Lawn and garden tractor interlock circuit

摘要

A simple operator presence override circuit is connected between available terminals on a PTO switch and a brake switch, and to the seat relay of the operator presence system. The override circuit permits continued operation of the engine under certain restricted conditions when the operator leaves the vehicle seat. A blocking diode connects one side of the seat relay to ground via the brake switch and one set of terminals on the PTO switch. With the PTO switch in the off condition and the vehicle braking system activated so the brake switch is closed, the seat relay remains activated to prevent operation of the ignition grounding circuit that otherwise would shut the engine down when the operator leaves his seat. Switching the PTO switch on or deactivating the braking system without an operator on the seat will automatically open the seat relay so that the engine is killed.