Single cam crossbow having level nocking point travel

• US 6,267,108 B1
• Filed: 02/11/2000
• Issued: 07/31/2001
• Est. Priority Date: 02/11/2000
• Status: Expired due to Term

• Current Assignee: MCP IP, LLC
• Original Assignee: Mathew A. McPherson
• Inventors: McPherson, Mathew A., Simonds, Gary L.
• Primary Examiner(s): Ricci, John A.
• Application Number:
  US09/502,152
• Time in Patent Office: 536 Days
• Field of Search: 124/25, 124/25.6, 124/900
• US Class Current: 124/25
• CPC Class Codes: F41B 5/105 Cams or pulleys for compound bows
• CPC Class Codes: F41B 5/123 Compound crossbows

Abstract

A crossbow with level nocking point travel comprises an inventive cam assembly having a first groove defining a primary string payout track, a second groove defining a secondary string payout track and a third groove defining a take-up track. The ratio of the length of the take-up track to the length of the primary string payout track is less than about 0.4.

Claims

1. A crossbow comprising:

a mounting portion;

a first limb supported by the mounting portion;

a second limb supported by the mounting portion;

a pulley rotatably mounted upon the first limb for rotation about a first axle, the pulley including a pulley track;

a cam assembly rotatably mounted upon the second limb for rotation about a second axle, the cam assembly having

a primary string payout track,

a secondary string payout track, and

a take-up track; and

wherein the ratio of the length of the take-up track to the length of the primary string payout track is less than about 0.4.

2. The crossbow of claim 1 further comprising:

a first cable having a first end portion terminating in a first end anchored to the cam assembly and a second end portion terminating in a second end anchored to the cam assembly, the first end portion received in the primary string payout track, the second end portion received in the secondary string payout track, a portion of the first cable trained about the pulley and received in the pulley track to form a bow-string section and a return section, and

an anchor cable extending between the first limb and the cam assembly and received in the take-up track.

3. The crossbow of claim 2 wherein the ratio of the length of the take-up track and sum of the lengths of the primary string payout track and the secondary string payout track is less than about 0.3.

4. The crossbow of claim 2 wherein the first and second limbs are flexible.

5. The crossbow of claim 2 wherein the first limb forms a fork with a first prong and a second prong and a gap therebetween, the pulley residing in the gap, and wherein the anchor cable bifurcates adjacent to the fork in the first limb, the bifurcated portion mounted to the first axle in the first limb fork.

6. The crossbow of claim 1 wherein the take-up track is substantially elliptical.

7. The crossbow of claim 6 wherein the elliptical take-up track has a minor axis and a major axis, the length of the minor axis being about one-half the length of the major axis.

8. The crossbow of claim 1 having a stock with a track for receiving a projectile.

9. The crossbow of claim 1 having a trackless stock.

10. The crossbow of claim 1 wherein the first and second limbs are made as a single unit.

11. The crossbow of claim 10 wherein the first and second limbs are supported centrally by the mounting portion.

12. The crossbow of claim 1 wherein the cam assembly further comprises a counteracting weight.

13. The crossbow of claim 1 wherein the pulley further comprises a counteracting weight.

14. In a crossbow having an upper limb and a lower limb, the upper limb having a rotatably mounted pulley with a track and the lower limb having a dual feed-out cam with a primary string payout track and a take-up track, the improvement comprising the ratio of the length of the take-up track to the length of the primary string payout track being less than about 0.4.

15. The crossbow of claim 14 having a track for receiving a projectile therein.

16. The crossbow of claim 14 having a trackless stock.

17. The crossbow of claim 14 wherein the cam further comprises a counteracting weight.

18. The crossbow of claim 14 wherein the pulley further comprises a counteracting weight.