Forklift Hydraulic System Simultaneous Cylinder Actuation
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Solution Overview
Problem
Industrial trucks with lifting masts experience prolonged load lowering times, leading to reduced handling capacity and unnecessary clearance height restrictions due to the sequential retraction of mast lift stages and free lift stages.
Innovation Solution
A hydraulic system with simultaneous actuation of mast lift and free lift cylinders, utilizing a third hydraulic return line and a controller to manage a third lowering valve, allowing for synchronized retraction of both stages and restoring the original lifting sequence, thus reducing lowering time and maintaining optimal clearance height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If sequential lowering of mast lift stages and free lift stage is used, then the lowering sequence is controlled, but the lowering time is prolonged
Solution Approach 1:
The patent merges the previously separate lowering operations of mast lift stages and free lift stage into a single simultaneous operation. By enabling both stages to lower at the same time through coordinated hydraulic control, the total lowering time is significantly reduced while maintaining controlled sequencing through the valve system.
Solution Approach 2:
The system dynamically adjusts the lowering process by allowing transition between sequential and simultaneous lowering modes. The control system can adapt the lowering sequence based on operational requirements, making the system flexible rather than fixed in its operation mode.
2Length of moving object
If mast lift stages are extended to increase lifting capacity, then the lifting height is increased, but the clearance height of the truck is reduced
Solution Approach 1:
The lifting system is segmented into multiple independent stages (mast lift stages and free lift stage), each capable of independent extension and retraction. This segmentation allows the free lift stage to be retracted separately to restore clearance height while maintaining the extended mast lift stages for continued lifting capacity.
Solution Approach 2:
The system dynamically adjusts the configuration of lifting stages based on operational needs. When clearance height is required, the free lift stage can be retracted independently while mast lift stages remain extended, providing dynamic adaptation between lifting capacity and clearance requirements.
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 solution significantly reduces the load lowering time, enhances handling capacity, and prevents unnecessary clearance height restrictions by synchronizing the retraction of mast lift and free lift stages, ensuring the load handling device can be lowered efficiently without protruding the mast beyond the truck's height.
Implementation Method 1
a hydraulic system for supplying the at least one mast lifting cylinder and the at least one free lifting cylinder with hydraulic fluid
Implementation Method 2
which incorporates a lowering valve... each stage has hydraulic cylinders with different cross-sections. If several mast lift stages are extended, the stage with the smallest total effective hydraulic cross-section retracts first during the lowering process
Data Source
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AI summary
A forklift truck (2) with a lifting mast (4) having at least one mast lifting stage (41, 42) driven by a mast lifting cylinder (12) and a free lifting stage driven by a free lifting cylinder (8), by which a load handling device (6) can be moved along the lifting mast (4). The forklift truck (2) includes a hydraulic system (10) for supplying the mast lifting cylinder (12) and the free lifting cylinder (8) with hydraulic fluid (14), which is configured for simultaneously actuating the mast lifting cylinder (12) and the free lifting cylinder (8). The hydraulic system (10) comprises a first hydraulic return line (181) and a second hydraulic return line (182), which are fluidically coupled to each other via a third connecting line (48) in which a third lowering valve (50) is integrated.