US20150285582A1

US20150285582A1 - Crossbow with take-up cables higher than let-off cable

Info

Publication number: US20150285582A1
Application number: US14/246,154
Authority: US
Inventors: Eldwin Chang
Original assignee: Poe Lang Enterprise Co Ltd
Current assignee: Poe Lang Enterprise Co Ltd
Priority date: 2014-04-07
Filing date: 2014-04-07
Publication date: 2015-10-08

Abstract

A crossbow includes a stock, a riser disposed at a front of the stock, a pair of limbs attached to opposite ends of the riser, first and second pulleys respectively mounted on rear tips of the limbs, and a bow string set. The stock. Each of the first and second pulleys includes a primary wheel and a secondary wheel. The bow string set includes a let-off cable, a first take-up cable and a second take-up cable. The let-off cable extends across and over the track of the stock and has opposite ends respectively trained about the primary wheels of the first and second pulleys. In particular, both of the first and second take-up cable extend across the stock and are substantially positioned higher than the let-off cable.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a crossbow, and more particularly to a crossbow with a bow string set having take-up cables higher than a let-off cable thereof.
2. Description of the Related Art
One type of compound bow is illustrated in U.S. Pat. No 3,486,495 (1969). In this bow, rotatable, variable leverage pulley members are equipped on the tips of the bow limbs. A bowstring is wound over the pulley members to provide mechanical advantage, and less force is required to hold the bowstring in a fully drawn position than to hold the bowstring at an intermediate draw position. Similar to the compound bow, a crossbow also employs the pulley members to provide similar functions.
FIG. 4 illustrates a conventional crossbow 900, comprising a stock 91, a riser 92 positioned at a front of the stock 91, two limbs 93, 94 with front ends attached to the riser 92, two eccentric pulleys 95, 96 respectively mounted to rear tips of the limbs 93, 94 and a bow spring set 97. The stock 91 has at its top a track 911 for receiving a projectile (not shown) and at its bottom a trigger 912 for launching the projectile. Each of the eccentric pulleys 95 (or 96) is consisted of a primary wheel 951 (or 961) and a relatively smaller secondary wheel (not shown) underneath the primary wheel 951 (or 961). The bow spring set 97 includes a let-off cable 970 and two substantially Y-shaped take- up cables 971, 972.
Specifically, the let-off cable 970 has opposite end portions respectively trained about the two primary wheels 951, 961 of the eccentric pulleys 95, 96. Each of the take-up cables 971 or 972 has one end trained about one of the secondary wheels, and the other end anchored to the other secondary wheel. The two take-up. cables 971, 972 are positioned at a height substantially lower than the let-off cable 970 and intersect with each other at the stock 91. In order to avoid interrupting the launching of the projectile, a slot 910 is defined in a front of the stock 91 so as to permit the take-up cables 971, 972 to pass therethrough and keep away from a launching path of the bow.
However, this configuration has disadvantages in that the slot 910 would have to be specially formed, thus raising the cost of the bow and lessening the strength of the front of the stock 91. This would further cause a lower collimation degree of the track 910 of the stock 91 by which the launching of the projectile would be adversely affected. In addition, the front of the stock 91 would have to be thick enough for the forming of the slot 910, thus raising the weight of the bow.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a crossbow to solve the aforementioned problems. The crossbow includes a stock, a riser disposed at a front of the stock, a pair of limbs attached to opposite ends of the riser, first and second pulleys respectively mounted on rear tips of the limbs, and a bow string set. The stock has at its top a track for receiving a projectile and at its bottom a trigger for launching the projectile. Each of the first and second pulleys includes a primary wheel and a secondary wheel adjacent to the primary wheel. The bow string set includes a let-off cable, a first take-up cable and a second take-up cable. The let-off cable extends across the track of the stock and is located at a height above the track of the stock. Moreover, the let-off cable has opposite ends respectively trained about the primary wheels of the first and second pulleys. The first take-up cable extends across the track of the stock with one end strung about the secondary wheel of the first pulley and the other end anchored to the second pulley. Similarly, the second take-up cable extends across the track of the stock with one end strung about the secondary wheel of the second pulley and the other end anchored to the first pulley. In particular, the first and second take-up cables are both substantially positioned higher than the let-off cable.
Preferred embodiment of the invention may have the following additional characteristics, either alone or in combination:
The crossbow further comprises a retaining rod positioned in between the first take-up cable and the let-off cable to lift up the first take-up cable to the height above the track of the stock. In one embodiment, the retaining rod has one end secured to the riser and the other end extending in between the first take-up cable and the let-off cable.
Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top side perspective view of a crossbow in accordance with the preferred embodiment of the present invention;

FIG. 2 is a partial enlarged view of the crossbow shown in FIG. 1;

FIG. 3 is a rear side view of the crossbow shown in FIG. 1; and

FIG. 4 is a prior art.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

In the accompanying drawings, a crossbow 100 is illustrated which includes a stock 1, a riser 2 disposed in a front of the stock 1, a pair of limbs 3, 4 connected at their front ends in fixed relation to the riser 2, first and second pulleys 5, 6 respectively mounted on rear tips of the limbs 3, 4, a bow string set 7 connecting the two pulleys 5, 6, and a stirrup 8.
As shown in FIG. 1, the stock 1 has in its top a track 10 for receiving a projectile 11 (see FIG. 3) and at its bottom a trigger 12 for discharging the projectile 11. Once the trigger 12 is squeezed, the projectile 11 would go off along the track 10.
Referring to FIG. 2, it will be best seen that the first pulley 5 includes a primary wheel 51 and a relatively smaller secondary wheel 52 adjacent to the primary wheel 51. Similarly, as shown in FIG. 1, the second pulley 5 includes a primary wheel 61 and a relatively smaller secondary wheel 62 adjacent to the primary wheel 61. The bow string set 7 includes a let-off cable 70, a first take-up cable 71 and a second take-up cable 72. The let-off cable 70 extends across the track 10 of the stock 1 at a height above the track 10 of the stock 1 and has opposite ends respectively trained about the primary wheels 51, 61 of the first and second pulleys 5, 6. The first take-up cable 71 extends across the track 10 of the stock 1 with one end strung about the secondary wheel 52 of the first pulley 5 and the other Y-shaped end anchored to an axis of the second pulley 6. In contrast, the second take-up cable 72 extends across the track 10 of the stock 1 with one end strung about the secondary wheel 62 of the second pulley 6 and the other Y-shaped end anchored to an axis of the first pulley 5. In particular, the first and second take- up cables 71, 72 are both substantially positioned higher than the let-off cable 70, as best seen in FIG. 3.
Preferably, a pair of parallel retaining rods 21, 22 may be employed to lift up the first and second take- up cables 71, 72 to the height above the track 10 of the stock 1, as best seen in FIG. 3. In this embodiment, each of the retaining rods 21 or 22 has one end secured to the riser 2 and the other end extending in between the let-off cable 70 and a combination of the first and second take- up cables 71, 72, as shown in FIG. 1 or 3. This ensures the projectile 11 can be discharged without any interrupt of the first take-up cable 71 or the second take-up cable 72. In this manner, no slots will be needed to be defined in the front of the stock 1 as taught in the prior art. Thus, the crossbow 100 can be produced at relatively lower cost and light weight with higher rigidity and collimation degree of the track 10 of the stock 1 for launching the projectile 11.
It is noted that although the retaining rods 21, 22 are shown in the preferred embodiment to be secured to the riser 2, the retaining rods 21, 22 may be in other embodiments secured to the stock 1 or other portions. It is also noted that, although the first and second pulleys 5, 6 shown in the preferred embodiment are both eccentric pulleys, any type of pulleys may be used as dictated by the convention. For example, one may be idle while the other be an eccentric pulley.
It is to be understood that the disclosed embodiments are illustrative in nature and the invention is not to be limited to any one or more embodiments except as set forth in the following claims.

Claims

1. A crossbow comprising:

a stock having at its top a track for receiving a projectile and at its bottom a trigger for launching the projectile;

a riser disposed at a front of the stock;

a pair of limbs attached to opposite ends of the riser;

first and second pulleys respectively mounted on rear tips of the limbs, each pulley including a primary wheel and a secondary wheel adjacent to the primary wheel;

a bow string set including a let-off cable, a first take-up cable and a second take-up cable; the let-off cable extending across the track of the stock at a height above the track of the stock and having opposite ends respectively trained about the primary wheels of the first and second pulleys; the first take-up cable extending across the track of the stock with one end strung about the secondary wheel of the first pulley and the other end anchored to the second pulley; and the second take-up cable extending across the track of the stock with one end strung about the secondary wheel of the second pulley and the other end anchored to the first pulley; and

at least one retaining rod positioned in between the first take-up cable and the let-off cable to lift up the first take-up cable to the height above the track of the stock, the retaining rod has one end secured to the riser and the other end extending in between the first take-up cable and the let-off cable;

wherein the first and second take-up cables are both substantially positioned higher than the let-off cable.

2. A crossbow as recited in claim 1, wherein at least the first pulley is eccentric.

3. (canceled)

4. (canceled)