Crossbow String-Unloading Mechanism for One-Handed Damage-Free Release

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Solution Overview

Problem

Existing crossbow string-unloading mechanisms are either damaging to the arrow or crossbow, or require inconvenient two-handed operation.

Innovation Solution

A string-unloading apparatus comprising a box, trigger assembly, switch, lever, pulling element, oar, torque spring, restraining element, and compression spring, allowing single-handed, safe unloading of the crossbow string.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the trigger is operated to release the string to shoot the arrow at a soft object, then the string can be unloaded, but the arrow is damaged

Engineering Contradiction:

Improvestring unloading capabilityVSAvoidarrow damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the string release function from the normal trigger mechanism by introducing a separate switching element that can independently release the string without activating the full trigger sequence, allowing the string to be unloaded without firing the arrow

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The switching element acts as an intermediary between the user and the trigger mechanism, providing a controlled intermediate state that releases the string while preventing the arrow from being launched, thus avoiding arrow damage

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the trigger is operated to release the string after the arrow is unloaded, then the string can be unloaded, but the crossbow is damaged

Engineering Contradiction:

Improvestring unloading capabilityVSAvoidcrossbow damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent enables preliminary string release through the switching element before the arrow is loaded or before firing, allowing the string to be unloaded in a controlled manner that prevents damage to the crossbow limbs and other components

Inventive Principle:

Principle #10Preliminary action

3Object-affected harmful factors

If one hand operates the trigger and the other hand operates the cocking device to pull the string, then the string can be unloaded gently, but the operation becomes inconvenient

Engineering Contradiction:

Improvecrossbow damageVSAvoidoperation convenience

Core Design Contradiction:

Object-affected harmful factorsVSEase of operation

Solution Approach 1:

The patent merges the string release function into a single-handed operation by integrating the switching element with the trigger assembly, allowing one hand to control both the trigger and the string release mechanism simultaneously

Inventive Principle:

Principle #5Merging (Combining)

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

Enables convenient and safe unloading of the crossbow string without damaging the arrow or crossbow, using a single hand.

Implementation Method 1

The torque spring is pivotally connected to the box. The torque spring includes an end movable between the dent and the second slope.

Methodology Applied

Scientific EffectTorque spring: Torsion Spring

Implementation Method 2

The compression spring is operable for biasing the tab toward the trigger assembly.

Methodology Applied

Scientific EffectCompression spring: Spring

Implementation Method 3

The lever includes an upper end inserted in the cutout, a middle section pivotally connected to the box, and a lower end.

Methodology Applied

Scientific EffectLever: Lever

Data Source

PatentUS12487049B2String-unloading apparatus of a crossbow

Publication Date: 2025.12.02 COMBIS SPORT ENTERPRISE CO LTD

AI summary

A crossbow includes a string, a trigger assembly, a safety and a string-unlocking apparatus. Only one hand is required to use a cocking device to operate the string-unlocking apparatus to move the safety to an unlocking position from a locking position and to pivot the trigger assembly to a releasing position from a hooking position.