ACS M7 CHASSIS “GENERAL LEE”

Self-propelled artillery 105mm setting M7 widely known as Priest (“Priest”). She was the main American destroyer during the Second world war and one of the most numerous, released at this time. The weapon was in service with many artillery units and all units of the armored forces of the United States. It was accepted into service in April 1942 as the M7 105mm Howitzer Motor Carriage howitzer was the end of the war “circulation” in 4316 copies.

Baptism of fire for the US army M7 received in November 1942 in operation Torch, the Tunisian campaign (1942 – 1943). At the same time the British, having ACS under lend-lease, included them in the composition of the 8th armored division and used in combat against German troops E. Rommel in El Alamein.

During the Second world war the American army was formed 67 divisional and separate battalions, the arms of which were M7. 62 of them (48 and 14 separate division) fought in Europe on the Western and Italian fronts. Especially the installation proved in the course of the Sicilian operation in Normandy on 6 June 1944, where they carried out fire support to units in landing their ships and the battle of the bulge.

In the Pacific theater of war SAU M7 were used sparingly and were part of the units. This was due to the specifics of military operations on the Islands, covered with hard-off jungle. Most successfully, the M7 self-propelled guns were used as assault guns, destroying fortifications built here by the Japanese, especially in “operation iceberg” in April 1945 during the battle for Okinawa in the 1st and 6th divisions of the marine corps.

States us army M7 SPG was adopted for service with the Panzer divisions as a field of self-propelled howitzers. In the division there were three battalions with eighteen plants in each six in the battery. Partly they were in the regimental artillery battalions infantry divisions and separate battalions of corps subordination; they were attached to the Marines.

In the USA mass production of the M7 SPG was established at the factories of the company American Locomotive Company in April 1942, later in March 1945 – and even the firm Fédéral Machine and Welder Company. It was made in 1942 -2028 units in 1943 – 486, in 1944, -1164, in 1945-338. All-4316.

The British under lend-lease was passed more than 800 units of M7. The first deliveries in the amount of 90 vehicles were produced in September 1942, They were immediately sent to North Africa to help mired in the wilderness of British troops. Here (as noted earlier) they were used in the November battle for El Apeman as part of the 5 th regiment of the 8th armored division. ACS successfully operated in the combat formations of units, the fire of supporting tanks attacking German positions.

SAU “the priest” in the Museum of weapons of the US army. Aberdeen proving ground. Maryland, USA

Later the British connections M7 participated in military operations of the 8th army group in Italy (1943 -1945 gg.), in the Burma campaign 1945

It is from the English setup received the name of Priest – machine-gun cutting that resembled the pulpit of the Church of the preacher.

The program lend-lease ACS M7 only got France, they gave the 2nd and 5th tank divisions of the French army in the amount of 180 units (according to others – 280) after the landing of allied troops in Normandy.

In the postwar period M7 in the framework of military aid was transferred to the army of other States, but not “retired” in the United States. So, they participated in the Korean war 1950 – 1953, consisting on arms of the 1st and 9th corps of the 8th army. Arrived installation at the front in February 1950 the city Directly from the U.S. army they sent only one battalion with the M7, the other four are mobilized from the National guard. Particularly active in ACS applied against the advancing Korean-Chinese troops in April – may 1951

Pakistan, which received in 1955 -1956. 150 M7, used them in wars with India in 1965 and 1971, Israel had acquired 100 ACS in 1961 – 1962; they participated in the Arab-Israeli “Sixth day war” of 1967 and the war “judgment day” in 1973

In the army of Norway had a battery of four M7, created in 1945, but it was in reserve and the installation was not used. Just received from France in 1957, a further 22 machines, it was decided to form one battery of self-propelled artillery battalion of the brigade “North” of the eight ACS. M7 remained in service until 1969

In Belgium, twenty units stationed in the army since 1951 and has written off only in 1964, Argentina in 1950 it acquired six units and kept them until 1980-ies. Until then, the M7 was kept in the army of Yugoslavia. In Brazil from 1951 , and to this day, SAU M7 are in service.

ACS M7. The view from the top

ACS M7. View from the stern

The number of ACS M7, which was adopted by the armies of the various States:

USA – 3300 units, of England, 828, Argentina – 6, Belgium 20, Brazil – 24, Israel – 100, Canada – 64, Norway -26, Pakistan – 150, Taiwan – 100, France – 180 (280).

In addition, the M7 was available in the armed forces of Germany, Italy, Portugal, Turkey, Yugoslavia, South Africa.

Production units began in April 1942, was carried out on the chassis of medium tank M3 “General Lee”, released in 1941, This tank weighing about 28 tons were stacked design and had a 75-mm gun M2 or M3, three 7.62-mm machine gun М1919А4 “Browning”.

In developing the ACS, the designers have not changed the layout scheme of the tank M3, leaving still the engine in the stern, and the office front. Warhead placed in an open top stationary cutting.

The frontal part of the machine body is cast, cylindrical form, three-piece; thickness – 51 – 108 mm with angles from 0° to 56°. Rolled side 18 mm sheets placed vertically, 13-mm aft at angles of inclination up to 10°. The bottom variable thickness; 25 mm in front and 13 mm under motorradreisen office.

Combat tower – from sheets of rolled homogeneous steel with a thickness of 13 mm; frontal leaves had a slope of 30°, side and aft – mounted vertically. Starboard cabin had a cylindrical sponson to embed machine gun turrets, in the Central part – the embrasure for guns, protected by a movable shutter shield.

SAU “the priest” on the streets of a town in Western Germany. 1945

SAU “the priest” at the trials in Fort Knox. February, 1942.

On the M7, and the basic tank, put a 9-cylinder four-stroke petrol engine continental R-975-EC2 air-cooled power: 340 HP at 2400 rpm; fuel – gasoline with octane number not lower than 80. The total volume of the fuel tanks was 660 l; two of them for 220 l were in the sponsons of the hull, two at 112 l – was mounted vertically on the bulkhead from the engine compartment.

The drivetrain consisted of a main double-disc dry clutch, single side gear transmission, dual differential; manual transmission with synchronizers had five gears forward and one backward.

Suspension – six rollers on each side, with a rubber single with a diameter of 508 mm, three rubberized support wheels of the roller; a driving wheel with a removable ring gear – front location, the guide – crank tension mechanism. Track rollers are interlocked in pairs in three trucks with suspension double conical springs. Caterpillar steel with rubber hinge, cycloid gear; number of tracks in each – 79 in width – 406 mm. on – Board brakes- belt type.

Armed with “priests for some” a 105 mm howitzer М2А1 with a barrel length of 22.5 caliber mounted on a standard carriage in the front of the case. She had a manual pinch valve and a hydropneumatic recoil device.

ACS M7:

1 – 105-mm howitzer; 2 – lakatnik guns; 3 – 12.7 mm anti-aircraft machine gun; 4 – turret machine gun; 5 – cylindrical sponson; 6 – wall of the conning tower; 7 – guide wheel; 8 – support roller; 9 – vertical suspension truck rollers; 10 – driving wheel; 11 – the breech of the gun; 12 – gunner; 13 – tray loading mechanism; 14 – the right ammo shells; 15 – louvers of the engine compartment; 16-towing cable; 17-left ammo rack shells; 18 – right headlight; 19 – the shield guns; 20 – cover of the driver’s hatch; 21 – rear wall of the deckhouse; 22 – fold hatch of the engine compartment; 23 – the aft wall of the engine compartment; 24 – front part of the hull

I suggest a weapon with a manual screw mechanisms. The corners of the vertical guidance – from -5° to +35°, in the horizontal plane, they are different; up to 15° on the port side to 30° on the right. When firing direct fire artillery observer used a periscopic optical sight M16, from concealed positions, firing was conducted with the help of artillery panorama М12А2.

It was fired high-explosive shells NOT M1, M80 smoke and М84, in addition, armor-piercing cumulative HEAT M67, which could penetrate 102 mm of homogeneous armor. For heat shells was used unitary shots for others polyurethane.

Maximum range of fire high-explosive shells at extreme elevation was 10 500 m, cumulative 8,000 m Rate of fire of a howitzer – 8 RDS./min.

The ammunition consisted of 69 shots. They were placed in the cells of the sponson and the hull sides and also under the floor of the fighting compartment.

On the ring of the turret sponson located on the starboard side, installed 12.7 mm anti-aircraft machine gun М2НВ Browning; his ammunition – 300 rounds of ammunition, loaded in six bands. In the standard weapons of the crew consisted of three 11,43 mm submachine gun M1928 or M3 and hand fragmentation and smoke grenades.

Self-propelled gun crew consisted of seven people: commander, driver, gunner and four numbers artillery calculations. When shooting the duties of a gunner was part of pointing the gun in a horizontal plane, and the introduction of amendments aiming No. 1 was engaged in vertical elevation and worked the shutter, No. 2 – was the loader, No. 3 and No. 4 – changed the charge fuse installed.

The driver was driving the car, watching the road through your manhole, in combat conditions, used a prismatic viewing device mounted in the hatch.

Engine compartment installation supplied stationary fire-fighting system – a disposable, manually operated from the conning tower. In it consisted of two cylinders with carbon dioxide with a capacity of 5.5 l and two portable fire extinguisher on a 1.8 l If necessary, the crew could use three degassing devices M2.

Internal connection of M7 was not equipped, the radio station was not established.

At the end of 1943 the US military command decided to transfer the “priests for some” more modern chassis of the M4 Sherman, which was a direct development of the M3 tank. The weight of the tank was 30.7 tons armament: 75 mm M3 gun, two 7.62-mm machine gun, one 12,7 mm.

Tank M4 had a welded construction made of rolled sheets of steel armor, unlike riveted from M3. The lower part of the body remained the same. The Board housing and the feed consisted of a vertically mounted armor plates with a thickness of 38 mm.

When switching on the chassis of the M4 in the design of ACS was made a number of improvements. However, it should be noted that the changes to the machine were made continuously since the beginning of their release. For instance, in the summer of 1942 the ammunition has increased from 57 to 69 of the shells, due to two additional berkedok. Expanded side sponson machine gun, put the machine gunner. Next summer the lower glacis of steel to release the cap, thus covering the armor and the sponsor.

The sides and rear of the wheelhouse, made higher, made them with the frontal plates, and mount this hinged armor panels. It was a forced measure, as the onboard stowage have proven to be very vulnerable to enemy fire. Made more convenient and stable mounting of the howitzer barrel in the stowed position. Improved brakes, sloths and dust the bulwarks over the tracks, move differently the boxes with equipment. The bottom of the forehead of the body begin to make Bronevoy steel with a thickness of 25 – 38 mm.

From March 1944, the upgraded M7 steel to be manufactured by the same American Locomotive Company, releasing until November of this year, 500 cars, and the firm Fédéral Machine and Welder Company in 1945, put another 176 units.

In the cockpit installation left of the gun – a workplace of the driver. Behind him at the side – stacking of ammunition and seat the calculation

The breech of the 105-mm gun М2А1

ACS M7 pushed to the forefront of the defence with infantry on Board. Philippines, island of Luzon. March 1945

Previously upgraded installation had engines R-975-EC1, but in the same 1944 year, the company Pressed Steel Car was put on the cars engine Ford GAA that was М4АЗ tanks with a larger capacity. These self-propelled guns in 1944 and 1945, produced by the mentioned firms 664 and 162, respectively. They received index М7В1.

Finally, the last upgrade of the ACS were produced in the post-war period during the “stay” installations in Korea. The angle of elevation of their guns, was not sufficient to conduct successful military operations in mountainous conditions. Therefore, the elevation was brought to the set in the first technical jobs, 65°, however by increasing the height of the installation. Then had again to build on the sponson to keep the circular firing the machine gun. Converted 127 machines. They are assigned an index М7В2.

ACS M7 was the largest self-propelled installation of the Second world war and the postwar period.

Similar machines are made in other countries. In Germany, for example, in armored and motorized divisions were successfully used SAU Sd.Kfz.165 Hummel (German for “bumblebee”) with 105-mm light howitzer. The gun on it was placed in the middle of the body over the engine. Range of fire high-explosive shells weighing

43.5 kg 13,3 km away and unit Weight of 23.5 tons, the crew – 6 people. In 1943 -1945 years. they were released 724 units.

Another notable German self-propelled guns were also 105mm setting Sd.Kfz.164. (translated from German – “OSA”) related to the stern of an open top deck. The firing range of her guns – 10.6 km vehicle Weight – of 11.48 tons, crew – 5 people. Note that baptism of fire she received in the battle of Kursk.

In England in 1943, he released 87,6-mm self-propelled howitzer Bishop (“Bishop”) with a maximum firing range of 8 km. Mounted the gun in a closed cabin on a chassis of a light tank Valentine II (“Valentine”), machine Weight – 17,54 t, crew – 4 persons. ACS participated in the fighting on the North African front. Firm Vickers has produced 80 units.

Considerable success in those years came and canadian ACS Sexton (“Sexton”) with the English division of 87.6 mm howitzer on the chassis of the canadian Ram cruiser tank (“REM”), created on the basis of the American M3. The gun was in the rectangular open top of the wheelhouse in the middle of the hull. Range of fire explosive projectile with a mass of 11.3 kg was equal to

12.5 km away. the unit Weight of 25.8 tons, the crew of 6 people. Produced in 1943 – 1945 the installation was a standard ACS countries of the British Commonwealth. All of them were produced 2,150 units. They participated in battles in Italy, in Normandy and further hostilities in Europe.

All of these ACS has shown itself as a good, actively used for fire support of tank and motorized joints, acting directly in combat formations.

Tactical and technical characteristics of ACS M7

PRODUCTION years 1942 – 1945

COMBAT WEIGHT, kg ……………22 900

CREW……………. ……………………7

LENGTH of BODY, mm ………………6020

WIDTH, mm ………………2870

The HEIGHT of CUTTING, mm ………………2946

BOOKING, mm:

the forehead of the body…………….. …………51 – 108

the Board body……………. ………………….18

feed……………………… ………………….13

the bottom…………………….. …………..13-25

the leaves of the cuttings……………. ………………….13

… ARMAMENT 105-mm howitzer М2А1,

12.7 mm machine gun “Browning”

AMMUNITION………….. shells – 69,

12.7 mm rounds – 300

ENGINE……………….. “Continental”

K-975-EC2

9-cylinder,

carburetor

air cooling

ENGINE POWER, HP……….340

TRANSMISSION…………. mechanical

SUSPENSION interlocked

pairs of rollers,

vertical conical springs

SPEED ON HIGHWAY, km/h 34 – 39

FUEL capacity, l ………………..662

OVERCOMING OBSTACLES in m:

the width of the pit……………… ………………..2,25

the height of the wall…………. ………………….0,6

fording depth…………. ………………….1,0

V. BORZENKO

Recommend to read

DRILL-GREGORATOS
This simple device will help with the help of ordinary hand drills to cut holes of any diameter in the plywood, hardboard and particleboard.
TRICKY BOLT
In carrying out various construction works it is often necessary to install and mount on wall panels are quite large and heavy products, devices and other structural elements. In...