An example of a machine that uses two limit switches in series to control two cylinders is a(n) ______ machine.

• A. Milling
• B. Drilling
• C. Grinding
• D. Crimping

Answer: (D)

The key idea is how multiple actuators are coordinated in a single machine cycle. When two limit switches are wired in series, the circuit only completes if both switches are activated. That creates an AND condition: both cylinders must reach their end positions before the machine proceeds. This setup is common in crimping operations, where one cylinder might first clamp the workpiece and the second applies the crimping force. Requiring both actions to be completed ensures the cycle only continues when the entire two-step process is finished, providing proper sequencing and safety.

In milling, drilling, or grinding, the typical action is driven by a single main spindle or tool path, not a two-cylinder sequence, so the two-limit-switch-in-series arrangement is less characteristic of those machines.