Tolerance for stopping not required for which systems?

• A. Electric motor
• B. Pneumatic
• C. Manual crank
• D. Direct-plunger or roped hydraulic

Answer: (D)

The key idea is how the drive stops. Some drive types rely on braking, deceleration, and the system’s inertia to reach a stop, which means you must specify a stopping tolerance to ensure the move ends in a safe, predictable position. Others use a direct, positive-stop mechanism where the motion is limited by the end of a hydraulic stroke or by a hydraulic lock, so the stop position is defined by the mechanism itself rather than by braking performance.

Direct-plunger or roped hydraulic drives are positive-stop systems: the movement is limited by the length of the hydraulic stroke and by end stops or hydraulic locks, so the stop occurs at a known, fixed position without needing an external stopping tolerance. In contrast, electric motor, pneumatic, or manual crank drives rely more on braking, slowing, and operator or control actions to stop, which introduces variability and thus requires a defined stopping tolerance to ensure safe, repeatable stops.