What occurs when a fluid coupling stalls under load?

When a fluid coupling stalls under load, the correct outcome is that both the runner/turbine and the impeller stop. A fluid coupling operates by transferring torque between the engine and the drive without any physical connection, utilizing the flow of fluid within the coupling to transmit power.

When stalling occurs, it means that the driven side (the load) is unable to continue moving, while the driving side (the power source) is still attempting to turn. This mismatch leads to a situation where the fluid’s ability to flow and transfer energy is compromised, causing both components to come to a halt. It is important to note that the stalling condition typically results in excessive heat buildup due to viscous drag and potential fluid slippage, but the immediate mechanical outcome is that both components stop.

This understanding highlights the pivotal role of fluid dynamics in the performance of couplings, as their effectiveness is largely dictated by the interaction of flow and resistance across the components involved.