PG-03A Momentary Normal Close (NC) Seat Switch: Safety Application Case for Lawn Mowers

Case Background​

GreenField Turf Equipment, a leading manufacturer of commercial lawn mowers, faced recurring safety incidents in 2024 involving unintended mower blade activation when operators temporarily left the seat (e.g., to clear debris). These incidents resulted in 3 reported minor injuries and 5 equipment damage cases, prompting the company to upgrade its safety interlock system. The key requirement was a reliable seat switch that could immediately cut off blade power when the operator vacated the seat, while ensuring quick resumption of operation once the operator re-seated.

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Product Selection Rationale​

After evaluating 4 competing seat switch models, GreenField selected the PG-03A Momentary Normal Close (NC) Seat Switch for the following critical advantages:​

Momentary NC Design: The switch maintains a closed circuit (power-on state) only when the operator’s weight is applied to the seat. The moment pressure is released (operator stands up), it instantly reverts to an open circuit, cutting off blade power—eliminating delays that caused past incidents.​

Mower-Specific Durability: With a reinforced thermoplastic housing, the PG-03A withstands harsh outdoor conditions (rain, grass clippings, vibration) common in lawn mower operations, exceeding the 2,000-hour lifespan requirement.​

Easy Integration: The switch’s standard 3/4-inch mounting bolt pattern and 18AWG lead wires matched GreenField’s existing mower chassis design, reducing retrofitting time by 40% compared to non-compatible models.

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Implementation & Results​

GreenField retrofitted 200 commercial ride-on mowers with the PG-03A switch between July and September 2024, followed by a 3-month field test:​

Safety Performance: Zero safety incidents related to unintended blade activation were reported during the test period—a 100% reduction from the previous 3-month average of 2 incidents.​

Operator Feedback: 92% of operators surveyed noted “seamless operation,” as the switch re-engaged power instantly when re-seating, avoiding workflow disruptions.​

Reliability Metrics: Only 1 switch required replacement (due to accidental impact, not component failure), achieving a 99.5% reliability rate—surpassing the target of 98%.

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Conclusion​

The PG-03A Momentary NC Seat Switch proved to be a cost-effective safety solution for GreenField’s lawn mowers. Its momentary NC functionality directly addressed the root cause of past incidents, while its durability and compatibility ensured minimal operational disruption. GreenField has since expanded the use of the PG-03A to all new mower models in 2025, positioning it as a core component of their safety compliance strategy.