Most tanks of this period used a crew of 5. Some had fewer, some had more.
The most common are:
1. Driver
2. Assistant Driver/Bow Gunner/Radio Operator
3. Loader
4. Gunner
5. Commander
A few tanks had dual driving controls up front which allowed either the driver or assistant to drive without changing positions, but this was not the norm. Ususally they would drive awhile and then switch positions.
This was necessary in the days before automatic or synchromesh transmissions, and power assisted steering or brakes. Driving a tank was exhausting work, and required a good deal of physical labor and strength.
When it came time for maintenance (usually every time the tank stopped for more than a few minutes), ALL of the crew pitched in to get the work done.
Tracks had to be inspected for wear and adjusted for proper tension (tightness),individual track blocks or pads had to be checked for wear and replaced by breaking the track apart to remove the defective parts, then re-assembled.
Road wheels and support rollers had to be inspected for wear and replaced, and their hubs greased or replaced.
Engine Fluids (lubricants and coolants) required constant attention and topping off.
Turret hydralics (if present) had to be topped off and maintained as well.
Maintenance was a constant chore, and even after the maintenance was done, there were other tasks for the crew to perform.
Any time the crew stopped for a rest or sleep stop, they had to provide their own local security. They would dismount and place sentries or observers out away from the vehicle to warn of the approach of enemy Infantry or vehicles.
Usually, at least one crew member stayed in the vehicle to man the weapons and to start the vehicle periodically to charge the batteries and keep the coolant and lubricants from getting too cold. They would man the radio, and provide periodic reports about their sector of the perimeter to the unit headquarters. The crewmembers would take turns or shifts of a few hours each at these duties throughout the night or rest period.
In the morning there would be more (preventative) maintenance while breakfast cooked, and then back on the road for another day of movement or combat.
Rinse & repeat.
CptA