What component prevents the plunger from leaving the cylinder?

The stop ring is a crucial component in hydraulic elevator systems, specifically designed to prevent the plunger from exiting the cylinder. This ring is positioned at the top of the cylinder and serves as a physical barrier that limits the vertical movement of the plunger. When the elevator system is in operation, the plunger is contained within the cylinder, allowing it to move only up and down as intended. The presence of the stop ring ensures that the plunger does not inadvertently disconnect from the system, which could lead to dangerous situations, including free fall or mechanical failure.

Other components mentioned, such as the sealing ring, serve different functions, such as maintaining a seal to prevent hydraulic fluid leaks, and are not designed to physically restrict the movement of the plunger. The pressure plate typically relates to components that manage hydraulic pressure within the system, while the safety lock is usually associated with emergency stop mechanisms in case of system failure. Thus, the stop ring is specifically tailored for the purpose of preventing the plunger from leaving the cylinder.