"Chi-Ha" Type "97" Model 1937 Medium Tank - Design
The layout of the tank "Chi-ha" was performed according to the classical scheme with the front of the transmission. Reservations were differentiated and ranged from 8.5 to 25 mm. The construction of "Chi-Ha" was carried out on a frame system. The maximum thickness of rolled hull sheets in the case of the Type 97 increased to 27 millimeters. This provided a significant increase in the level of protection. As practice later showed, the new thicker armor turned out to be much more resistant to the armament of the enemy. For example, the American Browning M2 large-caliber machine guns confidently hit Ha-Go tanks at distances of up to 500 meters, but on the Chi-Ha armor they left only dents. More solid armor led to an increase in the tank's combat mass to 15.8 tons. This fact required to install a new engine.
The crew of the tank was four people. Compartment of command is combined with combat. In the hull in front of the right in a protruding wheelhouse there was a driver, on the left - a machine gunner; in the turret to the right of the cannon — the commander; on the left — the gunner; he is the loader. The tank hull was assembled from rolled armor plates on a frame made of backing strips and corners with the help of round rivets and bolts with a six-sided bullet-proof head, although welding was also used on some units (the control compartment roof). The number of molded parts in the hull structure was minimized, with bent sheets being actively used (cutting room for the driver and the bottom stern sheet). The protection of the frontal part of the body somewhat increased the slope of the gable upper frontal sheet at 80 ° to the vertical, lower - 62 °.
For access to the transmission in the forward part of the hull there were two single door hatches. Side blinds were covered with special shutters, which were used to protect against enemy fire. The crew accessed the control compartment through the hatch of the radio operator; the driver had a front inspection hatch with horizontal viewing slots, as well as a signal hatch on the cabin roof. In the left part of the frontal cutting plate there was a ball mount for a 7.7-mm tank machine gun type "97". The middle part of the corps was occupied by the fighting compartment. Vertical boards made of armor plates with a thickness of 20 - 25 mm, however, the under-turret box had the shape of a truncated pyramid and had an armor thickness of 20 mm and an incline of 40 °. The front sheet of the fighting compartment was set at an angle of only 10°.
The tank installed a double turret of conical shape with a stern niche and the commander's turret, riveted design. The sides of the turret are curved, and the roof of the turret is made of two sheets joined by welding. As in the case, the cast parts in the turret construction were practically not used, with the exception of the gun mask. On the roof of the turret was mounted commander's turret with a round double hatch and with viewing slots, to the left of it - a double hatch of the gunner. The periscopic surveillance device with an armored cap was mounted here, and there was also a hole for signaling flags. Behind the commander's turret was attached a swivel for anti-aircraft fire from a machine gun, which the commander could lead, almost without protruding from the hatch, but in a very limited sector. In the turret and the case there were holes with armor valves for firing from the crew’s personal weapons.
The mechanism of rotation of the turret is mechanical. The main armament of the tank consisted of a 57-mm semi-automatic tank gun type "97" with a vertical wedge gate. Hydraulic recoil brake and spring knurled located under the barrel. For the convenience of pointing, the mask with the gun was fastened on the trunnions, which made it possible to make accurate aiming of the gun without turning the turret. The trigger mechanism was controlled by the trigger lever, mounted together with the pistol grip and trigger guard on the left side of the breech. Behind at the bottom of the breech, a shoulder rest with a leather cushion was attached. In the turret gun mounted in a double frame with a box mask. Vertical and horizontal trunnions of the gun and the framework allowed its guidance vertically in the range of -9 ° to + 21 °, and horizontally within 10 ° in both directions.
Ammunition guns consisted of 120 unitary shots, placed in racks in the fighting compartment. The standard ammunition consisted of 80 high-explosive and 40 armor-piercing rounds. The armor-piercing mass was 1.7 kg, and the initial speed was 820 m / s. Rate of fire was 20 shots / min. In the “Chi-Ha” tank, the auxiliary armament consisted of two 7.7-mm tank machine guns of the “97” type, of which one was mounted in a ball bearing in the rear of the turret and one on the left in the front hull plate. Barrels of machine guns defended box-armored.
The tank used a 12-cylinder 2-stroke V-type diesel engine type "97" air cooling company "Mitsubishi" with a capacity of 170 hp. On the Ha-Go tanks, an inline 6-cylinder two-stroke diesel Mitsubishi NVD 6120 air-cooled was installed with a normal power of 110 hp. (Maximum 120 hp.), Previously tested on an average Type 89 tank. The engine was distinguished by good reliability, even when working at low temperatures.
Access to the engine was carried out through the main hatch louver on the engine plate. The sides of the engine compartment also had blinds, covered in a combat situation with armored vehicles. On the march they were raised and fixed in a horizontal position. Fuel tanks for 120 and 115 liters located along the sides. Four-speed gearbox provides 8 forward and 2 reverse gears. It was mounted in front of the case. Torque from the engine was transmitted to the drive shaft, passing through the fighting compartment. The main friction - multi-plate. The two-stage planetary steering mechanism provided the tank with good handling. Onboard gears were placed in protruding crankcases. fastened to the body with rivets. Access to the turning mechanisms and onboard gears was carried out through two hatches in the upper front plate.
On the "Chi-Ha" type "97" tanks, the suspension was used according to the scheme of Tomio Hara with elastic elements in the form of springs located in a horizontal position along the hull. The tank had six double rubberized support rollers (as applied to one side), four of them were interlocked in pairs in two trucks. They were complemented by front and rear rollers with independent suspension - through the crank arms they were connected with inclined spiral springs, openly mounted on the board. Shock absorbers in the suspension was not. On each side there were also three dual rubber-supported rollers. The drive wheels are front, the track tackle engages. The mounting of the stamped non-rubberized guide wheel included a screw mechanism for adjusting the tension of the tracks with a ratchet locking device. Small steel caterpillars, with one crest developed lug, each of 96 tracks. The removal of the guides and driving wheels for the hull contours increased the length of the bearing surface of the tracks. The chi-ha chassis ensured good throughput, stability and comparative smoothness without slipping on weak soils. The suspension scheme gave a large dynamic course of the rollers and a large potential energy of elastic elements, differed good maintainability.
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