Safety Gear Types: EN 81-20 Instantaneous vs Progressive, 0.2–1.0 g Deceleration, EN 81-50 Type Test and Electronic Safety Gear

EN 81-20/50 defines two categories of safety gear based on their force-displacement stopping characteristic: (1) Instantaneous safety gear — stops the car within a very short engagement distance; suitable only for low-speed elevators (≤0.63 m/s); produces high deceleration forces (can exceed 2g) which are acceptable at low speeds but would be injurious at higher speeds; types: roller (wedge roller), dog-tooth, eccentric cam; simple and low-cost; (2) Progressive safety gear — applies the braking force progressively through a friction element (spring-loaded or guided wedge/roller on the guide rail) over a longer stopping distance; deceleration limited to 0.2g–1.0g per EN 81-20 requirements; suitable for all speeds above 0.63 m/s; EN 81-50 requires type testing of the progressive safety gear with the car at rated load and overspeed governor trip speed to verify that deceleration is within the permitted range; types: (a) Wedge with guide springs — the most common type; asymmetric wedges on both sides of the guide rail, spring-loaded to engage the rail face; (b) Roller progressive — large rollers engage the rail with controlled force; (c) Electronic safety gear (e-safety) — electronically controlled engagement; used in PESSRAL systems; allows self-resetting after test. Combined safety gear (dual progressive) is used on counterweights per EN 81-20. For hydraulic elevators, a hydraulic rupture valve (pipe rupture valve) provides equivalent protection against uncontrolled descent.

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