The Freewheeling Unit (Clutch) prevents a reverse power flow from the main transmission to the engines.

• A. Overrun Clutch
• B. Release Valve
• C. Torque Divider
• D. Freewheeling Unit (Clutch)

Answer: (D)

The main idea here is preventing backflow of power from the transmission into the engine by decoupling them when needed. A freewheeling unit acts like a clutch between the engine and the transmission that can disengage the engine from the drivetrain, so the wheels or transmission turning won’t push torque back into the engine. This keeps the engine from being forced to spin by the transmission and lets it idle or coast smoothly. While an overrun clutch also blocks backward torque in some setups, the freewheeling unit is the component specifically described for this behavior—isolating the engine from the drivetrain. Release valves control hydraulic pressure, not the backflow path, and torque dividers simply split torque and do not provide isolation.