Eccentric Bushing Locking for Industrial Truck Lifting Stands
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Solution Overview
Problem
The existing fastening method for lifting stands in industrial trucks is prone to stress and fatigue due to torque absorption, requires complex and time-consuming fine adjustments, and involves costly manufacturing and storage of paired components, with the use of clamps and screw joints complicating the process.
Innovation Solution
The use of bushings with eccentric holes and specific geometric configurations allows for radial displacement and locking of journals in the stand holder through simple rotary motion, eliminating the need for separate clamps and facilitating easier orientation and docking without vertical positioning, thereby reducing manufacturing costs and simplifying the fastening process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If journals are clamped in place by seat and clamp, then radial locking is achieved, but torque stresses cause fatigue failure in journals and weld joints
Solution Approach 1:
A bushing is introduced as an intermediary component between the journal and the seat. The bushing absorbs the clamping forces and torque stresses, preventing direct stress transmission to the journal and weld joints. The bushing rotates with the journal while being clamped by the seat, acting as a stress-absorbing mediator that maintains radial locking without causing fatigue failure.
Solution Approach 2:
The bushing changes the stress distribution parameters by providing a larger surface area for force distribution. Instead of concentrated clamping forces on the journal, the forces are distributed across the bushing's larger contact area, reducing stress concentration and preventing fatigue failure while maintaining the necessary radial locking.
2Stability of the object's composition
If clamp and screw joint are used for fastening, then radial locking is achieved, but fastening process becomes complicated and time-consuming
Solution Approach 1:
The screw joint and clamp mechanisms are extracted and removed from the fastening system. Instead of using complex threaded fasteners, the invention uses a simple bayonet-style coupling or push-fit mechanism that achieves radial locking through geometric interlocking alone, dramatically simplifying the fastening process while maintaining stability.
Solution Approach 2:
The bushing and seat are designed with self-aligning geometric features that automatically guide the journal into the correct position during insertion. The asymmetric profile of the bushing or seat creates automatic orientation, eliminating the need for separate alignment operations or complex adjustment mechanisms.
3Stability of the object's composition
If journals are made larger than cavity diameter, then axial locking is achieved, but torque absorption increases stress in journals
Solution Approach 1:
The bushing serves as a mediator that handles axial locking forces separately from torque transmission. The bushing's outer diameter provides axial locking through interference fit or friction, while its inner diameter provides clearance for the journal, allowing torque to be transmitted through the journal-bushing interface without excessive stress concentration on the journal itself.
Solution Approach 2:
The fastening function is segmented into two independent mechanisms: axial locking and radial locking. Axial locking is achieved through the bushing's interference fit with the seat, while radial locking is achieved through the geometric coupling mechanism. This segmentation allows each function to be optimized independently without compromising the other.
4Manufacturing precision
If paired seats and clamps are manufactured, then precise fitting is achieved, but manufacturing and storage costs increase
Solution Approach 1:
The bushing design incorporates universal geometric features that allow a single bushing type to fit multiple seat configurations. The standardized bushing profile can be used across different industrial truck models, eliminating the need for paired custom-manufactured seats and clamps for each application, thereby reducing manufacturing complexity and storage requirements.
Solution Approach 2:
The asymmetric profile of the bushing and seat creates a self-identifying connection system where the geometry itself ensures proper orientation and fit. This asymmetric design eliminates the need for complex pairing procedures, as the asymmetric features guide automatic correct assembly, reducing both manufacturing precision requirements and assembly complexity.
Data Source
Figure 1~2
Figure 3~4b
AI summary
The present invention relates to a industrial truck comprising a lifting stand (1) having a first and a second journal (11), in which each journal (11) is provided with a bushing (15) rotatable about the journal (11), a stand holder (7), which forms part of the chassis of the industrial truck and comprises a first and a second seat (21), in which each bushing (15) is rotatably mounted in one of the respective first and second seats (21) such that the stand holder (7) supports the lifting stand (1). The industrial truck is characterized in that the respective bushing (15) and seat (21) have such a mutual geometric configuration that when each bushing (15) assumes a first rotational position in the seat (21), the bushed journals (11) are radially displaceable in the respective seat (21) such that the lifting stand (1) is disposed detachedly in the stand holder (7), and when each bushing (15) assumes a second rotational position in the seat (21), the bushed journals (11) are radially locked in the respective seat (21) such that the lifting stand (1) is fixed in the stand holder (7).