
into the appropriate boreO The stop members and the locking
member are so arranged and positioned as to act in conjunc-tion~
with the locks being effective when the skid members have
been moved to the stops~ thereby obviating any need for
trying to locate the lock positions by eye or by movement~
of handle 35, and preventing undue strain on such locking
mechanism (since the stops will take such s-train). The lock-
ing mechanism illustrated is a single spring loaded one but
various other locks and biasing devices may be used instead,
too. For e~ample, in one such apparatus,reduced to practice
by the inventors,a simple door latch or bar bol-t (a sliding
rod)was utilized successully.
Although it is not clearly shown in the drawing,
because the additional lines would be confusing in FIG. 2,
the skid members 33 and 41, in addition to having skid parts
42 inclined outwardly beyond the car-t frame, for cart
stability, are inwardly directed -toward the front 90 -thereof
to promote good nes-ting of the carts, especially in s-torage
position.
To u-tilize the present skid attachmen-t so as to
facilitate movement of a loaded shopping cart through a
snowy or icy parking lot, which movement is extremely difficult
under normal circumstances without the skid attachment of
this invention being employed, is rela-tively simple. The
skid atkachment may be removed from the cart during the
summer months or may be left on year round. Of course, it
- 12 -
will be in inoperative position during use of the car-t in
the store and will be activated upon leaving the store and
entering -the parking lot, when that lot is in such condition
as -to make ordinary wheeling of -the shopping cart difficult~
The shopper may bend down, lift the front end of the cart,
release the locking mechanism, when present, and adjust the
skid attachment so that the skid members are in operative
position, after which she or he reengages the locking mechanism
and lowers the cart. It has been found that the present
relatively small skids, preferably with the contact surfaces
being straight and the forward portions being cur~ed, allow
easy movement of the supermarket shopping cart, even when it
is heavily loaded, over icy and snowy areas. Suprisingly,
with the present apparatuses steering is no problem and the
presence of the rear wheels does not interfere unduly with
movement of the cart. Because the skids raise the cart off
the front wheels only, they may be made much sturdier and
much less expensive than skiis or skid means which extend
under all the wheels of the cart. Additionally, they can be
made self-storing and nesting, which is important.
~ lthough it is relatively easy to utilize the
present invention, in some instances, as when the shopper is
not strong enough or is incapable of bending (and when the
cart is not equipped with "remote control" mechanisms) for
actuating the skid members, auxiliary equipment may be used
and different methods may be employed so as to raise or
lower the skid mechanism easily.
- 13 -
t~3~
In FI~o 6 ~ lower portion 27 of the framing
member of super~arket cart 11 is illustrated with skid
attachment 37 fastened -thereto. As illus-trated, forward
cas-ter 26, supp~rting whee~ 2~, is joined to transverse cart
~ar or plate 49 by nut 95. Plate ~9 is suitably fastened to
lower framing portion 27. Behind caster 26 is transverse
holding and spacing member 5~, to which is joined longitudinal
member 82, at the side thereof, with bearings 83 and journals
84 being held thereto and with skid members 41 thereby being
rotatably held to the mounting and positioning means of the
skid attachment. As illustrated, the cart wheel 24 and the
other cart parts associated therewith, are in partially
raised position, with lifting device 99, shown as foot
operated but also capable of being otherwise actuated,
having a backwardly (with respect to the shopping car-t) arld
upwardly directed open or U-shaped end 115 fitting about and
contacting the lowermost part of the downwardly inclined
forward portion 31 of t~e shopping cart frame. It will be
apparent that the lifting device includes a longitudinal
base member 101, with a transversely positioned mounting
portion 103, having vertical walls 107, with oper.ings therein
for a bearing, not il~ustrated, in which a journal or pin
109 may partially rotate. Fitting or contacting portion 115
of lifting device 39 is at one end of the lifter and the
device includes a foot pedal or other foot operated part
113 at the other end thereof, with a connecting lever
portion 111, communicating with the end part~ adapted to
contact the shopping cart frame. On depressing of the pedal
or rod 113 the shopping cart is lifted. Ilowever, although
such lifting makes it easier to place the skid a-ttachment in
operative position,it is still somewhat awkward to hold down
rod 113 and move skid attachment 37, so it is preferred that
a spring biased lockiny mechanism, illustrated at numeral
114, be employed, to hold the lif-ter in position once the
cart has been raised. Such lock may be released manually
after posi-tioning of the skid attachment so that the cart
may be lowered onto the skids. Stop 105 is shown as a means
for holding the lever ln position and preventing it moving
downwardly far-ther than that position at which it may normally
make suitable first contac-t with the front end portion 31 of
the lower frarne 27 of cart 11. Such stop height may be adjust-
able. Thus, when the lever is in start position, merely
moving the supermarket shopping cart against it will automatically
position the frame with respect to lever part 115, so that the
cart may then be raised to desired height merely by pushing it
against the lifterO
~n FIG. 7 there is shown a different mech~nism for
lifting the cart to assist in moving the skids into operating
position. Such mechanism, designated by numeral 117, is
normally storable in substantially horizontal position
forwardly of a combination mounting and positioning means 50
25 of the skid attachmen-t. As shown, bearings 121 and 127 and
journal portions 123 and 129 cons-titute rota-table mounting
2~
means, in which the journals are rotatable about a transverse
horizontal axis, for mounting lif-ting device 117 on the
skid attachment and -the cart. The liftiny device includes a
base portion 125 which has a roughened surface thereon 131
for frictionally engaging khe ground or other such support.
Such base is connected to -the rotatable means by connecting
means 133, which,in the embodiment illustrated,is a cylindrical
rod~ The lifting device is normally held in elevated position
by friction, spring means or a releasable catch, and may be
dropped or pushed downwardly into ground engaging position
when it is desired to lift the cart to facilitate movement
of the skid attachment into operative skid position. Such
downward movement of the lifting device can be effected
manually from the front of the cart or may be promoted by
means of a flexible cable or other connector mechanism or
linkage from the front or back (handle portion) of the car-t.
After the frictional portion 131 of base 125 engages the
ground or other support it is a simple matter merely -to push
the cart forward and it will ride up on the lift device as
that rotates and moves vertically. A stop, not illustrated,.
may also be provided to prevent the connecting rod going
past its uppermost position. After raising of the cart and
placing of the skid member in operative position, the lifting
device may be returned to initial horizonal orientation by
pulling the cart backward.
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3~
The various cart attachment and auxiliary device
parts mentioned will normally be made of steel, preferably
chromium or nickeL plated/ but other metals, including
aluminum, stainless steel and various other ferrous and non-
ferrous metal alloys may also be utilized, as may be syntheticorganic polymeric plastics and fiber reinforced plastics
(especially the "engineering plastics") and laminates, for
certain portions of the apparatuses. The various mechanical
elements of the apparatuses may be replaced hy others that
wi]l perform the same or similar functions effectively.
Thus, for example, different types of engaging, locking,
lifting, adjusting and fastening means may be subs-tituted
for those illustrated.
Various advantages of the present invention have
either been alluded to have been previously mentioned but
some of these and additional advantages will now be listed
(but the list is not ~o be considered as exhaustive). First
and foremost, the invention provides for an easy means for
overcoming adverse winter conditions in the more northern
states, and facilitating the use of shopping carts in the
normal push manner in supermarket parking lots which may be
covered with ice and snow. The invention promotes safe use
of the carts, allowing them to be moved forwardly in the
normal direction. The retractable skids, in effect, lift
the front wheels off the ground, preventing bogging down of
~ 17 -
23?~i
the shopping cart due to the wheels being imbedded in snow
or being stuck in rough ice formations. In operative position
the skids provide for greater stability, being outwardly
directed, as well as downwardly, so that the contacts of the
skids with the supporting surface are about at the dis-tance
apart of the rear cart wheels. This increased s-tability
feature is obtalnable and yet the carts remain satisfactorily
nesting and self-storing.
Although the skids are relatively thin (and strong)
it has been found that they are capable of satisfactorily sup-
porting the cart and of acting as a sliding surface for it in
a parking lot under bad weather conditions. (The cart is not
intended for use in very deep snow but will be operative under
moderate snow and ice conditions~. Surprisingly enough, although
the skids are fixed in a longitudinal direction they do permit
easy sliding steering, even on bare parking lot pavements,
providing that such are wet or damp or are otherwise lubricated.
The invented skid attachment is retained with the
cart (individual skids cannot be lost, removed or otherwise
separated from the attachment). By virtue of the type of
installation pos5ible, it does not interfere with nesting
features of the supermarket shopping cart and the bottom
shelf, which is raisable on some such carts to facilitate
nesting, can still be lifted as a plurality of the carts is
stored away ready for use. In addition to the storage
capabilities of carts equipped with the present skid a-ttach-
ments they may also be moved over the surface of a snowy or
icy parking lot as a nested train. Most shoppers are
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familiar with the sight of a young supermarke-t clerk to whom
is assigned the unhappy task of collecting -~he shopping carts
from the parking lot. ~is job is especially di~ficult in
bad wea-ther and under snow~ and icy conditions~ During good
weather, as he collects the carts he nests them so that he
may push a plu~ality of them back to the store and thereby
Cllt down on the number of trips needed. In bad weather it
is very difficult to manage more than one or two carts at a
time, but when they are equipped with the skid attachments
of the present invention it has been found that although the
number of carts being pushed may not be as grea-t as in good
weather, it is still possible to~push as many as five or six
carts over s~owy surfaces, having only the skids of the
first cart in operative position. The skid attachments from
the various carts (or every other cart) may be used at the
same time in such a cart train providing that the attachments
are so constructed and of such size as not to interfere with
nesting, in which case, more carts may be pushed at one time
despite the snow or ice.
The one somewhat difficult operation that has to
be performed in using the present attachment is the lifting
of a cart front to permit moving of the skid members into
operative position. Of course, it is also important that
after the skid members are in operative position they should
be locked or firmly held in place so that the weight of the
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3q3
cart will not be returned to the wheels, as when a turn is
made and sideward pressure is applied to a skid member.
Some means for more readily raising the cart into position
for activation of the skid attachment have been described
but it will be apparent that various other ways of accomplishing
this are also possible. For example, one way is to pull
the cart over an inclined plane between the wheels so -that
the cart and the wheels will be lifted off the ground, with
a clearance being supplied between the plane structure and
the portion of the cart behind the front longitudinal base
tubing thereof so that the skids will be freeiy movable to
position. Another way is to use.some type of hoist mechanism
or to assign a store clerk to the task of lifting the cart and
pulling the skids in positionO However, lever mechanisms,
such as those previously described, are normally preferable.
The illustrated linkages for moving the skid members into
and out of operative position have been shown in the embodi-
ment of this invention as being operated by handle actuation
at the site of the attachment. ~Iowever, it is contemplated
that remote operation thereof may be effected, by linkages,
rotatable shafks, flexible cables or o-ther suitable means,
preferably passing along or through portions of the framing
of the car-t and being operable at the handle or other convenient
location thereon. Similarly, the locking mechanism, if one
is employed (spring loading or similar semi-automatic locking
may be preferable) may be remotely actuated. lnstead of
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~2~3~
installing and removing the present apparatus it may be left
on year round and in some instances the skid "attachment"
may be built into the apparatus as a integral part thereof.
Due to the compactness of the present attachment
it is of superlor strength and is capable of resisting the
hard treatment absorbed by shopplng carts. For e~amplc,
because relatively little material ls employed in its
construction, wlth only the front wheels having lifting
skids associated wlth them, the various plate members,
linkages, stops, etc. (the flat items) may be of a thickness
within the range of 2 to ~ millimeters, preferably 3 to 6
mm., e.g., 5 mm., and the bar st~uctures may be from about 6
to 16 mm., preferably 8 to 1~ mm., e.g., 11 mm. in thickness
bu-t it is also within the invention to utilize other sizes of
lS materlals, too. Of course, when stronyer materials of
construction are employed thinner parts may be utilized tooO
In addition to the above recited advantages,
various others will be apparent to those of skill in the art
from the prevîous descrlptions.
Although various embodlments and illustrations o
the invention have been mentioned and preferred embodiments
havebeen described, it will be clear to those of skill in
the art, with the present descrlption befoxe them, that
various substitutes and equivalents may be employed without
departing from the invention.
~ 21
