Abstract:
A wheel for an in-line skate or other wheeled vehicle is disclosed that may be modified to alter the rolling resistance of the wheel. The wheel may be disassembled to change a tire on the outer surface of the wheel to one made of a harder or softer material, and to insert or change a grease of a chosen viscosity into a chamber inside the wheel. The two changes may be utilized singly or collectively to help set the rolling resistance of the wheel. The wheel may be retrofit onto existing in-line roller skates.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a wheel providing variable rolling resistance to a wheeled vehicle. More particularly, the present invention relates to an adjustable wheel for varying the amount of rolling resistance of a roller ski or an in-line skate. 
     BACKGROUND OF THE INVENTION 
     Roller skis are used for ski training in the off season when there is no snow. Such training must simulate skiing on wet snow and on dry, powdery snow. Roller skis are also used by many non skiers for a low impact aerobic exercise. In order to duplicate the energy expenditure of snow skiing it is desirable to have relatively slow wheels on such roller skis. The rolling speed is mainly a function of the energy return of the tire material on the wheels. Tires made with low rebound, high energy absorbing materials offer more rolling resistance but they can become extremely hot and often fail prematurely. In such cases entire wheels must be replaced, all too frequently. Conversely, tires made with high rebound, low energy absorbing materials offer little rolling resistance but these wheels roll too fast and do not properly simulate skiing on snow. In order to duplicate the energy expenditure of snow skiing it is desirable to have slow wheels without having the heating problems normally associated therewith. 
     As the popularity of in-line skating grows, more and more people are using in-line skates for purposes other than purely recreational skating. Several different categories of skaters and skates have evolved. For example, there are aggressive skates, speed skates, hockey skates, and many levels of recreational and fitness skates. Those people familiar with in-line skating often transition from recreational skating to fitness skating as they become more experienced therewith. 
     Many experienced fitness and speed skaters use their in-line roller skates for conditioning and endurance training. However, because the wheels and bearings of in-line skates offer little or no resistance, skaters must travel at very high speeds to achieve a desired heart rate and muscular conditioning. Many skaters do not wish to travel at the high speeds required for such training. Further, it is often difficult to safely travel at high speeds when skating on a busy bicycle path or street. 
     Thus, there is a need for means to vary the rolling resistance of one or more of the wheels used on roller skis to simulate skiing on different types of snow, such as wet snow or powdery snow, or on in-line roller skates to accommodate different exercise routines. 
     SUMMARY OF THE INVENTION 
     A novel wheel for wheeled vehicles such as roller skies and in line skates is taught that comprises a wheel that may be modified to adjust the rolling resistance thereof to meet individual requirements. In that way roller skis equipped with the novel wheels and used for ski training in the off season can properly simulate skiing on different types of snow. In line skates equipped with the novel wheels may simulate different competition and training conditions. In addition, by changing the wheels in line skates used for competition may also be used for training. This is particularly beneficial when skates are custom made to accommodate physical peculiarities or problems of a skater&#39;s feet, such as falling arches. A skater does not have to invest in two or more pairs of custom in line skates to accommodate competition and different training routines. 
     A skier in training during the off season may replace the standard wheels on their roller skis with the new adjustable wheel. The skier may modify their new adjustable wheels to simulate skiing on different types of snow, such as wet snow or powdery snow, or they may have a plurality of sets of the new adjustable wheels, each set modified to simulate skiing on different types of snow. The skier would then just change between their sets of adjustable wheels for the snow conditions they want to simulate. 
     Similarly, an in line roller skate skater may replace the standard wheels on their in line skates with the new adjustable wheel. A fitness skater can adjust the rolling resistance of the adjustable wheels on their in line skates to provide variable degrees of resistance so that the skater can achieve different levels of elevated heart rate and improved muscular conditioning without having to travel at high speeds. They can also adjust the rolling resistance of the wheels to decrease the rolling resistance to its minimum for competition skating. Alternatively, the skater may have a plurality of sets of the new adjustable wheels, each set modified to simulate different competition, training or exercise routines, and they change sets of wheels depending on what conditions they want to simulate, 
     The rolling resistance of the novel wheel is varied in two different ways. First, the rolling resistance of a wheel is varied by using grease of different viscosities to change the kinematic shear action of the grease. Very simply stated this creates a “drag” effect on a rolling wheel. The grease is held in a closed, sealed area inside the rim of each wheel in contact with the shaft on which the wheel rotates. Second, the outer edge of the rim of each wheel has a replaceable “tire”. Different “tire” materials affect the rolling resistance of a wheel. Tires made of soft rubbery materials have more rolling resistance than tires made of hard materials. The “tire” may easily be changed. By changing the tire of a wheel the rolling resistance of the wheel may thereby be changed. 
     The variable rolling resistance wheels of the present invention may be used to replace existing wheels on roller skis and on in line roller skates. For in line skates a new pair of skates need not be purchased for different applications such as training and competition. In addition, a skier or skater may have multiple sets of variable rolling resistance wheels in which they have inserted greases of selected viscosities, coupled with selecting “tires” of different materials to achieve a range of custom rolling resistances for the wheels of their roller skis or inline roller skates. 
    
    
     
       DESCRIPTION OF THE DRAWING 
       The invention will be better understood upon reading the following Detailed Description in conjunction with the drawing in which: 
         FIGS. 1   a - c  show three views of a wheel rim portion, two of which portions are assembled together to make a rim of the present invention; 
         FIG. 2  is an exploded view showing how two of the wheel rim portions are to be assembled together with ball bearings and a new grease seal to make a rim on which a tire is mounted; 
         FIG. 3  shows two of the wheel rim portions assembled together with ball bearings and the new grease seal to make the new rim on which a tire is mounted; 
         FIG. 4  is an exploded view showing how two of the wheel rim portions and a tire are to be assembled together with ball bearings and the new grease seal to make a variable rolling resistance wheel in accordance with the teaching of the invention; 
         FIG. 5  shows two of the wheel rim portions and a tire are assembled together with ball bearings and the new grease seal to make a wheel in accordance with the teaching of the invention; and 
         FIG. 6  is an exploded view of a grease seal on a shaft showing how grease of different viscosities is held against the shaft to affect the rolling resistance of the wheel in which the grease seal is located. 
     
    
    
     DETAILED DESCRIPTION 
     On a typical roller ski or in line roller skate two or more wheels with shaft or ball bearings are rotatably mounted on axles attached to the ski or skate. Other features of such roller skis or inline roller skates are well known in the art and are not discussed further herein. 
     The present invention is a novel, adjustable wheel that may used to replace the existing wheels on existing roller skis or in line roller skates, and the novel wheels may be manually and easily modified to change the rolling resistance of the wheels. Briefly, this is accomplished by changing a viscous grease on the inside of the wheel and in contact with a shaft on which the wheel turns and/or by changing a “tire” on the outer edge of a wheel. 
     There are a number of distinct advantages offered by the present invention. A roller skier can realistically simulate skiing on different types of snow. In addition, a roller skier may have multiple sets of wheels in which they have inserted greases of selected viscosities, coupled with selecting “tires” of different materials in order to achieve a range of custom rolling resistances for the wheels which thereby provides the different simulations. To change snow condition simulations the skier merely changes the wheels on their roller skis. 
     An inline roller skater can achieve different levels of elevated heart rate for improved muscular conditioning. A skater can also adjust the rolling resistance of the wheels to decrease the rolling resistance to its minimum for competition skating. In addition, a pair of in line roller skates used for competition may also be used for training. This is particularly beneficial when skates are custom made to accommodate physical peculiarities or problems of a skater&#39;s feet. A skater does not have to invest in two or more pairs of custom in line roller skates to accommodate competition and different training routines. In addition, the in line roller skater may have multiple sets of wheels in which they have inserted greases of selected viscosities, coupled with selecting “tires” of different materials in order to achieve a range of custom rolling resistances for the wheels which thereby provides the different conditions they want to achieve. 
     In  FIGS. 1A-1C  is shown a portion  11  of the complete rim  10  of the novel wheel that is shown assembled in  FIG. 3 .  FIG. 1A  shows the outer surface of each rim portion  11 ,  FIG. 1B  shows an edge view of each portion  11 , and  FIG. 1C  shows the inner surface of each rim portion  11 . The assembled rim  10  shown in  FIG. 3  is made up of two of these identical rim portions  11  as shown in  FIG. 2 . When two rim portions  11  of  FIGS. 1A-1C  are assembled together to make up a rim  10  the inner surfaces of two rim portions  11  contact each other as shown in  FIG. 3 . 
     Each rim portion  11  has four holes  16  there through as shown in  FIGS. 1A and 1C  through each of which a screw  17  is inserted to fasten two rim portions  11  together as shown in  FIGS. 2 and 3 . Although not shown in the figures for the sake of simplicity a hex head nut may be embedded into the outer surface over each of the four holes  16  through one of the two rim portions  11  and the screws  17  are inserted through the holes  16  of the other rim portion  11  to screw into the nuts. Alternatively, the hex head nuts may lie on the outer surface of the rim portion  11 . Other non-permanent fastening arrangements may also be utilized. 
     The outer surface of each rim portion  11 , seen in  FIG. 1A , has a recess  14  into which a ball bearing  18  is placed on assembly of a rim  10 , as seen in  FIGS. 2 and 3 . The inner surface of each rim portion  11 , as seen in  FIG. 1C , has a recess  15  into which a grease seal  19  is placed on assembly of a rim  10  as shown in  FIGS. 2 and 3 . When two rim portions  11  are attached to each other as shown in  FIG. 3 , the two facing recesses  15  create a cavity into which the grease seal  19  is contained as shown in  FIG. 3 . The two rim portions  11  making up a complete rim  10  as shown in  FIGS. 2 and 3  each have a rim extension  11   a  or  11   b  around their edge, as shown in  FIGS. 2 and 3 . When two rim portions  11  are fastened together as shown in  FIG. 3  the two rim extensions  11   a  and  11   b  create a groove  21 , as shown in  FIG. 3 , into which a user selected tire  22  is captivated as shown in  FIG. 5 . 
     The ball bearings used in wheels for roller skis and inline roller skates are typically 22 millimeter diameter ball bearings. In split rims used in the prior art there is one bearing in each rim half and the inner race of each bearing is separated by a spindle, so that when the wheel is mounted to wheel forks the pressure generated by the bolt and nut of the forks does not distort the bearing. If a wheel bolt is tightened without a spindle, the inner race of the bearing is forced out of alignment with the outer race resulting in rapid bearing failure. The possibility of such distortion is eliminated with the present invention by utilizing a hollow shaft  23  as shown in  FIG. 5 . An axle passes through the hollow shaft  23  and the bolts and nuts of the wheel forks is applied to hollow shaft  22 , but never to the bearings  18 . 
       FIG. 2  shows how two rim portions  11  are assembled (without a tire  22 ). A first rim portion  11  (shown on the left) has a ball bearing  18  friction fitted into its outer recess  14 , and a grease seal  19  friction fitted into its inner recess  15 , as shown is  FIG. 2 . A second rim portion  11  (shown on the right) then has a ball bearing  18  friction fitted into its outer recess  14 . The two rim portions  11  are then pushed together as represented by arrow W with their screw holes  16  aligned with each other. The screws  17  are then inserted through the aligned screw holes  16  from the outer side of the right hand rim portion  11  and screwed firmly into a receiving nut (not shown) on the outer surface of the left hand rim portion  11 . Only two screws  17  are shown in  FIG. 2  for the sake of simplicity and to avoid cluttering the drawing. 
     A completely assembled rim  10  (without a tire  22 ) is shown in  FIG. 3 . Tire  22  is eliminated from  FIG. 3  so as not clutter up the drawing and detract from the understanding of rim  10 . Tire  22  is shown in and described with reference to  FIGS. 4 and 5 . When a user desires to initially configure the rolling resistance of a wheel  10 , or to alter the rolling resistance of a previously configured wheel  10 , the four screws  17  are removed, the two rim portions  11  are separated, a tire  22  may then be changed to alter the rolling resistance, and the grease seal  19  may be cleaned and a new grease inserted therein to further alter the rolling resistance. 
       FIG. 4  is alike  FIG. 2  except a tire  22  is shown, which is the normal assembly of a wheel. First, the left hand rim portion has a ball bearing  18  friction fitted into its outer recess  14 , and a grease seal  19  friction fitted into its inner recess  15 . The right hand rim portion  11   b  then has a ball bearing  18  friction fitted into its outer recess  14 . A tire  22  is then inserted onto ledge  12  of the left hand rim portion  11 . The two rim portions are pushed together as represented by arrow W 1  with their screw holes  16  aligned with each other. The screws  17  are then inserted through the aligned screw holes  16  from the outer side of right hand rim portion and screwed firmly into a receiving nut (not shown) on the outer surface of left hand rim portion  11   a . Rim extensions  11   a  and  11   b  now comprise groove  21  ( FIG. 3 ) and hold tire  22  therein as shown in  FIG. 5 . Only two screws  17  are shown in  FIGS. 4 and 5  for the sake of simplicity. 
       FIG. 5  is alike  FIG. 3 , the two rim portions  11  are attached to each other, except tire  22  is retained in groove  20  ( FIG. 3 ). Also shown is a hollow bushing  23  that is inserted through the holes  20  in each of rim portion  11  and through the two ball bearings  18  and grease seal  19  mounted therein. An axle of the in line skates (not shown) passes through hollow bushing  23 . The purpose for having bushing  23  extend outside the assembled rim is as described in the following paragraph. 
     In split rims used in the prior art there is one ball bearing mounted in each rim half and the inner race of each bearing is separated by a spindle, so that when the wheel is mounted to wheel forks the pressure generated by the bolt and nut of the forks on the inner race of the bearings does not distort the bearing. If a wheel bolt is tightened without a spindle, the inner race of the bearing is forced out of alignment with the outer race resulting in rapid bearing failure. The possibility of such distortion is eliminated with the present invention by utilizing a bushing  23  as shown in  FIG. 5 . An axle passes through the hollow bushing  23  and the bolts and nuts of the wheel forks (not shown) in which wheel with bushing  23  are mounted is applied to bushing  23 , but never to the inner race of bearings  18 . 
     Bushing  23  is heat treated and polished to meet the specifications in diameter, hardness and surface roughness of the manufacturer of seal  19 . Seal  19  meets the German DIN 3760 Type AS specification. 
       FIG. 6  is an enlarged cutaway view of radial grease seal  19  mounted on hollow bushing  23 . Such radial seals are used for a variety of applications for both static and rotating shafts. In motors and gear boxes the seals prevent the lubricants from leaking. Radial seals come in a variety of types. DIN type radial seals have one or two elastomer wiping lips that contact a rotating shaft. Grease seal  19  is circular and has an outer wall  24  that is friction fit into the recess  15  in the center of the inner surface of each rim portion  11  as shown in  FIGS. 4 and 5 . There is a groove with a donut shaped garter spring  27  lying therein which applies pressure to the inner wall  30  of grease seal  19  which pushes ring shaped flat lips  28  and  29  into contact with the outer surface of bushing  23 . On the opposite surface of inner wall  30  there are ring shaped flat lips  28  and  29  with a recess between them as shown. Lips  28  and  29  are termed the dust lip and the wiping lip. The shape of the recess is not important and may be different. 
     When grease seal  19  is placed on a shaft, such as bushing  23 , there is an annular space  26  created between the recess and the outer wall of the bushing  23 . Before grease seal  19  is assembled into a wheel  10  a silicon grease (not specifically shown) having a selected viscosity is packed into the recess that is part of space  26 . By filling the recess between lips  28  and  29  with a high viscosity silicone lubricant the rolling resistance is increased not only by the friction of lips  28  and  29  of the radial seal, but also by the kinematic shear action of the fluid. In the preferred embodiment of the invention we are using a silicone fluid with 60,000 centistoke viscosity. 
     After grease seal  19  is mounted inside an assembled rim with a tire  22  thereon, as shown in other Figures, the bushing  23  of fully assembled wheel  10  is mounted on an axle of the in line roller skates. Bushing  23  is captivated by the wheel forks of the roller skis or in line roller skates and does not rotate. 
     As a wheel with its grease seal  19  rotates on bushing  23 , the high viscosity of the silicone grease creates a “drag” effect called kinematic shear action which creates resistance to the turning of wheel  10 . The more viscous the grease the more rolling resistance there is, and visa versa. 
     Thus, between selecting a tire  22  having more or less rolling resistance and selecting the viscosity of a grease that creates more or less rolling resistance, the rolling resistance of an assembled wheel may be manually determined. It has been found in testing that the increase in rolling resistance with one grease seal  19  ranges between 12 to 25% depending on the tire material used. Harder, high rebound, tire materials have a higher percentage increase in rolling resistance than softer, lower rebound, tire materials. 
     While what has been described herein is a preferred embodiment of the invention those skilled in the art will appreciate that numerous changes may be made without departing from the spirit and scope of the invention.