| 摘要 |
PURPOSE:To generate an alarm tone for an overload, by providing a warning device in an oil passage through which pressure oil for dangerous side operation is discharged with a strip valve when the held pressure of derrick cylinder increases above a prescribed value. CONSTITUTION:When a crane is overloaded, the oil pressure of derrick cylinder 24 moves spool 4 of a stop valve to the left via operation piping 23 of dangerous side to isolate oil chambers 5 and 6 from each other. As a result, oil returned to a tank via chocke 22 is stored in oil chamber 5 to hold oil chambers 5, 8 and 10 under an equal pressure, and poppet 7 moves down to isolate oil chambers 10 and 11 from each other, so that oil returned to the tank via duct 21 will be stopped to enter warning device H via duct 17. Hydraulic warning device H generates a jet flow by nozzle mechanism 13 to discharge the oil, and also sucks the outside air via whistling mechanism 15 by holding the pressure of chamber 14 negative to give an alarm, sending information on the overload. |
