Which sensor would best inform an operator that a hydraulic cylinder has reached its end of stroke?

A contact limit switch is best suited for informing an operator that a hydraulic cylinder has reached its end of stroke. This component is designed to activate when the moving part of the hydraulic system, such as the cylinder rod, reaches a specific position, thereby providing a clear signal indicating that the stroke limit has been achieved.

When the hydraulic cylinder extends or retracts to its maximum point, the contact limit switch is physically pressed or activated, which results in a direct electrical signal to alert the operator. This physical engagement means the switch can precisely indicate the end positions of the cylinder's travel, ensuring timely and safe operation.

In contrast, while a pressure switch can provide information about system pressure, it may not indicate the exact position of the cylinder. A non-contact limit switch uses sensors to detect the position without physical contact, but it may not be as reliable in environments with high vibration or dirt. A tachometer measures the speed of rotation and would not provide positional information on a hydraulic cylinder's stroke. Hence, the contact limit switch is the most effective and reliable choice for this application.