Neutral start and park brake safety interlock circuitry for a tractor

In combination with a lawn and garden tractor including an electrically responsive engine starting means and an ignition means, a transmission shift means movable between neutral-effecting and drive-effecting positions, park brake control means movable between park brake release and park brake engage positions, and a power take-off clutch control means movable between clutch-engage and clutch-disengage positions, a safety interlock circuit, comprising:

• a source of electric energy;
• an ignition switch means connected to the source;
• a starting circuit including a first lead means connected between the ignition switch means and the engine starting means;
• a normally open power take-off clutch condition responsive switch means mounted for actuation to a closed position by the clutch control means only when the latter is moved to its clutch-disengage position;
• a first normally open transmission condition responsive switch means mounted for actuation to a closed position by the transmission shift means only when the latter is moved to its neutral-effecting position;
• said clutch condition responsive switch means and first transmission condition responsive switch means being connected between the ignition switch means and the engine starting means in the first lead means in series with each other and with the ignition switch means and the engine starting means;
• an ignition circuit including a second lead means connected to the ignition switch means and the ignition means;
• a second normally open transmission condition responsive switch means mounted for actuation to a closed position by the transmission shift means only when the latter is moved to it neutral-effecting position;
• a normally open park-brake condition responsive switch means mounted for actuation to a closed position by the park brake control means only when the latter is moved to its park brake disengage position;
• and said second transmission condition responsive switch means and said park brake condition responsive switch means being connected in said second lead means between the ignition switch means and the ignition means in parallel to each other, whereby the tractor cannot be started with the transmission or power take-off clutch engaged or driven with the park brake engaged.