Field of Invention

[oooi] The present invention relates to footwear and in particular an assembly for selectively extending or retracting grip-enhancing spikes from a shoe.

Background

[0002] Footwear intended for use on a low friction surface such as ice or in certain commercial, construction or industrial settings typically have soles that are intended to securely grip the ground to prevent slipping. Increased traction is often achieved by fabricating the sole from a material having a high co-efficient of friction such as rubber, providing a deep tread pattern or a combination of these. Alternatively, one can attach a traction device such as crampons to footwear. Such devices tend to be only suitable for limited situations and are not suitable for use on surfaces subject to wear, such as many indoor surfaces. This can be a disadvantage for travel between different types of terrain or environments, particularly when the device is required only part time. When not required, the device must be removed and carried, which can be problematic for construction workers, casual users and the like. As well, such devices can slip or twist and may not securely fasten to workboots.

[0003] It has been proposed to integrate a retractable spike assembly with a shoe for selectively improving traction on slippery surfaces. Examples are shown in U.S. Patent No. 8,510,973 to Bachmann et al. and WO 2013/151495 to Karlsson et al.

Previous such efforts have typically resulted in relatively complex assemblies that add significant weight to the shoe, can be potentially subject to breakage or jamming and result in significantly increased manufacturing costs.

[0004] It is an objective to provide a relatively simple and robust assembly that optionally can be integrated within the sole of a shoe for selectively extending downward spikes to provide enhanced grip when desired. Such an assembly may also be adapted as a detachable assembly that can be attached to an existing shoe and removed when not in use. Summary of the Invention

[0005] The invention relates to an improved traction assembly for the sole of a shoe, which may be integrated within the shoe sole or temporarily secured to the sole.

[0006] For directional references herein, the shoe is in a normal upright position and can be defined by a longitudinal axis extending between the toe and heel.

[0007] According to one aspect, the invention relates to a traction assembly for installation or integration within a cavity in the sole of a shoe. In this aspect, the assembly comprises: a housing comprising an interior space defined by upper and lower surfaces; at least one spike assembly within said interior space comprising a base configured for vertical travel within said housing between a lowered position and an elevated position, the spike assembly further comprising an array of spikes protruding downwardly from the base wherein, when said base is in the lowered position, said spikes protrude from a bottom surface of said sole for improved traction and when said base is in the elevated position, said spikes are at least partially retracted within said sole; and an actuator assembly retained within the housing for reciprocal fore and aft axial travel along the longitudinal axis between a first position and a second position.

In this aspect, the spike assembly and actuator assembly comprise a plurality of wedges that define wedge surfaces and a plurality of corresponding wedge contact surfaces opposed to the wedge surfaces and in contact therewith for acting between said spike assembly and actuator assembly wherein axial travel of said actuator assembly toward the first position urges said spike assembly downwardly toward the extended position for extending said spikes and axial travel of said actuator assembly towards the second position permits the spike assembly to move upwardly toward the retracted position for retracting said spikes.

[0008] The actuator assembly may be confined within the housing for vertical travel within the housing. The actuator assembly may further comprises a latch for retaining the actuator in the extended position, said latch comprising mating surfaces of said actuator and said housing wherein said surfaces are selectively engaged or disengaged with each other by vertical travel of said actuator relative to the housing wherein when engaged the actuator is retained in the first position and when disengaged the actuator may be moved into the second position.

[0009] Furthermore, the wedges referred to above may extend downwardly from said actuator. The wedge contact surfaces in this aspect comprise surfaces of said spike assembly in contact with said wedge surfaces.

[0010] The spike assembly may be confined for vertical travel within the housing by at least one guide member extending between the upper and lower surfaces of the housing, said base member is configured to engage said at least one guide member.

[0011] The base of said spike assembly may comprise a plate having an axially- oriented slot therein and said actuator assembly comprises a projecting slot traveller for travelling within said slot.

[0012] The traction assembly may further comprise a biasing member for biasing said actuator assembly towards the second position and for retaining said latch in an engaged position. Furthermore, at least one spike assembly biasing member may be provided for urging said spike assembly toward the retracted position for retraction of said spikes. This member may comprise at least one spring encircling a

corresponding one of said spikes, wherein said spring is at least partially housed in a recess within said base plate.

[0013] The actuator assembly may include a handle configured to project rearwardly from the shoe to permit a user to selectively urge the actuator assembly forwardly for extending the spikes and rearwardly for retracting the spikes.

[0014] The actuator assembly may comprise a plate and a plurality of said wedges extending downwardly from said plate for contact with corresponding surfaces of said at least one spike assembly wherein axial movement of said actuator assembly toward the first position urges said spike assembly downwardly toward the extended position for extending said spikes and axial movement of said actuator assembly towards the second position permits the spike assembly to move upwardly toward the retracted position for retracting said spikes. Each wedge comprises a horizontal upper surface positioned to contact said base member at a position directly opposed to a corresponding one of said spikes when said spikes are extended, thereby aligning each of said spikes when extended with a corresponding one of said upper surfaces to transmit transmitting upward forces acting on said spikes directly vertically to said actuator plate and said housing.

[0015] The lower surface of said housing may comprise a plurality of apertures for receiving said spikes wherein the spikes are fully withdrawn in the housing when retracted, the assembly further comprising at least one resilient flap for covering said aperture when the spike is withdrawn.

[0016] In another aspect, the housing may comprise a fore region, an aft region and an intermediate region between the fore and aft regions, where said at least one spike assembly comprises a first and second spike assemblies separated from each other and comprising spaced apart fore and aft base members within fore and aft regions of the housing respectively, wherein said actuator assembly is configured to contact both of said spike assemblies for simultaneous actuation. The housing may comprise a recessed arch portion between said fore and aft assemblies. The actuator assembly may comprise a plate within said fore, aft and intermediate region of said housing and a plurality of wedges extending downwardly from said plate for concurrent contact with corresponding surfaces of said first and second spike assemblies. The actuator assembly may further comprise a handle for actuating the actuator assembly between the first and second positions and a latch for retaining the actuator in said first position, said latch comprising a resilient member on said handle selectively engageable with said housing when in the first position. The resilient member and said housing may comprise mutually engaging projections configured to be in engagement in the first position and moveable out of engagement to release the actuator from the first position. The mutually engageable projections may be further configured to be engagement when in the second position and moveable out of engagement to release the actuator from the second position.

[0017] According to another aspect, the traction assembly may further comprise a cam member for urging the actuator assembly forwardly, said cam member comprising a rotatablc arm having a cam surface configured to engage a cam follower on the actuator assembly to effect movement of said actuator assembly between said first and second positions thereof wherein rotation of the arm into a first position extends the spike assembly and rotation of the arm to a second position retracts the spike assembly. The cam member may be pivotally mounted to the housing and may protrude rearwardly from said housing to extend from the heel region of the shoe. The cam surface may comprise an arcuate edge surface of said rotatable arm. The cam member may underlie said actuator and the cam follower extends downwardly from the actuator base for contact with the cam surface of the rotatable arm. The base member of the spike assembly may comprise a recess for accommodating said cam follower, wherein the base member is interposed between the actuator and the rotatable arm. The cam surface may be configured to provide an overcenter mode of operation wherein when the cam is fully rotated to the first position, the actuator may partially retract towards the second position and is retained therein by said biasing member.

[0018] The traction assembly ma y be configured for integration within a cavity within a shoe sole.

[0019] The invention further relates to a sole for a shoe or boot comprising the assembly described herein, integrated or housed within said sole. The invention further relates to a shoe or boot comprising this sole.

[0020] Directional references in this specification such as "up", "down" "lower", "upper" etc. as used herein are intended purely for convenience of description and are not intended to limit the scope of the invention. Directional references herein are normally with reference to a shoe in an upright, horizontal position unless otherwise stated. The term "forward" generally refers to the direction towards the toe and "rearward" refers to the direction towards the heel. Terms that refer to conventional aspects or components of a shoe such as "sole", "upper" etc. are intended to have their ordinary meaning in the art. References to specific dimensions, materials,

configurations and the like are intended only to describe specific examples and are not intended to limit the scope of the invention.

Definitions

[0021] The following terms shall have the meanings set out below within this patent specification, unless otherwise stated or the context otherwise requires:

[0022] "Boot", "shoe" and footwear are generally interchangeable and mean essentially any type of outdoor footwear including conventional work boots, hiking or other outdoor boots. In general, references to these terms relate to footwear that is compatible with an integrated spike assembly within the sole.

[0023] "Spike" refers to a rigid member which can protrude downwardly from the sole of a shoe to improve traction, having sufficient hardness and ductile properties to provide suitable traction, grip and wear resistance for use on a hard surfaces. A spike can have essentially any desired configuration that serves this purpose and is not limited to an elongate sharpened rod-like member.

Brief Description of the Drawings

[0024] Figures 1 is a perspective view of a sole of a boot that incorporates a traction assembly according to the invention.

[0025] Figure 2 is a cross sectional view along line 2-2 of Figure 1.

[0026] Figure 3 is a perspective view of the traction assembly according to the present invention.

[0027] Figure 4 is a perspective view of the traction assembly according to the present invention shown in a retracted (elevated) position, with the bottom plate removed to show internal structure.

[0028] Figure 5 is a perspective view of the traction assembly shown in an extended (lowered) position, with the bottom plate removed.

[0029] Figure 6 is an exploded perspective view of the traction assembly according to the present invention.

[0030] Figure 7 is a side elevational view of the assembly in the lowered position.

[0031] Figure 8 is a side elevational view of a rear portion of the assembly of the present invention, shown in the lowered position.

[0032] Figure 9A is a side elevational view of a further embodiment of the invention.

[0033] Figure 9B is a front elevational view thereof.

[0034] Figure 9C is a plan view from above thereof.

[0035] Figure 9D is a perspective view thereof.

[0036] Figure 10 is an exploded perspective view of the embodiment shown in

Figures 9A-9D. [0037] Figure 11 is a perspective view of the embodiment shown in Figure 9A- 9D, shown in the lowered position.

[0038] Figure 11A is a cross-sectional view of a portion of the embodiment shown in Figure 11, along line 11-11 of Figure 11, shown in the lowered position and partially in perspective.

[0039] Figure 12 is a perspective view of the embodiment shown in Figure 9A- 9D, shown in the elevated position.

[0040] Figure 13 is a bottom view, in perspective, of the embodiment shown in Figure 9A-9D.

[0041] Figure 14 is a perspective view of a rear portion of the embodiment shown in Figure 9A-9D.

[0042] Figure 15 is a cross-sectional view of a rear portion of the embodiment shown in Figure 9A-9D.

[0043] Figure 16 is a side view of a cover plate portion of the embodiment shown in Figure 9A-9D.

[0044] Figure 17 is a bottom plan view of a portion the embodiment shown in Figure 9A-9D.

[0045] Figure 18 is a table showing the results of a deflection test conducted on the embodiment shown in Figure 9A-9D, made with Delrin™.

[0046] Figure 19 is a table showing the results of a deflection test conducted on the embodiment shown in Figure 9A-9D, made with Zytel™.

[0047] Figure 20 is a graph showing the results of a compression test conducted on the embodiment shown in Figure 9A-9D.

[0048] Figure 21 is a bottom view of a further embodiment of the invention.

[0049] Figure 22 is a plan view from above of the embodiment shown in Figure 21. [0050] Figure 23A is a bottom plan view of the embodiment shown in Figure 21, showing the actuation lever in the first position wherein the spike assembly is extended.

[0051] Figure 23B is a bottom plan view of the embodiment shown in Figure

21, showing the actuation lever in the second position wherein the spike assembly is retracted.

[0052] Figure 24 is an exploded view, in perspective, of the embodiment shown in Figure 21.

[°°53] Figure 25 is a cutaway view, in perspective, of the embodiment shown in Figure 21, shown in the retracted (elevated) position.

[0054] Figure 26 is a further cutaway view, from above and in perspective, of the embodiment shown in Figure 21, shown in the partially lowered position, and in partial transparency to show internal structure.

[0055] Figure 27 is a further cutaway view, in perspective, of the embodiment shown in Figure 21, showing a portion of the device in the elevated position.

[0056] Figure 28 is a further exploded view, in perspective, of the embodiment shown in Figure 21, showing a portion of the device.

Detailed Description

[0057] Figure 1 shows a sole 2 of a boot having a traction assembly 100 according to one embodiment of the present invention integrated into the sole 2. Sole 2 is generally conventional in overall configuration, having a heel 4, a recessed arch 6, a metatarsal (ball of foot) region 8 , toe 10 and opposing lateral sides 14. For convenience of description, sole 2 is considered to have a longitudinal axis "a" extending between heel 4 and toe 10. Herein, heel 4 defines a "rearward" or "proximal" position and toe 10 represents a "forward" or "distal" position. Sole 2 has an essentially continuous sidewall 16 which is substantially vertical and which extends around the perimeter of sole 2. Sole 2 can have a conventional ribbed, lugged or otherwise textured lower surface 17. Sole 2 is normally fabricated from conventional materials such as synthetic rubber. As will be apparent from the description herein, sole 2 should be relatively thick to accommodate the traction assembly 100 built into and integrated with the sole. For example, sole 2 can be the sole of a construction-style boot and may be at least l inch (25.4 mm) thick.

[0058] Figure 1 shows assembly 100 in an extended position for use on a slippery and/or rugged surface that resists damage from spikes. In this position, spikes 220 (described below) are extended to protrude downwardly from sole surface 17. In a retracted position, spikes 220 are elevated and at least partially retracted into sole 2 and, depending on the sole thickness, also at least partially retracted into housing 210 of assembly 100, so as not to protrude from surface 17.

[0059] Figure 2 is a cross-sectional view of sole 2 along line 2-2, showing an internal cavity 24 within sole 2 within which traction assembly 100 is retained. Cavity 24 extends from adjacent the rear end of heel 4 to approximately the midpoint of metatarsal region 8. Since assembly 100 is essentially rigid, it should not normally extend past the midpoint of metatarsal region 8 to allow the boot to properly flex during walking. However, depending on the specific application, the above configuration can vary. For example, it may be desirable for traction assembly 100 to extend substantially the full length of sole 2 or alternatively to terminate at the arch 6 or otherwise be installed within essentially any selected portion of sole 2, depending on the functional requirements intended for the protruding land-gripping spikes.

[0060] Cavity 24 may be configured whereby assembly 100 may installed therein during fabrication of sole 2. In this aspect, assembly 100 becomes essentially fully enclosed within the sole so as to be moulded in place therein and cannot be removed without cutting away a portion of sole 2. Alternatively, cavity 24 may comprise a recess open to below, such that assembly 100 is removably installed from below. This arrangement permits replacement of assembly 100 if required or access to the interior thereof for repair or maintenance. According to this embodiment, the lowermost surface of assembly 100 forms a ground-contacting surface continuous with surface 17 of sole 2. This lower surface can be lugged and/or faced with a resilient material which maybe the same material and configuration as surface 17 of sole 2.

[0061] At heel end 4 of sole 2, cavity 24 communicates with a horizontal channel

26 which extends rearwardly through heel 4 to open to the rear of sidewall 16 at the heel. Channel 26 accommodates an actuator handle 236, seen in Figure 3 and discussed below, which can be gripped or otherwise manipulated by the user. Handle 236 is actuated by a user to extend or retract spikes 220. [0062] Figures 3 to 7 depict traction assembly 100 in isolation. Traction assembly 100 comprises a rigid external housing 210 which is fabricated from a rigid, robust material such as injection moulded plastic, preferably a high di-electric, safe, low flammability plastic. By way of example, the housing 210 (as well as other non-metal assembly components) can be made of plastic such as Delrin™ or Zytel™. Housing 210 is generally box-like in configuration having a flat cover plate 214 (seen in Figure 6), vertical sidewalls 212 and a flat bottom plate 216 (seen in Figures 3 and 6). Sidewall

212 extends around the perimeter of housing 212 and is defined by front and rear end walls 213 and 215 and lateral walls 217. Longitudinal axis a extends between end walls

213 and 215. The cover and bottom plates are spaced apart to define an interior space. Preferably, cover plate 214 and sidewall 212 are integrally formed but alternatively sidewalls 212 may be independent of plate 214 and assembled thereto. Bottom plate 216 is removable from sidewalls 212 to access the interior of housing 210 and is secured to sidewalls 212 by tabs 120 projecting from plate 216 that snap-lock into apertures 122 within sidewalls 212. An outsole, not shown, may be fastened to bottom plate 216 or integral therewith. The outsole may comprise a rubber-like material which can be ribbed, lugged or otherwise textured for grip, and may be continuous with the lower surface 17 of the sole when installed therein.

[0063] The configuration of assembly 100 generally mirrors the portion of sole 2 within which it is fitted and consists of a heel portion 124, a relatively narrow-waisted arch portion 126 and a metatarsal portion 128. Bottom plate 216 has apertures 130 therein that permit spikes 220 to slide within these openings to reciprocate between a retracted position seen in Figure 4 and an extended position seen in Figure 5.

Apertures 130 are dimensioned to snugly fit spikes 220 whereby spikes 220 may freely slide through apertures 130 but passage of dirt and moisture into the interior of traction assembly 100 is substantially prevented.

[0064] A spike assembly 140 is housed within housing 210, seen in part in Figures 4-6. Assembly 140 comprises a base plate 222 having plurality of spikes 220 extending downwardly therefrom and an actuator assembly 230 with a handle 236 projecting from a rear side thereof for selectively retracting or extending spikes 220 through apertures 130. Base plate 222 and actuator assembly may be fabricated from a polyacetal or other a self-lubricating plastic having a low coefficient of friction. When actuator handle 236 is extended rearwardly from traction assembly 100 as shown in Figure 4, spikes 220 are elevated and are at least partially into the interior of housing 210. When actuator handle 236 is pushed forwardly (proximally) as shown Figures 3 and 5, spikes 220 are lowered to protrude downwardly from apertures 130. Base plate 222 has a depression 270 that is recessed into its upper surface around each aperture 130 to accommodate a corresponding spike spring 224, described below.

[0065] When actuator handle 236 is moved to its maximum inward extent, a latching mechanism (which will be described in greater detail below) engages, holding the actuator handle 236 in its proximal position and the spikes 220 in their extended position. The latch can be released by urging actuator handle 236 downwardly, at which point handle 236 can then be retracted rearwardly to thereby retract spikes 220.

[0066] Handle 236 can be pushed inwardly to extend the spikes using a hands- free operation, for example by contacting handle 236 with the other boot. This allows the user to extend the spikes with hands full or otherwise being unable to bend over to grasp the handle.

[0067] Spikes 220 are removeably mounted to base plate 222 by threaded engagement. Alternative ways to engage spikes 220 to plate 222 include permanently bonding spikes 220 to base plate 222 or forming spikes 220 integrally with base plate 222. Spikes 220 are arranged in an array whereby four spikes are located to protrude from the heel 124 in a 2 x 2 (two rows of two spikes) array and two spikes from metatarsal portion 128 of assembly 100 in a 1 x 2 array (1 row of two spikes). It will be evident that other spike arrays can be provided to accommodate specific requirements.

[0068] Spikes 220 can be made of any long-wearing material suitable for providing increased traction, such as stainless steel, cromoly steel, enhanced plastics such as glass filled nylon, ultem or polyetherimide, or tungsten. Ceramic materials also may be suitable for spikes 220. Spikes 220 can have a single pointed end as shown herein or alternatively multiple points or a flat end. Spikes 220 may be cylindrical or other configuration.

[0069] Spikes 220 can be reciprocated for vertical travel. In an elevated position, spikes 220 are retracted above the lower surface of sole 2 and can be at least partially retracted into housing 210. On a lower position, spikes 220 protrude downwardly from sole 2. The reciprocating vertical travel of spikes 220 is generated by the vertical travel of base plate 222 within housing 210. In order to guide plate 222 vertically, an array of vertically posts 142 is provided that protrude downwardly into the interior of housing 210 from cover plate 214. Posts 142 are received within openings 144 within base plate 222 whereby plate 222 can slide vertically along posts 142 while being restricted against horizontal movement within the interior of housing 210. Plate 222 can travel vertically between lowered and elevated positions. In a first, lowered position, seen in Figures 3, 5 and 7 , plate 222 is adjacent to the lower plate 216, which corresponds to the extended position of spikes 220. In a second, elevated position seen in Figures 4 and 8, base plate 222 abuts or is adjacent to cover plate 214, wherein spikes 220 are retracted.

[0070] Spike springs 224 are provided to urge the base plate 222 upwardly towards the retracted position. Springs 224 wrap around at least some of spikes 220 whereby springs 224 are interposed between base plate 222 and bottom plate 216. In particular, one end of each spring 224 engages base plate 222 adjacent to the base of spike 220, and the other end of spring 224 engages bottom plate 216 adjacent to aperture 130. Springs 224 are biased to urge the base plate 222 and bottom plate 216 apart when these plates are brought into adjacency whereby the springs arc compressed. When compressed, springs 224 fit within depressions 270 in base plate 222 (see Figure 8). This allows base plate 222 to be flush against actuator plate 234 when retracted.

[0071] Actuator assembly 230, housed within housing 210, comprises an actuator plate 234, a plurality of wedges 232 and actuator handle 236 (see Figure 6). Actuator assembly 230 is retained within housing 210 for travel in a linear path along axis a between a forward (distal) position wherein spikes 220 are extended downwardly and a rearward (proximal) position wherein spikes 220 are retracted upwardly at least partially into the housing 210. Actuator assembly 230 is configured to urge spike assembly 140 downwardly towards the extended position when actuator plate 234 is moved forwardly. For this purpose, actuator is provided with wedges 232 which each have a sloping wedge surface 235 which contacts base plate 222 for urging spike assembly 140 downwardly when actuator assembly 230 is moved forwardly. Base plate 222 has angled surfaces 235, described below, that contact and interact with wedge surfaces 235. Actuator assembly 230 directly overlies spike assembly 140 to allow actuator assembly to urge spike assembly downwardly.

[0072] Wedges 232 are integral with actuator plate 234, although it is also possible for wedges 232 to consist of separate components mounted to actuator plate 234. Wedges 232 extend downwardly from actuator plate 234 and have a sloping wedge surface 235 that extends at an acute angle from actuator plate 234, merging or joining with a horizontal plateau surface 237 that is parallel to actuator plate 234. A vertical surface 239 of wedges 232 opposes sloping surface 235. Horizontal travel of actuator plate 234 brings wedge surfaces 235 to bear against base plate 220, thereby translating the horizontal movement of plate 234 into vertical travel of pla te 220. The slope of the wedge surfaces 235 of wedges 232 convert horizontal travel of actuator assembly 230 into vertical travel of spike assembly 140. This provides the effect whereby forward travel of actuator assembly 230 along axis a urges spike assembly 140 downwardly and rearward travel of actuator assembly 230 allows the spike assembly to travel upwardly.

[0073] Base plate 222 includes cutaway regions therein each having a rearward- facing transverse surface 241 that is configured to contact and engage a corresponding wedge surface 235. Surfaces 241 are sloped to match the slope of wedge surfaces 235 whereby the respective surface are in full contact to permit wedge surface 235 to slide along a respective surface 231. Actuator assembly 230 can reciprocate between a rearward position, seen in Figure 4, wherein base plate 222 is urged into a raised position and spikes 220 are retracted, and a forward position as seen in Figures 5 and 7 wherein base plate 222 is urged into a lowered position wherein spikes 220 are extended.

[0074] When actuator assembly 230 is in the rearward position, base plate 222 is disengaged from wedges 232. As plate 234 travels forwardly, wedge surfaces 235 engage and slide along corresponding surfaces 241 of base plate 222 to thereby urge base plate 222 downwardly against the countervailing force applied by spike springs 224. The forward, horizontal movement of plate 234 is thus translated into vertical, downward movement of base plate 222. Continued forward movement of actuator assembly 230 causes base plate 222 to ride along wedge surfaces 235 until base plate 222 reaches flat plateau surfaces 237 of wedges 232 which define the maximum downward travel of plate 222. Wedges 232 then slide beneath plate 222 whereby flat surfaces 237 retain plate 222 in the lowered position, spaced apart from bottom plate 216 and wherein spikes 220 are extended. In this position, plate 222 is held in position against flat plateau surfaces 237 by the upward forces exerted by spike springs 224.

[0075] Assembly 100 is configured whereby, when base plate 222 is thus engaged with plateau surfaces 237, each of spikes 220 are aligned with a corresponding one of plateau surfaces 237 such that the plateau surface directly overlies the corresponding spike 220 when spike 220 is extended. In this manner, the upward force from each spike 220 is directly transmitted to a corresponding wedge 232 and thereby to actuator plate 234 and housing cover plate 216, all of which are aligned with spike 220. In this fashion, the load transmitted from each spike 220 is directly communicated upwardly through the respective members and the possibility of flexing or torsion of any individual component is reduced. Since each spike can bear a significant load in a concentrated area, this permits an efficient configuration for transmitting this pressure to the housing, which can be made of a rigid material for effectively distributing the forces.

[0076] Actuator plate 234 includes a downwardly-projecting tab 243 that is configured to travel within an axially-extending central slot 245 within base plate 222 to guide base 222 along a path for linear fore-aft (axial) travel along an elongate axis extending between the front and rear ends of the assembly. Slot 245 also provides a space to accommodate a coil actuator spring 239 (see figure 4) that serves to urge actuator assembly 230 rcarwardly towards the spike-retracted position, as described below. One end of spring 239 is coiled around and supported by a spring mount 247 projecting from cover plate 214. The opposed second end of spring 239 contacts tab 243 for urging actuator assembly 230 rearwardly. When actuator plate 230 is moved forwardly (towards the spike-extended position), actuator spring 239 engages tab 243 and is compressed. Spring 239 contacts tab 243 when actuator assembly 230 is sufficiently forwardly positioned whereby base plate 222 is retained in the lowered position by contact with the flat plateau surfaces 237 of wedges 232. When actuator plate is thus in the fully forward, spike-extended position, spring 239 is maximally compressed. When the latch 238, described below, is released, spring 239 urges plate 234 rearwardly to allow spikes 224 to retract under the urging of spike springs 224. Spring 239 must be designed to provide sufficient force to overcome frictional forces acting on plate 234.

[0077] Actuator assembly 230 further comprises an actuator handle 236 that extends rearwardly from actuator plate 234. Actuator handle 236 comprises an elongate member that travels axially within a cutaway portion 249 of sidewall 212 of housing 210. Handle 236 comprises a knob 251 to permit the user to grasp and manipulate handle 236. Handle 236 projects rearwardly through slot 26 and extends outwardly from sole 2 for manipulation by a user.

[0078] Actuator assembly 230 further comprises a latch assembly 238 that latches actuator plate 234 into a forward position to prevent inadvertent retraction of the spikes during use of the assembly. Latch 238 is shown in greater detail in Figure 8. Latch 238 comprises a wedge-shaped member extending upwardly from actuator plate 234 adjacent to the actuator handle 236. Latch 238 has a sloping surface 253 that faces forwardly and an opposing flat, vertical engagement surface 255 facing rearwardly. Latch 238 is configured to engage a transverse rib 257 extending downwardly from the housing 210 at cutaway portion 249 wherein respective opposing vertical surfaces thereof contact each other to prevent rearward movement of actuator assembly 230 when engaged. When actuator plate 234 is moved forwardly, sloping surface 253 of latch 238 engages rib 257 and urges actuator plate 234 downwardly. At the point where actuator assembly 230 has been moved to its maximal forward position, latch 238 travels past rib 257. Actuator assembly 230 can then move upwardly, and is urged upwardly by the force of base plate 222 acting thereon. When actuator plate 234 is urged upwardly at this point, the respective vertical surfaces of latch 238 and rib 257 engage each other, thereby preventing rearward movement of actuator plate 234. The force exerted by actuator spring 239 urges actuator assembly 230 rearwardly against latch 238 toward the rear of housing 210, thereby urging surface 255 against rib 257 to prevent inadvertent release of handle 236 and retraction of spikes 220 until latch 238 is disengaged. Latch 238 is disengaged by pushing actuator handle 236 downwardly which disengages respective surfaces 253 and 255 from each other to allow retraction of actuator assembly 230.

[0079] Traction assembly too can normally be assembled without special tools or mechanical fasteners by snap-locking the various components together.

[0080] In operation, when traction assembly 100 is installed within footwear 110, spikes 220 can be retracted by moving actuator handle 236 rearwardly. Spikes 220 may be extended by the reverse movement wherein actuator handle 236 is urged forwardly. This movement slides actuator assembly 230 forwardly to engage base plate 222. Base plate 222 is urged downwardly to extend spikes 220 downwardly as depicted in Figures 5 and 7, where they can protrude from apertures 130. The movement of actuator handle 236 forwardly also brings tab 243 into contact with spring 239 and compresses spring 239. Once compressed, spring 239 exerts a force on tab 243 (and thus, on actuator assembly 230) urging tab 243 in a proximal direction towards rear wall 215. When moved into its forwardmost position, actuator assembly 230 is locked into the extended position by retainer 238. The positive force exerted by actuator assembly 230 on the spike assembly is capable of extending the spikes relatively quickly and with force to expel any debris which may have entered into and clogged the apertures 130.

[0081] In order to retract spikes 220, the user pushes downwardly on actuator handle 236. This causes latch 238 to disengage from actuator assembly 230. Actuator assembly 230 is urged in a proximal direction in response to the proximal force exerted by spring 239, causing plateau surfaces 237 to move out from under the plate 222. The upward force exerted by spike springs 224 on plate 222 causes plate 222 to move upwardly, toward cover plate 214, causing spikes 222 to retract.

[0082] Since the traction assembly too is normally installed within footwear, it will be convenient for a user to operate the actuator handle 236 with an opposing foot. To retract the spikes 220, the user can push down on the actuator handle 236 with his other foot to release latch 238 and allow the actuator assembly 230 to move rearwardly. To allow for such operation, the properties of spring 239, such as the diameter of the spring, wire gauge and spring force exerted by the spring, should be selected to provide a somewhat high degree of resistance against inadvertent actuation caused by casual contact during use. Spring 239 should not urge actuator assembly 230 rearwardly with such force that it is unreasonably difficult or practically impossible to move the actuator handle 236 forward with one's foot using normal human-powered forces. As well, spring 239 should urge actuator assembly 230 rearwardly with sufficient force such that, when latch 238 is disengaged, spikes 220 retract quickly and actuator assembly 230 is retained in the retracted position such that it does not rattle as one walks.

[0083] Figures 9 through 17 depict a further embodiment of a traction assembly 900 according to the invention. Assembly 900 comprises a housing 910 having a flat cover plate 914, a sidewall 912 and a bottom plate 916 integral with sidewall 912. Sidewall 912 includes front and rear end walls 913 and 915 and lateral walls 917. A central longitudinal axis "a" extends between the front and rear end walls. Housing 910 defines an interior space for housing the spike assembly components described below. Cover plate 914 is separable from the sidewalls to access the housing interior. Cover plate 914 is secured to the housing by way of pins 1510 and 1520 (shown in detail in Figure 16) that extend downwardly from cover plate 914 and are received within socket-like interiors of hollow pegs 1516 (shown in detail in Figure 10) that protrude upwardly from bottom plate 916 and span the interior of housing 910 from top to bottom. Pegs 1516 each have a hollow interior open at the top to define a socket 1502. Pins 1510 and 1520 comprise an arrow-shaped head 1512 having a central slot 1514 that defines two resilient prongs to allow the head to compress. When compressed, heads 1512 can be inserted into sockets 1502 to be engaged therein.

[0084] Assembly 900 comprises an arch region 926 which is defined by an inwardly stepped waist portion 918 of lateral walls 917 and an upwardly recessed portion 919 of bottom plate 916. Arch region 926 is located somewhat forwardly of the midpoint of assembly 900 at a location that approximates a typical user's transverse arch. The configuration of arch region 926 can depend on the shape of the arch of a boot in which traction assembly 900 will be installed or other factors. Housing 910 comprises forward and rearward portions 940 and 942 located fore and aft of arch region 926. These portions are relatively deeper in vertical height than arch region 926, which defines a shallow region of housing 910.

[0085] Assembly 900 further comprises separate forward and rear spike base plates 922 and 923 for supporting spikes 920. Spikes 920 are anchored to plates 922 and extend downwardly. Plates 922 and 923 are located within forward and rearward portions 940 and 942 respectively of housing 910 located on opposing sides of arch region 926. Plates 922 and 923 can travel vertically within the interior of housing 910 to extend or retract the spikes 920 as described below, following a similar principle as the first embodiment described above. Plates 922 and 923 are free to slide vertically, guided by pegs 1516 within housing 910. Plates 922 and 923 are spring-loaded by helical springs 936 which urge these plates upwardly. Springs 936 wrap around pegs 1516 and are secured at the bases of these pegs. Vertical travel of plates 922 and 923 is driven by an actuator assembly 934 which is able to travel in a for/aft direction along axis "a" to urge plates 922 and 923 downwardly against the upward biasing exerted by springs 936.

[0086] Plates 922 and 923 are actuated for coordinated vertical travel by a single actuator member acting on both of said plates. Actuator assembly 934 extends substantially the full length of housing 910 for contacting and actuating both of base plates 922 and 923 simultaneously. Assembly 934 is engaged within housing 910 for travel horizontally within a range defined by slots 938 within assembly 934 in an axial (fore/aft) direction along axis a. Actuator assembly 934 includes wedges 940 that face downwardly and are configured to contact sloping cam surfaces 942 of base plates 922 and 934 whereby forward travel of actuator assembly 934 drives plates 922 and 934 downwardly thereby extending spikes 920 downwardly. Rearward travel of actuator assembly 934 removes the downward force against plates 922 and 923, which allows springs 936 to urge the plates upwardly to retract spikes 920. Upward travel of spikes

920 may also be effected by pressing downwardly on the shoe when actuator assembly 934 is released. Actuator assembly 934 is confined within housing 910 for axial travel by axially-oriented slots 938 therein which receive guide pins 1510 extending from cover plate 914. [0087] Spikes 920 may be selectively extended and retracted through openings 130 within bottom plate 916. Each opening 130 is lined with an o-ring 1010 seal which seals the space between the spike 920 and opening 130 to inhibit the entry of contamination into housing 910 when spikes 920 are extended. The positioning of o- ring 1010 is shown in Figure 11A.

[0088] Openings 130 are further protected against entry of contamination by planar seals 1210 (shown in greater detail in Figure 13) that substantially cover openings 130 to form a barrier against entry of contaminants when spikes 920 are retracted. Seals 1210 may be integral with bottom plate 916 and comprise a flexible sheet approximately 0.01 inches thick. Bottom plate 916, including the seals 1210, is molded from a suitably flexible material, such as Hytrel™. Seals 1210 each have an X- shaped opening 1220 therein which defines four flexible, resilient triangular flaps 1222. Opening 1220 is configured whereby when spike 920 is retracted into housing 910, flaps 1222 revert to a planar configuration in contact with each other to form a barrier against entry of contaminants into housing 910. When a spike 920 extends through opening 1210, flaps 1222 are deflected downwardly. O-rings 1010 and planar seals 1210 cooperate to substantially seal the interior space of housing 910 against outside contaminants when spikes 920 are either extended or retracted. When spikes 920 retract into the apertures 130, the edges of flaps 1222 of planar seals 1210 rub against the spikes 920, providing a wiping function that cleans the spikes 920. Once the spikes 920 are completely retracted into the assembly 900, the cutouts 1220 of the planar seals 1210 close off the apertures 130.

[0089] Spikes 920 of traction assembly 900 may be thinner and shorter than spikes 220 of the traction assembly 100. By way of a non-limiting representative example, each of spikes 920 can be 2- 4 mm wide at its widest point, and 10-15 mm long from the tip of the spike to the end of its base. Spikes 220 are 4mm wide at their widest point, and 1 cm long from tip to base. Spikes 220 and 920 can be different sizes as well, depending on the application.

[0090] The relatively shorter spikes 920, as compared with the embodiment of figures 1-8, allow the traction assembly 900 to have a thinner profile than that of traction assembly 100. Traction assembly 900 has vertical sidewalls 912 that are 1.7 cm wide (except at the arch 910). This is .2 cm shorter than the vertical sidewalls 212 of traction unit 100. The shallower depth of assembly 900 also permits actuation of spikes 920 with a relatively reduced travel distance of actuator assembly 934. [0091] Traction assembly 900 has a handle 930 for actuating spikes 920, shown in detail in Figure 14. Handle 930 comprises a flat upper surface 931 and a skirt 932. Handle 930 may have a length of 2.5 cm, which is 1.5 cm shorter than handle 236. When spikes 920 are extended, handle 930 extends from the rear of the traction assembly 900 by about 1.5 cm. When spikes 920 are retracted, handle 930 extends from the rear of the traction assembly by about 1.8 cm.

[0092] Handle 930 is associated with a latch 950, shown in greater detail in

Figures 14 and 15 for retaining actuator assembly 934 in the forward position wherein spikes 920 are extended. When latch 950 is engaged, actuator assembly 934 can be retained either in the forward position wherein assembly 934 is prevented from travelling rearwardly or in the rearward position wherein assembly 934 is prevented from travelling forwardly. Releasing latch 950 when assembly 934 is fully forward allows assembly 934 to travel rearwardly whereby spikes 920 are retracted upwardly by assistance from the main spring and spike springs.

[0093] Latch 950 comprises a tab 1330 which is capable of flexing vertically. Tab

1330 is defined by a U-shaped slot 1340 in the upper surface 931 of handle 930 whereby the forward end of tab 1330 is continuous with surface 931. The rearward end of tab 1330 is unattached to surface 931 and able to travel vertically relative to handle 930 whereby in an unflexed position, tab 1330 is flush with surface 931. Tab 1330 has an upwardly-projecting dome 1320 adjacent to its forward end and an upwardly-projecting button 1310 adjacent to its rearward (free) end. As can be seen in Figure 15, when tab 1330 is in its unflexed, flush position, dome 1320 projects upwardly to engage rib 1457 that extends downwardly from cover plate 914. When the actuator plate 234 is in the forwardly- extended position and handle 930 is forward, dome 1320 is located forwardly of rib 1457 whereby rearward movement of handle 930 is blocked. This prevents retraction of handle 930 and retains spikes 920 in their downwardly-extended position. In order to release tab 1330, a user can press downwardly on button 1310 which flexes tab 1330 downwardly. This moves dome 1320 out of engagement with rib 1457 and allows actuator 134 to be retracted rearwardly to retract spikes 920 into housing 910.

[0094] Latch 950 can also operate in a reverse fashion to the above to prevent inadvertent extension of spikes 920. In this mode, when handle 930 is fully withdrawn rearwardly, rib 1457 blocks forward travel of handle 930 unless tab 1330 is urged downwardly to move dome 1320 out of engagement with rib 1457. The user is required to urge tab 1330 downwardly whilst urging handle 930 forwardly in order to extend spikes 920.

[0095] Handle 930 includes a recessed lower surface 1410 configured to seal the gap between the lower face of handle 930 and an opening 1349 within sidewall 915 that admits handle 930. When the actuator assembly 934 is in the forward position whereby spikes 920 are extended, recess 1410 engages the edge of cutaway portion 1349, effectively sealing the interior of the housing 910.

[0096] Traction assembly 900 operates in substantially the same manner as assembly 100 of Figures 1-8. To retract spikes 920 from the extended (protruding) position, the user pushes down on the button 1310. This causes tab 1330 to flex downwardly to release handle 930 from rib 1457. Handle 930 is then retracted causing actuator assembly 934 to move rearwardly. This in turn removes the downward force on spike base plates 922 and 923 which allows them to travel upwardly under the urging of springs 936, causing spikes 920 to retract. It will seen, however, that actuator assembly 934 is configured solely for fore-aft horizontal travel along axis "a" without vertical travel. The locking function is provided by vertical flexure of tab 1516 rather than vertical travel of the actuator as a whole, as in the first embodiment.

Example 1

[0097] The performance and durability of traction assembly 900 was tested for impact strength, extended cycle times (movement and wear to failure) compressive strength (amount of load on each spike) and memory of the components to revert back to original shape after excessive loading using minimal components.

[0098] In one test, actuator handle 930 was cycled repeatedly between extended and retracted positions. The test was run at a fixed rate of approximately 49

impacts/min., representing an excess over expected usage of the assembly. After approximately 54,600 cycles over 18 hours, the front of housing 910 became cracked. After 100,000 cycles the rib 1457 appeared to have become worn but the springs remained functional and no other internal components appeared to have worn or lost shape.

[0099] After about 125,000 cycles, the tested product remained functional, although the latch mechanism became worn out. The test was stopped at 137,000 cycles. This cycle test simulated use of the assembly over approximately 26 years of use wherein the spikes would be actuated about 20 times a day, 5 days/ week, which greatly exceeds the expected life of conventional footwear.

Example 2

[00100] This example tested the degree by which actuator handle 930 and the housing 910 could be deflected before breaking, by applying a force to one end thereof. Figures 18 and 19 show the results of the deflection test on assemblies 900 made from Delrin™ and Zytel™ respectively.

[00101] As seen in Figures 17 and 18, the components fabricated from Delrin™ had less deflection than the Zytel™ when the same force was applied. As for the main body, it was noted that in this test, arch portion 926 begins to deflect on the longitudinal axis around 30kg. It appears from this test that the unit can accept a load greater than 30 kg without significant deformation, using either of these materials.

Example ¾

[00102] This example used an Instron™ compressive test machine to determine the maximum load each spike can withstand before breaking. After each spike is loaded to its break point, the assembly 900 was tested to see if it was still functional. The test applied a compressive force with weight added in increments of .5 kg/s until failure. The test was conducted on indivudual spikes, simulating full load bearing on a single spike.

[00103] The highest spike load at break was 480 lbs ( 217 kg) and the lowest was 293 (133kg). The low break was most likely due to material failure at one point in the area of the spike. The highest stress on break was shown to be 8960 PSI, after loading continuously for 8 minutes; the lowest was 5482 PSI after loading continuously for 5 minutes. A sample of the results on one spike is shown in Figure 20.

[00104] After testing all the spikes one by one, the assembly 900 was actuated and still was functional. One area of the housing fractured around the spike location and again this can be assumed material failure during the molding process. The compressive test and loading was extreme and much higher loads were put on the unit than would normally be experienced during ordinary use.

[00105] Figures 21-28 depict an embodiment of traction assembly 2000, in which the spike assembly is actuated by a rotatable lever that protrudes from the footwear. Referring first to figures 21 and 22, assembly 2000 comprises a housing 2002 configured to be fitted within a cavity in an article of footwear (not shown). Housing 2002 comprises a lower plate 2042, an opposed upper plate 2005 and a sidewall 2003 which together define an interior space (seen in Figure 24). Housing 2002 may comprise discrete heel and toe regions 2004 and 2006, separated by a narrowed, recessed arch region 2008. An elongate axis a-a extends between the respective ends of the toe and heel regions. Housing 2002 may alternatively be similar in configuration to housing 210 described above wherein the housing is not configured to form discrete toe and heel regions.

[00106] Referring to Figure 24, housing 2002 includes a cutaway region 2010 adjacent the heel to accommodate a lever 2020, described below.

[00107] The interior space of housing 2002 accommodates an actuator assembly 2022 and two discrete spike assemblies 2024a and b, seen in Figure 24. Spike assemblies 2024a and b are housed in the heel and toe regions 2004 and 2006 respectively. Assembly 2000 may be modified to provide a unitary spike assembly, not shown, that extends substantially the full length of housing 2002 as described in the embodiment of Figures 1-8.

[00108] Actuator assembly 2022 comprises an elongate plate extending substantially the length of the housing, aligned along longitudinal axis a. Actuator assembly 2022 is somewhat shorter than the interior of housing 2002 to permit fore and aft travel within the housing along axis a-a, in the same manner as the embodiments described above. Actuator assembly 2022 has at least one first wedge 2030 extending downwardly from a lower surface thereof, configured to contact corresponding portion of spike assembly 2024a and at least one second wedge 2032 to contact spike assembly 2024b. Actuator assembly 2022 may include multiple first and second wedges, as shown. Wedges 2030 and 2032 each have a sloping wedge surface 2034 which slopes downwardly and rearwardly (shown in detail in Figure 28). Wedges 2030 and 2032 are configured to engage surfaces 2036 of spike assemblies 2024 and 2026 whereby wedge surface 2034 contacts a corresponding surface 2036 of the spike assemblies. Surfaces 2036 may have a sloping orientation that complements that slope of surfaces 2034. The slope of wedges 2030 and 2032 convert horizontal travel of actuator assembly 2022 into vertical travel of the spike assemblies. This provides the effect whereby forward travel of actuator assembly 2022 along axis a-a urges spike assemblies 2024a and b downwardly and rearward travel of actuator assembly 2022 allows the spike assemblies to travel upwardly. [00109] Wedges 2030 and 2032 have a flat plateau surface 237, whereby when actuator assembly 2022 is positioned in the first position (in which the spike assemblies are extended), surfaces 237 are aligned with and contact the underlying spike assembly plates 2024. Flat surfaces 237 thus bear directly on spike assemblies 2024. At this point, upward forces acting on the spike assemblies, resulting from the user's weight bearing down on the shoe, are directly transmitted to actuator assembly 2022 through the flat plateau surfaces 237. Since the upper surface of actuator assembly 2022 directly contacts the upper surfaces 2004 and 2006 of housing 2002, which in turn contacts the shoe cavity, all upward forces are directly transferred through vertically aligned components into the shoe.

[00110] Referring to Figure 25, lever 2020 is pivotally mounted to housing 2002 by a pin-type pivot mount 2040 which attaches lever 2020 to the housing. Pivot mount 2040 is located within the housing interior. Pivot mount 2040 comprises a vertical shaft or pin 2040 which projects upwardly from the floor 2042 of housing 2002 and which allows lever 2020 to rotate within a horizontal plane around a vertical axis defined by pin 2040. . Pin 2040 is received within a sleeve 2041 that extends downwardly from the lower surface of lever 2020 whereby sleeve 2041 rotates freely about pin 2040.

[00111] Referring to Figure 26, in which actuator assembly 2022 has been removed to show internal structure, lever 2020 may be configured as an elongate, generally flat plate having a generally triangular shape. Pin 2040 is received at a hypotenuse of lever 2020. A lever arm portion 2042 extends from one side of mount 2040 and a cam surface 2046 extends from the opposed side thereof, on defining a cam portion 2049 of lever 2020. The respective portions 2042 and 2046 comprise regions of lever 2020 that are arbitrarily defined and do not represent separate structures; rather, lever 2020 is an essentially monolithic member that encompasses both of these regions.

[00112] Lever arm portion 2042 protrudes outwardly (rearwardly) from housing 2002 through opening 2010, which constitutes a relatively wide slot to accommodate the horizontal travel of arm 2042 during use. Arm 2042 has a sufficient length to allow a user to conveniently grasp this portion and to exert sufficient leverage to easily actuate the spike assemblies, as described below. Lever arm 2042 may include a handle 2048 to permit the user to more easily rotate lever 2020 about its axis of rotation. Lever 2020 may have an essentially triangular shape whereby mount 2040 and the opposing ends of arm 2042 and cam 2044 are located adjacent to respective apexes thereof. [00113] Cam surface 2046 of lever 2020 consists of a rounded edge surface which is located within housing 2002. Cam surface 2046 is arcuate for engaging a cam traveller surface associated with actuator assembly 2022 for urging actuator assembly 2022 forwardly as lever 2020 is rotated towards the first position, as discussed below. Cam surface 2046 is configured to maintain contact with a cam follower 2056 of actuator assembly 2022 and to urge this member to travel horizontally, as described below, during rotation of lever 2020. Arm 2042 provides leverage to more allow the user to urge actuator assembly 2022 between its respective positions.

[00114] Referring to Figure 27, cam surface 2046 is configured to interact with actuator assembly 2022 in the manner described below to permit actuator assembly 2022 to travel in forward or rearward directions along axis a-a, which causes the spike assemblies 2024a and b to extend and retract. Figure 27 only shows assembly 2024b; assembly 2024a follows a similar trajectory. It will be seen that rotation of lever 2020 in a first direction urges actuator 2020 forwardly, which impels spike assemblies 2024a and b downwardly to extend the spikes. Rotation of lever 2020 in an opposed second direction allows the actuator assembly 2022 to travel rearwardly to retract the spike assembly. Rearward travel of actuator assembly 2022 is impelled a combination of forces, including an actuator spring 2048. As well, upward forces may act on spike assemblies 2024 a and b, which may be applied by springs (not shown) acting on the respective spike assemblies as described in connection with the previous embodiments. As well, if the user is applying weight on the footwear, this urges the spike assemblies upwardly towards to the elevated, retracted position. A rearward force on actuator assembly 2022 may be applied by a horizontally-disposed coil spring 2048 mounted within a receptacle 2050 in actuator assembly 2022. Spring 2048 is braced between spaced apart opposing engagement surfaces (not shown) of actuator assembly 2022 and housing 2002 respectively whereby spring 2048 is compressed as actuator 2020 travels forwardly. Spring 2048 thus applies a biasing force that urges actuator 2020 rearwardly, thereby counteracting forces that can be applied by lever 2020 as this is rotated to the first position thereof.

[00115] Lever 2020 acts through cam follower 2056 to make contact with actuator 2002. Cam follower 2056 comprises a peg or fin that extends downwardly from the lower surface of actuator assembly 2022 and which may be formed integrally with actuator assembly 2022 or may comprise a separate component that is attached to actuator assembly 2022. Cam follower 2056 has a rounded surface that is configured to maintain engagement with cam surface 2046 of lever 2020 as this rotates between its respective first and second positions, whereby follower 2056 may slide easily over cam surface 2046 during rotation of lever 2020. Actuator assembly 2022 is mounted within housing 2002 in a suitable position whereby cam follower 2056 maintains engagement with cam surface 2046. In this fashion, rotation of lever 2020 in the first direction causes cam surface 2046 to pivot an arc. Cam surface 2046 is arcuate along its full length, with one end thereof being adjacent to pivot 2040 and the opposed end being remote from pivot 2040. As a result, as cam follower 2056 contacts surface 2046, rotation of lever 2020 in the first direction urges follower 2056 forwardly. Cam surface 2046 thus acts as a cam to dislocate cam follower 2056 laterally as lever 2020 is rotated. Cam follower 2056 maintains a sliding contact with surface 2046 and is urged forwardly as lever 2020 is rotated in its first direction, which is counter-clockwise in the view shown in Figure 21. As discussed above, actuator assembly 2022 is biased rearwardly whereby when lever 2020 is rotated in the second direction, cam follower 2056 maintains contact with cam surface 2046 to allow controlled rearward travel of actuator assembly 2022.

[00116] Referring to Figure 26, to accommodate the lever 2022 and cam follower 2056 when the traction unit 2000 is fully assembled, rear spike plate 2024b has a recess 2060, defined by a curvilinear wall 2062. Lever 2022 and cam follower 2056 fit within this area when the traction unit 2000 is assembled. Recess 2060 permits cam follower 2056 to move horizontally forward and rearward and accommodates rotation of lever 2020. In this fashion, vertical travel of spike assembly 2024b does not interfere with lever 2020 and cam follower 2056.

[00117] The components of assembly 2000, except the metal spikes and springs thereof, may be fabricated from a lightweight, rigid material such as plastic. These components may be fabricated by injection moulding and assembled into the finished assembly.

[00118] Figure 23B shows traction assembly 2000 with spikes in their fully retracted position. Lever 2020 is rotated into the second position wherein actuator assembly 2022 has been urged into its fully rearward position and cam follower 2056 has been urged into its forward-most position. Spike assembly 2024b is in its fully raised position wherein the spikes are retracted. Figure 21 shows the spikes in an intermediate, partially retracted position.

[00119] Figure 23A shows traction assembly 2000 with spikes in their fully extended position. In this position, lever 2020 is rotated into the first position wherein actuator assembly 2022 is in its fully forward position and cam follower 2056 is positioned its rearwardmost position. Spike assembly 2024b is in its fully lowered position wherein the spikes are extended.

[00120] Lever 2020 and associated cam surface 2046 may be configured whereby the full range of motion of lever 2020 thaL is required to fully elevate or lower the spikes is provided by an angular range that is less than the full range of motion of the lever as shown in Figures 23A and 23B. For example, these figures show a pivotal range of lever 2020 of close to i8o°, whereby in the extreme ends of this range, as seen in Figures 23A and B, lever 2020 is flush or nearly flush with the sole of the shoe for preventing unwanted contact during use. In one aspect, the shoe may be provided with a recess, not shown, to accommodate lever 2020 in its extreme positions whereby lever 2020 is fully flush with the sole of the shoe. Lever 2020 may have an operative range wherein it actuates actuator assembly 2022 within a range of rotation (the "actuation range") that is less than its full range of rotation. This allows lever 2020. For example, the full range of motion of lever 2020 may be i6o° to i8o° and the actuation range may be within 150 ⁰ - 30 ⁰ , such as i20°-45°, or about go ⁰ , Furthermore, lever 2020, housing 2002 and other components may be configured to generate frictional resistance against rotation of lever 2020 to reduce unwanted movement. Of course, the degree of friction must not be so great as to make operation difficult. Furthermore, the friction may increase at the respective extreme ends of the range of motion shown in Figures 23A and B, to retain lever 2020 in these extreme positions.

[00121] Cam surface 2046 of lever 2020 is configured to generate an "over center" effect when rotated into the first position of figure 23A. As seen in Figure 27, cam surface 2046 comprises a first region 2047 which when in contact with cam follower 2056, urges cam follower 2056 forwardly as lever 2020 is rotated towards the first position. Continued rotation of lever 2020 brings a second region 2049 into contact with follower 2056. Region 2049 is the "nose" of cam surface 2046 and represents the point of maximal forward travel of follower 2056. Further rotation of lever 2020 towards the first position causes third region 2051 of cam surface 2046 to contact follower 2056. Region 2051 is the "overcenter" region, wherein follower 2056 slightly retract towards the second position as it slides along surface 2051. As well, in this actuator assembly 2022 effects contact between the flat plateau surfaces 237 of wedges 2034 and the underlying spike assembles 2024. In this position, the respective horizontal surfaces of wedges 2034 and spike assemblies 2024 are in contact and retraction of the spike assemblies cannot occur until these horizontal surfaces are brought out of contact.

[00122] Actuator assembly 2022 is retained in the overcenter position by spring 2048, which urges actuator assembly 2022 towards this position. When lever 2020 is fully rotated into the first position, it is effective retained in this position. Lever 2020 may be released from the overcenter position by urging it towards the second position with sufficient force to overcome the force exerted by spring 2048, which causes the contact point between cam surface 2046 and follower 2056 to move past nose region 2049 towards the first region 2049. At this point, the rearward bias of actuator assembly 2022 serves to urge lever 2020 towards the second position.

[00123] From the extended position of Figure 23A, spike assemblies 2046 may be retracted into their elevated position of Figures 21 and 23B. When lever 2020 is shifted back to the first position, actuator assembly 2022 is able to move rearwardly under the urging of spring 2048 and, optionally, the upward forces exerted by springs, not shown, acting on the spike assemblies. By this action, the spike assemblies are retracted into their elevated positions.

[00124] The present invention has been described with reference to particular embodiments of a traction assembly in accordance with the present invention. It will be apparent to those of ordinary skill in the applicable art that various modifications and alterations to the embodiments described herein are possible. As such, the scope of the present invention should not be limited to the particular embodiments described therein, but should be defined by the claims, which are to be given the broadest possible interpretation consistent with the specification as a whole.