Antagonistic Spring Locking Mechanism for Stretcher Shell Retention
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Solution Overview
Problem
Existing shell handling devices require operator intervention to open and close jaws, making them cumbersome and inefficient, especially when shells need to be securely blocked on a stretcher during recoil or firing phases, and the jaws must remain open during shell extraction.
Innovation Solution
A shell blocking device with a cam and pivoting lever mechanism, actuated by external forces, uses antagonistic springs to maintain jaws in an open position until the shell is completely extracted, eliminating the need for operator intervention and ensuring secure shell retention on a stretcher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the device uses a single spring to return the lever to the raised position, then the structure is simpler, but the lever cannot be delayed sufficiently during shell extraction
Solution Approach 1:
The single spring is segmented into two distinct springs (first spring and second spring) with different stiffness characteristics. The first spring provides the primary return force, while the second spring delays the lever return during extraction. This segmentation allows independent optimization of each spring's properties to achieve both structural simplicity and precise timing control.
Solution Approach 2:
The system changes the stiffness parameter of the spring by using two springs with different stiffness values. The second spring is specifically designed to be stiffer than the first, creating a progressive resistance that delays lever return. This parameter variation enables the system to adapt its mechanical response during different phases of operation.
2Speed
If the lever returns to the raised position immediately after shell placement, then the locking action is faster, but the jaw cannot maintain the open position during extraction
Solution Approach 1:
The system transitions from a static spring configuration to a dynamic two-spring arrangement that adapts its mechanical behavior during operation. During shell extraction, the second spring activates to delay lever return, maintaining the jaw in the open position. After extraction completes, the first spring dominates to quickly return the lever to the raised position. This dynamic adaptation ensures both reliability during extraction and speed during reloading.
3Device complexity
If the device requires operator intervention to activate the release lever, then the locking mechanism is simpler, but the operation becomes cumbersome and inefficient
Solution Approach 1:
The system implements self-service by automatically detecting the shell extraction phase and autonomously delaying the lever return through the second spring. The mechanism serves itself by using the extraction motion to compress the second spring, which then controls the timing of lever return without operator intervention. This eliminates cumbersome manual operation while maintaining a relatively simple locking mechanism structure.
4Reliability
If the jaws close immediately upon shell placement, then the locking is more secure, but the jaws cannot remain open during extraction phase
Solution Approach 1:
The system employs periodic action through the sequential engagement of two springs at different operational phases. The first spring dominates during normal operation to ensure secure locking, while the second spring periodically activates during extraction to delay lever return and maintain jaw opening. This periodic switching between spring dominance enables the jaw to adapt its position according to the operational phase, providing both security and extractability.
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 automatic and secure shell handling by maintaining jaws in an open position during extraction, preventing premature closure and ensuring reliable shell retention on a stretcher without operator action, enhancing operational efficiency and safety.
Implementation Method 1
the first spring having the effect of returning the lever to the raised position so as to bring the cam lug into contact with the jaw
Implementation Method 2
the second spring being intended to be actuated by the push of the member and having the effect of counteracting the action of the first spring, thus delaying the upward movement of the lever
Implementation Method 3
the locking device includes a push rod capable of transmitting the pushing movement of the external member onto the second spring
Implementation Method 4
the second spring being a compression spring interposed between the shoulder and the lever
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a device (3) for locking a shell and to a stretcher (2) comprising said device. The device comprises a jaw (5) pivoting about an axis (6) for clamping the shell, a lower end (5b) of the jaw receives the shell (100) to allow it to close and comprises a notch (7) intended to interfere with a catch (11) of a cam (9) for retaining the jaw in the closed position. The cam is rigidly connected to a pivoting lever (10). The pivoting of the lever allows the catch to be moved clear from the path of the notch (7) to allow the jaw to open. The lever (10) is intended to be pivotally activated through the force of an external component. The device comprises a first spring (13) and a second spring (14) each acting on the lever in an opposing manner, the second spring being stiffer than the first spring. The effect of the first spring is to lift the lever. The second spring counters the action of the first spring in order to delay the lifting of the lever and the catch when removing the component.