Abstract:
A triple action roller skate steering and suspension mechanism includes upper and lower cushions clamped on either side of a skate truck, plus a third action comprising a floating cushion mechanism supporting and surrounding the pivot cup portion of a pivot joint mechanism. A pivot pin is threaded into the skate truck and can be preloaded against the pivot cup and floating cushion mechanism, thereby providing improved shock absorbing, durability and adjustability. The roller skate base plate is a unitary structure including a hollow arch for lightweight structural reinforcement.

Description:
[0001]    This patent application claims the benefit of the priority date of Provisional Patent Application No. 61/398,371 filed Jun. 24, 2010 entitled ROLLER SKATE STEERING AND SUSPENSION MECHANISM. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates generally to a roller skate steering and suspension mechanism, and more particularly to a triple action steering and suspension mechanism providing more responsive and durable operation during competitive roller skating. 
         [0004]    2. Description of the Prior Art 
         [0005]    Roller skate steering and suspension mechanisms have been in production for over a century. The modern quad roller skate, with a forward pair of wheels and a rear pair of wheels, generally has each pair of wheels secured to an axle which is mounted in a truck that is pivotally connected to a skate base plate, which is in turn secured to the skate boot or shoe. The trucks provide steering response whereby when a skater shifts weight laterally across the base plate, the truck twists, causing the axle to turn. The forward and rear trucks are mounted oppositely so that the axles will turn in opposite directions, causing the wheels to travel in an arc. The trucks also serve, by means of a resilient suspension system, to resist the skater&#39;s lateral tilt of the base plate, thus stabilizing the base plate and returning it to a centered and horizontal position when the turn is completed. Skate trucks generally sacrifice the ability to turn in exchange for lateral stability, thus becoming stiff and unresponsive when tightened sufficiently. Conversely, loosening the trucks for improved turning can lead to mechanical instability. Stiffer skate mechanisms will more efficiently transfer muscle power to skate speed, and are preferred by speed skaters who aren&#39;t likely to be making many sudden turns. Additional factors affecting roller skate performance include base plate weight, stiffness and durability, where the ideal roller skate base plate balances the tradeoffs of light weight, high stiffness and sufficient durability. 
         [0006]    The steering and the resilient suspension system are generally implemented including a single or a double action mechanism. The single action mechanism has one cushion, usually made of rubber or a urethane compound, that sits on the side of the truck facing towards the base plate. This is referred to as the load bushing or inner cushion. The double action mechanism has two cushions, one above and one below the truck, relative to the base plate. This second cushion is referred to as the steering bushing or outer cushion. The single action mechanism is older and generally is not used for skating styles requiring fine control. Most modern skating mechanisms are of the double action variety. Skateboards generally use steering and suspension mechanisms very similar to those used by roller skates, and have similar shock absorbing, steering and lateral stability requirements. 
         [0007]    The truck typically also includes a cushion mount and a tubular stem which in higher quality roller skates is threaded to hold an adjustable pivot. The cushion mount typically has a ring-shaped area with recesses on both axial faces to position a pair of tubular cushions formed from urethane or other elastomeric material. A stud or kingpin is typically fastened into the base plate and is inserted through the ring-shaped area and through axial openings in the cushions and in many higher quality roller skates is secured with a nut along a threaded length protruding outward from beyond the cushions. In some cases a portion of the threaded length is split and the nut may have compression calibration marks for setting cushion compression as part of the skate suspension and steering adjustment. This kind of nut is called a micrometer nut and is typically locked in place with a taper-headed set screw. A ball ended stud (or ball stud) functions as a rounded pivot and is typically threaded into the tubular stem of the truck and the ball end of the stud is seated in a pivot cup, which in the prior art is typically made of rubber, elastomer, brass, steel, or a polymer such as Delrin. Frequently in high performance quad skates the ball stud can be threaded inward or outward from the truck to adjust the action of the skate steering and suspension. Prior art adjustable pivots allow skaters to set the angle of the trucks and also set the degree of preload on both the load bushing and the steering bushing. Washers and other fasteners may be used to adjust the elastic performance of the cushions. Typically the two pair of wheels and their support hardware are identical for front and back. 
         [0008]    The truck geometry also influences skate steering and lateral stability, where major factors include the orientation of the pivot pin, the axle and the kingpin, and the angular relationship between these parts. If the axle is positioned between the pivot pin and the kingpin, the skate will have better lateral stability but less responsive steering. If the pivot pin and the kingpin are adjacently positioned and the axle is positioned out beyond the kingpin, the steering will be more responsive but the lateral stability will decrease. This geometry also tends to shorten the wheelbase, thus further decreasing overall stability. It has been found that having an approximately 45 degree angle between the pivot pin and the base plate, and also an approximately 45 degree angle between the kingpin and the base plate, yields a very responsive steering geometry, though with a consequent decrease in lateral stability. Depending on the skating style, this may be preferred. 
         [0009]    For competitive roller skating activities such as roller derby, the skate mechanism is subjected to extreme impacts during jumps and falls, as well as the stresses of high speed skating, tight turns and the dynamic forces caused by sudden acceleration and deceleration. One particular problem with prior art skate mechanisms is wear and damage to the pivotal connection between the truck and the base plate. The simplest pivotal connection is generally a protruding portion of the truck with a rounded end, engaging a rounded recess in the base plate. As the resiliently mounted truck moves, the pivotal connection will rotate through some amount of arc, but it may also momentarily separate and then re-contact with some amount of impact, an effect known as “slap”. This will wear the joint and over time the amount of separation and slap will increase. The skate mechanism will also feel looser and less tightly controlled, and may eventually fail due to stress and impact. Additionally, slap and mechanism play will cause fatigue to the skater and may even promote joint injuries. Mechanism play can also increase the probability of sudden component failure. The impacts experienced by the skate mechanisms can cause the cushions to suffer heavy uneven wear, the pivot cups to wear and even crack, and the kingpins to crack as well. Sudden component failure can easily lead to skater injuries. Also, increasing steering responsiveness by overly loosening the resilient clamping around the trucks can lead to sudden pivot joint separation and consequent spinning of the truck around the kingpin, with skater injury being a likely result. 
         [0010]    Prior art improvements on this pivotal connection have generally taken one of two forms. A cup formed of resilient material is inset into the base plate to receive the pivot, thus providing some degree of shock absorbing. This cup will wear over time and under extreme circumstances (which are not infrequently encountered in activities such as roller derby) may actually crack apart. Alternatively, a metal insert formed of a relatively slippery alloy such as bearing bronze and having a spherical section recess may be inset into the base plate, and a pivot having a ball end engages it. The pivot action may be further improved by threading into the truck and being pre-loaded against the metal insert. This style of pivotal connection will provide no shock absorbing but will pivot smoothly for a while. Eventually it will wear and then slap will increase. 
         [0011]    The tradeoff between skate lateral stability and steering performance has been a source of many skate inventions too. U.S. Pat. No. 7,287,762 entitled TRUCK FOR SKATEBOARDS teaches a truck mechanism with a pin-kingpin-axle configuration in order to permit tighter turns, and incorporating the standard paired elastomeric cushions and a resilient cup to cushion the pivot pin. The &#39;762 patent also teaches having the kingpin perpendicular to the pivot pin with the axis of each at approximately 45 degrees to the base plate, which tends to provide a highly responsive steering geometry. Also taught are a variety of angular orientations for the kingpin and pivot pin, thus affording a variety of performance styles to a skateboard. 
         [0012]    However, the &#39;762 patent does not teach any means for preloading the pivot mechanism for protection against static and dynamic forces, and the resilient cup provides a very limited amount of shock absorbing and historically has been prone to high wear and even splitting apart. 
         [0013]    U.S. Pat. No. 6,547,262 entitled SKATEBOARD TRUCK ASSEMBLY teaches the use of different geometries of load and steering bushings, including a necked-down bushing for increased ease in steering. Also taught is a pivot pin mechanism comprising a pivot pin having a cylindrical section engaging a ball bearing seated in an elastomeric cup. This mechanism provides free rotary pivoting and some shock absorption for the ball bearing and pivot pin. 
         [0014]    However, the pivot pin taught by the &#39;262 patent primarily offers free rotation around a single axis rather than in all directions as a ball joint provides, and suffers the well known problems of the limited shock absorbing response and limited durability provided by a resilient cup. Nor is the pivot pin adjustable for preloading. Additionally, the pin-axle-kingpin geometry will provide less tight turning capability than a pin-kingpin-axle geometry. 
         [0015]    U.S. Pat. No. 6,182,987 entitled TRUCK ASSEMBLY WITH REPLACEABLE AXLES AND BALL JOINT PIVOTS teaches the use of different geometries of upper and lower elastomeric cushions, including a hemispherical cushion engaging a socket in the truck for improved rotation and steering. An adjustable pivot pin with a ball end engaging a spherical section shock-absorbent socket is also taught. 
         [0016]    However, the &#39;987 patent also suffers from the problems of the limited shock absorbing response and limited durability provided by a resilient cup, even though the ball joint will provide an improvement in rotation. In addition, the pin-axle-kingpin geometry will provide less tight turning capability than a pin-kingpin-axle geometry. 
         [0017]    A more capable and robust roller skate steering and suspension mechanism would provide a pre-loadable, adjustable, durable yet resilient pivoting connection between the skate truck and the base plate, effectively creating a third action to augment the double action skate mechanism. Additionally, the base plate portion of the mechanism would be extremely lightweight and stiff to reduce skater fatigue and increase performance, and very durable to avoid breakage during competitive skating activities. Such a skate mechanism would be usable in skateboards as well. 
       SUMMARY 
       [0018]    A more responsive and durable roller skate steering and suspension mechanism comprises a base plate having at least one pivot cup mounting hole and at least one kingpin mounting hole, a pivot cup with a cup socket and a cup body and a cup end, wherein the pivot cup is disposed in the pivot cup mounting hole such that the cup socket faces outwards, a kingpin having an axis and being mechanically fastened into the kingpin hole, a skate truck having a wheel axle holder and a pivot pin socket and a kingpin aperture wherein a portion of the kingpin is radially surrounded by the kingpin aperture, a pivot pin having a rounded pivot end and a threaded end and an axis, wherein the threaded end is threaded into the pivot pin socket and the rounded pivot end rotationally engages the cup socket, the pivot cup mounting hole having interior sides and a bottom, a radially disposed resilient means for shock absorbing in mechanical communication between a portion of the cup body and a portion of the pivot cup mounting hole interior sides, an axially disposed resilient means for shock absorbing in mechanical communication between a portion of the cup end and a portion of the pivot cup mounting hole bottom, the pivot pin axis and the kingpin axis being intersecting, an upper resilient cushion disposed above the skate truck and a lower resilient cushion disposed below the skate truck, and, the upper resilient cushion and the lower resilient cushion being clamped against the skate truck along the kingpin axis. 
         [0019]    According to another aspect of the present invention, the pivot pin is axially adjustable to regulate force of contact between the pivot and the pivot cup, thereby providing mechanical preloading for the roller skate steering and suspension mechanism against both static and dynamic loads. 
         [0020]    According to yet another aspect of the present invention, the base plate is made of a single piece of material and includes a transversely open reinforcing arch to provide lightweight lengthwise stiffening, wherein the transverse opening through the arch is an oval and the area underneath the arch is open through the body of the base plate, thus providing further lightening of the base plate with a minimum of decrease in structural strength. 
       OBJECTS AND FEATURES OF THE INVENTION 
       [0021]    It is an object of the present invention to provide a roller skate steering and suspension mechanism with a triple action to improve the performance and robustness of both steering and suspension under both static and dynamic loads. 
         [0022]    It is another object of the present invention to provide a lighter, stiffer and more durable base plate as part of the roller skate steering and suspension mechanism. 
         [0023]    It is a feature of the present invention to provide a third action comprising a floating pivot assembly having both radial and axial resilient means for support. 
         [0024]    It is another feature of the present invention to have a floating pivot assembly having means for preloading. 
         [0025]    It is yet another feature of the present invention to have a base plate formed of a single piece of material and having a transversely open reinforcing arch. 
         [0026]    It is still another feature of the present invention for the transverse opening through the arch to be approximately an oval and the area underneath the arch to be open through the body of the base plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The present version of the invention will be more fully understood with reference to the following Detailed Description in conjunction with the drawings of which: 
           [0028]      FIG. 1  is a perspective view of a first roller skate steering and suspension mechanism; 
           [0029]      FIG. 2  is an elevation view of a first roller skate steering and suspension mechanism; 
           [0030]      FIG. 3  is a partially exploded view of a first roller skate steering and suspension mechanism; 
           [0031]      FIG. 4  is an elevation view of a second roller skate steering and suspension mechanism; 
           [0032]      FIG. 5  is an elevation view of a third roller skate steering and suspension mechanism; 
           [0033]      FIG. 6   a  is a first view of a pivot and pivot cup assembly; 
           [0034]      FIG. 6   b  is a second view of a pivot and pivot cup assembly; 
           [0035]      FIG. 7   a  is a first perspective view of a first truck; 
           [0036]      FIG. 7   b  is a second perspective view of a first truck; 
           [0037]      FIG. 7   c  is a first perspective view of a second truck; 
           [0038]      FIG. 7   d  is a second perspective view of a second truck; 
           [0039]      FIG. 7   e  is a first perspective view of a third truck; 
           [0040]      FIG. 7   f  is a second perspective view of a third truck; 
           [0041]      FIG. 8  is a perspective view of a fourth truck. 
           [0042]      FIG. 9  is a base plate underside perspective view. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0043]      FIG. 1  shows a first version of the roller skate steering and suspension mechanism  10 . A skate truck assembly  12  is mounted at each end of the base plate  50  by means of a kingpin  40  upon which are sequentially placed an inner cushion support  38 , an inner cushion  42 , a skate truck  32 , an outer cushion  44 , an outer cap  43 , a micrometer nut  58  and a kingpin set screw  56 . The inner cushion  42  and outer cushion  44  are clamped against the skate truck  32  and the micrometer nut  58  is used to set the degree of clamping pressure with fine control. The micrometer nut  58  is locked in place by the kingpin set screw  56 . This portion of the mechanism provides a means for double action steering and suspension and is shown both as an assembly and in an exploded form in  FIG. 3 . Preferably the inner cushion  42  and the outer cushion  44  are made of a elastomeric materials such as urethane. Identical or different resilient materials can be used to additionally tune the steering and suspension response. The kingpin  40  of the present invention has radiused shoulders to further distribute shearing load, wherein a radius of 1 mm or greater is preferred. 
         [0044]      FIG. 2  shows the profile of the roller skate steering and suspension mechanism, wherein the profile shape of the skate truck  32  can be more clearly seen. The axle  36  is placed out beyond the kingpin  40 , thereby increasing the steering responsiveness of the skate mechanism. By curving the tubular axle holder  34  portion of the skate truck  32  up from the main body plane, the axles  36  and the skate wheels (not shown) are thereby further apart and the wheelbase is lengthened to improve lateral stability of the roller skate.  FIGS. 3 ,  7   a  and  7   b  show the truck in greater detail, including the inner cushion recess  37  for holding the inner cushion  42 , the outer cushion recess  39  for holding the outer cushion  44 , and the kingpin aperture  33  through which the kingpin  40  is placed. The tapered top of the outer cushion  44  is a prior art feature. 
         [0045]    The base plate  50  has an integral arched stiffener bar  46  with oval side openings  48 , effectively forming a double arch for structural strength and light weight, thus adding torsional and bending rigidity to the base plate  50  and reducing weight without adding the safety hazards associated with a vertically oriented stiffening rib, or the weight penalty of a heavier prior art stiffener such a box beam, or a separate bent stiffening rib. The kingpins  40  are threaded into the kingpin recesses  41  but the weight reduction in the base plate  50  design does not decrease the ability of the kingpin  40  to transfer loads to the base plate  50 . The outside shape of the base plate  50  is configured to follow more closely the shape of a skate boot bottom, thus providing more complete and uniform support of the boot. Mounting holes  51  are used in combination with appropriate fasteners to secure the base plate  50  to a skate shoe or boot. The top surface of the plate  52  has a fillet  60  along both sides to prevent stress cracking under impact. This fillet extends past the bumper clamping features  62 .  FIG. 9  shows the bottom surface  53  of the base plate  50 , including the weight reduction pockets  54  and the bottom opening  64  which provides additional weight savings under the arched stiffener bar  46 . 
         [0046]    The truck assembly  12  includes a tubular stem  35  having a pivot pin recess  23  to hold a pivot pin  13  with a rounded pivot  14  at one end.  FIGS. 6   a  and  6   b  show the pivot pin  13  and related components in detail, including a cup recess  26  formed in the base plate  50 , with a cup recess bottom  29  and cup recess sides  27 . Preferably there is a vent hole in the cup recess bottom  29  to prevent air or debris from being trapped. The pivot pin  13  also has a threaded end  15  which is threaded into the pivot pin recess  23  in order to enable precise axial adjustment via a pair of wrench flats  21  or equivalent gripping surfaces. A nut  17  is used to lock the adjusted pivot pin  13  in place. 
         [0047]    The rounded pivot  14  engages a pivot cup  16 , which in the present invention is preferably made of phosphor bronze alloy for durability and low friction. The pivot cup  16  has a radiused cup socket  18  inside, configured to rotationally engage the rounded pivot  14 , and includes a radial groove  20  sized to hold an O-ring  22  and has an inner lip chamfer  24  allowing greater angular movement by the pivot pin  13 . The O-ring  22  provides friction against the cup recess sides  27  to retain the pivot cup  16  in place in the cup recess  26  formed in the base plate  50 , allowing the pivot cup  16  to float in the cup recess  26  of the plate  50  during skate use. The pivot cup  16  sits on a small axially oriented axial cushion  28  which when pressed against the cup recess bottom  29  serves to establish the typical “bottom” position of the pivot cup  16  and which acts as a shock absorber during use, particularly during impact. Preferably the axial cushion  28  is made of an elastomeric material such as a urethane. The additional controlled flexure and impact damping provided by a friction retained floating pivot cup  16  sitting on an axial cushion  28  provides superior impact absorption over the skate designs of the prior art. The O-ring  22  being a radially oriented resilient element also absorbs lateral loads experienced during skating and permits a necessary degree of lateral movement, further isolating the base plate  50  and thus the skater from vibration and impact. Wear on the pivot cup  16  is greatly reduced, permitting smoother pivoting action (and thus better steering control) and a longer lifespan for the pivot pin  13  and the pivot cup  16 . The combination of the pivot pin  13 , the floating pivot cup  16 , the axial cushion  28  functioning as an axially oriented resilient element and the O-ring  22  functioning as a radially oriented resilient element serve to provide a third steering and suspension action. 
         [0048]    Preferably there is a recess  30  in the cup end  19  bottom surface of the pivot cup  16 , whereby the use of a narrower diameter elastomeric axial cushion  28  axially positioned by the recess  30  permits radial expansion of the axial cushion  28  during downward movement of the pivot cup  16  under load and thus permits a greater range of cushion movement and improved tuning of shock absorption. Axial adjustment of the pivot pin  13  provides the ability to preload the triple action mechanism for best performance under a range of use conditions. With such a preloaded triple action steering and suspension mechanism, when the inner cushion  42  (as opposed to the outer cushion  44 ) compresses, the pivot cup  16  and rounded pivot  14  are now kept mechanically engaged, thus giving superior steering control. In prior art roller skate steering and suspension mechanisms, a high force applied to the inner cushion  42  would tend to cause the rounded pivot  14  to pull up and out of the pivot cup  16 . 
         [0049]    By using the axial cushion  28  and floating pivot cup  16  in combination with the inner cushion  42  and outer cushion  44  positioned by the king pin  40 , the distance between the axles  36  remains more constant. Additionally, there is no impact-generated “slap” of the suspension running into a hard limit during jumps and other impact-generating skating maneuvers. Further, there is less lateral (shearing) stress on the kingpins  40 . Additionally, the floating pivot cup mechanism will also provide improved performance with standard prior art skate trucks. The triple action mechanism allows the skate trucks to more accurately maintain a set orientation during use, because the pivot mechanism can now follow the truck motion up and down in concert with changes in the loading on the bushings. Because there is no metal on metal or metal on hard plastic contact and all joints are cushioned, the steering and suspension mechanism provides improved shock and vibration isolation and thus smoother skating and less fatigue and injury to the skater. 
         [0050]    In the first version of the present invention, the pivot pin  14  held in the tubular stem  35  of the truck  32  is preferably positioned at approximately 45 degrees from the plane of the base plate  50 , and likewise the kingpin  40  is also preferably positioned at approximately 45 degrees from the plane of the base plate  50 . The kingpins  40  are threaded into a kingpin recess  41  in the plate  50 . The preferred included angle between the pivot pin  14  and the kingpin  40  in a given truck assembly  12  is thus approximately 90 degrees, giving a more even distribution of forces between the parts of the skate wheel suspension. The floating pivot cup  16  also aids in evening out the distribution of forces. This mechanical configuration also permits more uniform movement of the axles  36  up and down rather than backward and forward during high loads and impacts, thus serving to keep a more constant distance between the axles  36 , and thereby providing more control to the skater. This dual 45 degree angular configuration, and the extension of the axle  36  out beyond the kingpin  40 , serve to lessen the required angle needed for a given degree of steering, and thus the skater doesn&#39;t need to lean as far to steer. 
         [0051]    A second version of the present invention is shown in  FIG. 4 , wherein a second roller skate steering and suspension mechanism  110  features a second truck assembly  112  based on a second truck  132 . The second base plate  150  has a similar arched stiffener bar  146  and oval side opening  148 , as well as fillets  160  and bumper clamping features  162 .  FIGS. 7   c  and  7   d  show the second truck  132  in greater detail, where the tubular axle holder  134 , the kingpin aperture  133 , the inner cushion recess  137  and the outer cushion recess  139  are similar to those of the first truck  32 . The significant differences in the second truck  132  are the tubular axle holder  134  being in the main plane of the second truck  132 , and the tubular stem  135  being angled approximately 45 degrees to the main plane of the second truck  132 . The pivot pin recess  123  is thus approximately perpendicular to the base plate  150  and the axles  36  are closer together, giving a shorter wheelbase and more responsive steering, though with an incremental decrease in lateral stability. Optionally, a pivot retainer (not shown) may be fastened over the rounded pivot  14  to prevent possible separation from the cup socket  18  during some high-force skating maneuvers. 
         [0052]    A third version of the present invention is shown in  FIG. 5 , wherein a third roller skate steering and suspension mechanism  210  features a third truck assembly  212  based on a third truck  232 . The third base plate  250  has a similar arched stiffener bar  246  and oval side opening  248 , as well as fillets  260  and bumper clamping features  262 .  FIGS. 7   e  and  7   f  show the third truck  232  in greater detail, where the tubular axle holder  234 , the kingpin aperture  233 , the inner cushion recess  237  and the outer cushion recess  239  are similar to those of the first truck  32  and the second truck  132 . The third pivot pin recess  223  is also threaded similarly to the other pivot pin recesses. The significant differences in the third truck  232  are the positioning of the tubular axle holder  234  between the kingpin aperture  233  and the tubular stem  235 , the included angle between the kingpin  40  and the pivot pin  13 , and the approximately 85 degree angle of the kingpin  40 . The geometry for the third roller skate steering and suspension mechanism  210  greatly enhances lateral stability, requiring more lean by the skater for a given amount of steering, as compared to the first roller skate steering and suspension mechanism  10  or the second roller skate steering and suspension mechanism  110 . 
         [0053]    A fourth truck  332  as shown in  FIG. 8  is similar to the first truck  32  except that the fourth truck  332  is symmetrical about a center plane with respect to the tubular axle holder  334 , the kingpin aperture  333 , the pivot pin recess  323  and the tubular stem  335 . The kingpin aperture  333  is disposed between the tubular axle holder  334  and the tubular stem  335 . The inner cushion recess  337  and the outer cushion recess  339  are offset from and generally oppositely disposed with respect to the center plane, although they may differ with respect to depth, angle, exact diameter and contour. The tubular axle holder  334  is in line with this center plane and both perpendicular to and bisected by the pivot pin axis. The kingpin aperture  333 , the pivot pin recess  323  and the tubular stem  335  are substantially similar to that of the first truck  32 . For some skating applications, the fourth truck  332  may be used in a front truck assembly in combination with a rear-mounted first truck assembly  12  or in fact any other different truck assembly, in order to produce a hybrid performance roller skate with a slightly shorter wheelbase and a slight forward angular tilt. 
         [0054]    The axles  36  and ball studs  14  are preferably made of hardened and tempered chromoly type alloy steel. Alternatively the axles  36  may be preferably made of heat treated titanium alloy of a high strength type such as Grade 5. The trucks  32 ,  132 ,  232 ,  332  and plate  50  are preferably made of high strength aluminum alloy such as 7075T6. Other skate steering and suspension mechanism hardware is preferably made of 7000 series high strength aluminum alloys. 
         [0055]    An alternate embodiment of the roller skate steering and suspension mechanism has the top face of the inner cushion  42  being a spherical section, mating with a matched radius formed into the inner cushion recess  37  in the truck  32 . These mated spherical surfaces permit even more responsive steering, as well as more even cushion wear and less chance of the cushions splitting during use. This more even cushion wear reduces the need to rotate or replace cushions, thus reducing the needed amount of skate maintenance. 
         [0056]    Another alternate embodiment of the roller skate steering and suspension mechanism, particularly applicable to the third roller skate steering and suspension mechanism  210 , has the inner cushion  42  optimized for larger skaters by increasing the bushing base diameter and tapering upwards to fit existing trucks, while also using a softer material. The combination of the wider inner cushion  42  base diameter and softer (lower durometer) cushion material provide smoother response during leaning and improved turnability even for larger skaters. In particular, when steering, the use of larger base diameter and softer outer cushions allows all four wheels to stay in contact with the floor while the skate wheels are toeing in for turning, thus providing better stability and more uniform wheel wear. With heavier skaters, this can also reduce the occurrence of axle bending. The use of larger diameter inner cushions also allows a softer bushing without wheel bite (wheels contacting the bottom of the skate shoe or boot) resulting from excessive truck deflection. Differential steering is a prior art term for the use of different hardnesses or durometers of inner and outer cushions to improve steering and stability. The use of a wider inner cushion base diameter and softer (lower durometer) cushion material in combination simultaneously provides improved steering and stability for larger skaters. 
         [0057]    Having described herein illustrative embodiments and best mode of the present invention, persons of ordinary skill in the art will appreciate various other features and advantages of the invention apart from those specifically described above. It should therefore be understood that the foregoing is only illustrative of the principles of the invention, and that various modifications and additions can be made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, the appended claims shall not be limited by the particular features that have been shown and described, but shall be construed also to cover any obvious modifications and equivalents thereof.