Staff Writer (Updated: 7/1/2014):
Design of the Carro Armato M13/40 series was conventional throughout. Its long running, side-mounted track systems sported the drive sprocket at the front of the assembly with the track idler at the rear. There were three track return rollers along the top portion of the track system with no fewer than eight small, paired road wheels with two wheels per bogey and two of these bogies per suspension installation. The hull was suspended from the wheels by a leaf-spring bogie system with the chassis itself was based on the earlier M11/39 series. The running gear of the tank was heavily influenced by Italian usage of the British Vickers 6-Ton tank prior to the war - the Vickers 6-Ton being a very popular light tank that went on to influence several other designs before the war. The hull featured a heavily sloped glacis plate (nearly horizontal) and fixed superstructure with slightly sloped facings. The turret assembly was mounted to the top of the superstructure and provided for a tall profile. Construction was riveted steel with 42mm armor thickness along critical facings.
Power for the M13/40 series was derived from a single fitting of a SPA TM40 V8 diesel engine. This powerplant developed up to 125 horsepower and was fitted to the rear of the hull with a shaft driving the front sprockets. This allowed the vehicle to reach top speeds of 20 miles per hour on level roads (lesser so off road) with a range out to 120 miles. The 120 mile range was actually an excellent quality of the tank while her 20 mile per hour top speed was rather slow for such a light tank design (despite her classification as a medium tank). Overall weight was in the vicinity of 14 tons.
The Carro Armato M13/40 was crewed by four personnel made up of the driver, tank commander, main gunner and machine gunner. The driver maintained a front-left seating in the hull with the machine bow machine gunner to his immediate right. This machine gunner also doubled as the tank radio operator, a practice consistent with the times. However, radios were not fitted as standard equipment to all of the completed M13/40s. The commander and gun layer both resided in the cramped turret. Access to the turret was through a two-piece hatch on the roof. The hull crew managed with a left-side rectangular hatch along the superstructure.
Primary armament for the series was the 47mm Cannone da 47/32 M35 main gun. 104 x 47mm projectiles were afforded to the gunnery crew and this consisted of a mix of Armor-Piercing (AP) and High-Explosive (HE) rounds to be used against "hard" and "soft" targets respectively as required. The gun mount allowed for +20 and -10 elevation while the turret allowed for a full 360-degree traversal. Between three and four Modello 38 series 8mm machine guns were fitted throughout the design. One machine gun was fitted coaxially with the main gun in the turret and operated by the gunner. The machine gunner/radio operator managed a double 8mm machine gun pairing in the front hull by way of a flexible ball-mount. While the pairing could be seen as advantageous, the firing arc and the position's vision was relatively limited. If equipped, a fourth 8mm machine gun could be installed on the turret roof and serve double-duty in combating both enemy infantry or low-flying attack aircraft. Up to 3,048 x 8mm ammunition was provided for all of the available machine gun emplacements.