Multi-Point Shovel Lifting with PLC Level Control
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Solution Overview
Problem
Current methods for lifting heavy machinery, such as mechanical shovels, are unsafe and inefficient, as they often result in unbalanced loads, risk of jack failure, and lack automated control, leading to potential accidents and increased maintenance time.
Innovation Solution
A system using at least six jacking points, monitored by a Programmable Logic Controller (PLC), with adjustable rear jack stands and level detectors, allows for safe and controlled lifting of the shovel as a whole, maintaining a level plane and compensating for ground deformations, and includes contingency measures for hydraulic or electrical failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple jacking points are used to lift the shovel, then the lifting safety and balance are improved, but the system complexity and setup time increase
Solution Approach 1:
The lifting system is divided into multiple independent jacking points (at least six) distributed across the shovel structure - four under the carbody and two under the counterweight. Each jack operates independently but is coordinated by a PLC to provide balanced lifting, improving safety through load distribution while managing complexity through modular arrangement.
Solution Approach 2:
The PLC-based control system serves multiple functions simultaneously: it coordinates all jacking points, maintains lifting plane parallelism, compensates for ground settling, and provides contingency management for hydraulic or electrical failures. This multi-functionality consolidates what would otherwise require multiple separate systems into a single integrated controller.
2Manufacturing precision
If automated PLC control is used to maintain level lifting plane, then the lifting precision and safety are improved, but the device complexity and cost increase
Solution Approach 1:
Level detectors are installed at multiple positions on the shovel to continuously monitor the lifting plane orientation. The PLC receives this feedback data and automatically adjusts hydraulic pressure at individual jacking points to maintain the lifting plane parallel to the initial plane, achieving high precision without manual intervention.
Solution Approach 2:
The PLC system automatically performs calculations and adjustments for each jacking point based on real-time level detector readings, eliminating the need for operator intervention. The system self-regulates to maintain even pressure distribution and compensate for ground deformations, reducing operational complexity despite increased initial system complexity.
3Ease of operation
If the shovel is lifted as a whole with dipper remaining on ground, then the maintenance accessibility is improved, but the lifting balance and stability become more difficult to maintain
Solution Approach 1:
Different regions of the shovel are equipped with different numbers of jacking points based on their structural characteristics and load requirements. The carbody has four jacking points while the counterweight has two, with each location optimized for its specific structural features. This local customization ensures stable lifting while maintaining the dipper on the ground for maintenance access.
Solution Approach 2:
The counterweight's inherent mass is utilized as a stabilizing element during the lifting operation. By positioning two jacking points under the counterweight, the system leverages the counterweight's mass to balance the lifted shovel, improving overall stability while allowing the dipper to remain grounded for maintenance work.
4Ease of operation
If adjustable rear jack stands are used to prevent interference with counterweight slabs, then the ease of shovel positioning is improved, but the device complexity increases
Solution Approach 1:
The rear jack stands incorporate adjustable height mechanisms that allow the stands to be dynamically configured for different shovel models and counterweight geometries. This adjustability enables the jacks to be positioned optimally without interfering with counterweight slabs, improving ease of positioning while the standardized adjustment mechanism keeps added complexity manageable.
Data Source
AI summary
There is disclosed a lifting apparatus and a method for lifting a shovel including its upper part, its lower part, and its boom while the shovel handle and dipper remain on the ground. The lifting system may comprise six lifting devices arranged in three pairs that are disposed under the shovel on three lines: front, middle and rear (ref. FIG. 10), the rear line being under the shovel counterweight. The lifting system is connected to a power and control unit from which, through the use of a programmable logic controller and level detectors, metered hydraulic power is selectively applied at each lifting point in order to raise the shovel to a desired height while in doing so maintaining it level with a pre-set lifting plane throughout the entire operation.