Tank
Most modern tanks most often have four crew members, or three if an auto-loader is installed. These are the:
Historically, crews have varied from just two members to a dozen. For example, pre-World War II French tanks were noted for having a two-man crew, in which the overworked commander had to load and fire the gun in addition to commanding the tank. First World War tanks were developed with immature technologies; in addition to the crew needed to man the multiple guns and machine guns, up to four crewmen were needed to drive the tank: the driver, acting as the vehicle commander and manning the brakes, drove via orders to his gears-men; a co-driver operated the gearbox and throttle; and two gears-men, one on each track, steered by setting one side or the other to idle, allowing the track on the other side to slew the tank to one side.
Tanks in World War I
The first fifty had been delivered to France on 30 August. They were 'male' or 'female', depending upon whether their armament comprised two 6-pounder cannon and three Hotchkiss machine guns or four Vickers machine guns and one Hotchkiss. It had a crew of eight, four of whom were needed to handle the steering and drive gears. The tanks were capable of, at best, 6  km/h (4  mph), matching the speed of marching infantry with whom they were to be integrated to aid in the destruction of enemy machine guns. In practice, their speed on the broken ground could be as little as 1  mph.