What allows a cylinder to extend at full speed and then slow down near the end of the stroke?

The option that allows a cylinder to extend at full speed and then slow down near the end of the stroke is the use of a roller cam that shifts a valve. This mechanism works by controlling the flow of hydraulic fluid to the cylinder. During the initial phase of the movement, the roller cam positions the valve to allow maximum fluid flow, which enables the cylinder to extend rapidly. As the cylinder approaches the end of its stroke, the cam's design shifts the valve position to restrict the flow of hydraulic fluid, causing the cylinder to decelerate smoothly. This gradual reduction in speed helps prevent damage to the cylinder and allows for precise positioning.

Other options may deal with different aspects of hydraulic systems or control, but they do not provide the same level of control over the speed dynamics of cylinder movement. For example, pilot operated valves typically help in routing fluid based on the pressure signals but do not inherently control speed in the same way a roller cam does. Similarly, hydraulic accumulators are used for storing energy or providing pressure support rather than controlling the speed of a cylinder's extension directly. An unloading valve is typically used to relieve pressure rather than control movement speed during the stroke.

In summary, the roller cam's ability to control the valve's position in relation