An energy-absorbing device positioned in the elevator pit beneath the counterweight travel path to decelerate and stop an over-travelling counterweight safely.
Full Definition
The counterweight buffer is the counterpart to the car buffer and is located directly beneath the counterweight travel path in the elevator pit. Its function is to absorb the kinetic energy of the counterweight if it descends beyond its normal lower limit — which occurs when the car is at the top landing and an upward overspeed or brake failure allows further upward car travel, driving the counterweight down. EN 81-20 requires counterweight buffers whenever there is a risk of counterweight pit contact. Buffer type — spring or oil-filled — must match the elevator speed rating. Buffer stroke and compression tests are performed during acceptance testing and at major maintenance intervals. The buffer must be inspected for oil level (oil type), oil leakage, and structural condition at every periodic inspection.
