Depends on the persons' position, Tank Driver, Tank Loader, Tank Gunman, Tank Commander. Most are just called Tankmen to sum up all positions
space above and beyond
They dipped it in gas tanks.
Cavalry is now soldiers in tanks and AFV's
Space: Above and Beyond
They are called tanks, unless you refer to a specific tank in which case it is called by its particular name.
They invented military tanks mainly to make advances where the machine gun fire was too heavy for unprotected soldiers to advance on foot.
Soldiers wore leather helmets inside tanks for protection against head injuries caused by bumps and jolts during movement. The helmets helped cushion the impact and reduce the risk of injury.
Tanks were first used to tear away masses of barbed wire to permit foot soldiers to attack, to cross over trenches, and to carry the attack to defenders using machine guns and cannon aboard the tanks.
the Soviet Union
Indian soldiers were also called "Sepoys".
Is the word you're looking for "cavalry"? This is the general term for mounted troops. (In modern armies, it sometimes refers to mechanized divisions... i.e. tanks... rather than soldiers on actual horses.)
An army of soldiers or a troop of soldiers or a platoon of soldiers.