Sight devices such as those used in archery must be adjustable to fit the user precisely to provide maximum accuracy, particularly where the sight is used in tournaments or other competition. Sights are normally adjustable in three dimensions, with the most important adjustment being in elevation. The present invention relates to an improved elevation adjustment mechanism and tension assembly which allows quick and efficient adjustment of the sight holder relative to an archery bow.
Many archers attempt to mount their sight approximately thirty inches from their anchor point. A sight bracket is mounted on the bow and an extension bar is connected with the mounting bracket. The extension bar generally extends horizontally when the bow is in use. An elevation bar is connected with the extension bar and is generally perpendicular relative to the elevation bar so that it extends vertically when the bow is in use. A carriage is arranged on the elevation bar and a sight is connected with the carriage. The carriage is displaced by the user along the elevation bar to precisely position the sight at the optimum position. Displacement of the carriage is usually done incrementally, which can be time consuming where more than fine tuning adjustment is required such as where different target distances are used in a tournament. Moreover, conventional adjustment mechanisms do not provide the user with the ability to adjust and lock the tension of elevation travel between the carriage and the elevation bar.
The Summers et al U.S. patent application Ser. No. 14/034,035 discloses an elevation adjustment mechanism for a sight in which an elongated screw is used to displace a carriage for a sight on an elevation bar connected with a bow. A pivot nut is used to connect the carriage with the screw so that the carriage may be engaged with or released from the screw. A tension system is provided to adjust the tension between the carriage and the elevation bar so that the user may adjust the freedom of movement of the carriage.
While the prior devices operate satisfactorily, they may be compromised by forward and backward bow forces that occur during the bow firing sequence. In addition, prior devices do not provide yardage selectable positions for the sight which can be adjusted and set by the user.
The present invention was developed in order to overcome these and other drawbacks of the prior adjustment devices by providing an elevation adjustment mechanism capable of adjustment of the elevation carriage and sight to desired positions and improved tension adjustment between the carriage and the elevation base.
A sight elevation assembly for a bow includes a variable tension assembly. The variable tension assembly includes a tension lever having a cam surface. A yoke is connected with the elevation assembly and the cam surface engages the yoke. Rotation of the tension lever in opposite directions displaces the yoke to increase and decrease the tension applied to the elevation assembly. The tension lever passes through an adjustment plate which controls the range of rotation of the lever to limit rotation of the lever between low and high tension positions, respectively.
The sight elevation assembly includes a base connected with a bow mount. A rail is slidably connected with the base for linear movement relative thereto. The tension assembly is connected between the rail and the base to vary the tension between the rail and base. A traction wheel is supported by the yoke and engages a portion of the rail so that rotation of the traction wheel displaces the rail relative to the base. The traction wheel has a knurled surface and the rail is formed of a synthetic plastic material which is imprinted by the tension wheel surface when the tension wheel is pressed against a surface of the rail by the tension assembly.
An elevation carriage is connected with the rail and a detent assembly is connected with the base and the elevation carriage for retaining the carriage in at least one linear position relative to the base corresponding to a desired elevation of the sight. The detent assembly includes at least one detent adjustably connected with the base and at least one housing adjustably connected with the carriage. The base includes side walls each of which contain a longitudinal slot in the upper portion thereof. The detents are arranged in the slots for sliding movement along the base. Each detent includes a screw which is operable to fix the detents in the desired position corresponding to an elevation selected by the user.
Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawing, in which:
Referring first to
As shown more particularly in
The tension adjustment assembly includes a tension lever 16 which passes through a central opening 18 in an adjustment plate 20 and into an aligned opening 22 in the lower portion of the elevation base 8. The adjustment plate is connected with the base 8 via a screw (not shown) which passes through a slot 24 in the adjustment plate and engages a threaded opening 26 in the elevation base. The tension lever 16 includes a cam surface 28.
The tension adjustment assembly also includes a yoke 30 arranged in the elevation base 8 beneath the slot 10. The yoke contains a pair of channels 32 in the upper surface for supporting a shaft 34 of an elevation knob 36 which is used to displace the elevation rail 14 relative to the elevation base as will be described below. The shaft 34 includes a raised portion 38 which provided an interference fit with an axial opening 40 in a traction wheel 42. The yoke channels 32 support the portions of the shaft 34 on opposite sides of the traction wheel 42.
Referring now to FIGS. 4 and 7-9, the traction wheel 42 is arranged beneath the lower surface of the elevation rail 14. The elevation rail is formed of a synthetic plastic material such as Delrin® material which has a rigid but also deformable or imprintable. The traction wheel has a knurled surface 44 (best shown in
The tension adjustment assembly increases or decreases the force applied by the traction wheel 42 against the elevation rail 14, thereby varying the tension between the rail and the base 8 in accordance with the user's preference. Rotation of the tension lever 16 in opposite directions rotates the cam surface 28, which abuts against the bottom of the yoke as shown in
Through use, the traction wheel 42 creates an impression in the lower surface of the elevation rail that provides a repeated tracking relationship that remains consistent when turning the elevation knob 36 in opposite directions. After wear from use over an extended period of time, the adjustment plate 20 can be adjusted relative to the elevation base to allow the tension lever to be rotated farther in the clockwise direction to press the traction wheel even further into the lower surface of the rail renewing an impression or footprint in the rail for greater traction and quality of operation.
Referring now to
Also shown in
In addition to the ramps or stops 50 which limit the linear displacement of the rail at the ends of the base slot, an adjustable stop assembly is provided which can be set by the user to stop the elevation rail and carriage at selected locations relative to the elevation base. The stop assembly includes at least one detent 54 and at least one housing 56 which contains a spring biased ball. The housing is connected with one of a plurality of openings 58 in the sides of the elevation carriage by a screw 60 or other suitable fastener. A housing may be provided on both sides of the elevation carriage, if desired. The detent is connected with the side of the elevation base. As shown in
As noted above, each housing 56 contains a ball 66 and a spring 68 which are shown in
The windage carriage 70 includes two recesses (not shown) in the central bottom region of the carriage. The recesses receive two synthetic plastic ball bearings 72. The bearings are preferably formed of Delrin® material. The windage 70 and elevation 52 carriages are configured to mate via dovetails on the elevation carriage. A screw 72 passes through a washer 74 and through aligned openings 76 and 78 in the windage carriage and elevation carriage, respectively. The opening 76 in the windage carriage is threaded whereas the openings in the elevation carriage are not. Thus, rotation of the screw displaces the windage carriage along the screw relative to the elevation carriage.
In order for the user to manually rotate the screw 74, a knob 80 is connected with the free end of the screw opposite the head end thereof. A spring 82 and steel ball 84 are arranged between the knob 80 and the windage carriage. A washer 86 is arranged on the free end of the screw to which the knob is attached. A synthetic plastic ball (not shown) is arranged in a tapped hole in a side surface of the knob and held in place by a set screw 88. Rotation of the knob 80 incrementally displaces the windage carriage along the screw relative to the elevation carriage.
A unique feature of the connection of the windage carriage and the elevation carriage is the use of a contoured or wavy windage gib 90 between the windage carriage and the dovetail portion of the elevation carriage as shown in
While the preferred forms and embodiments of the invention have been illustrated and described, it will be apparent to those of ordinary skill in the art that various changes and modifications may be made without deviating from the inventive concepts set forth above.
This application claims the benefit of U.S. provisional application No. 61/906,149 filed Nov. 19, 2013.
Number | Date | Country | |
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61906149 | Nov 2013 | US |