Lift Cylinder Locking Device for Boom Positioning
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Solution Overview
Problem
Long lift cylinders in personnel hoists, used in firefighting and construction, experience flexibility due to large fluid volumes, causing significant movement impairments in boom positioning, and existing locking devices risk damaging the piston rod with excessive force.
Innovation Solution
A locking device with independent first and second locking members, featuring rotationally non-symmetric shapes, allows for precise locking and unlocking of the lift cylinder, applying forces that do not damage the cylinder structure, and includes sealing to protect against impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wedge locking device is used to lock the piston rod, then the boom can be locked in position, but the excessive force damages the piston rod surface and causes leakage
Solution Approach 1:
A locking member with a locking surface is introduced as an intermediary between the piston rod and the cylinder body. This locking member distributes the locking force over a larger area through its specific geometry (locking surface with angle alpha), preventing excessive point loads that would damage the piston rod surface while maintaining effective locking.
2Device complexity
If the locking device is integrated into the basic cylinder structure, then the structure is compact, but the locking forces damage the cylinder components
Solution Approach 1:
The locking function is segmented from the basic cylinder structure. The locking member is designed as a separate component with specific locking surfaces that interface with both the piston rod and cylinder body, allowing the locking function to be isolated and optimized without compromising the main cylinder components.
3Ease of manufacture
If the locking members have rotationally symmetric shapes, then the structure is simple, but precise positioning and locking cannot be achieved
Solution Approach 1:
The locking members are designed with rotationally non-symmetric shapes, where the locking surfaces have specific angular orientations. This asymmetry enables precise positioning and locking at specific angles while maintaining relatively simple manufacturing processes for the asymmetric geometries.
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 locking device securely locks the boom in a desired position without damaging the lift cylinder, ensuring precise positioning and protection against impurities, enhancing safety and reliability by preventing unintentional movements.
Implementation Method 1
the first locking member and the second locking member are locked in a shape-locked manner in relation to each other in at least one pre-determined locking position
Data Source
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Figure 5~6
AI summary
The invention relates to a method for locking an operating position of a boom, to a personnel hoist and a lift cylinder for a boom. The boom (3) may be raised up to an operating position (A) by the lift cylinder (8). The movement between a piston rod (13) of the lift cylinder (8) and the cylinder body (14) may be locked at least in the return direction by means of a locking device (17). The locking device comprises a first locking member (10) moving together with the piston and a second locking member (15) coupled to the cylinder body.In the locking position of the locking device the relative longitudinal movement between the locking members is prevented mechanically, which allows the boom to be locked to its operating position.