Patent ID: 6720679
Filing Date: 2004-04-13
Classification: A01B,B60K,B60W,B60Y

Abstract:
An interlock circuit for a working vehicle having a vehicle body, a working implement attached to the vehicle body, a clutch mechanism switchable between an engaged state for transmitting power to the working implement and a disengaged state for breaking power transmission to the working implement, and a shifting device for determining a traveling direction of the vehicle body, the interlock circuit having a check function to check a backward operational run in which the vehicle body travels backward with the clutch mechanism engaged, and a release function to permit a backward operational run by canceling the check function, said interlock circuit comprising:a check function circuit for performing said check function, said check function circuit being Formed of a circuit portion for checking said backward operational run based on a signal indicating a state of said clutch mechanism and a signal indicating a traveling direction of said vehicle body determined by said shifting device; a release function circuit for performing said release function, said release function circuit being formed of a circuit portion having a release switch operable to cancel said check function continuously when said signal indicating a state of said clutch mechanism indicates that said clutch mechanism is engaged, and said signal indicating a traveling direction of said vehicle body indicates forward or neutral; a prohibition circuit unit for prohibiting said release function circuit from canceling said check function; and a clutch switch, wherein disengaging said clutch mechanism turns said clutch switch ON, to allow the vehicle body to travel backward by the shifting device even when said check function circuit performs said check function; and engaging said clutch mechanism turns said clutch switch OFF, to cause the current in the interlock circuit to bypass through said prohibition circuit unit when said release function circuit performs said release function.