Will a Defective Safety Switch Allow a Yard Tractor Engine to Turn Over?
Three switches safeguard modern yard tractors against overrunning and operation with no operator. One safeguards braking, one handles cutting blades or other accessories and the third guards against a riderless, runaway tractor, mowing madly as it races across the landscape. The latter switch, called the seat safety switch, harassing the motor — or keeps it from starting — unless the operator is sitting on the tractor’s seat.
How It Works
The chair safety switch appears like a four-pronged plug having a push button at top. Inside, the foundation of the button contains two sets of contacts. One set completes a circuit between two of the blades and the other completes the circuit between the second pair. One pair connects to the motor and the other is seated. When you sit on the seat and also depress that button, then the connection is completed between the battery and the motor, but when you move, then it breaks and grounds itself and the engine stops.
What Can Go Wrong
Safety switches are simple components, but the little wires which ride the foundation of the button may corrode, break or bend. A defective switch cannot complete the circuit which the motor needs to operate. The circuit could be “jumped” using the switch eliminated and the tractor begins and operate — with or having the operator seated. Manufacturers, however, caution strongly against overriding the inexpensive, easily replaced switch.