Lap Bar Locking Mechanism with Ratchet Pawl and Trip Cam
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Solution Overview
Problem
Conventional lap bar assemblies in amusement park rides only lock in the ride or down position, failing to provide support or grab bar functionality in the up position, and often require manual operation, which can be unreliable due to friction lock wear and environmental factors.
Innovation Solution
A locking mechanism using a ratchet wheel with multiple ratchets and pawls, combined with a trip cam and cam follower, allows the lap bar to automatically lock in both the ride-down and released-up positions, enabling it to function as a restraint during rides and a grab bar during loading and unloading, with redundant locking for increased safety and adjustability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a friction lock device is used to lock the lap bar in the down position, then the lap bar can be restrained during the ride, but the locking mechanism becomes unreliable due to wear, grease, dirt, and lubricants that decrease frictional force over time
Solution Approach 1:
The patent replaces the friction-based locking mechanism with a positive mechanical engagement system using ratchet teeth and pawls. This substitution eliminates reliance on frictional force, which degrades over time due to wear and contamination. The ratchet teeth provide deterministic mechanical interlocking that maintains reliable locking throughout the service life of the device.
Solution Approach 2:
The patent incorporates redundant pawls that can engage with ratchet teeth as a backup locking mechanism. This redundancy provides a safety cushion in case the primary locking mechanism fails, ensuring continuous reliable operation without requiring frequent maintenance or adjustment.
2Adaptability or versatility
If the lap bar is designed to lock only in the down position, then restraint function is provided during the ride, but the lap bar cannot function as a stable grab bar during loading and unloading
Solution Approach 1:
The patent designs the lap bar system to perform multiple functions: it locks in the down position for restraint during the ride, and locks in the up position to serve as a stable grab bar during loading and unloading. The ratchet and pawl mechanism enables the lap bar to be locked in either position, providing universal functionality that adapts to different operational phases.
Solution Approach 2:
The locking mechanism is segmented into multiple independent pawls that can engage with different sets of ratchet teeth at different positions. This segmentation allows the system to provide discrete locking at various angles, enabling both the down-position restraint function and the up-position grab bar function without requiring a completely different mechanism for each mode.
3Adaptability or versatility
If a single locking position is provided for the lap bar, then the structure is simple, but the lap bar cannot accommodate passengers of varying sizes effectively
Solution Approach 1:
The patent makes the locking system dynamic by providing multiple adjustable locking positions through the ratchet teeth arrangement. The lap bar can be locked at various angles corresponding to different passenger sizes, transforming a static single-position system into a dynamic multi-position system that adapts to different user requirements.
Solution Approach 2:
Different sections of the ratchet wheel have teeth configured for different functions: some teeth engage with pawls to lock the lap bar in the down position for restraint, while other teeth engage with different pawls to lock the lap bar in the up position for grab bar functionality. This local differentiation of tooth configurations enables multi-position locking tailored to specific operational needs.
4Ease of operation
If the lap bar locks automatically as soon as it is lowered, then restraint is provided immediately, but the operator cannot ensure proper spacing or positioning relative to the passenger
Solution Approach 1:
The operator first positions the lap bar at the desired location and spacing relative to the passenger before the locking action occurs. The ratchet and pawl mechanism is designed to allow free movement during positioning, then automatically locks once the desired position is reached. This preliminary positioning action ensures measurement precision is achieved before automatic locking engages.
Solution Approach 2:
The ratchet teeth act as an intermediary mechanism between the operator's positioning action and the final locked state. The teeth allow the lap bar to move freely during positioning while providing discrete stopping points, enabling the operator to achieve precise positioning before the pawl engages and locks the position automatically.
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 mechanism ensures secure restraint and support for passengers of varying sizes, reduces maintenance needs, and operates reliably in dirty environments without manual intervention, providing improved safety and comfort by locking in multiple positions and automating the locking process.
Implementation Method 1
A locking mechanism using a ratchet wheel with multiple ratchets and pawls
Implementation Method 2
combined with a trip cam and cam follower
Data Source
AI summary
A lap bar assembly with dual lap bar and grab bar functions. The assembly includes a locking mechanism and a lap bar pivotally mounted to the locking mechanism via a support shaft. The locking mechanism includes a ratchet wheel affixed to the support shaft. A pawl is pivotally supported within the locking mechanism on a pawl support axle parallel to and spaced apart from the lap bar support shaft. The locking mechanism includes a trip cam pivotally attached to the lap bar support shaft. The locking mechanism includes a cam follower that selectively engages the pawl. The locking mechanism is configured to automatically first lock in a first position (or ride position) with the pawl engaging teeth of the ratchet wheel and then second lock in a second position (or released position) with the pawl engaging the ratchet wheel on an uplock surface spaced apart the ratchet teeth.