Self-propelled howitzer, designed on the basis of the M3 medium tank, and later on the M4. This vehicle was designed to provide mobile fire support for tank divisions. In February 1942, Terms of Reference 2 was standardized as M7 HMC. Serial production began in April 1942 by the American Locomotive Company, Federal Machine and Welder Company, and the Pressed Steel Car Company. In the period from April 1942 to February 1945, 4316 self-propelled artillery mounts of this type were manufactured in two main modifications: the basic version - M7 and modifications M7V1.
The M7 served as the main tank destroyer of the United States of America in World War II. ACS M7 was the standard artillery of tank divisions, and was also used by corps artillery and infantry units. The M7 was used by American forces in all theaters of operations, primarily in Western Europe, where many tank divisions operated. In addition, more than 1000 SPGs were transferred under the Lend-Lease program to France and Great Britain.
The M7 self-propelled artillery unit began its history in October 1941, after Major General J. Devers, the head of the Armored Forces, recommended the development of a 105-mm self-propelled howitzer based on the new M3 medium tank. Interestingly, production of the M3 began just three months earlier. For this assignment, prototypes, designated 105mm Howitzer Motor Carriage T32, were manufactured by Baldwin Locomotive Works. The tests took place at the Aberdeen Proving Ground. The first prototype on February 5, 1942, after preliminary tests, was transferred to Fort Knox, where tests continued for three days. According to the test results, the Armored Committee of the US Army concluded that after revision, the T32 would meet the requirements put forward by the army.
Medium Tank M3
The thickness of the casemate's armor was reduced to 13 mm in accordance with the recommendations of the Armored Committee. Also, the howitzer was moved to the right to provide a horizontal guidance sector of 45 degrees. To reduce the height of the self-propelled gun, the Armored Committee allowed to reduce the maximum elevation angle to 35 degrees in comparison with 65 specified in the original TK. Another requirement was to equip the self-propelled gun with a 12, 7-mm anti-aircraft machine gun mount. Various options for placing a folding swivel unit above the engine compartment, or a turret in the corner of the wheelhouse, were being worked out. As a result, preference was given to the second option, which entailed changes in the configuration of the frontal part. The height of the stern and sides of the cabin was reduced by 280 mm, the frontal part was increased by 76 mm. The ammunition load was increased to 57 rounds due to the change in the ammunition stowage.
In February 1942, all these changes at the Aberdeen Proving Grounds were made to the second prototype T32, which was then sent to the American Locomotive Company plant for use as a sample during mass production. The T32 entered service in April 1942 as the 105mm Howitzer Motor Carriage M7.
The M7 ACS retained the layout of the M3 base tank. The engine compartment was located in the aft part, the fighting compartment was located in the middle part in an open-top fixed wheelhouse, and the control compartment and the transmission compartment were located in the frontal part. The self-propelled gun crew consisted of 7 people: squad leader, driver, gunner and four crew numbers. In addition, Squad M7 included a supply vehicle driver and two ammunition carriers.
The differentiated armor protection of the M7 self-propelled artillery mount was designed to protect against small arms fire and shrapnel. On machines of early production, the lower part of the hull consisted of a cast three-section cylindrical frontal part. Thickness - from 51 to 108 mm, tilt angles - from 0 to 56 degrees. The thickness of the rolled vertical side plates was 38 mm, the stern plate was 13 mm. Tilt angles - from 0 to 10 degrees. In the area of the engine compartment, the thickness of the bottom was 13 mm, in the frontal part - 25 mm. In the production of the first self-propelled guns, rivets were used when assembling the lower part of the hull, but later these connections were made by welding. In addition, on later production machines, the three-section frontal part was replaced with a one-piece one. Starting in 1944, on the M7, the lower part of the hull was made of non-armor steel (13 and 25 mm thick), and the cylindrical frontal part was replaced with a wedge-shaped part.
On all M7s, the upper part of the hull, including the space above the engine compartment, was assembled from 13-mm rolled sheets of homogeneous armor steel and had a 30-degree slope in the frontal part. The sides and sterns were installed vertically. 13mm engine compartment roof sheets were installed at an angle of 83 degrees. The stern and sides of the cabin had a lower height in comparison with the frontal part, however, on self-propelled guns of later releases, this difference was compensated by the use of folding panels. On the starboard side there was a cylindrical sponson for an annular machine-gun turret, in the frontal part - a gun embrasure, closed from the inside by a movable shield. To protect the fighting compartment from bad weather, a tarpaulin awning was used. The embarkation / disembarkation of the crew was carried out through the top of the wheelhouse. Access to the transmission and engine assemblies was provided through hatches in the stern and roof of the engine compartment, as well as a removable frontal hull part.
The basic modification of the M7 ACS was equipped with a radial aviation 9-cylinder four-stroke air-cooled carburetor engine of the Continental company, model R975 C1. This engine, with a working volume of 15945 cm³, developed an object power of 350 hp. and maximum 400 hp. at 2400 rpm. The object and maximum torque at 1800 rpm was 1085 and 1207 N • m (111 and 123 kgf • m), respectively. Four fuel tanks (total volume 662 liters) were installed in the engine compartment: two vertical 112-liter tanks - at the partition between the fighting and engine compartments, two tanks with a capacity of 219 liters - in the hull sponsons. As fuel for the engine, gasoline with an octane rating of more than 80 was used.
The power plant of the M7B1 modification was an 8-cylinder V-type aircraft four-stroke liquid-cooled carburetor engine from Ford, model GAA. The working volume is 18026 cm³. At 2600 rpm, the GAA engine developed a target power of 450 hp. and maximum 500 hp. At 2200 rpm, the object and maximum torque was 1288 and 1410 N • m (131 and 144 kgf • m), respectively. The fuel requirements were similar to those for the R975 engine. The total volume of the fuel tanks was reduced to 636 liters.
The transmission of the ACS M7 consisted of: a two-disc semi-centrifugal main dry friction clutch (type D78123), a propeller shaft, a mechanical five-speed (5 + 1) gearbox, a double differential swing mechanism, belt side brakes, single-row final drives of the type with chevron gears (gear number 2.84: 1).
On each side, the undercarriage of the M7 self-propelled unit consisted of 6 rubberized single-sided road wheels (diameter 508 mm), 3 supporting rubberized rollers, a sloth and a drive wheel equipped with removable gear rims. The suspension of the VVSS type road wheels was interlocked in pairs. Two balancers with road wheels fixed on them, pivotally connected to the suspension bogie body, are connected through sliding supports with a rocker arm, through a buffer platform connected to an elastic element in the form of two conical springs located along the tank axis. A carrier roller was attached to the suspension bogie body. The balancer, when the suspension is operating through the sliding platform, raises the end of the rocker arm, through the buffer platform compressing the springs and evenly distributes the load to both rollers. The first M7s were equipped with D37893 suspension bogies, but in December 1942, SPGs began to be equipped with reinforced D47527 bogies. The main difference is that the carrier roller is not positioned above the center of the bogie, but above the rear track roller.
Steel tracks M7 fine-link, pinned engagement, rubber-metal hinge consisted of 79 tracks (width - 421 mm, pitch - 152 mm) each. On the M7 ACS, 4 models of tracks were used: with rubberized tracks with a chevron - T48, with steel tracks with grousers - T49, with flat rubberized tracks - T51, with steel tracks with a chevron - T54E1.
The main armament of the M7 ACS was a modified 105 mm M2A1 howitzer. The barrel length of the M2A1 was 22.5 caliber. The howitzer had hydropneumatic recoil devices and a manual horizontal wedge breech. Howitzer recoil length was 1066 mm. The gun was placed in the frontal part of the hull (offset to the starboard side) on a standard field gun carriage. This placement of the gun in a self-propelled gun limited the maximum vertical guidance angles to -5 … + 35 degrees and in the horizontal plane on the left side to 15 degrees and on the right to 30 degrees. Guidance was carried out using manual screw mechanisms. When firing direct fire, the gun was guided using an M16 periscopic optical sight, firing from closed positions was carried out using the M4 quadrant and the M12A2 artillery panorama.
105 mm howitzer M2A1
When firing, the crew's functions were distributed as follows: the commander carried out the general management of the crew, the driver held the self-propelled gun brakes when firing a shot, the gunner carried out horizontal guidance and amendments, No. 1 of the crew operated with vertical guidance of the gun and the bolt, No. No. 3 and 4 installed the fuse and changed the charge, and also fired with a periscopic sight when firing direct fire.
With continuous firing, the rate of fire of the gun in the first minute and a half of firing was 8 shots per minute, in the first four minutes - 4 shots and in the first 10 minutes - 3 shots. Within an hour, the gun could fire up to 100 shots. The maximum firing range of smoke and high-explosive fragmentation projectiles was 10,424 m.
On the early M7 self-propelled guns, the ammunition consisted of 57, and on the subsequent ones - 69 shots. The ammunition load included smoke and high-explosive fragmentation shells, as well as cumulative shells that pierced 102-mm homogeneous steel armor. For the M2A1 howitzer, semi-unit shots were used for various types of ammunition, except for cumulative, which used unitary shots with a fixed charge. Of the 69 shots, 19 and 17 were located in the left and right sponsons of the corps, the remaining 33 - under the floor of the fighting compartment in boxes. Also, the self-propelled gun could tow the M10 trailer, which carried an additional 50 rounds.
First T32 prototype being tested at Fort Knox
As an auxiliary weapon of the M7 ACS, a 12, 7-mm M2HB anti-aircraft machine gun was used, located in an annular turret mount, which provided circular fire. Machine gun ammunition - 300 rounds placed in 6 belts loaded in the magazine-box. Initially, the belts were loaded with 90% armor-piercing and 10% tracer bullets. Subsequently, this ratio was changed by 80/20 percent. For self-defense, the crew had three 11, 43 mm M1928A1 or M3 submachine guns with 1620 rounds in 54 box magazines. In addition, there were hand grenades: two Mk. II fragmentation grenades and six smoke grenades.
On the march, the driver of the M7 self-propelled guns observed the terrain through the inspection hatch, on which a removable windshield was installed. For review during the battle, a prismatic viewing device mounted in the hatch cover was used. The rest of the crew did not have special surveillance equipment, except for sighting devices. Also in the M7 there were no special means of internal communication, means of external communication - the signal flags Flag Set M238. The ACS was also equipped with Panel Set AP50A signal signs. The M7 fire control center at equipped firing positions was usually contacted by laying field telephones. In the British troops "Priest", thanks to the reduction in ammunition by 24 rounds, could be equipped with a radio station for external communication.
For extinguishing fires, the M7 was equipped with a stationary single-action carbon dioxide manual fire-extinguishing system, which consisted of two 5, 9-liter cylinders installed in the fighting compartment under the floor and connected by pipes with nozzles located in the engine compartment. Also, the self-propelled gun was equipped with two portable fire extinguishers, which contained 1.8 kg of carbon dioxide and were placed in the sponsons of the corps. The set of ACS also included three 1, 42-kg degassing devices M2.
At one time, the M7 self-propelled guns interested the leadership of the British army. The British, having barely seen the "pilot" model, ordered 5,500 units. The British tank mission ordered the first 2,500 M7 self-propelled guns in the United States in March 1942. Their delivery was to be carried out before the end of 1942. Another 3,000 self-propelled guns were supposed to arrive during the 1943 year. But the priority in obtaining self-propelled artillery mounts belonged to the American army, in connection with which the British were unable to obtain the desired number of M7s. In September 1942, the British received the first 90 M7 self-propelled guns. The British renamed the M7 to "105mm SP, Priest" (Priest, priest). The vehicles entered the artillery battalions of the tank divisions. The main task of "Priest" was the implementation of fire support from remote positions in the advance of infantry and armored vehicles. In this regard, the armor protection of the self-propelled gun was no more than 25 mm and protected only from shrapnel and bullets.
Self-propelled guns M7 in November 1942 took part in the 5th regiment of the Royal Horse Artillery in the battle of El Alamein. This battle led to the defeat of the German troops in the desert. In 1943, these self-propelled guns as part of the 8th Army participated in the landing in Italy. By this time, the British army received an additional 700 vehicles, some of which were used for operations in Normandy.
In 1942, the British General Staff ordered the creation of its own support ACS based on the M7. The American 105mm gun was replaced with an 87.6mm howitzer. Having considered possible options for modernization, we chose the chassis of the Ram tank as a basis, having mounted a new armored wheelhouse on it. The driver's workplace was shifted to the right, and the gun mount was shifted to the left. Due to the tightness of the fighting compartment, a small amount of ammunition was placed near the left side, and the anti-aircraft machine gun had to be removed. An experienced self-propelled gun was assembled at the end of 1942 at the Montreal Locomotive Works. The car was immediately sent to the UK for testing. In 1943, the serial production of the self-propelled unit under the name "Sexton" began. By the end of 1943, 424 vehicles had been built, until the spring of 1945 (production was discontinued) 2,150 SPGs had been delivered, with the last lots used the chassis of an M4 medium tank. "Sexton" gradually supplanted the American M7, but in service with the British army, both self-propelled guns remained after the end of the war.
ACS M7 in the summer of 1944 began to be gradually replaced with self-propelled artillery mounts "Sexton". In part, the abandonment of the M7 self-propelled artillery mounts was motivated by the desire to unify the supply of ammunition. British engineers took the M7 as a basis for the development of the Priest OP and Priest Cangaroo armored personnel carriers. The howitzer was dismantled from the M7, the frontal embrasure was closed with armor plates, and the compartment was equipped to transport 20 people. The American army willingly used the M7 during the fighting on the Western Front, but in January 1945 they were transferred to the second line and replaced by the M37 self-propelled artillery mounts.
ACS M7 in the post-war period were in service in the American army, as well as in some other states. M7 took part in the Korean War. During the 1967 Arab-Israeli war, these self-propelled guns were used by the Israel Defense Forces.
Israel received 36 M7 Priest self-propelled guns in 1959, and the following year, 40 more of these self-propelled guns arrived without guns. Apparently, the hulls of the latter were used in the production of 160-mm self-propelled mortars and / or 155-mm self-propelled artillery units. ACS "Priest" were in service with three divisions - the regular "Shfifon" (previously armed with self-propelled guns AMX Mk 61) and two reservist (including the 822nd). In total, at the beginning of the 1960s, Israel had 5 divisions armed with 105-mm self-propelled artillery mounts (2 Mk 61 and 3 Priest), one of which was the regular Shfifon.
Self-propelled guns "Priest" were used in the Battle of Water 1964-1965, the Six-Day War of 1967 and the War of Attrition 1969-1970 (at that time all these self-propelled guns were already in reserve). It is known that on July 26, 1969, during an attack by Egyptian aircraft on the position of the Bet battery of the 822th battalion of the 209th artillery regiment, two Priest self-propelled guns were destroyed.
Two divisions "Priest" in 1973 fought on the Syrian front - in the 213rd and 282nd artillery regiments of the 146th and 210th divisions. Soon after the war, both divisions were re-equipped with M107 SPGs, and all Priest self-propelled guns were transferred to storage.
The story of the use of the Priest self-propelled guns in the Israel Defense Forces did not end there.
In April 1974, Rafael Eitan (Raful) became the commander of the SVO, who paid much attention to strengthening the territorial defense. Among other vehicles, there were 10 Priest self-propelled guns, which were withdrawn from warehouses and re-equipped. The transmission and engines were removed from the self-propelled guns, replacing them with additional ammo rack. The vehicles were installed in pairs in 5 settlements in order to fire at pre-selected critical targets, such as the Jordan crossings. It is unclear how long the Priest was maintained in working order - probably until the August 1978 change in NWO commander. It is possible that these 10 SPGs did not leave their positions for a long time.
According to Jane's, Israel had 35 M7 Priest in 2003, which were in the column "in service", according to IISS 34 such self-propelled artillery mounts were listed in the Israel Defense Forces until 1999/2000 inclusive. For 2008, Priest was no longer on Jane's lists.
In the Israel Defense Forces, this self-propelled gun did not have a special name, and was designated "TOMAT Priest".
Specifications:
Combat weight - 22, 9 tons.
Crew - 7 people.
Production - 1942-1945.
The number of issued - 4316 pcs.
Body length - 6020 mm.
Case width - 2870 mm.
Height - 2946 mm.
Clearance - 430 mm.
Armor type: cast homogeneous and rolled steel.
Body forehead - 51 … 114 mm / 0 … 56 deg.
Hull side - 38 mm / 0 deg.
Hull feed - 13 mm / 0 deg.
The bottom is 13-25 mm.
Cutting forehead - 13 mm / 0 deg.
Cutting board - 13 mm / 0 deg.
Cutting feed - 13 mm / 0 deg.
The roof of the cabin is open.
Armament:
105-mm howitzer M2A1 with a barrel length of 22.5 calibers.
Angles of vertical guidance - from -5 to +35 degrees.
Angles of horizontal guidance - from -15 to +30 degrees.
The firing range is 10, 9 km.
Gun ammunition - 69 shots.
12.7 mm machine gun M2HB.
Sights:
Telescopic sight M16.
Panoramic sight M12A2.
Engine - 9-cylinder radial air-cooled carburetor with a capacity of 350 hp. with.
Highway speed - 38 km / h.
In store down the highway - 190 km.
Prepared based on materials:
