| 摘要 |
<p>A method of lowering a loader arm assembly (16) of a wheeled loader which has a hydraulic system, including a hydraulic ram means (20) with first (25) and second (26) chambers, the hydraulic system further including a selection valve means (40) connected to each of the first and second chambers (25, 26) of the hydraulic ram means (20), a check valve (39) connected between the first chamber (25) and the selection valve means (40) and a control valve (33) which is connected between the second chamber (26) and a low pressure region (35), the control valve (33) being moveable between a first position in which passage of hydraulic fluid therethrough to the low pressure region (35) is permitted, and a second position in which the flow of hydraulic fluid to the low pressure region (35) is prevented, the method including operating the selection valve means (40) to feed fluid under pressure to the second chamber (26) of the hydraulic ram means (20) and to receive fluid at a lower pressure from said first chamber (25) of the hydraulic ram means (20) to lower the loader arm assembly (16), characterised in that the method includes sensing operation of the selection valve means (40) to lower the loader arm assembly (16), and moving the control valve (33) to the second position in response to prevent the passage of hydraulic fluid to the low pressure region (35). <IMAGE></p> |
