Like other world militaries, the Japan Ground Self-Defense Force (JGSDF) went ahead with its adoption of a self-propelled 155mm-armed track howitzer vehicle to serve as a support weapon for its ground actions. The vehicle became the Type 75 and was adopted in 1975, joining the limited-run Type 74 model which featured a 105mm howitzer weapon and production totaling just 20 units. The Type 75 managed a more healthy production run of 201 vehicles and has remained in service since its adoption. It fills a clear role in its service to the JGSDF. The Type 99 of 1985 has since been developed as its modern successor and 99 of the new breed have been completed to date.
The Type 75 saw design and development work begin in 1969 and run through 1975 before formal adoption and serial production. Pilot vehicles emerged during 1971-1972 for testing and evaluations. The vehicle weighed 28 tons (short) and featured a configuration not unlike the classic American M109 series. The driver was seated at front-right with the powerpack to his left. The turret was sat upon the rear section of the hull. The chassis was taken from the Type 74 Main Battle Tank and included six double-tired road wheels to a hull side with the drive sprocket at front. No rear track idler was used as were no track return rollers featured. The Type 74 MBT held a rear-mounted sprocket with front-mounted idler and the driver seated at front-left with the engine in the rear of the hull. So obvious changes were made to the Type 74 MBT's design to begat the Type75 SPH. Development of the chassis fell to Mitsubishi Heavy Industries which also supplied the engine - a 6ZF 6-cylinder diesel engine of 450 horsepower. Maximum speed reached 29 miles per hour with a road range of out to 190 miles. Suspension was through a proven torsion bar arrangement. Armor protection was of aluminum.
Japan Steel Works was charged with development of the turret and gun system. The latter became a 155mm L30 howitzer weapon whose mounting allowed for inherent elevation for indirect fire. The turret provided a full 360-degree traversal allowing the vehicle to engage at all angled without having to turn itself in the direction of the target area. The main gun was fitted with the requisite fume extractor at its midway point and a double-baffled muzzle brake. 28 x 155mm projectiles were carried aboard and the projectiles are loaded separately from the required bag charge. Local defense was through a single 0.50 caliber heavy machine gun at the right side turret hatch with 1,000 x 0.50 caliber rounds carried. The driver, loader and commander all operated under armored hatches while a full crew of six was featured (two gunners, a layer and radioman were also part of the crew).
The Type 75 featured a effective firing range of 21,000 yards utilizing its basic High-Explosive (HE) munitions. Rocket-Assisted Projectiles (RAPs) went as far as 26,000 yards providing the Type 75 with a fairly good reach on the modern battlefield. The gun system, coupled with a well-trained crew, could reach a rate-of-fire of six rounds per minute. Several vehicles firing in concert could therefore supply a lethal barrage at range, ahead of the main fighting force and useful in destroying enemy fornications or dislodging concentrations of enemy troops.
Despite its successor having already been named and appearing in growing numbers, the Type 75 maintains an active presence in the inventory of the JGSDF.