SAFETY DEVICE FOR AUTOMATIC REFRIGERATOR OPERATION

PURPOSE:To prevent the supply of pressure oil from a main hydraulic pump to an actuator, and to maintain a stationary state by forcibly holding a direction changeover valve at a neutral position when a starting switch is turned off during automatic refrigerator operation. CONSTITUTION:When a key switch 5 is turned off from the state of the operation of an engine 1, whether or not a turbo timer switch 20 commanding automatic refrigerator operation is turned on is discriminated. When the timer switch 20 is turned on, an electromagnetic control valve 23 is changed over to a closed position by a driving signal. A timer starts its operation, and operation that the counted number is decreased by one and the result is compared is repeated, and a driving signal is output to an engine stop device 22 from a controller 21 and the engine 1 is stopped when the count reaches zero. The connection of a pilot hydraulic pump 10 and an operating device 11 is interrupted during automatic refrigerator operation, thus keeping the type of a hydraulic shovel at a time when the key switch 5 is changed over to off as it is.