| 摘要 |
An agricultural implement includes a header or platform suspended from a main frame by a suspension permitting movement of the header between a lowered working position and a raised transport position. The suspension includes single-acting float cylinders and a single-acting lift cylinder controlled by anelectrohydraulic control system including a programmable microprocessor in whicha signal representative of a minimum acceptable float pressure may be set. The microprocessor contains an electronic switch that couples a warning device lead to ground to effect energization of the warning device in response to the microprocessor receiving an electronic signal representative of a float circuit pressure below the minimum acceptable float pressure. In one embodiment, the microprocessor contains a timing device which is triggered whenever a control switch is connected to energize a "lower" signal lead the timing device being set to time out when sufficient time has elapsed to ensure that the header has reached its working position. The timing device works to suppress the signal representative of the float circuit pressure so that a premature energization of the warning device does not occur when a low float pressure is due to the header being elevated from the ground. In another embodiment, a normally open mechanical switch is connected in series with the electronic switch and is closed only when the header reaches its working position. Replenishing of float pressure to a desirable level may be done either manually or automatically once the low pressure warning device has been energized.
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