Importance

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Abstract

An apparatus for controlling the fluid flow delivered to work elements of a work vehicle. In the operation of hydraulic work vehicles, when quick or multiple implement movement is required, the fluid pumps often are requested to surpass their capability in providing fluid flow to the work elements. A flow-limiting situation then occurs wherein some of the work elements are not receiving the requested flow and therefore cannot perform their requested functions. To solve this problem, the total available flow and the total requested flow from the pumps are monitored. If the total requested flow is not great enough to cause a flow-limiting situation, the operators demands are communicated to control valves which control fluid flow to the respective work elements. However, if the total requested flow is greater than the total available flow, the operators demand signals are 'scaled down' in order to prevent a flow-limiting situation. The signals are communicated to the control valves in proportion to the operator demand. Therefore, the work elements move precisely as the operator demands even under high load conditions. This apparatus proves particularly useful on machines such as hydraulic excavators, where multiple work elements are used simultaneously, and precise controllability is desired.

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First Claim