Over-travel limit switches or physical hard stops should be set for robot axes to contact two to three degrees beyond the axis software limits.

• A. Not specified
• B. Sometimes
• C. True
• D. False

Answer: (C)

Over-travel limit switches provide a safety buffer beyond the software limits so the controller can stop the axis before it actually reaches the physical hard stops, protecting gears, bearings, and actuators from damage due to inertia, dynamic overshoot, or sensing/command errors. Setting that switch to trigger a couple of degrees beyond the axis software limits gives enough margin for deceleration and any small disturbances, while still keeping the axis within a safe range. If the margin is too small, normal motion or transient effects can cause false trips or collisions; if it’s too large, you unnecessarily shorten usable travel and risk hitting the physical stop more frequently. Two to three degrees beyond is a reasonable, practical compromise that aligns with good safety practice.