Movable Counterweight on Crane Rotating Bed
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Solution Overview
Problem
Mobile lift cranes with lower capacities face challenges in increasing lifting capacity without increasing total counterweight, and existing systems require additional components and ground preparation for operation, leading to instability issues during atypical conditions.
Innovation Solution
A mobile lift crane design featuring a rotating bed with a movable counterweight unit that adjusts position to balance the combined boom and load moment, eliminating the need for additional counterweights and ground support, using a counterweight support frame and movement device to maintain stability without a fixed mast structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If additional counterweight attachments are added to increase lifting capacity, then the lifting capacity is improved, but the device complexity and the need for additional ground support increase
Solution Approach 1:
The counterweight is made movable along the rotating bed rather than fixed, allowing dynamic repositioning to optimize balance during different operational phases. This dynamic adjustment eliminates the need for additional fixed counterweight attachments and ground support structures.
Solution Approach 2:
The movable counterweight unit serves multiple functions: it provides ballast during transport, enables lifting capacity adjustment, and maintains stability during operation. This multi-functionality replaces what would traditionally require separate dedicated components for each function.
2Stability of the object's composition
If a fixed mast structure is used to support the counterweight, then the counterweight stability is improved, but the ease of operation and adaptability to different job sites deteriorates
Solution Approach 1:
The counterweight support system transitions from a fixed mast structure to a movable carriage system that travels along the rotating bed. This dynamic system maintains stability through controlled movement while enabling easy repositioning and adaptability to different operational requirements.
Solution Approach 2:
The rotating bed acts as an intermediary platform that carries the movable counterweight carriage. This intermediary structure provides a stable base for the dynamic counterweight system, allowing it to maintain stability without requiring a fixed mast structure.
3Power
If the counterweight is positioned far from the center of rotation to maximize lifting capacity, then the lifting capacity is improved, but the stability during transport and operation deteriorates
Solution Approach 1:
The counterweight position is dynamically adjusted based on operational requirements. During lifting operations, the counterweight can be positioned far from the center of rotation to maximize lifting capacity. During transport or when no load is present, the counterweight is repositioned closer to the center to maintain stability and prevent excessive moments.
Data Source
AI summary
A lift crane includes a carbody and movable ground engaging members mounted on the carbody. A rotating bed is rotatably connected to the carbody and includes a counterweight support frame including a rack coupled directly to a lower surface of the rotating bed. A boom is pivotally mounted to the rotating bed. A counterweight unit movement device is configured to move the counterweight unit toward and away from the boom. At least one auxiliary member includes a counterweight pad that is configured to not touch the ground during a pick, move, and set operation. A linear actuator is configured to adjust a distance that the counterweight pad is above the ground.