Abstract:
A trolley assembly comprises a frame incorporating at least one tire encompassing a wheel bearing and a bumper comprising a first portion made of a comparably incompressible material and a second portion made of a comparably compressible material. The bumper is mounted on the frame such that the bumper moves upon impact with an object, compressing the compressible material. For example, the incompressible material may be a polyamide and the compressible material may be a neoprene extrusion.

Description:
FIELD OF THE INVENTION 
     The field relates to gates using a wheeled trolley riding in a track. 
     BACKGROUND 
     Trolley assemblies are known that use steel tracks and other steel components for sliding, cantilever gates; however, all of the known assemblies are noisy and having significant issues with wear. U.S. Pat. No. 7,980,570 discloses a trolley and channel with typical steel wheels and a simple metal channel. European publication, EP1770235 A1, was filed and received application number EP20050021280 on Sep. 29, 2005, with a priority date of Sep. 29, 2005. U.S. Pat. No. 8,196,353 B2, uses two opposing and offset wheels, engaging opposing rails of the track. U.S. Pat. No. 3,705,468 discloses a cantilevered gate with a trolley assembly. U.S. Pat. No. 3,705,468 has tapered wheels and a tapered channel. These cantilevered gates are known and various improvements have been made in each of the patents. None of these references provide for quiet operation of a cantilevered gate and some use much more complicated systems attempting to correct for other perceived problems with cantilevered gates. Centering wheels at opposite ends of the trolley assemblies use standard wheel bearings. The wheels are usually standard wheel bearings, also. 
     SUMMARY 
     A trolley comprises a frame and a bumper extending from one side of the frame. The frame is comprised of a rigid member. The rigid member has a first end and a second end, the first end extending in a first direction and the second end extending in a second direction, opposite of the first direction. At the first end of the rigid member, the bumper is mounted. The bumper is resilient, meaning that it is capable of absorbing the energy of an impact between the frame and an object and is substantially restored to its previous condition after the impact. 
     The trolley and track substantially reduces clatter and noise of gate operation compared to known systems. Especially, when a gate reaches its maximum open or closed position and the end of the trolley impacts a stop, conventional systems generate a sharp report, and efforts to reduce the noise tend to work for only a limited time before weathering and wear substantially reduce the effectiveness. 
     For example, a resilient bumper may comprise a compressible portion and an incompressible portion. Herein, compressible and incompressible are utilized and defined as would be understood by a person having ordinary skill in the art, when informed by this application. “Compressible” means comparatively compressible, such as a foam or elastic material that is capable of being compressed, absorbing energy of an impact and providing a bias force in a direction opposite to the force of the impact expected during use of the trolley. For example, a neoprene portion may be used as a material for the compressible portion. “Incompressible” means comparatively incompressible, when compared to the compressible materials, such as a plastic or other comparatively rigid material, which is capable of substantially maintaining its shape during the impacts expected during use of the trolley. For example, the incompressible portion may have a contact surface at an end of the incompressible portion facing in the first direction, and it is the contact surface that makes the initial contact with the object or stop. The material for the incompressible portion may be a nylon or polyamide, for example. 
     For example, the incompressible portion of the resilient bumper may be mounted slidably on the first end of the frame such that the contact surface of the incompressible portion extends outwardly from the first end of the frame in the first direction. The compressible portion may be disposed between the incompressible portion and a portion of the frame. The frame may be a substantially rigid member, such that, when the contact surface of the incompressible portion impacts an object, the compressible portion of the bumper is squeezed between the incompressible portion of the bumper and the frame. Upon impact, the incompressible portion slides toward the frame, and the compressible portion compresses between the incompressible portion and the portion of the frame. The compressible portion absorbs energy of the impact and applies a bias force against movement of the incompressible portion toward the frame, in the second direction. The bias force increases as the compressible portion is compressed until the bias force is sufficient to stop the trolley. The distance that the trolley travels during compression is greater than would be the case, if the bumper were made of only the comparatively incompressible portion. After each impact, the biasing force of the elastic, compressible portion substantially restores the incompressible portion back to its original position relative to the frame, for example. 
     In one example, a trolley further comprises at least one wheel comprised of a resilient, non-metallic tire. “Resilient” means a material that substantially maintains its shape while absorbing more energy than a rigid, steel wheel. For example, a polymer, such as a nylon, may be used for a resilient, yet comparatively incompressible material for both the tire and the incompressible portion of the bumper. The tire may be fit on a wheel bearing mounted on a support wheel shaft or axle, extending through the frame, for example. 
     In one example, a pair of wheels are disposed on opposite sides of the rigid member of the frame using a common support wheel shaft. Opposite ends of the support wheel shaft extend from opposite sides of the rigid member of the frame, providing a pair of axles for a pair of wheels on opposite sides of the frame. Herein, rigid means substantially stiff during normal operations. 
     The hub of a wheel may engage an axle. In one example, a set screw extending through the frame fixes the support wheel shaft within the frame. A plurality of paired wheels may be used to support the weight of a gate, such as two pairs, four pairs or more. Alternatively, wheel bearings capable of supporting a greater weight per wheel bearing may be specified and fewer pairs of wheels may be used to support the same weight of a gate. 
     In one example, a wheel bearing has an outer radial surface rotatably mounted on a hub, and a tire, such as a resilient tire, engages the outer radial surface of the wheel bearing, such that the tire and outer radial surface of the wheel bearing rotate about the hub together, without slippage of the tire on the wheel bearing. Compared to a metal wheel bearing having a metal outer radial surface, the tire can be comparatively resilient, reducing operating noise of the trolley, while not substantially increasing friction of the wheel as it rolls along a track. 
     In one example, the shape of the wheel is selected to have a convex portion or a convex contact surface, and a channel of the track is selected to have a concave portion or a concave contact surface, such that the convex portions fit into the concave portions. For example, the absolute value of the curvature of the convex portion may be greater than the absolute value of the curvature of the concave portion, such that contact is made only along a limited contact area between the tire and the channel contact surfaces. By providing a slope on an inside surface of the track, the tires of the trolley may be retained in region of the channel, such that no guide roller is required or a guide roller present on the trolley seldom impacts a side of the track. This helps to reduce chatter and noise during operation of the gate, also. 
     In one example, a trolley comprises a frame comprised of a rigid member, the rigid member having a first end and a second end, the first end extending in a first direction and the second end extending in a second direction, opposite of the first direction. A resilient bumper, comprises a compressible portion and an incompressible portion having a contact surface, and the incompressible portion of the resilient bumper is mounted slidably on the first end of the frame such that the contact surface of the incompressible portion extends outwardly from the first end of the frame in the first direction. The compressible portion is disposed between the incompressible portion and a portion of the frame, such that, when the contact surface of the incompressible portion impacts an object, the incompressible portion is capable of sliding in the second direction, and the compressible portion resiliently compresses between the incompressible portion and the portion of the frame, absorbing energy of the impact and applying a bias force against movement of the incompressible portion in the second direction. 
     For example, the trolley has at least one wheel, the wheel being comprised of a resilient, non-metallic tire, a wheel bearing and an axle. The wheel bearing has an outer radial surface rotatably mounted on a hub, and the hub of the wheel bearing is coupled by the axle at a side of the frame, such that the wheel is disposed between the first end of the frame and the second end of the frame. The tire engages the outer radial surface of the wheel bearing, such that the tire and outer radial surface of the wheel bearing rotate about the hub together, without slippage of the tire on the wheel bearing. In one example, a guide roller is coupled to the frame. The guide roller is attached under the bumper, such that the contact surface of the incompressible portion of the bumper extends beyond an outer circumference of the guide roller. In an alternative example, no guide roller is required, because a sloped portion of the track and a curved portion of the wheel recenter the trolley in the track without no need of a guide roller. 
     In one example, the bumper is coupled to the frame by at least one pin, the at least one pin engaging a slot formed in a portion of the incompressible portion of the bumper. For example, the at least one pin may be two pins, and the two pins each may extend through respective holes in the frame such that opposite ends of the two pins extend into respective slots formed in portions of the incompressible portion on opposite sides of the frame. The two pins and respective slots limit travel of the bumper in both the first direction and the opposite direction. In one example, portions of the incompressible portion on opposite sides of the frame engage a central portion of the compressible portion of the bumper, retaining the central portion of the compressible portion between the portions of the incompressible portion. Also, the compressible portion may have two legs extending from the central portion of the compressible portion, and the two legs may engage a central portion of the incompressible portion, such that the compressible portion is retainably engaged without any other retention device. This reduces wear by allowing the compressible portion to be compressed and uncompressed repeatedly without causing substantial wear to any portion of the compressible portion of the bumper, for example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The following drawings are illustrative examples and do not further limit any claims that may eventually issue. 
         FIG. 1  illustrates an example of an 8-wheel trolley assembly. 
         FIG. 2  illustrates an exploded view of the example of  FIG. 1 . 
         FIG. 3  illustrates a detail view of a frame. 
         FIG. 4  illustrates a detail view of a first portion of a bumper. 
         FIG. 5  illustrates a detail view of a second portion of a bumper. 
         FIG. 6  illustrates a detail view of a support wheel shaft. 
         FIG. 7  illustrates a detail view of a wheel bearing. 
         FIG. 8  illustrates a detail view of a tire. 
         FIG. 9  illustrates a detail view of a roll pin. 
         FIG. 10  illustrates a detail view of a set screw. 
         FIG. 11  illustrates a detail view of retaining ring. 
         FIG. 12  illustrates a detail view of a guide roller. 
         FIG. 13  illustrates a detail view of a guide roller sleeve. 
         FIG. 14  illustrates a detail view of a guide roller bushing. 
         FIG. 15  illustrates a detail view of a clevis. 
         FIG. 16  illustrates a detail view of a clevis pin. 
         FIG. 17  illustrates a plan view of a track profile. 
         FIG. 18  illustrates a profile view of a short segment of a track. 
         FIG. 19  illustrates a schematic view of an end a 4-wheel trolley engaging channels of a cross-section of a track. 
         FIG. 20  illustrates a perspective view of an example of a 4-wheel trolley. 
         FIG. 21  illustrates a side plan view of another example of a 4-wheel trolley. 
         FIG. 22  illustrates a partial top plan view of the example in  FIG. 21  omitting the clevis and the guide rollers. 
         FIG. 23  illustrates another example of a track profile and a pair of wheels and a support wheel shaft of a trolley joining the two wheels. 
     
    
    
     When the same reference characters are used, these labels refer to similar parts in the examples illustrated in the drawings. 
     DETAILED DESCRIPTION 
     A trolley and track provide substantially reduced chatter and noise compared to known trolleys and tracks during opening and closing of gates. In addition, wear and tear is reduced on components. In one example, a trolley assembly  100  comprises 2 wheels, 4 wheels or 8 wheels. For example, in  FIGS. 1-3 , a trolley assembly  100  has eight wheels  108  mounted in pairs along opposite sides of a frame  1 . As best seen in  FIG. 3 , the frame  1  comprises a rigid member having holes  102 ,  103 ,  104 ,  105 ,  106  bored through the frame  1 . Set screw holes  105  are tapped and threaded for accepting a set screw  10  as seen the in detail view of  FIG. 10 . A first end  101  and a second end  110  of the frame  1  extend beyond a wider portion of the rigid member, and both ends  101 ,  110  provide roll pin holes  103 ,  113  and guide roller screw holes  104 ,  114  for securing bumpers  130  and guide rollers  140  onto the frame  1 . All holes represented in the drawings are through holes unless otherwise indicated. In one example, the guide rollers  140  are disposed in a notch formed by the wider portion of the rigid member and the ends  101 ,  110 . Four of the holes  102  in the frame  1  are for inserting support wheel shafts  6 , each having two opposite ends or axles  64 , attached by a cylindrical body  68  for mounting a pair wheels  108  using a retaining rings  13  that engage grooves  62 , for example. A through hole or blind hole  60  is provided for engaging with a set screw  10 , fixedly securing the body  68  in the frame  1 . The remaining hole  106  is for a clevis pin  5 , which couples a clevis  4  to the frame  1  for attaching the trolley assembly  100  to a gate, for example. 
     Now referring to  FIG. 2 , an exploded view of the example in  FIG. 1 , the frame  1  is illustrated in relation to the remainder of the assembly. In this example, a comparatively compressible, biasing portion  2  of the bumper  130  is retained between each of the ends  101 ,  110  of the frame  1  and bumper blocks  3 . Each of the bumper blocks  3  are retained on the frame  1  by a pair of roll pins  11 , for example, which fit in slots  33  of the bumper blocks  3 , as best illustrated in  FIG. 4 . In  FIG. 4 , a detail view of the biasing portion  2  is shown, which fits into the channel  32  formed by the u-shaped ends of the bumper blocks  3 , illustrated in  FIG. 3 . The u-shaped members  42  of the biasing portion  2  have a dimension B larger than the thickness A of the base portion  34  of the bumper block  3 , such that the members  42  of the biasing portion  2  extend on both sides of the base portion  34  of the bumper block  3 , for example. Thus, each of the biasing portions  2  is retained between a respective one of the ends  101 ,  110  of the frame  1  and a bumper block  3 , while allowing the bumper block  3  to move, whenever the contact surface  35  of the bumper block  3  impacts an object, such as a stop inserted to arrest the trolley assembly  100 . 
     For example, the biasing portion  2  may be made of a comparatively compressible material, such as a foam material or an elastic material. In one example, the material selected for the biasing portion  2  is a neoprene extrusion. In contrast, the bumper block  3  is made of a comparably incompressible material, such as a harder plastic. In one example, the material selected for the bumper block  3  is a nylon or polyamide, a fiber reinforced polyamide or the like. For example, a carbon fiber reinforced polyamide 6/6 provides superb impact resistance, dimensional stability and wear resistance. 
       FIG. 6  illustrates a detail view of a wheel support shaft  6  having a body  68 , which fits into one of the four holes  102  along the length of the frame  1 , as illustrated in  FIG. 3 , for example. A set screw  10 , as illustrated in  FIG. 10 , may be threadingly engaged within one of the four holes  105  in the frame  1 , as illustrated in  FIG. 3 , and a blind bore hole  60  of the wheel support shaft detailed in  FIG. 6 , for example. The two axles extending from the body  68  of the shaft  6  each have a groove  62  for retaining a retaining ring, such as illustrated in  FIG. 10 , for example. The retaining ring  13  engages the groove  62  and retains each of the wheel bearings  7  on their respective axles  64 , for example. A detail view of a wheel bearing  7  is illustrated in  FIG. 7 , showing contact surface  80 , for example. For example, a wheel bearing may be comprised of a ball bearing providing rotation of the wheel with very low friction. This is a commercially available component. 
     An example of a tire  8  is illustrated in  FIG. 8 . The dimensions may be selected to provide a press fit onto a standard wheel bearing  7 , for example, which prevents any slippage when the tire  8  is press fit onto the wheel bearing. The surface  88  engages the contact surface  80  of the wheel bearing  7 , for example. The tire  8  may be made of a nylon or polyamide, for example. In one example, the tire may be made of the same material as the bumper block  3 , for example. 
       FIGS. 12, 13 and 14  illustrate detail views of components of a guide roller assembly  140 , which may utilize a wheel bearing  7  in the assembly of the roller guide as illustrated in  FIG. 2 , for example. A guide roller  14  may be made of a zinc plated steel, for example, and is illustrated in the detail view of  FIG. 12  and the exploded view of  FIG. 2 . A guide roller sleeve  15  is illustrated in detail in  FIG. 13 , fits within the guide roller  14  and may be made of the same material, for example. A guide roller busing  16 , as illustrated in detail in  FIG. 14 , helps to retain a wheel bearing  7  within the guide roller assembly  140 , for example, and may be made of zinc plated steel, also. 
       FIGS. 15 and 16  illustrate a clevis and clevis pin, which may be used to hang a gate from the trolley assembly. The clevis  4  and clevis pin  5  are shown assembled in  FIG. 1  and in an exploded view in  FIG. 2 . Both may be made of a zinc plated steel, for example. 
       FIGS. 17-19  illustrate a track  200  for use with the trolley assembly, for example. In  FIG. 17  a cross-sectional representation shows two contact surfaces  201  as part of an extruded track. The track may be made of a metal, such as steel. In one example, the track is made of an extruded aluminum. In this particular example, there is no significant contact between any steel components and the aluminum extrusion. Instead, the tire  8 , which may be a polymer, such as a polyamide, contacts the contact surfaces  201 .  FIG. 18  illustrates a perspective view of a short length of a track  200 , which may extend for longer distances, depending on the span needed for opening and closing a gate, for example. 
       FIG. 19  illustrates a schematic view of a trolley assembly  101  engaging the track  202 , for example. The curvature of the wheels fits within the curvature of the track in this example. A sloped portion  107  of the track  200  keeps the wheels  108  centered in the trolley channel formed in the track  200 , such that the contact surface of the wheels  108  ride on the contact surface  210  of the track  200 . Alternatively, as illustrated in  FIG. 23 , the contact  210  between the wheel and the channel may be planar, and the curved surface of the wheel may have a curvature greater than that of the curvature of the curved portion of the track. Nevertheless, the sloped portion  107  of the tracks  200 ,  201  will still function to keep the trolley centered in the channels formed in the tracks  200 ,  201 , reducing or eliminating any impacts of the guide rollers  140 , if guide rollers are even present, on the side walls of the track  200 ,  201 . 
     In the example of  FIG. 20 , a four-wheel trolley  111  is shown. Another example of a four-wheel trolley  111  is illustrated in  FIG. 21 . In this example, the wheel bearings  7  are used without tires. All of the other label numbers in  FIG. 21  identify the same components as illustrated in the eight-wheel example of  FIG. 2 . As can be best seen in the top plan view of  FIG. 22 , the trolley  111  comprises pairs of wheel bearings  7  without tires on opposite sides of the frame  1 . Alternatively, the example in  FIG. 20  includes tires  8 ′ that may be similar to the tires  8  illustrated in  FIG. 1  or may have a more planar contact surface, for example. 
     This detailed description provides examples including features and elements of the claims for the purpose of enabling a person having ordinary skill in the art to make and use the inventions recited in the claims. However, these examples are not intended to limit the scope of the claims, directly. Instead, the examples provide features and elements of the claims that, having been disclosed in these descriptions, claims and drawings, may be altered and combined in ways that are known in the art.