The distance an elevator buffer compresses or deflects when struck by the car or counterweight during an overrun.
Full Definition
Buffer stroke is the designed compression or deflection distance of an elevator buffer—oil buffer or spring buffer—that absorbs the kinetic energy of the car or counterweight during an overrun beyond the terminal landing. EN 81-20 specifies minimum buffer stroke based on rated speed, with oil buffers required above 1 m/s. The stroke must be sufficient to bring the car to rest within defined deceleration limits. During the annual thorough examination, buffer stroke is measured and compared to design values. After a buffer strike, both the buffer and the car frame must be inspected for damage before the lift is returned to service.
