Which statement about fluid couplings and torque converters is correct?

Which statement about fluid couplings and torque converters is correct?

• A. Technician A
• B. Technician B
• C. Both Technician A and Technician B
• D. Neither Technician A nor Technician B

Answer: (A)

A fluid coupling transfers power through circulating oil between a driving impeller and a driven turbine. Because the two sides aren’t physically connected, the oil flow can slip, so the output speed is typically less than the input and there is no inherent torque multiplication in a plain fluid coupling. Power is transmitted, but the torque at the driven shaft is limited and varies with speed, and efficiency comes mainly from reducing mechanical friction rather than multiplying torque. A torque converter builds on the same hydraulic link but adds a stator in the fluid path. The stator redirects the pumped fluid to push back against the impeller in a way that increases the torque delivered to the driven shaft at low speeds, creating torque multiplication. As the system speeds up, the multiplier decreases toward 1:1, and many designs include a lock-up mechanism at higher speeds to mechanically couple input and output and minimize slip for better efficiency. So the correct statement is the one that identifies torque multiplication as a feature of torque converters due to the stator, while a plain fluid coupling does not provide torque multiplication.

A fluid coupling transfers power through circulating oil between a driving impeller and a driven turbine. Because the two sides aren’t physically connected, the oil flow can slip, so the output speed is typically less than the input and there is no inherent torque multiplication in a plain fluid coupling. Power is transmitted, but the torque at the driven shaft is limited and varies with speed, and efficiency comes mainly from reducing mechanical friction rather than multiplying torque.

A torque converter builds on the same hydraulic link but adds a stator in the fluid path. The stator redirects the pumped fluid to push back against the impeller in a way that increases the torque delivered to the driven shaft at low speeds, creating torque multiplication. As the system speeds up, the multiplier decreases toward 1:1, and many designs include a lock-up mechanism at higher speeds to mechanically couple input and output and minimize slip for better efficiency.

So the correct statement is the one that identifies torque multiplication as a feature of torque converters due to the stator, while a plain fluid coupling does not provide torque multiplication.