The starter is a simple DC motor. When the key is turned, it begins to turn immediately very fast. A gear is mounted on the output shaft and slides on the shaft in a spiral groove. The inertia of the spinning starter motor mskes the gear slide forward and engage the ring gear on the flywheel and, together, away they go. A spring is mounted on the end of the starter gear which throws the gear off the flywheel ring gear when the engine starts so that it doesn't get caught and spin into oblivion when you rev up the engine. Since the Bendix Co. was the primary manufacturer of these sliding gear-spring things we have called it a, "bendix", ever since. The sliding gear needs lube to continue to slide smothely for zillions of starts. After that many, the grease may go south and a dry fit causes the sliding gear to be fixed gear even in the summer sometimes. I winter, whatever lube is left may be too stiff to let the gear slide and we hear the starter motor whirr away without engaging the ring gear. No need to hold it there, Turn the key off and blip it a few times till it engages. If the engine coughs but does not start, the return spring may kick the starter gear off the ring gear and the starter will whirr away but not turn the engine. Once started, everything warms up eventually and no sweat till it freezes again. Remedy: take the starter off and have the output shaft lubed with a cold-weather grease--or, move to Florida.