The Type 60 was a Japanese self-propelled 106mm recoilless rifle gun platform designed for use by the Japan Ground Self-Defense Force (JGSDF) during the Cold War. She saw a protracted development period that culminated in a few hundred production examples being delivered. Production wrapped up in the late 1970s and the vehicle continued operations in a some type of capacity with the JGSDF as recently as 2008.
The Type 60 originated from a JGSDF need for a tracked tank killer mounting sufficient armament to combat modern tank armor while supplying the platform with adequate off road mobility. The engine of choice became a six-cylinder diesel engine delivering 110 horsepower. Armament would come from two 105mm recoilless rifles semi-fixed into a fixed superstructure. With design beginning in 1956, the Komatsu and Mitsubishi firms both submitted prototypes under the respective "SS1" and "SS2" designations. SS3 was then used to signify another prototype vehicle (often called "pilot" vehicles in tank-speak) and this featured a battery of 4 x 105mm recoilless rifles in place of the original two arrangement. However, the later selection of the American-made M40 recoilless rifle forced a third round of prototypes to exist, these under the SS4 designation and mounting 2 x 105mm M40 recoilless rifles in a revised superstructure as well as a new and more powerful powerpack. Three SS4 pilot vehicles were constructed for evaluation and the vehicle was formally adopted into service with the JGSDF in September of 1960. Komatsu production of the Type 60 would run from 1960 until 1977, resulting in the manufacturer of some 252 examples.
The Type 60 sported a noticeably low profile when viewed at any profile. Her glacis plate was severely angled for maximum forward ballistics protection. The sides of the superstructure were flat as were the top and rear panels. As a tracked vehicle, the Type 60 made the most of off road mobility from its pair of tracks, one mounted to either hull side. Each track featured a forward-mounted drive sprocket and rear-mounted idler, three track return rollers and five road wheels. The vehicle was crewed by three personnel made up of the driver, commander (doubling as the gunner) and a loader. When the vehicle is "buttoned down", the driver makes use of small vision ports to pilot the tank. The commander mans the recoilless rifles and manually operates their elevation and traverse. The loader must exit the vehicle to reload the rifles. Armor protection is only 0.47 inches (12mm) at its thickest and consists of steel. There was no NBC (Nuclear, Biological, Chemical) protection for the crew and a lack of night vision equipment further limited its battlefield usefulness. The tactical reach of the Type 60 is further limited by its 6-projectile reload capacity.
Structurally, the vehicle displaced at 18,000lbs (8,000kg) and featured a hull length of 14 feet (4.3 meters). Width was out to 7.3 feet (2.23 meters) while the vehicle height came in at just 4.5 feet (1.38 feet). Beginning in 1974, a single Komatsu 6T 120-2 series air-cooled, 6-cylinder diesel engine delivering 150 horsepower was installed in the Type 60 production line from then on. Gear actuation was accomplished by way of a manual transmission system featuring four forward speeds and a single reverse speed. Road speed was a reported 34 miles per hour while range was limited to 160 miles on a 37 gallon (US) internal fuel tank capacity.
Primary armament centered around a pair of M40 106mm recoilless rifles buried inside of the forward panel of the superstructure, offset to the left. These weapons were American in origin and saw service beginning in the middle of the 1950s. The 105mm rifle was a crew-served, man-portable recoilless rifle design developed specifically to combat enemy armor. While the Type 60 utilizes what was essentially the same weapon system, the "106mm" designation was accepted here to differentiate the base 105mm system from using the 105mm projectile ammunition developed from the abandoned M27 project. The M40 was a weapon cleared to fire HEAT, HEP, HEAP and Canister projectiles. The main guns were more or less "fixed" into the forward superstructure wall, seeing a traverse limitation of 60-degrees with an elevation range limitation of +15-degrees to -20-degrees. The guns were ranged out to 2,750 meters effective, though they could extend their reach out to 7,700 meters at the cost of accuracy and penetration value. A 12.7mm (.50 caliber) air-cooled heavy machine gun was also fitted to the hull, but this was generally reserved more as a spotting rifle firing tracer rounds then an anti-infantry defense system.
Use of the Type 60 SP 106mm tanks have since dwindled substantially over their previous peak numbers. To date, roughly less than 150 systems are known to be in operational service with the JGSDF.