Which statement about torque converter stall characteristics is correct?

Which statement about torque converter stall characteristics is correct?

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

Answer: (D)

Torque converter stall characteristics describe how the torque being transmitted from the engine to the transmission changes as the turbine (output) speed rises from zero. At stall the turbine is held, slip is at its maximum, and the torque multiplication from the engine to the transmission is at or near its peak. As turbine speed increases, slip decreases, the torque multiplication falls toward a 1:1 relationship, and once the converter lock-up engages, slip is eliminated to improve efficiency at higher speeds. This behavior is affected by fluid properties, clearances between the pump and turbine, stator design, and whether a lock-up clutch is present. Because stall behavior involves maximum torque multiplication at near-zero turbine speed and a progressive reduction in multiplication as turbine speed increases, any statement that claims constant torque multiplication, zero torque at stall, or that stall torque increases with turbine speed would be inaccurate. In this context, saying that neither technician’s description correctly captures how stall characteristics work aligns with the correct understanding.

Torque converter stall characteristics describe how the torque being transmitted from the engine to the transmission changes as the turbine (output) speed rises from zero. At stall the turbine is held, slip is at its maximum, and the torque multiplication from the engine to the transmission is at or near its peak. As turbine speed increases, slip decreases, the torque multiplication falls toward a 1:1 relationship, and once the converter lock-up engages, slip is eliminated to improve efficiency at higher speeds. This behavior is affected by fluid properties, clearances between the pump and turbine, stator design, and whether a lock-up clutch is present.

Because stall behavior involves maximum torque multiplication at near-zero turbine speed and a progressive reduction in multiplication as turbine speed increases, any statement that claims constant torque multiplication, zero torque at stall, or that stall torque increases with turbine speed would be inaccurate. In this context, saying that neither technician’s description correctly captures how stall characteristics work aligns with the correct understanding.