Container Lifting Spreader Cut-Off Coupling Collision Protection
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Solution Overview
Problem
Container-lifting spreaders face damage from collision forces due to the transfer of shock loads to the driving means and pusher, especially in tight spaces, as existing solutions lack effective protection mechanisms for the drive components during telescopic movements.
Innovation Solution
A power transmission system with an irreversible angle gear and a cut-off coupling, such as a friction clutch, is introduced to absorb and release abnormal torsional moments, disconnecting the pusher from the driving means to prevent damage, and eliminating the need for additional braking mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed connection is used between the pusher and driving means, then the beams are held firmly in position, but the drive components are vulnerable to damage from collision forces
Solution Approach 1:
A friction clutch is introduced as an intermediary element between the pusher and the driving means. This clutch allows normal operation while providing protection against collision forces through controlled slippage when abnormal torsional moments occur.
Solution Approach 2:
The friction clutch is pre-configured with specific friction characteristics that allow it to slip at predetermined torque thresholds. This beforehand cushioning protects the drive components from shock loads by dissipating collision energy through frictional slippage before damage can occur.
2Reliability
If an electromechanical brake is added to protect against collision, then the driving means is protected, but the device complexity and weight increase
Solution Approach 1:
The friction clutch performs dual functions: it serves as both the driving connection element and the protection mechanism. The system protects itself through the inherent friction characteristics of the clutch, eliminating the need for separate braking mechanisms and reducing overall system complexity.
Solution Approach 2:
The friction clutch is designed to perform multiple functions: transmitting driving torque during normal operation and providing collision protection through controlled slippage. This multi-functionality eliminates the need for separate protection mechanisms, reducing device complexity and weight.
3Strength
If a friction clutch is used to protect against collision, then the drive components are protected, but the pusher may slip during normal operation
Solution Approach 1:
The friction clutch parameters (friction coefficient, contact pressure, contact area) are carefully selected and adjusted to ensure that the slip torque threshold is higher than the maximum torque required for normal beam extension and retraction operations, yet lower than the collision torque. This parameter optimization prevents slippage during normal use while maintaining protection capability.
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 solution effectively protects the drive components from collision forces, reduces weight, and simplifies the mechanical design by preventing deformation and maintaining the pusher's integrity, while eliminating the need for electromechanical braking in electrically operated spreaders.
Implementation Method 1
a cut-off coupling arranged to release in result of an abnormal torsional moment being externally applied to the output shaft
Data Source
Figure 1~3
AI summary
A container- lifting spreader is disclosed, comprising at least two beams (1, 2) which are movably supported in a housing (3) and provided a drive by which the beams can be driven in telescopic movements for adjusting the length of the spreader, the drive comprising an electric motor (5) and a pusher (7) acting on the beams, the pusher interconnecting the beams for simultaneous telescopic movements in mutually opposite directions in the longitudinal direction of the spreader, and a power transmission (6) operatively coupled between the motor (5) and the pusher (7), the power transmission comprising an input shaft (11) carrying an external gear ring (12) driven by the motor, and an output shaft (14) likewise carrying an external gear ring (13) that operates the pusher, the gear rings (12, 13) in mutual engagement forming an angle gear (11, 12, 13, 14) arranged with an irreversible mesh of teeth such that rotation of the input shaft causes rotation of the output shaft whereas the reverse is prohibited by the irreversible mesh of teeth. A cut-off coupling is arranged in the power transmission, between the angle gear (11, 12, 13, 14) and the pusher, the cut-off coupling arranged to release in result of an abnormal torsional moment being externally applied to the output shaft (14).