Chapter X: Equipment

Section III: Artillery Equipment

1. GENERAL. a. Optical instruments are outstanding among specimens of Japanese artillery equipment. Examination of them shows good, versatile design, sturdy construction, and satisfactory definition. Knowledge of antiaircraft fire-control equipment is limited; specimens examined to date are obsolescent, although it is entirely possible that much improved designs exist, but have not yet been encountered.

b. Artillery communication equipment is described in the Signal Equipment section of this chapter. Trucks and other automotive equipment are described in the Automotive and Land Transport section.

c. Although the Japanese Army is provided with a variety of prime movers, few types of these have been encountered in forward areas. These have been older models; more modern types, with improved specifications, well may exist.

2. ARTILLERY FIRE CONTROL INSTRUMENTS. a. General. Illustrated and described on the following pages are various examples of artillery fire control equipment used by the Japanese. Their optical equipment is well made, sturdy, and versatile, but none examined differs from standard optical design. Panoramic sights for artillery weapons have not been recovered, but sights for infantry guns and mortars (described in sec. II) suggest that the Japanese have suitable sights for use on artillery pieces.

b. Off-carriage fire-control instruments.

Figure 296. The 75-cm. base range finder is an inverted coincidence-type range finder with a 12 X magnification, a vertical field of view 2°, and a 3° horizontal field of view. It is calibrated to measure ranges up to 10,000 meters.

Figure 297. One meter base stereoscopic range finder. The reticle of this instrument is graduated from 250 to 6,000 (presumed to be meters). Markings indicate an 8 X magnification, a 4.5° vertical and 5° horizontal field of view.

Figure 298. The model 93 battery commander's telescope permits measurement of angle of site from -300 to +300 mils, as well as measurement of azimuth. An unusual feature is that the telescopes cannot be placed in a horizontal plane for better stereoscopic vision. It has an 8 X magnification and a 6° field of view.

Figure 299. This battery commander's telescope has an 8 X magnification and a 6° field of view. It is constructed so that the telescopic arms may be placed in a horizontal position for better stereoscopic vision.

Figure 300. Battery commander's telescope. Although giving a high magnification and wide field of view, the individual telescopes cannot be placed in a horizontal position to improve stereoscopic vision.

Figure 301. This artillery spotting telescope may be used with three different eyepieces, each of which gives a different magnification—the maximum being 33 power. Provision is made to measure azimuth, and elevation (from -30° to +30°).

c. Aiming and laying devices.

Figure 302. This panoramic sight appears to have been designed for use on more than one artillery piece. It is shown above mounted on the model 41 (1908) infantry gun. The sight has a 3 X magnification and a 13° field of view.

Figure 303. This aiming circle has a 4 X magnification and a 10° field of view. Similar to the American aiming circle, it is used by artillery units for measuring angles in azimuth and site, and for general topographical work.

Figure 304. This gunner's quadrant is calibrated from 0 to 90°, with a vernier reading to 1/16 of a degree.

Figure 305. This gunner's quadrant is calibrated in units of 10 mils, extending from 0 to 1,410 mils (79°). A vernier scale enables adjustment to the nearest mil. It is considered possible that this quadrant has been designed primarily for use with the model 41 (1908) 75-mm infantry gun.

3. ANTIAIRCRAFT FIRE CONTROL EQUIPMENT. a. Automatic weapons. The model 92 (1932) 7.7-mm and the single mounted model 93 (1933) 13-mm machine guns, described in chapter 9, are provided with antiaircraft ring sights. The latest type ring sight recovered, illustrated in figure 306, is rotated automatically around its horizontal axis as the gun is elevated. It is believed that the purpose of this design is to correct automatically for the angle of approach. The following automatic weapons are provided with more complex sights than the ring sights.

Figure 306. Front and rear antiaircraft sights mounted on the model 92 (1932) 7.7-mm machine gun.

(1) Dual-mounted model 93 (1933) 13-mm machine gun. To date only incomplete sights (fig. 307) have been examined on dual mounts. They are constructed in such a manner that estimates of target course and speed are fed into the instrument, which then applies the appropriate deflection to the sighting telescope. The sight would appear to require 3 men for its operation.

Figure 307. Computing head for AA sight used on dual mounted model 93 (1933) 13-mm machine gun.

(2) Model 98 (1938) 20-mm automatic cannon. Complete antiaircraft sights for this weapon have not yet been recovered. It is known that some form of computing sight is used.

(3) Model 96 (1936) 25-mm automatic cannon. A computing sight, similar to the one described in a (2) for the 13-mm machine gun, is provided for this weapon (fig. 308).

Figure 308. Computing sight for Japanese model 96 (1936) 25-mm automatic cannon.

(4) Vickers type 40-mm automatic cannon. This weapon also has a computing sight for use in antiaircraft fire. In addition, an automatic fuze setting mechanism is provided. The time setting given to each fuze is adjusted, thru a complex series of gears and linkages, by the manipulation of the gun in elevation and depression.

b. Heavy antiaircraft weapons. According to modern standards the Japanese heavy antiaircraft fire control equipment seen to date has been outmoded and designed for use with the Model 88 (1928) 75-mm antiaircraft gun. Off-carriage fire-control instruments and computing mechanisms used with these guns are as follows:

(1) 2-meter-base height and range finder. This instrument (fig. 309) is of good optical construction and standard, but most specimens recovered had no provision for electrical data transmission. It supplies the "present altitude" to the guns.

Figure 309. 2-meter-base height and range finder.

(2) Target-speed and course-angle calculator. This instrument (fig. 310) is mounted on a tripod for use. The illustration in figure 310 does not include an elbow telescope, which must be mounted on its top in order to operate the instrument. The calculator supplies the angle of approach (course angle) of the target at the present position and ground speed of the target.

Figure 310. Target speed and course angle calculator with carrying box.

(3) Corrector scale. This is a metal board (fig. 311) on which may be read mechanically the correction angles required for wind direction and powder temperature.

Figure 311. Powder-charge temperature and wind correction scale.

(4) Spotting binoculars. These are used to obtain spot corrections, and have 15 X magnification and 4° field of view (fig. 312).

Figure 312. Model 89 (1929) 10-cm AA spotting binoculars.

Data from each of the instruments shown in figures 309, 310, 311, and 312, are shouted to the gun crew, certain individuals of which operate the "on carriage" components. This procedure theoretically results in the gun being correctly aimed and the time fuzes being so adjusted that the projectiles burst on the target. The "on carriage" components are:

c. Computing director. A few data computing directors have been captured, and provision for electrical data transmission has been seen on height finders. Mounting surfaces for data receivers have been found on some model 88 (1928) 75-mm anti-aircraft guns. There is evidence of more general use of electrical data transmission and computing directors than would be indicated by the equipment captured to date.

d. Searchlights. Japanese searchlights include the following sizes:

The following equipment is used by Japanese searchlight units:

Figure 313. 150-cm searchlight.

(1) Generator truck {standard 2-ton truck chassis).

(2) Searchlight comparator. The searchlight comparator illustrated in figure 314 is an instrument with which an observer, by keeping a plane in the crosslines of the telescope, automatically directs the searchlight on the plane. It was found satisfactory for operation of U.S. searchlights.

Figure 314. Searchlight comparator.

(3) Sound locator. Several varieties of Japanese sound locators are known to exist. One of the small models is illustrated in figure 315.

Figure 315. Small sound locator.

4. PRIME MOVERS AND TRACTORS. a. Komatsu tractor. This small, full-tracked vehicle (fig. 316) is designed solely for towing purposes. Steering is of the clutch-brake type, with hand levers operating the clutches. Two foot brakes are located on the right side, and are so placed that either or both brakes may be operated by the right foot. The gear box allows 3 forward and 2 reverse speeds. The vehicle is supported by 4 small bogie wheels on each side. Examination of a specimen revealed that a number of the bearings were of Swedish manufacture. Characteristics are as follows:

Weight		3 tons (estimated).
Length		8 feet 2 inches.
Width		4 feet 4 inches.
Engine		4 cylinder, gasoline.
Cooling		Water.
Ignition		Bosch magneto.
Length of track in contact with ground		5 feet 7 inches.
Width of track		10 inches.

Figure 316. Komatsu tractor.

b. Light prime mover. The model number and date of manufacture of this vehicle (fig. 317) are not known.

Figure 317. Light prime mover.

In the case of a specimen examined, the word "seventy" was found marked in English on the side of the radiator, probably indicating the engine horsepower. A name plate on the power unit shows it to be a "Kato engine model K 3." Suspension consists of 2 bogies mounted on each side of the vehicle. Each bogie has 3 small wheels, and the sprocket is at the rear. Details are reported to be as follows:

Approximate characteristics
Weight		4 tons (estimated).
Length, width, height		No details.
Engine		4 cylinder, gasoline.
Cooling		Water.
Length of track in contact with ground		7 feet 5 inches.
Diam. of sprocket		2 feet 2 inches.

c. Model 92 (1932) 5-ton prime mover. It is reported that there are 2 variations of this vehicle. Model A is powered by a 6-cylinder in-line "L" head "Sumida" gasoline engine, and model B by a 6-cylinder in-line, air-cooled "Isuzu" Diesel. As far as may be ascertained, with exception of a modification in radiator design, the general appearance and suspension of these 2 models are similar. Both vehicles are reported to be identical in the following respects:

Common characteristics
Length		11 feet 8 inches.
Width		5 feet 11 inches.
Height		7 feet 8 inches.
Ground clearance		11 3/4 inches.
Fording depth		1 foot 7 1/2 inches.
Grade		30°.
Turning radius		Can pivot.
Winch capacity		2 3/4 tons.

(1) 5-ton prime mover (model A) (fig. 318).

Characteristics
Weight		5 1/3 tons.
Engine		6 cylinder, "Sumida."
Cooling		Water.
Cylinder bore		110-mm (4.3 inch).
Piston stroke		135-mm (5.3 inch).
Horsepower		64 to 98 (160 theoretically indicated hp at 2,800 rpm—based on reported engine specifications).
Ignition		Bosch magneto.
Generator		Bosch 12 volts.
Storage batteries		2—12 volts, 60 amperes.
Fuel tank capacity		Main 27.5 gallons, auxiliary 12.1 gallons.

Note. The model A is believed to be similar to, if not identical with, a recently examined prime mover. This vehicle was found to be well constructed and capable of operating over most types of terrain. The present gasoline engine is estimated to be of approximately 140 horsepower, considerably more powerful that the standard unit. It is believed that this particular engine is a replacement of the unit originally installed.

Figure 318. 5-ton prime mover (model A).

(2) 5-ton prime mover (model B) (fig. 319).

Characteristics
Weight		5.5 tons.
Engine		6 cylinder, Diesel.
Cooling		Air.
Cylinder bore		110-mm (4.3 inch).
Piston stroke		140-mm (5.5 inch).
Horsepower		65 to 90 (135 theoretically indicated hp at 2,000 rpm—based on reported engine specifications).
Ignition		Compression.
Generator		12 volts, 300 watts.
Storage batteries		2—12 volts, 120 amperes.
Fuel tank capacity		Main 22 gallons, auxiliary 13.2 gallons.

Figure 319. 5-ton prime mover (model B).

d. Model 92 (1932) 8-ton prime mover. It is reported that 2 versions exist of this vehicle; the model A is powered by a 6-cylinder in-line, watercooled gasoline engine, and the model B by a 6-cylinder in-line water-cooled Diesel. The following data are believed to be common to both models A and B:

Common characteristics
Length		14 feet 1 inch.
Width		6 feet 6 inches.
Height		8 feet 6 inches.
Grade		15°.
Winch capacity		5 tons.
Cylinder bore		130-mm (5.1 inches).
Characteristics of model A
Weight		8.4 tons.
Ground clearance		11 1/2 inches.
Engine		6-cylinder, gasoline.
Cooling		Water.
Piston stroke		5.6 inches.
Horsepower		80 to 130 (230 theoretically indicated hp at 2,800 rpm—based on reported engine specifications).
Ignition		Bosch magneto.
Generator		12 volts, 100 watts.
Storage batteries		2—12 volts, 100 amperes.
Fuel tank capacity		Main 39 1/2 gallons, auxiliary 9 gallons.
Characteristics of model B
Weight		9.3 tons.
Ground clearance		12 inches.
Engine		6 cylinder, Diesel.
Cooling		Water.
Piston stroke		6.4 inches.
Horsepower		105 to 120 (215 theoretically indicated hp at 2,000 rpm—based on reported engine specifications).
Generator		12 volts, 500 watts.
Storage batteries		4—12 volts, 140 amperes.
Fuel tank capacity		Main 39 1/2 gallons, auxiliary 9 gallons.

e. Model 98 (1938) 4-ton prime mover. It is believed that this prime mover, powered by an 8-cylinder V-type air-cooled gasoline engine, is capable of hauling a load at 25 miles per hour, and that it can travel a distance of 125 miles in a period of 10 hours. Steering is of the clutch brake type, with foot and hand operated brakes. A central selector type gear box allows 4 forward speeds and 1 reverse. Although no 4-ton model has been encountered as yet, it is believed that the following data apply:

Characteristics
Weight		4 tons.
Length		12 feet 5 inches.
Width		6 feet 1 inch.
Height		7 feet 3 inches.
Ground clearance		11 1/2 inches.
Tread		No details.
Fording depth		20 inches.
Grade		30°.
Turning radius		Can pivot.
Winch capacity		Over 2 tons.
Engine		8 cylinder V-type, gasoline.
Cooling		Sirocco type fan.
Cylinder bore		90-mm (3.5 inch).
Piston stroke		125-mm (4.9 inch).
Horsepower		73 to 88 (130 theoretically indicated hp at 2,800 rpm—based on reported engine specifications).
Ignition		Bosch magneto.
Generator		Bosch, 75 watts.
Storage batteries		12 volts, 80 amperes.
Fuel tank capacity		Main 22 gallons, auxiliary 13 gallons.

f. Model 98 (1938) 6-ton prime mover. Examination of this prime mover (fig. 320) indicates that it is an unarmed artillery tractor, suitable for the additional roles of reconnaissance vehicle and ammunition carrier. Suspension follows the pattern of the model 2597 medium tank. Since steering is of the clutch-brake type, the vehicle is capable of turning within its own length. It is reported that this vehicle is used as a prime mover for the 105- and 150-mm howitzers and the 105-mm gun. Details are believed to be as follows:

Weight		Weight 7.75 tons.
Length		14 feet 1 inch.
Width		6 feet 9 inches.
Height		6 feet 3 inches.
Ground clearance		13 1/2 inches.
Grade		15° pulling field gun.
Turning radius		19 feet.
Winch capacity		5.5 tons.
Engine		6 cylinder, Diesel.
Cooling		Water.
Cylinder bore		120-mm (4.7 inch).
Piston stroke		155-mm (6.1 inch).
Horsepower		88 to 110 (175 theoretically indicated hp at 2,000 rpm—based on reported engine specifications).
Generator		24 volts, 100 watts.
Storage batteries		2—12 volts, 180 amperes.
Fuel tank capacity		Main 17.6 gallons, 1st auxiliary 18.7 gallons, 2d auxiliary 6.6 gallons.

Figure 320. Model 98 (1938) 6 ton prime mover.

g. Model 95 (1935) 13-ton prime mover. This heavy prime mover is reported to be produced in two models: the model A is powered with a 6cylinder in-line, water-cooled, gasoline engine; the model B with a 6-cylinder, water-cooled Diesel. Both models are believed to be equipped with multiple disc, clutch type steering, with hand and foot operated brakes. The following data is reported to be common to both types:

Length		16 feet.
Width		7 feet 6 inches.
Height		9 feet 3 inches.
Ground clearance		12 inches.
Grade		13 tons, 15°—29 tons, 7 1/2°.
Turning radius		65 feet.
Winch capacity		11 1/4 tons.
Characteristics of Model A
Weight		14.3 tons.
Engine		6 cylinder, gasoline.
Cooling		Water.
Cylinder bore		5.4 inches.
Piston stroke		6 inches.
Horsepower		130 to 160 (265 theoretically indicated hp at 2,800 rpm—based on reported engine specifications).
Ignition		Magneto.
Storage batteries		2—120 volts, 80 amperes.
Fuel tank capacity		Main 61.6 gallons, auxiliary 9 1/2 gallons.
Characteristics of Model B
Weight		15 tons.
Engine		6 cylinder, Diesel.
Cooling		Water.
Cylinder bore		5.6 inches.
Piston stroke		7.6 inches.
Horsepower		145 to 165 (295 theoretically indicated hp at 2,000 rpm—based on reported engine specifications).
Generator		300 watts.
Storage batteries		2—12 volts, 80 amperes.
Fuel tank capacity		60 gallons.

5. CAISSONS, LIMBERS, AND OTHER ARTILLERY VEHICLES. a. Caissons and limbers. (1) Horse-drawn caisson and limber. Figure 321 depicts a typical Japanese horse-drawn caisson and limber, for use with the 75-mm field gun. Mounted on standard artillery, iron shod, wooden wheels, the two units are drawn by six horses. Characteristics are reported as follows:

Total weight (empty)		2,130 pounds (approximately).
Weight (loaded):
Limber only		1,750 pounds.
Caisson only		2,080 pounds.
Capacity:
Limber		40 rounds.
Caisson		60 rounds.
Diameter of wheels		55 inches.

Caissons and limbers of design similar to figure 321, but carrying fewer rounds, are provided for field guns of heavier caliber.

Figure 321. Typical horse-drawn caisson and limber.

(2) Alternative type caisson and limber. The caisson and limber illustrated in figure 322 is an alternative type for use with the 105-mm field gun. Primarily designed to be towed by a tractor, it also may be drawn by six horses. The heavy artillery-type wheels have solid rubber tires. Characteristics are reported as follows:

Total weight (empty)		2,530 pounds.
Total weight (loaded)		5,040 pounds.
Total capacity		48 rounds.
Diameter of wheels		55 inches.

Figure 322. Alternative type caisson and limber for 105-mm field gun.

(3) High-speed caisson. The photographs illustrated in figure 323 show the most modern type of Japanese caisson seen to date. Constructed of metal, it is mounted on steel disc wheels, of comparatively small diameter, fitted with solid rubber tires. The probable capacity of the caisson is 48 complete rounds of 75-mm ammunition. Units of similar appearance carry a smaller quantity of 105-mm ammunition.

Figure 323. High speed caisson for 75-mm ammunition.

b. Battery wagons. (1) Battery wagon for antiaircraft gun. The trailer (fig. 324) apparently is constructed for high-speed transportation of communication equipment, miscellaneous spare parts, and bulk ammunition. The body is made from lightweight metal plate, which is not considered to be proof against small-arms fire. Compartments are provided for the stowage of the various items of equipment carried. This vehicle is mounted on metal disc wheels fitted with pneumatic tires. For antiaircraft defense, a tripod, apparently designed for the model 92 (1932) 7.7-mm heavy machine gun, is mounted on the roof. Characteristics of the vehicle are as follows:

Overall length of frame		11 feet 10 inches.
Width		6 feet 3 inches.
Wheel base		7 feet 7 inches.
Ground clearance		12 inches.

Figure 324. Battery wagon for model 88 (1928) 75-mm antiaircraft gun.

(2) Battery wagons for field artillery. These units are similar to the horse-drawn limber and caisson in construction (fig. 325). They are used for the transportation of general artillery equipment, such as range finder, binoculars, battery commander's telescopes, communication materials, tools, etc. Characteristics are reported to be as follows:

Total weight loaded (limber and caisson)		4,318 pounds.
Diameter of wheels		55 inches.

Figure 325. Battery wagons for use with field artillery.

c. Spare parts wagons. These are used for the transportation of spare parts, tools, and maintenance and repair materials (fig. 326).

Characteristics are believed to be as follows:

Total weight loaded (limber and wagon)		3,770 pounds.
Diameter of wheels		55 inches.

The two units are normally drawn by 6 horses.

Figure 326. Spare parts wagon for 150-mm howitzer.

6. PACK EQUIPMENT. a. General. Great attention has been paid to the development of pack transportation of infantry support guns, namely, models 41 (1908) and 94 (1934) 75-mm mountain pack guns (sec. II, chap. 9), as well as of machine guns, ammunition, supplies, etc. Illustrations on the following pages show in detail pack saddles, draught harness, and an infantry support gun, broken down into loads averaging 200 pounds per load and packed for horse transportation.

b. Pack saddles. Two standard pack saddles are illustrated in figure 327. The saddle is adjustable so that it comfortably fits the back and girth of the horse. Saddle A carries the weapon (such as a heavy machine gun); Saddle B is fitted to hold ammunition or spare-parts chests. (See also figs. 328-334.)

Figure 327. Standard pack saddles.

Figure 328. Tube of model 41 (1908) 75-mm infantry (mountain) gun fastened to pack saddle.

Figure 329. Trail of 75-mm infantry (mountain) gun disassembled and fastened to pack saddle.

Figure 330. 75-mm infantry (mountain) gun cradle on pack saddle.

Figure 331. Shield for 75-mm infantry (mountain) gun folded and fastened to pack saddle (with tool chest attached to side).

Figure 332. Breech mechanism and tray for 75-mm infantry (mountain) gun.

Figure 333. Wheels and axle attached to pack saddle.

Figure 334. Method of fastening ammunition chest to pack saddle.

Figure 335. Standard ammunition chest for 75-mm infantry (mountain) gun. The chest, made of steel plate, carries 6 rounds. It weighs 29 pounds empty and 118 pounds with ammunition. Two chests can be carried on one pack saddle.

c. Draught horses. Extensive use of draught horses is made by the Japanese. Figure 336 shows a typical 4-horse harness hookup, with the type of saddle (which differs from the cavalry saddle) used by artillery and infantry gun crews.

Figure 336. 4 draught horse harness with saddles.

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