Pit Depth: EN 81-20 Buffer Stroke 0.0674v², Safe Space 0.5×0.6×1m Below Car, 1.2-1.5m Typical 1m/s Traction

The pit is the section of the hoistway below the lowest landing floor. EN 81-20 specifies the minimum pit depth based on the rated speed and the type of buffer installed: (1) For energy-accumulation buffers (spring/solid) — minimum pit depth is the buffer compressed height plus the required clearance between the buffer top and the car underside in the fully compressed position, plus the safety space below the car; for typical low-speed lifts this results in a pit depth of approximately 1.0–1.5 m; (2) For energy-dissipation (oil) buffers — required at rated speeds above 1.0 m/s — the oil buffer stroke is longer and the pit depth must accommodate the full buffer stroke (stroke = 0.0674 × v² metres, where v is the rated speed); (3) Minimum safe working space below car when the car rests on fully compressed buffers: at least 0.5 m × 0.6 m × 1.0 m; (4) Additional pit equipment adds to the required depth: car buffers, counterweight buffers, pit ladder, pit lighting, stop switch, socket, and any compensation chain/rope takeup. During building design, inadequate pit depth is one of the most common causes of costly late-stage modifications, as it requires either deepening the pit (excavation) or raising the building entry level. Minimum pit depth for a standard 1 m/s traction lift is approximately 1.2–1.5 m.

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