What must be installed at the top of the hoistway on a hand powered counterbalanced manlift?

In the context of hand-powered counterbalanced manlifts, the installation of a spring buffer at the top of the hoistway serves a crucial safety function. Spring buffers are designed to absorb kinetic energy and prevent damage to the manlift and its occupants during a potential over-travel scenario. If the lift ascends too high, the spring buffer engages, dampening the impact and allowing for a safer operation.

The use of spring buffers is particularly important in elevating devices where manual operation can lead to variable speeds and motions, increasing the risk of uncontrolled stops. By incorporating spring buffers, the system is better equipped to handle abrupt movements and enhance overall safety for users.

Other options such as emergency stop buttons and safety cages pertain to different aspects of lift operation and safety protocols, but they do not specifically address the function of cushioning or impact absorption at the top of the hoistway. A weight limits sign, while necessary for ensuring safe operation in terms of load, does not provide the necessary physical safety feature that spring buffers do. Thus, for improving safety and operational integrity at the top of a manlift hoistway, a spring buffer is essential.