Tank
With World War II the multi-turreted tanks proved impracticable, and as the single turret on a low hull design became standard, crews became standardized around a crew of four or five. In those tanks with a fifth crew member, usually three were located in the turret (as described above) while the fifth was most often seated in the hull next to the driver, and operated the hull machine gun in addition to acting as a co-driver or radio operator. Well-designed crew stations, giving proper considerations to comfort and ergonomics, are an important factor in the combat effectiveness of a tank, as it limits fatigue and speeds up individual actions.
Tanks in the Spanish Army
The first 50 T-26 tanks which arrived in Spain, under the command of Krivoshein, were crewed by Soviet personnel. Nevertheless, the Soviet lieutenant colonel opened a training school in the town of Archena, near Cartagena, recruiting mainly truck and bus drivers from cities such as Madrid and Barcelona. The next month, he opened a second school in Alcalá de Henares, north of Madrid. However, only Communist soldiers were allowed to crew Soviet tanks, and as a result the pool of soldiers to recruit from was narrow and often less adept drivers were picked over better ones, due to their political ideologies. For example, in one instance a tank commander broke contact with the enemy because he had not learned how to fire his main gun. Furthermore, at first, the Soviet trainers did not have interpreters to communicate with their Spanish students.