Interlock circuit for a working vehicle

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;
• and
• a release function circuit for performing said release function, said a 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.