A solid elastomeric energy-accumulation device installed in the pit to arrest a descending car or counterweight.
Full Definition
An elevator rubber buffer is a pit-mounted energy-accumulation device fabricated from moulded natural or synthetic rubber, designed to provide a cushioned final stop for the elevator car or counterweight in the event of over-travel beyond the lowest terminal landing. Unlike oil hydraulic (energy-dissipation) buffers, rubber buffers store kinetic energy elastically and release it after impact, making them suitable only for rated speeds not exceeding 1.0 m/s under EN 81-20 clause 5.8.2.2. The buffer must be capable of absorbing the impact energy of the fully loaded car or the counterweight travelling at 115 % of rated speed from the lowest terminal position. Rubber buffers are characterised by a defined compression stroke and a load–deflection characteristic verified by type testing. EN 81-20 requires that, during buffer engagement, the deceleration does not exceed 1 g_n for more than 0.04 s. Pit buffer heights must comply with the minimum buffer stroke requirements so that the free buffer height is not less than 150 mm after full compression. Periodic inspection checks for hardening, cracking, base plate corrosion, and correct fixing; hardened or cracked buffers must be replaced immediately as their energy-absorption capacity is compromised.
