Crossbow Bolt Retention Plunger Linear Force Distribution

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Solution Overview

Problem

Existing bolt retention systems in crossbows, such as roller and bristle retainers, provide inconsistent or unreliable retention of bolts, leading to potential loss and trajectory issues due to point contact, rolling, or wear over time.

Innovation Solution

A bolt retention plunger system that exerts an evenly distributed and centered force on the bolt via a planar surface, utilizing tunable fasteners and biasing elements to maintain consistent engagement and retention, ensuring the bolt is securely held against the rail.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If roller retainers are used to retain the bolt, then the bolt can be held against the rail, but the roller can roll and allow the bolt to slide along the rail and fall out of the crossbow

Engineering Contradiction:

Improvebolt retention reliabilityVSAvoidretainer position stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

Instead of using a roller that rotates to retain the bolt, the patent uses a plunger that moves linearly in a fixed orientation. The plunger is biased by a spring to maintain constant contact with the bolt, preventing it from rolling away while still allowing reliable retention. This inverts the traditional rolling mechanism into a linear pressing mechanism that eliminates the rolling problem.

Inventive Principle:

Principle #13The other way round (Inversion)

2Reliability

If bristle retainers are used to retain the bolt, then the bolt can be retained against the rail, but the bristles might part or separate to engage the bolt inconsistently, affecting its travel and trajectory

Engineering Contradiction:

Improvebolt retention reliabilityVSAvoidengagement consistency

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent uses a solid plunger with a planar surface that provides uniform, consistent contact with the bolt. This homogeneous contact surface eliminates the variability inherent in bristle retainers where individual bristles may part or separate. The planar surface ensures that the force is applied consistently across the bolt's length, maintaining reliable engagement and consistent trajectory.

Inventive Principle:

Principle #33Homogeneity

3Reliability

If bristle retainers are used to retain the bolt, then the bolt can be retained against the rail, but the bristles can wear out over time, affecting their consistent engagement with the bolt

Engineering Contradiction:

Improvebolt retention reliabilityVSAvoidretainer service life

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The plunger is designed as a simple, robust component with a planar surface that can be easily manufactured and replaced if needed. While the individual plunger may have a service life, the simplicity of the design allows for easy replacement, and the wear is distributed across a large surface area rather than concentrated on individual bristles, effectively extending the operational duration of the retention system.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Manufacturing precision

If a planar surface is used to engage the bolt, then an evenly distributed and centered force can be exerted on the bolt, but the plunger must be precisely positioned to maintain the line of tangency

Engineering Contradiction:

Improveforce distribution uniformityVSAvoidplunger positioning complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The plunger is equipped with a spring biasing element that automatically maintains contact with the bolt and exerts the necessary force. The spring self-adjusts to maintain the plunger in the correct position, eliminating the need for complex external positioning mechanisms. The planar surface of the plunger naturally aligns with the bolt, and the spring ensures continuous contact, providing self-regulating force distribution.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The bolt retention plunger system provides consistent and centered force on the bolt, ensuring reliable retention and stable trajectory, reducing the risk of loss and improving the crossbow's operational safety and efficiency.

Implementation Method 1

a second biasing element disposed between a second tunable fastener and the bolt retention plunger

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS20260002754A1Crossbow bolt retention plunger

Publication Date: 2026.01.01 KILLER INSTINCT INC

AI summary

A crossbow can include a bolt retention plunger configured to retain a bolt against a rail of a crossbow. The bolt retention plunger can be movable between a retention mode and a neutral mode and can be operable in the retention mode to engage a bolt to consistently and evenly hold it adjacent the rail. The bolt retention plunger can define a planar surface facing the rail. The planar surface can contact the bolt along a linear line of tangency, rather than a point, extending parallel to a longitudinal axis of the bolt. The crossbow can include a safety extending in the receiver and an anti-dry fire element movably disposed in the receiver. The bolt retention plunger can be separately operable from and distal from the anti-dry fire element and the safety.