Engineering360: "How do thermal actuators work?"

Some years ago General Motors had the bright idea (sarc) to use this type of actuator to engage the front differential when their trucks and SUV's were shifted into 4 wheel drive.

This worked fine, until you drove into water, snow or mud, which chilled the actuator to the point where it would disengage the front wheels, leaving you with 2wd only, and severely stuck in the mud or snow.

The heating element wasn't powerful enough to keep the diff engaged while wet.

Just one of many of the General's goofs. LOL