Excavator Jib Assembly Lever Arm Force Redirection
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Solution Overview
Problem
Existing jib assemblies for excavators and material handlers face issues with stress concentration and bending fatigue due to direct hydraulic cylinder attachment, leading to reduced lifting capacity and inefficient energy use, and geometric limitations that result in unnecessary lifting moments at high angles.
Innovation Solution
A jib assembly featuring a linear hydraulic actuator, a lever arm, and a draw member that redirects lifting forces, reducing bending moments and allowing for more efficient hydraulic cylinder sizing by distributing force along the jib, particularly effective at high angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If hydraulic cylinders are directly attached to the support and jib, then the lifting function is achieved, but stress concentration and bending fatigue occur at the jib base
Solution Approach 1:
A lever arm is introduced as an intermediary component between the hydraulic cylinder and the jib. The lever arm transfers the lifting force from the hydraulic cylinder to the jib at a location that avoids direct attachment at the jib base, thereby reducing stress concentration and bending fatigue at the critical joint while maintaining the lifting function.
2Strength
If the jib structure is made heavier to withstand bending moments, then structural strength is improved, but lifting capacity and energy economy are reduced
Solution Approach 1:
The lever arm acts as a force redistribution intermediary that transfers lifting forces away from the jib base to other structural points. This allows the jib structure to be lighter while maintaining adequate strength, as the critical base area is no longer subjected to concentrated bending moments, thereby preserving lifting capacity and energy economy.
3Device complexity
If the hydraulic cylinder is attached directly to the jib, then the structure is simplified, but the lifting moment cannot be directed to optimal locations
Solution Approach 1:
The lever arm serves as a directional intermediary that enables controlled transfer of lifting forces to specific locations on the jib. By adjusting the lever arm's geometry and attachment points, the lifting moment can be directed to optimal locations that match the structural load-bearing capacity, improving lifting moment control without significantly increasing overall structural complexity.
4Adaptability or versatility
If the piston travel of the hydraulic cylinder is increased to achieve required lifting angles, then the lifting range is improved, but the accumulator volume and cost increase
Solution Approach 1:
The lever arm acts as a mechanical amplifier that converts small piston movements into large jib angular displacements. This mechanical advantage allows the hydraulic cylinder to achieve the required lifting angle range with a shorter piston stroke, thereby reducing the accumulator volume needed and lowering system cost while maintaining adaptability.
5Ease of operation
If extra lifting moment is generated at high angles, then the jib can be raised to vertical position, but pressing force is required to lower the jib when unloaded
Solution Approach 1:
The lever arm redistributes the lifting moment so that it is applied at locations and angles that better match the gravitational load distribution. This reduces unnecessary lifting moments at high angles, allowing the jib to be lowered more easily when unloaded and improving energy efficiency by eliminating the need for continuous pressing force.
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
This configuration significantly reduces lifting moments at vertical positions, minimizes hydraulic cylinder length changes with angular movement, and distributes stress along the jib, enhancing lifting capacity and energy efficiency while reducing structural fatigue.
Implementation Method 1
a linear hydraulic actuator (13) for regulating pivotal movement of the jib (12)
Implementation Method 2
a draw member (15) attached to the lever arm (14) and to the jib (12)... a part of the lifting moment is transmitted by the draw member (15) to a further point of the jib (12)
Implementation Method 3
a lever arm (14) attached to the jib (12)... the lever arm (14) is arranged to extend in the direction above the jib (12)
Data Source
AI summary
A jib assembly includes a support; a jib attached pivotally to the support for pivotal movement of the jib in relation to the support about a horizontal axis; a first linear hydraulic actuator attached to the support for regulating pivotal movement of the jib and for maintaining the jib in a specific position relative to the support; a lever arm attached unrotatably to the jib; and a draw member attached to the lever arm and to the jib; wherein the first linear hydraulic actuator is attached to the lever arm, and the lever arm is arranged to extend in the direction above the jib.