Patent Application
20160221630
The subject of this invention relates to the bicycle industry. More specifically, the disclosed invention teaches a novel hub mounting skewer that compensates for the presence of the mandatory safety tabs on the frame forks of a bicycle. Advantageously, the present invention may be used on both front and rear hubs, as well as on a wide variety of contemporary human powered vehicles including bicycles, both fixed gear and variable cog types, recumbent cycles, and tandems.
Chain driven bicycles have existed for many years. These human powered vehicles come in many forms, for example the classic sitting upright bicycle, recumbent sitting reclined bicycle, tandems, fixed gear, BMX and so on. Each of these is driven by a cog and chain means. Generally the chain receives power input from a peddle crank that has a rotational motive force exerted upon it from a rider's legs. The force is transferred by the chain to the driven wheel via a geared chain-ring/cog combination, for example, wherein the cog is in turn mechanically linked to a hub. The hub is attached to the drive wheel by means of spokes or solid inserts such as in the so-called disk wheels. The drive wheel may be located at the front or the rear of the human powered vehicle. In this way linear force from a rider's legs is transformed to rotational force applied to the driven wheel and then to the road surface. A second, non-drive wheel is generally present at the end of the vehicle opposite the driven wheel.
From time to time the wheels of a bicycle must be detached from the bicycle frame, for example, to change a flat tire or to replace a worn part. There exist many contemporary methods for attaching a wheel to the bicycle frame. One method uses a solid axle threaded on both ends, generally found in the BMX type bicycle. Once the axle ends have been located correctly in the frame lugs, the nuts are tightened to fix the wheel in place. A second method uses a hollow axle through which a rod, referred to in the art as a skewer, is run. One end of the skewer has a lever and the other end an adjustable nut. Once the wheel is in the correct position in the lugs of the bicycle frame the lever is operated which results in a clamping force to fix the wheel in place. This latter method represents the majority of wheel mounting techniques in use today.
While these methods are functional, they suffer from a common flaw. In both cases the rider must perform multiple steps to remove the wheel from the bicycle frame to perform service. In the first case, a wrench or pair of wrenches must be used to loosen both nuts, then the nuts run out away from the frame lugs prior to removing the wheel. In the case of the lever operated skewer, once the tension on the skewer rod has been released by operating the lever, the nut on the opposite side from the lever must be loosened further, or run out in order to clear the frame lugs to allow removal of the wheel for service. In all cases the nut(s) on the apparatus must be operated sufficiently to clear the safety tabs mandated by regulatory policy. These tabs, so called lawyer tabs, are in place to prevent a wheel from slipping out of the frame lugs if the mounting apparatus has inadvertently become loosened, for example by road vibration or improper installation.
Once the wheel is clear, maintenance can occur. But the same problems exist in reverse upon remounting of the wheel. For the case of the solid axle, the wheel must be inserted into the frame lugs, then each of the nuts run in to fix the wheel in place, then a wrench or pair of wrenches must be applied to both nuts to firmly secure the wheel in place. For the case of the lever operated skewer, the wheel must be located in the frame lugs, then the nut run in to the approximate position required to engage the lever, then the rider must operate the lever to see if the nut is in the correct position. This process must be repeated several times in order to ensure proper capture of the hub in the bicycle frame with the appropriate clamping force. As can be seen, both of these methods require numerous steps and are very inefficient.
What would be desirable is a method for mounting/dismounting a bicycle wheel that eliminates the need for the user to deal with nuts or inefficient lever mechanisms. The apparatus of the present invention provides an improved wheel mounting/dismounting method that accomplishes this as well as eliminating other problems related to the prior art methods discussed above.
The present invention teaches a novel double-acting skewer that provides sufficient safety tab clearance with a single lever motion without the need to manipulate any other component of the mounting apparatus. Once the apparatus of the present invention has been mounted and adjusted to a specific frame, the wheel may be mounted and dismounted using only the clamping lever. More importantly, once adjusted properly, the clamping force is repeatable and the clamping lever returns to the same location consistently.
The apparatus of the present invention is comprised of three main components: a skewer rod, a clamping nut and a double-acting cam-and-lever mechanism. The clamping nut and skewer rod are of the contemporary type, with the significant difference that the skewer rod is threaded on both ends in order to provide a wide range of adjustment to accommodate a similarly wide range in frame lug separation.
The double-acting cam-and-lever mechanism is a sub-assembly further comprised of a cam housing, a cam housing cap, a cam actuator, a double-acting cam and a clamping lever. The double-acting cam is permanently attached to the clamping lever such that when the clamping lever is rotated the double-acting cam follows the same rotational movement. The double-acting cam is located within a sliding cam actuator such that when rotational movement occurs by the double-acting cam [hereinafter dacam] the sliding cam actuator moves laterally in response.
In turn, the sliding cam actuator is permanently attached to a first end of a skewer rod via threads on that first end. As the sliding cam actuator moves laterally in response to the rotation of the dacam, the skewer rod follows. The second end of the skewer rod has a threaded section that is mated to a clamping nut. As the skewer rod moves in response to the sliding cam actuator, a clamping force is either applied or removed depending on the direction of the skewer rod travel. The length of the travel of the skewer rod is such that a gap sufficient to clear the safety tabs on a bicycle frame is created, allowing the wheel to be dropped out without further intervention by the rider.
Of importance is that the apparatus of the present invention has both a very repeatable gap and a very repeatable clamping force, thus once the apparatus has been properly fitted to a specific bicycle frame, it may be removed and replaced repeatedly without any need for adjustment of the various components. Due to the double action of the cam, even if the clamping lever should become accidentally displaced, the wheel will remain mounted. This is due to the fact that upon initial operation of the clamping lever only a portion of the dismounting gap is created. It is the second, or double action of the clamping lever that provides the gap needed. As well as the advantages discussed above, other advantages of the present invention are discussed below in conjunction with the drawings and figures attached.
As described briefly above, the improved fixed gap skewer apparatus of the present invention provides a number of advantages over the prior art, including importantly both safety and efficiency. To best understand the advances made by the present invention it is important to understand the prior art methods used. Note that while the method of using a pair of clamping nuts and a solid axle is still in use, particularly on BMX and fixed gear bicycles, it will not be discussed in detail since those skilled in the art will recognize the rudimentary characteristics of this method.
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The wheel formed by hub 14 and spokes 16 have a skewer assembly comprised of clamping nut 19, skewer rod 20, and lever sub-assembly 21. When in use the lever 23 is in position A. A cam internal to the lever sub-assembly 21 applies a pulling force on the skewer rod 20 such that when in position A the wheel is firmly mounted in the lugs 18A and 18B of the frame forks 12A and 12B. It will be recognized by those of skill in the art that the internal cam of lever sub-assembly 21, while not discussed here in detail, is of the single acting type common in the industry.
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In order for a rider to remove the wheel from the bicycle, for example, to fix a flat tire, the lever 23 must first be moved approximately 180 degrees from position A to position B to release the clamping pressure. Once the clamping pressure has been released, the lever 23 must be turned counter-clockwise in direction C a number of times [while holding the clamping nut 19] to create the gap G needed to allow the wheel to clear the safety tabs 17A and 17B. Depending on the specific bicycle configuration, the rider may be required to turn the lever up to six or more times.
Supposing now that the tire has been repaired and that the wheel is ready to be remounted, the rider places the wheel in the frame lugs 18A and 18B, then turns the lever 23 a number of times clockwise to re-clamp the wheel into the frame. Unfortunately, since the number of turns completed to dismount the wheel is random, and since the cam in the lever sub-assembly 21 is only single acting, it may take several attempts to re-achieve the proper setting for the skewer assembly. Additionally, even if the rider manages to get the number of turns correct on the first try, there is no guarantee that the lever 23 will return to the proper orientation without having to mess about with the clamping nut 19. Returning to the proper orientation is important since it is highly undesirable to have the lever interfere with other bicycle components or with an adjacent bicycle, for example, in a race. In all, the trial-and-error method of remounting a wheel is highly inefficient and leaves a lot to be desired.
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In a preferred embodiment of the present invention the lever 51 is made from aluminum; however, it will be recognized by those of skill in the art that other materials, for example titanium, could be used without departing from the spirit of the invention. Dacam 70 of the current invention is made from hardened steel, for example heat treated B4A2 stock. This harder material is used to ensure that the lever 51 and skewer rod 60 do not wear the surface of the cam or the hexagonal stub 71. Skewer rod 60 is made from stainless steel.
Also inside the cam shell housing 52 is a cam actuator 58. The cam actuator 58 has a cavity 55 through which dacam 70 may be inserted. When properly assembled, as lever 51 is rotated, dacam 70 also rotates inside the cam actuator cavity 55 causing the cam actuator 58 to move in a lateral direction in response to the rotational motion of lever 51. In a preferred embodiment of the present invention the cam actuator 58 is made from steel; however, it will be recognized by those of skill in the art that other materials, for example heat treated aluminum, could be used without departing from the spirit of the invention.
The apparatus of the present invention is completed when release spring 56 is fitted about the collar of cam actuator 58 and cam housing cap 59 is threadably attached to cam shell housing 52. Skewer rod 60 passes through a hole 57 in cam housing cap 59 and threadably attaches to cam actuator 58. As cam actuator 58 moves laterally in response to a rotational movement of lever 51 skewer rod 60 and cam housing shell 52 move laterally with respect to each other ultimately creating a gap sufficient to allow a bicycle wheel to clear the safety tabs on a bicycle frame as explained in detail in conjunction with
The hexagonal section 71 of dacam 70 is used as a mounting pin for the lever [51 in
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Note that while the lever 51 is shown in a vertical orientation, it is not mandatory that the locked closed position be vertical. Pragmatically, the lever 51 could be in any orientation and is shown in the vertical only because, as a matter of practice, most riders prefer this orientation. Note also that the lever 51 is shown in dotted lines in order to more clearly illustrate the internal details of the present invention.
In the locked closed position dacam 70 has been wedged between the inner surface of the cam actuator 58 and the tapered tip of skewer rod 60. In obtaining this position a release spring 56 has been completely decompressed such that only a minimal lateral force exists on the face of the cam actuator 58. The cam actuator 58 is free to slide laterally inside cam housing 52. The cam actuator 58 and the release spring 56 are held in place by cam housing cap 59. To begin the dismounting operation the rider will rotate the lever 51 in direction indicated by the arrow A.
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One advantage of the present invention is that a wheel on a bicycle may be removed from the frame lugs without the need to be concerned about clearing the safety tabs. The apparatus of the present invention is able to do this through the use of a double-acting cam that creates a gap sufficient to clear the safety tabs without the need to manipulate the clamping nut or the release lever.
A second advantage of the present invention is that once the apparatus has been properly installed, the captive nut used to create the clamping pressure no longer needs to be manipulated. This means that each time the wheel is removed and replaced all that need be done is operate the lever of the apparatus. When reinstalling the wheel to the bicycle the lever will repeatedly apply the proper clamping force without the need to readjust the clamping nut.
A third advantage of the present invention is that is has a spring loaded intermediate state that ensures that, even if the lever is inadvertently opened, the wheel will remain located in the lugs of the bicycle frame. A second motion of the lever of the apparatus is used to lock the improved skewer open in order to drop the wheel away from the frame of the bicycle.
A fourth advantage of the present invention is that it may be used for both front and rear mounting skewers. This is so since the double-acting cam mechanism that creates the required gap is contained entirely in the lever housing.
