Variable Hydraulic Pressure Relief Systems and Methods for a Material Handling Vehicle
AssigneeThe Raymond Corporation
InventorErik C. Tracy
Life of this patent
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Abstract
A method of controlling a hydraulic control system of a material handling vehicle is provided. The method includes detecting an elevated height of a fork assembly, determining if the elevated height is above a first predetermined height threshold, and actuating a first low pressure control valve from a control valve closed position to a control valve open position to provide fluid communication from a supply passage to the first low pressure relief valve when the elevated height is above a first predetermined height threshold.
Claims17
A method of controlling a hydraulic control system of a material handling vehicle, the material handling vehicle including a pump in fluid communication with a supply passage, a reservoir in fluid communication with a return passage, a fork assembly attached to a mast, a high pressure relief valve configured to provide fluid communication from the supply passage to the reservoir when a pressure upstream of the high pressure relief valve exceeds a high pressure threshold, a first low pressure relief valve connected between the supply passage and the return passage, and a first low pressure control valve arranged upstream of the first low pressure relief valve, the method comprising:
- detecting an elevated height of the fork assembly;
- determining if the elevated height is above a first predetermined height threshold;
- and
- actuating the first low pressure control valve from a control valve closed position to a control valve open position to provide fluid communication from the supply passage to the first low pressure relief valve when the elevated height is above a first predetermined height threshold.
A method of controlling a hydraulic control system of a material handling vehicle, the material handling vehicle including a pump in fluid communication with a supply passage, a reservoir in fluid communication with a return passage, a fork assembly attached to a mast, a height sensor configured to detect a height of the fork assembly, and a variable pressure relief valve configured to provide fluid communication from the supply passage to the reservoir when a pressure upstream of the variable pressure relief valve exceeds a variable pressure threshold, the method comprising:
- measuring a height of the fork assembly;
- and
- adjusting the variable pressure threshold of the variable pressure relief valve based on the height of the fork assembly.
A method of controlling a hydraulic control system of a material handling vehicle, the material handling vehicle including a pump in fluid communication with a supply passage, a reservoir in fluid communication with a return passage, a fork assembly attached to a mast, a height sensor configured to detect a height of the fork assembly, a pressure sensor configured to detect a pressure within the supply passage, and a variable pressure relief valve configured to provide fluid communication from the supply passage to the reservoir when a pressure upstream of the variable pressure relief valve exceeds a variable pressure threshold, the method comprising:
- measuring a height of the fork assembly;
- measuring a pressure within the supply passage;
- adjusting the variable pressure threshold of the variable pressure relief valve based on the measured height of the fork assembly and the measured pressure within the supply passage.
Dependencies are inferred from the claim text.