Patent Grant
11613909
The disclosures of U.S. application Ser. No. 17/892,938 entitled A KEY BLANK, A KEY AND A CYLINDER LOCK AND KEY COMBINATION filed on Aug. 22, 2022 and U.S. application Ser. No. 17/892,992 entitled A KEY PLUG, A CYLINDER LOCK, A CYLINDER LOCK AND KEY COMBINATION AND A METHOD TO MANUFACTURE A KEY PLUG, filed on Aug. 22, 2022 the entire contents of which are hereby incorporated by reference.
The present invention relates to a key blank having a grip portion, serving to facilitate the insertion of a substantially flat key blade in a forward direction and the withdrawal of the substantially flat key blade in a backward direction along a longitudinal axis, and also the turning of the substantially flat key blade so that it rotates around the longitudinal axis. The substantially flat key blade extends from the grip portion along the longitudinal axis and includes, as seen in the forward direction, a connecting portion adjoining to the grip portion, a major longitudinal bitting portion to be provided with a row of coded cuts, and a free tip portion. The substantially flat key blade has a cross-sectional profile which is confined within a rectangle having a height being at least 2.5 times greater than a width thereof. The cross-sectional profile includes a lower relatively wide part, having a maximum width being substantially the same as or slightly less than the width of the rectangle, the maximum width being 75% to 100% of the width of the rectangle with an upper relatively narrow part being narrower than the lower part and possibly an interconnecting part extending between the lower and upper parts. The connecting portion of the substantially flat key blade is provided with a first selectable abutment surface facing in the forward direction.
The present invention also includes a key blank having a coded bitting portion, so as to form a coded key, as well as a cylinder lock and key system, including a coded key and an associated lock with a key plug.
A key blank and a coded key is known, for example from the European patent specification EP 3,219,882 B1 (ASSA AB). In the embodiment shown in this document, there are selectable axial positions for first stop or abutment surfaces on each key, cooperating with second abutment surfaces on the key plug and being located adjacent to each other side by side, and being equidistantly separated in a respective set of keys by a stop separation distance, the selectable positions of one set being axially offset to at least one other set. Also, the first stop surfaces on the keys are all located on a step-like transition at a connecting portion of the substantially flat key blade. In this way, the security of the system cylinder lock and key system is enhanced because the offset configuration of the axial positions of the two adjacent first abutment surfaces is difficult to predict for unauthorized persons who wish to reproduce the first surfaces correctly in an attempt to copy the key.
However, since the first abutment surfaces on each key (see
An object of the present invention is to accomplish an improved stop arrangement which provides a flexible arrangement for stopping the insertion of a key into a key plug of an associated lock at a selectable position.
It is an object of the present invention to provide a more flexible structure of the substantially flat key blank or coded key so that the selectable position of the abutment surface is broadly variable within the whole connecting portion between the grip portion and the bitting portion of the substantially flat key blade. Thus, the selectable position should not be confined to a step-like transition. With such a more flexible structure, it is possible to update an existing system of cylinder locks and keys, so as to add a new, separate group of keys to the existing system, where the new, separate group of keys includes at least one lock and key combination which is backwards compatible with the existing system. Alternatively or additionally, it should be possible to create a totally new system, which includes sub-groups being either separated from each other or forming a hierarchical system with sub-groups of different ranks.
Another object of the present invention is to provide such a structure of the key wherein the abutment surface on the key will contribute to strengthening the key, at least for an added new group of keys, and making it resistant to rather strong torques that may appear during attempts to open a lock with the new key.
The above objects are achieved by a key blank, and a coded key, of the kind stated above, wherein the first abutment surface on the key is formed as a forward end surface of a longitudinal rib portion that is located at a lateral side of the upper relatively narrow part of the substantially flat key blade at a vertical level lying within a vertical range of the bitting portion of the substantially flat key blade and extending in parallel to the longitudinal axis of the substantially flat key blade and being confined longitudinally to the connecting portion of the substantially flat key blade and within the contour of or slightly laterally outside the above-mentioned rectangle, with a possible lateral extension exceeding the width of the rectangle by at most 25%, and having a selectable length, measured from the grip portion to the forward end surface of the rib portion, being any desired fraction of the length of the connecting portion. The location of the forward end surface of the rib portion, forming the first abutment surface on the key, is selectable along the whole length of the connection portion.
Owing to the structure provided by the present invention, in particular the longitudinal rib portion extending along a selected fractional part of the connecting portion, at a lateral side of the upper relatively narrow part of the substantially flat key blade, there will be obtained a great flexibility in designing a separate cylinder lock and key combination or system, being backwards compatible with an existing system, or in creating a totally new cylinder lock and key system, which may include various separate sub-groups of cylinder locks and keys or a hierarchical system with sub-groups of different ranks. Also, for a normal connecting portion of a key, typically of a length up to about 10 mm, the longitudinal range of the longitudinal rib portion will allow a wide span of possible lengths to be selected, such as 0 to 10 mm for a key blank or a coded key, for example for use in a small format interchangeable core type of lock.
Since the rib portion is located within a vertical range of the bitting portion of the substantially flat key blade, it is independent of any possible step-like transition at the connecting portion of the substantially flat key blade. Therefore, the key may have or may not have such a step-like transition. Consequently, in case there is no step-like transition forming the first abutment surface, it will be more difficult for an unauthorized person to determine exactly how long the key is supposed to be inserted into an associated lock, since it cannot easily be determined where the corresponding, second abutment surface of the key plug of the associated lock should be located in the longitudinal direction.
Advantageously, the longitudinal rib portion is located in the vicinity of an upper edge of the upper part of the substantially flat key blade at the connecting portion thereof. This will strengthen the relatively narrow part of the substantially flat key blade adjacent to the grip portion, in particular in respect of torques being applied to the grip portion when the latter is turned in order to rotate the key plug of an associated lock. The rib portion, being unitary or firmly attached to the grip portion, will effectively transfer the torque from the grip portion to the key plug, especially in embodiments where the second abutment surface is located in a cavity or recess in the front end portion of the plug, so that the torque is transmitted directly via the walls of a keyway to the plug of the associated lock, with a minimum stress affecting the relatively narrow upper part of the substantially flat key blade.
The prior art includes published documents where attempts have been made to minimize the torque transmitted to the key plug during turning of the key to actuate a cylinder lock, see for example the U.S. Pat. No. 5,272,895-A (Best Lock Corporation). In this prior art embodiment, there is a drive shoulder located adjacent to the grip portion of the key, the drive shoulder forming a step-like transition at the portion of the blade between the grip portion and the bitted portion of the substantially flat key blade, as shown in FIG. 5 of the '895 patent. However, as clearly described in the specification, column 4, lines 42-48, “the stop shoulder 56 is formed near the distal tip of blade 14.” So, in this case, the drive shoulder 16, serving to minimize the torque transfer, and the stop shoulder 56, serving as a stop or abutment surface, are separated and located far away from each other. According to the present invention, on the other hand, the longitudinal rib portion serves both as a stopping device and a torque minimizing device.
The longitudinal rib portion may be located on one lateral side only or on both lateral sides of the upper relatively narrow part of the substantially flat key blade. As indicated above, it is located at a vertical level lying within a vertical range of the bitting portion of the substantially flat key blade. Accordingly, it is not located at any shoulder or step-like transition provided at a higher vertical level.
In case where the upper narrow part of the substantially flat key blade is located in the vicinity of a central vertical plane of the substantially flat key blade is it feasible to have two rib portions, one on each lateral side thereof. Then, the selected lengths of the two longitudinal rib portions may be mutually equal or mutually different.
In case where there are two longitudinal rib portions, one on each side of the upper part of the substantially flat key blade, and a first rib portion on one lateral side is too short to secure a proper alignment of the coded cuts of the key and the central locking pins of the key plug, and a second rib portion on the other lateral side is longer than the first rib portion, the second longer rib portion may serve as a further abutment surface and replace the first rib portion so as to secure a proper stopping of the key when the key reaches the fully inserted position inside the key plug. Such further abutment surfaces may be formed also in other ways, as will be indicated below.
The cross-sectional profile of the upper relatively narrow part of the substantially flat key blade may be configured in various ways, as will be explained as follows:
In a first embodiment, the profile of the substantially flat key blade of the key blank (and thus also the keyway of the key plug) includes the above-mentioned interconnecting part between the lower and upper parts, wherein a substantially vertical portion adjoins to one lateral side portion of the lower part, and the upper part is located substantially centrally along a mid-plane of the rectangle, within which the profile is confined, and wherein the longitudinal rib portion is located on one or both lateral sides of the upper, centrally located part of the substantially flat key blade, at the connecting portion thereof.
In such an embodiment, the substantially vertical portion of the interconnecting part may form an inner surface of an undercut groove being formed in a lateral side surface of the substantially flat key blade, the lateral width of the substantially vertical portion of the interconnecting part above the undercut groove being narrower than the lower part of the substantially flat key blade. Here, an undercut portion of the undercut groove may form an inside of a security ridge extending upwards from the lower part of the substantially flat key blade in parallel to the interconnecting part. The undercut groove may extend vertically downwards into a pocket having opposite side surfaces and a lowermost bottom surface. These opposite side surfaces may be substantially parallel to each other. Possibly, an upper inside portion of the security ridge may be inclined so as to face upwards towards an upper part of the undercut groove, the upper part of the groove being open in a lateral direction.
In a second embodiment, the cross-sectional profile of the substantially flat key blade includes, at one side of the substantially flat key blade, an undercut profile groove, and the lateral side surfaces located vertically above and below the undercut profile groove will lie substantially in a same vertical plane, whereas, at the opposite side of the substantially flat key blade, there is a shelf surface. In this embodiment, the longitudinal rib portion is located at the connecting portion of the key blade at a lateral side of the upper part of the substantially flat key blade, above the shelf surface.
In a third embodiment, the cross-sectional profile of the key blank comprises two deep grooves in the two opposite lateral side surfaces of the substantially flat key blade, the two deep grooves being located in the interconnecting part of the substantially flat key blade, and the depths of these two grooves are greater than half the width of the rectangle in which the substantially flat key blade is confined, whereas the upper part of the substantially flat key blade is located substantially centrally along a mid-plane of the rectangle, and the longitudinal rib portion is located on one or both lateral sides of the upper part of the substantially flat key blade at the connecting portion thereof. Advantageously, when there a two rib portions, one on each side of the upper part of the substantially flat key blade (even in other embodiments), a second longitudinal rib portion may be shorter and possible also displaced vertically in relation to a first one. In this way, there will be a large number of possible variants that will provide distinct differences between key blanks within a group or sub-group.
In a fourth embodiment, the upper part of the substantially flat key blade is inclined 3° to 12° relative to a mid-plane of the rectangle within which the cross-sectional profile of the substantially flat key blade is confined. Such an embodiment is disclosed in two other patent applications filed on the same day by the same applicant as the present application, these other patent applications being related to a key blank and a key plug, respectively. As indicated above, the disclosures of the U.S. Patent Applications filed on even date herewith are incorporated herein by reference.
As indicated above, the present invention also includes a key blank where the upper part of the major longitudinal portion of the substantially flat key blade is provided with a row of coded cuts so as to form a coded key.
The substantially flat key blade may also be provided with an additional code pattern located in the lower part of said major longitudinal portion of the substantially flat key, the additional code pattern being located at a bottom surface of a pocket formed at an undercut profile groove, between an interconnecting part and an upward security ridge, the additional code pattern including coded concavities longitudinally along said longitudinal portion at a number of different vertical levels, said coded concavities being at least partially concealed by said security ridge when being observed laterally sideways in a horizontal direction being substantially perpendicular to the vertical mid plane of said substantially flat key blade.
Moreover, the present invention includes a coded key in combination with a cylinder lock so as to form a cylinder lock and key system. Generally, such a cylinder lock and key system may include at least one cylinder lock and key combination forming a matching pair, so that a coded key can release the associated matching cylinder lock. Such a matching pair includes a coded key as recited above, and a cylinder lock of the kind including a housing having a cylindrical bore, and a key plug with a cylindrical body portion, being journaled in the cylindrical bore, and an adjoining radially widened portion having a larger radius than the cylindrical portion. The key plug has a longitudinal keyway extending from a front end portion to a rear end portion of the key plug. The longitudinal keyway includes a specific cross-sectional profile corresponding to the cross-sectional profile of the substantially flat key blade of the coded key, so that the coded key fits slidingly in the longitudinal keyway. A row of central locking pins are provided which are vertically movable in vertical bores in the cylindrical body portion in a central plane of the key plug, and the locking pins cooperate with the coded cuts of the coded key, wherein the coded key is insertable in the forward direction into a releasing position in the keyway of the key plug, where it enables releasing of the lock by turning the coded key around the longitudinal axis and causing a corresponding rotary motion of the key plug, and the cylinder lock and key in each matching pair are provided with mutually cooperating first and second abutment surfaces facing in opposite directions along said longitudinal axis.
According to an embodiment of the present invention the first abutment surface is formed by the forward end surface of the longitudinal rib portion of the substantially flat key blade. The forward end surface is located at a desired position along said connecting portion of the substantially flat key blade. The second abutment surface is formed by a matching front end surface located at the front end portion of the key plug, and the longitudinal length of the longitudinal rib portion of the substantially flat key blade and the longitudinal position of the matching front end surface at the key plug are selected so that, in each matching pair, the forward end surface of the longitudinal rib portion and the matching front end surface at the key plug will make contact with each other when the key reaches the releasing position in the key plug.
The matching front end surface of said key plug of the cylinder lock may be formed by a bottom or end surface in a longitudinal cavity located in the front end portion of the key plug, with the longitudinal cavity being formed by a laterally sideways extended part of the keyway. The longitudinal cavity is configured so as to accommodate the longitudinal rib portion of the substantially flat key blade and may have a selected depth measured from an entrance opening in the radially widened portion of the key plug to the bottom portion of the longitudinal cavity The longitudinal cavity of the key plug is located at a vertical level lying within a vertical range of the coded cuts in the upper part of the substantially flat key blade, when the latter is inserted into the keyway. In each matching pair, the selected longitudinal length of the longitudinal rib portion of the coded key is equal to the selected depth of the longitudinal cavity of the key plug.
As indicated above, a cylinder lock and key system may include totally separate lock and key combinations, wherein any key fits only into a separate group of locks and keys, or the system may be a hierarchical system with sub-groups of locks and keys of different ranks.
In the latter case, i.e. in a hierarchical system, each sub-group may include, in addition to two or more matching pairs with various selected lengths of the rib portions of the keys, and corresponding selected longitudinal locations of the second abutment surface of the key plug, other possible cylinder lock and key combinations within the sub-group wherein the rib portion of the key is too short, which would result in a misalignment of the coded cuts of the substantially flat key blade and the locking pins of the key plug, so that the key would never reach its releasing position. Such a misalignment is avoided by means of a supplemental stop arrangement including a further abutment surface on the key which will replace the longitudinal rib portion being too short, and a further abutment surface on the key plug which will replace the matching front end surface at the key plug. The further abutment surfaces will secure a correct stopping of the key in the key plug, for one or more of the other lock and key combinations where the central locking pins of the key plug would be misaligned relative to the coded cuts of the key because of a too short longitudinal rib portion on the key, wherein the further abutment surfaces are configured to make contact with each other when the key reaches said releasing position in the key plug.
Such further abutment surfaces in a cylinder lock and key system, provided on lock and key combinations other than the matching pairs, may be of different kinds.
In one kind of such further abutment surfaces, the further abutment surface on the coded key is located at the free tip portion of the substantially flat key blade, and the further abutment surface on the key plug is formed on a fixed stop member at the rear end portion of the key plug.
Such a fixed stop member may, for example, be formed by a stop ring or washer of the kind usually being used at key plugs so as to prevent them from being pulled out from the housing of the lock.
Other kinds of further abutment surfaces on the key and at the key plug, that will replace the first and second abutment surfaces in certain situations, will be disclosed in the detailed description of preferred embodiments below and will also be defined in the appended claims.
An embodiment of the present invention concerns a cylinder lock and key system including at least one sub-group of lock and key combinations which are backwards compatible with an existing cylinder lock and key system of the same kind but having neither any longitudinal rib portions on the keys, nor any corresponding cavities in the key plugs. In these new lock and key combinations, the radially widened front end portion of each key plug may have an enlarged thickness, as measured longitudinally along the key plug, the enlargement being equal to the selected depth of the cavity therein, and an optional step-like abutment portion, serving as a further abutment surface, on the key may have a reduced length, the length reduction being equal to the enlargement of the thickness, whereby the longitudinal rib portions of the keys in this sub-group will also enable opening of the cylinder locks of the existing system, and secure a correct stopping of the keys when being inserted into the corresponding key plugs belonging to the same sub-group by making contact with the front end surface of the corresponding key plug when the key reaches its releasing position.
The key blanks of the present invention are normally made of brass or of a nickel-silver alloy. Alternatively, they can be made of other metals, such as steel or aluminum.
Typical methods of production include stamping, milling and coining,
The key grip may be unitary in one piece with the connecting portion and the major longitudinal part of the substantially flat key blade. However, it is also possible to make key blanks as cutting lengths of a drawn elongated bar, and subsequently add on separate grip portions on each cutting length.
Further possible manufacturing methods are sintering, casting and also additive methods in a wide range of materials, such as polymers, metals and metal alloys, including 3D printing methods.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
aa to 17dd show the further abutment surfaces in
The key blank 100 includes a bow or grip portion 110 and a substantially flat key blade 150. The grip portion 110 serves to facilitate the insertion of the substantially flat key blade 150 in a forward direction (towards the right in
The key blank 100 extends along the longitudinal axis A and includes, as seen in the forward direction (towards the right in
According to an embodiment of the present invention, there is provided, adjacent to the grip portion 110, a longitudinal rib portion 121, being relatively short and serving to provide an axial stop for the key blank 100, upon being provided with the above-mentioned coded cuts at the positions 131, when it is being inserted into the keyway 910 of the key plug 900. The longitudinal rib portion 121 cooperates with a corresponding stop at the key plug, so as to provide a pair of abutment surfaces, viz. a first abutment surface on the connecting portion 120 of the key blank 100, formed by a forward end surface 125 of the longitudinal rib portion 121, see
The first and second abutment surfaces, formed by the forward end surface 125 on the longitudinal rib portion 121 and the bottom surface 925 in the longitudinal recess or cavity 921, are located at such selected positions that, when the forward end surface 125 and the bottom surface 925 make contact with each other during insertion of the key into the key plug, there are central locking pins (960 in
In order to provide the above-mentioned flexibility of the stopping arrangement, the longitudinal rib portion 121 of the key blank 100 (and the finished, coded key) is located at a lateral side (the downward side in
The lower relatively wide part 160 has a slightly curved lower edge 161, and the upper relatively narrow part 170 has an upper edge 171.
As appears from
The length of the longitudinal rib portion 121, measured from the grip portion 110 along the axis A of the substantially flat key blade, should be selected as any desired fraction of the total length of the connecting portion 120. So, this length may be minimal (as short as possible and close to zero) or any desired length up to the total length of the connecting portion 120. Thus, the forward end surface 125 may be located at any position between the grip portion 110 and the major longitudinal bitting portion 130. Possibly, the longitudinal rib portion 121 has such a length that its forward end surface 125 is located close to the bitting portion 130 of the substantially flat key blade 150. It may even be located so as to adjoin directly to a first coded cut in the bitting portion 130. Accordingly, the location of the forward end surface 125 of the rib portion is selectable along the whole length of the connecting portion 120.
It should be noted that the cross-sectional profile of the substantially flat key blade may consist only of a lower part 160 and an upper part 170, with no interconnecting part 165 therebetween. If so, the upper relatively narrow part 170 will adjoin directly to the lower part 160, possibly at a central mid location between the lateral sides of the rectangle R.
As shown clearly in
As will appear from various embodiments to be described below, the key blank may be provided with one or more longitudinal rib portions, possibly two (or more) longitudinal rib portions, at least one on each lateral side of the upper relatively narrow part of the substantially flat key blade, the selected lengths of the longitudinal rib portions being mutually equal or mutually different. See for example the
The cross-sectional profile of the key blank may be configured in various ways.
A first embodiment of the cross-sectional profile comprises, see
The substantially vertical portion of the interconnecting part 165, 265, 265a, 265b, 265c, 265c, 265d forms an inner surface 167, 267, 267a, 267b, 267c, 267d of an undercut groove 168, 268, 268a, 268b, 268c, 268d formed in a lateral surface (to the left in
In this first embodiment of the cross-sectional profile, the undercut portion of the undercut groove forms an inside of a security ridge 166, 266, 266a, 266b, 266c, 266d which extends upwards from the lower part of the substantially flat key blade in parallel to the interconnecting part. The security ridge will make it more difficult to manipulate a key plug of an associate lock (a tongue may reach into a keyway at a level below central locking pins in the lock, as is known per se in this technology). Furthermore, the undercut portion of the undercut groove is extended downwards into a pocket 269e (see
As will be apparent when comparing the detailed configuration of the cross-sectional profiles in
In the variant of the first embodiment, shown in
If desired, it is also possible to cut out a second code pattern in the security ridge 266e itself, for example, a more shallow code with concavities located higher up than those shown in
A still further modified variant of the first embodiment is shown in
When utilizing the concealed code pattern shown in
A second embodiment of the cross-sectional profile of the key blank 300a, 300b is shown in
A third embodiment of the cross-sectional profile of the key blank 400 is shown in
A fourth embodiment of the cross-sectional profile is shown in
The substantially flat key blank 500a, shown in
As indicated above, see
The present invention also concerns a coded key, as described above, in combination with a cylinder lock so as to form a cylinder lock and key system. Such a system may comprise one or more cylinder lock and key combinations where at least one cylinder lock and key combination forms a matching pair. In such a matching pair, the coded key can be inserted into a releasing position in which it can be turned together with the rotatable key plug in the lock so as to open the lock.
The longitudinal rib portion 121 (see
The length of the longitudinal rib portion 121, and the corresponding length of the matching longitudinal cavity 921, can be selected as desired. In this way, a great flexibility can be obtained. In principle, the length of the rib portion can be selected as any desired fraction of the length of the connecting portion 120 of the substantially flat key blade, see
It is possible to build a cylinder lock and key system with totally separate matching pairs, where a particular key can only be used to release the matching key plug in the same pair but not in any other key plug in the system. For each matching pair, a group of individual cylinder lock and key combinations may be formed by selecting the particular pins in the key plugs and coded cuts in the keys as is well-known per se.
Another way to make use of the flexibility inherent in the wide range of longitudinal lengths of the rib portions of the keys is to form a hierarchical system with sub-groups of different ranks, so that certain keys can open more than one sub-group of cylinder lock and key combinations, whereas other keys can open a smaller number cylinder lock and key combinations and possibly only one such combination in a sub-group.
One way to form such a hierarchical system is to form a sub-group including, in addition to two or more matching pairs with various selected lengths of the rib portions of the keys and corresponding selected longitudinal locations of the second abutment surface (for example the bottom surface of the cavity described above), other lock and key combinations where the rib portion of the key is too short to provide a matching pair. If the rib portion is too short, the key may travel too far into the keyway, and it will then be difficult to find the releasing relative positions of the key and the key plug. In order to avoid such a misalignment, a supplemental stop arrangement may be provided for these other lock and key combinations. Such supplemental stop arrangements can be provided in a number of ways, as will be explained below. The supplemental stop arrangements all include further abutment surfaces on the key and on the key plug which will replace the above described abutment surfaces.
A first kind of such a supplemental stop arrangement, illustrated in
A second kind of supplemental stop arrangement is shown in
A similar supplemental stopping arrangement is shown in
Another supplemental stopping arrangement is shown in
A modified variant of the second kind of supplemental stopping arrangement is shown in
When the new substantially flat key 5100 is inserted into the key plug 4900′ of the existing system (see
Moreover, see
In
The grooves 6168a, 6168b extend longitudinally backwards from the free tip portion 6140 (
The obstructing pins 6169a, 6169b serve to partially obstruct a passage from the relatively wide lower part of the keyway 6960 up to the central locking pins (not shown) which are located centrally in the key plug 6900 in the pin holes in the bitting portion 6130. The obstructing pins 6169a, 6169b will make it more difficult to manipulate the cylinder lock when there is no key in the keyway.
It is possible to have such obstructing pins 6169a, 6169b on only one side of the substantially flat key blade, and there may be more than one of them on each side, possibly one or two obstructing pins underneath most of the central locking pins in the key plug, in order to increase the security of the key plug against manipulation from below.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
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