M107 Self-Propelled Gun
Encyclopedia
The M107 175 mm self-propelled gun was used by the U.S. Army from the early 1960s through to the late 1970s. It was part of a family of self-propelled artillery that also included the M110
and was intended to provide long-range fire support in an air-transportable system. It was exported to several other countries including Germany, South Korea, Spain, Greece, Iran, Israel, Italy, the Netherlands, the United Kingdom, and Turkey. The M107's combat history in U.S. service was limited to the Vietnam War
and also saw extensive combat use in Israeli service. The M107 was the last self-propelled gun (high velocity, low trajectory, long range) in the U.S. Army inventory. It shared many components with, and in many cases was replaced by later versions of, the M110. Although withdrawn from U.S. service in the late 1970s it continues in service with some armies as of 2010.
, which used some components from the M48
tank. The weight of the M55, at 44 metric tons, prohibited air transportation and its gasoline engines limited its range to approximately 260 km, as well as presenting an explosion hazard in combat.
This led the U.S. Army to issue a requirement for a new series of self-propelled artillery: lighter to be transportable by air, while continuing the practice of deriving several vehicles from the same chassis which simplified maintenance and training. The Pacific Car and Foundry
(Paccar) company developed several prototypes. The 175 mm T235 self propelled gun and 203 mm T236 self-propeleld howitzer were driven by a diesel engine and, aside from the different armament, were essentially the same vehicle. They were introduced into U.S. Army service as the M107 and M110 in 1962 and 1963, respectively.
Paccar received the M107 and M110 design contracts and initial manufacturing single source bid from Detroit Arsenal. This based on patented key features of the M55: the gas equalibrator [2911209] balance of the barrel that hydraulically trimmed with terrain fall line sensing pendulum [2857815], no back pawl limits on aiming, parabolic taper hydraulic recoil cylinders [not patentable], and hydraulic lock out of suspension when shooting [3117800]. Two other firms also produced the M107: FMC, between 1965 and 1980, and Bowen-McLaughlin-York
.
Both the M107 and M110 use the same drive train components as the M578 Light Recovery Vehicle
. In addition to its use in performing maintenance on the M107 and M110, and for recovery of damaged or inoperable vehicles, this vehicle has seen wide use in a variety of engineering roles.
Many of the M107's were rebuilt into the M110A2 configuration.
turbo supercharged diesel with the turbocharger connected to the supercharger
by a steel pencil sized “quill” shaft. The engine and transmission are mounted in the front right with the driver to its left. The engine had an attached hydraulic pump used to traverse the turret with a manual backup hand crank.
The hydraulic pump was sometimes improperly used to dig in the rear spade, resulting in damage to the hydraulic spade cylinders after the first round was fired. The manual backup was used to lay the gun since the hydraulic control was too coarse. The primary purpose of the hydraulic pump was putting the barrel into battery, ramming ammunition and charges, raising or lowering the rear spade, rapid course deflection adjustment by the gunner and rapid course elevation adjustments by the assistant gunner.
Training Area, Germany, on a tank trail. This speed was also achieved in an M107 by the U.S. Army's Vilseck Maintenance Facility after replacing a broken torsion bar.
. This allows for faster reload times and its high maneuvering speed and fast reload time allows the M107 to practice shoot-and-scoot
, redeploying before the firing position can be zeroed in on.
One drawback of the M107 in combat was that laying the gun involves skilled minute movements of the entire vehicle. The gunner uses hand signals to the driver who views them in the left rear view mirror and moves the vehicle left or right by tapping on the steering bar. The other cannoneers set the collimeter and aiming stakes under the direction of the gunner.
Only two rounds are carried with its gun tractor on "loading trays". These rounds can be fired by the onboard crew of five (Section Chief, Driver, Gunner, Assistant Gunner, Number One Cannoneer) of the crew of thirteen. The rest of the ammunition and crew follow in the M548 Ammunition Carrier. If the gun was facing hostile artillery the gun would fire and relocate where these crewmen would reload the M107 at the new location to avoid counter-battery fire.
Each member of the M107 crew has specific duties when the vehicle is firing:
The section chief operates the hydraulic load and ram, verification with "gunner's quadrant", as well as operating the rear spade and left spade unlock. The driver operates the positions spade and the barrel travel lock. The gunner controls deflection (the horizontal direction in which the gun is pointing). The assistant gunner controls elevation. The number one cannoneer opens and closes the breech, verifies ramming of the round with ram rod and powder load red on the rag (which means he can see the red igniter patch to verify that the powder is not put in backwards), loads the primer, hooks up the lanyard (pig tail), pulls lanyard on command, and unlocks the right spade lock. Cannoneers two through nine set up the collimeter, aiming stakes, bore sight (in direct fire missions only), communications, prepare additional ammunition (including fuzing) and powder zones, provide security, drive the M548, operate the ring-mounted M2
.50 caliber machine gun, set up camouflage nets, dig a burn pit, and conduct the resupply of ammunition
Early barrels were limited to 300 firings with the maximum zone 3 propellant but later examples extended this to between 700 and 1,200 firings with extensive bore scoping by the supporting ordnance company.
Retubing the barrel was necessary when the barrel had exhausted its service life or when converting the M107 to an M110. In U.S. Army service the lowest level of retube was done at the artillery battalion's maintenance shop. Retubing could also be done by Ordnance Depot Support Units or at fixed depots such as Anniston Army Depot
, Picatinny Arsenal
, or the Miesau Army Depot in Germany. When retubing was done at the battalion level the M578 Light Recovery Vehicle
was used. The barrels could not be replaced using a single M578 due to weight and the need for precise placement of the barrel into the cradle to prevent damaging the barrel brass runners. Two cranes were used – one on either end of the barrel. A single M578 was used to lift the engine or transmission from the hull once a month to clean the engine and transmission compartment which was covered by two aluminum deck plates. Retubing could also be used to convert the 175 mm M107 to the 203 mm (8 inch) M110. This retubing was usually accomplished by the supporting ordnance company or a fixed depot as it requires an overhead electric rail winch and chassis modifications for the E2 barrel.
.
The M107 also had disadvantages. In addition to its long range it was also noted for its inaccuracy at longer ranges. The gun was assigned to corps artillery units and a number of M107/M110 composite units were formed allowing the option of responding with the longer range M107 or the more accurate M110. In addition, as noted above, the tube on the M107 required changing frequently on early versions. Individual batteries did not have the necessary support equipment for changing the tube so higher-level maintenance support was required.
The M107 was also used by the Israel Defense Forces
in the various Arab–Israeli conflict
s. When these guns were outranged by rocket fire from Tyre, they were upgraded with the addition of extended range, full bore ammunition and new powder supplied by Gerald Bull
's Space Research Corporation
. This allowed operations over 50 km with increased accuracy.
The M107 was retired from the U.S. Army in the late 1970s but it continues to see use in many armies around the world.
.: Israel Defense Forces
.: Republic of Korea Army
. Out of service since 2008.: Turkish Army
.: Spanish Army
. 12, converted to M110A2 in the early 1990s.: United States Army
and United States Marine Corps
.: Royal Artillery
.
M110 howitzer
The 8 inch Self-Propelled Howitzer M110 was the largest available self-propelled howitzer in the United States Army's inventory. It was deployed in division artillery in general support battalions and in separate corps- and Army-level battalions. Missions include general support, counter-battery...
and was intended to provide long-range fire support in an air-transportable system. It was exported to several other countries including Germany, South Korea, Spain, Greece, Iran, Israel, Italy, the Netherlands, the United Kingdom, and Turkey. The M107's combat history in U.S. service was limited to the Vietnam War
Vietnam War
The Vietnam War was a Cold War-era military conflict that occurred in Vietnam, Laos, and Cambodia from 1 November 1955 to the fall of Saigon on 30 April 1975. This war followed the First Indochina War and was fought between North Vietnam, supported by its communist allies, and the government of...
and also saw extensive combat use in Israeli service. The M107 was the last self-propelled gun (high velocity, low trajectory, long range) in the U.S. Army inventory. It shared many components with, and in many cases was replaced by later versions of, the M110. Although withdrawn from U.S. service in the late 1970s it continues in service with some armies as of 2010.
Design and Production History
During the 1950s the standard of US Army motorized 203mm artillery was the M55, based on the chassis and the turret of the M53 155mm Self-Propelled GunM53 155mm Self-Propelled Gun
M55 was an American fully enclosed and armored self-propelled artillery based on the M53 155 mm assault gun. It had a traversable, to a certain degree - 30° left or right, turret armed with a 203.2 mm howitzer, carrying only 10 rounds of ammunition. The gun had a maximum range of 16,916 meters with...
, which used some components from the M48
M48 Patton
The M48 Patton is a medium tank that was designed in the United States. It was the third and final tank to be officially named after General George S. Patton, commander of the U.S. Third Army during World War II and one of the earliest American advocates for the use of tanks in battle It was a...
tank. The weight of the M55, at 44 metric tons, prohibited air transportation and its gasoline engines limited its range to approximately 260 km, as well as presenting an explosion hazard in combat.
This led the U.S. Army to issue a requirement for a new series of self-propelled artillery: lighter to be transportable by air, while continuing the practice of deriving several vehicles from the same chassis which simplified maintenance and training. The Pacific Car and Foundry
PACCAR
PACCAR Inc is the third largest manufacturer of heavy-duty trucks in the world , and has substantial manufacture in light and medium vehicles through its various subsidiaries.-History:...
(Paccar) company developed several prototypes. The 175 mm T235 self propelled gun and 203 mm T236 self-propeleld howitzer were driven by a diesel engine and, aside from the different armament, were essentially the same vehicle. They were introduced into U.S. Army service as the M107 and M110 in 1962 and 1963, respectively.
Paccar received the M107 and M110 design contracts and initial manufacturing single source bid from Detroit Arsenal. This based on patented key features of the M55: the gas equalibrator [2911209] balance of the barrel that hydraulically trimmed with terrain fall line sensing pendulum [2857815], no back pawl limits on aiming, parabolic taper hydraulic recoil cylinders [not patentable], and hydraulic lock out of suspension when shooting [3117800]. Two other firms also produced the M107: FMC, between 1965 and 1980, and Bowen-McLaughlin-York
United Defense
United Defense Industries was a United States defense contractor which is now part of BAE Systems Land and Armaments. This company produces combat vehicles, artillery, naval guns, missile launchers and precision munitions.-History:...
.
Both the M107 and M110 use the same drive train components as the M578 Light Recovery Vehicle
M578 Light Recovery Vehicle
M578 Light Recovery Vehicle was a US Cold War era armored recovery vehicle. The M578 utilized the same chassis as M107 Self-Propelled Gun and M110 Self-Propelled Howitzer. The M578 provided maintenance support to mechanized infantry and artillery units...
. In addition to its use in performing maintenance on the M107 and M110, and for recovery of damaged or inoperable vehicles, this vehicle has seen wide use in a variety of engineering roles.
Many of the M107's were rebuilt into the M110A2 configuration.
Chassis
Both the M107 and M110 are based on a common chassis which features five road wheels on either side of the chassis with idler arms attached to torsion bars, tracks driven from the front by a 450 hp General MotorsGeneral Motors
General Motors Company , commonly known as GM, formerly incorporated as General Motors Corporation, is an American multinational automotive corporation headquartered in Detroit, Michigan and the world's second-largest automaker in 2010...
turbo supercharged diesel with the turbocharger connected to the supercharger
Supercharger
A supercharger is an air compressor used for forced induction of an internal combustion engine.The greater mass flow-rate provides more oxygen to support combustion than would be available in a naturally aspirated engine, which allows more fuel to be burned and more work to be done per cycle,...
by a steel pencil sized “quill” shaft. The engine and transmission are mounted in the front right with the driver to its left. The engine had an attached hydraulic pump used to traverse the turret with a manual backup hand crank.
The hydraulic pump was sometimes improperly used to dig in the rear spade, resulting in damage to the hydraulic spade cylinders after the first round was fired. The manual backup was used to lay the gun since the hydraulic control was too coarse. The primary purpose of the hydraulic pump was putting the barrel into battery, ramming ammunition and charges, raising or lowering the rear spade, rapid course deflection adjustment by the gunner and rapid course elevation adjustments by the assistant gunner.
Key recognition features
- Long thin barrel without a fume extractor or muzzle brake.
- Gun is in an unprotected mount towards the rear of the hull with a large spade at the rear that is raised for traveling.
- Chassis is same as M110 203 mm self-propelled howitzer with five large road wheels on each side, a drive sprocket front wheel and has no track-return rollers.
Performance
The top speed recorded by one M107 driver was 50 mph at the GrafenwöhrGrafenwöhr
Grafenwöhr is a town in the district Neustadt , in the region of the Upper Palatinate in eastern Bavaria, Germany. It is widely known for the United States Army military installation and training area, called Grafenwöhr Training Area, located directly south and west of the town.- Early History:The...
Training Area, Germany, on a tank trail. This speed was also achieved in an M107 by the U.S. Army's Vilseck Maintenance Facility after replacing a broken torsion bar.
Operations and maintenance
The M107 has a larger open working space than the closed space of tank-like self-propelled artillery such as the M109 howitzerM109 howitzer
The M109 is an American-made self-propelled 155 mm howitzer, first introduced in the early 1960s. It was upgraded a number of times to today's M109A6 Paladin...
. This allows for faster reload times and its high maneuvering speed and fast reload time allows the M107 to practice shoot-and-scoot
Shoot-and-scoot
The term shoot and scoot refers to an artillery tactic of firing at a target and then immediately moving away from the location where the shots were fired. The reason for this is to avoid counter-battery fire - fired by enemy artillery or delivered by attack aircraft and helicopters, in order to...
, redeploying before the firing position can be zeroed in on.
One drawback of the M107 in combat was that laying the gun involves skilled minute movements of the entire vehicle. The gunner uses hand signals to the driver who views them in the left rear view mirror and moves the vehicle left or right by tapping on the steering bar. The other cannoneers set the collimeter and aiming stakes under the direction of the gunner.
Only two rounds are carried with its gun tractor on "loading trays". These rounds can be fired by the onboard crew of five (Section Chief, Driver, Gunner, Assistant Gunner, Number One Cannoneer) of the crew of thirteen. The rest of the ammunition and crew follow in the M548 Ammunition Carrier. If the gun was facing hostile artillery the gun would fire and relocate where these crewmen would reload the M107 at the new location to avoid counter-battery fire.
Each member of the M107 crew has specific duties when the vehicle is firing:
The section chief operates the hydraulic load and ram, verification with "gunner's quadrant", as well as operating the rear spade and left spade unlock. The driver operates the positions spade and the barrel travel lock. The gunner controls deflection (the horizontal direction in which the gun is pointing). The assistant gunner controls elevation. The number one cannoneer opens and closes the breech, verifies ramming of the round with ram rod and powder load red on the rag (which means he can see the red igniter patch to verify that the powder is not put in backwards), loads the primer, hooks up the lanyard (pig tail), pulls lanyard on command, and unlocks the right spade lock. Cannoneers two through nine set up the collimeter, aiming stakes, bore sight (in direct fire missions only), communications, prepare additional ammunition (including fuzing) and powder zones, provide security, drive the M548, operate the ring-mounted M2
M2 Machine Gun
The M2 Machine Gun, Browning .50 Caliber Machine Gun, is a heavy machine gun designed towards the end of World War I by John Browning. It is very similar in design to Browning's earlier M1919 Browning machine gun, which was chambered for the .30-06 cartridge...
.50 caliber machine gun, set up camouflage nets, dig a burn pit, and conduct the resupply of ammunition
Early barrels were limited to 300 firings with the maximum zone 3 propellant but later examples extended this to between 700 and 1,200 firings with extensive bore scoping by the supporting ordnance company.
Retubing the barrel was necessary when the barrel had exhausted its service life or when converting the M107 to an M110. In U.S. Army service the lowest level of retube was done at the artillery battalion's maintenance shop. Retubing could also be done by Ordnance Depot Support Units or at fixed depots such as Anniston Army Depot
Anniston Army Depot
Anniston Army Depot is a major United States Army facility fulfilling various depot operations. Primary missions are the repair of tracked vehicles and storage of chemical weapons . The depot is located in Bynum, Alabama....
, Picatinny Arsenal
Picatinny Arsenal
The Picatinny Arsenal is an American military research and manufacturing facility located on a lot in northern New Jersey near Lake Denmark. The Arsenal is the headquarters of the United States Army Armament Research, Development and Engineering Center...
, or the Miesau Army Depot in Germany. When retubing was done at the battalion level the M578 Light Recovery Vehicle
M578 Light Recovery Vehicle
M578 Light Recovery Vehicle was a US Cold War era armored recovery vehicle. The M578 utilized the same chassis as M107 Self-Propelled Gun and M110 Self-Propelled Howitzer. The M578 provided maintenance support to mechanized infantry and artillery units...
was used. The barrels could not be replaced using a single M578 due to weight and the need for precise placement of the barrel into the cradle to prevent damaging the barrel brass runners. Two cranes were used – one on either end of the barrel. A single M578 was used to lift the engine or transmission from the hull once a month to clean the engine and transmission compartment which was covered by two aluminum deck plates. Retubing could also be used to convert the 175 mm M107 to the 203 mm (8 inch) M110. This retubing was usually accomplished by the supporting ordnance company or a fixed depot as it requires an overhead electric rail winch and chassis modifications for the E2 barrel.
Combat history
The M107's combat experience with the U.S. military was almost entirely limited to the Vietnam War. There it proved its effectiveness by having one of the longest ranges of any mobile artillery piece operated during the Cold War. The M107 was able to launch a 147 lb (67 kg) projectile out to 21 miles (34 km), at 0 deflection and 800 mil (45°) elevation. This range advantage, along with the ability to rapidly move from its last position, made it an effective weapon for destroying North Vietnamese Army and Viet Cong command, control, communications facilities and supply trains while evading counter-battery fire from the longest-range Soviet counterparts. This was proven in 1968 at Khe SanhBattle of Khe Sanh
The Battle of Khe Sanh was conducted in northwestern Quang Tri Province, Republic of Vietnam , between 21 January and 9 July 1968 during the Vietnam War...
.
The M107 also had disadvantages. In addition to its long range it was also noted for its inaccuracy at longer ranges. The gun was assigned to corps artillery units and a number of M107/M110 composite units were formed allowing the option of responding with the longer range M107 or the more accurate M110. In addition, as noted above, the tube on the M107 required changing frequently on early versions. Individual batteries did not have the necessary support equipment for changing the tube so higher-level maintenance support was required.
The M107 was also used by the Israel Defense Forces
Israel Defense Forces
The Israel Defense Forces , commonly known in Israel by the Hebrew acronym Tzahal , are the military forces of the State of Israel. They consist of the ground forces, air force and navy. It is the sole military wing of the Israeli security forces, and has no civilian jurisdiction within Israel...
in the various Arab–Israeli conflict
Arab–Israeli conflict
The Arab–Israeli conflict refers to political tensions and open hostilities between the Arab peoples and the Jewish community of the Middle East. The modern Arab-Israeli conflict began with the rise of Zionism and Arab Nationalism towards the end of the nineteenth century, and intensified with the...
s. When these guns were outranged by rocket fire from Tyre, they were upgraded with the addition of extended range, full bore ammunition and new powder supplied by Gerald Bull
Gerald Bull
Gerald Vincent Bull was a Canadian engineer who developed long-range artillery. He moved from project to project in his quest to launch economically a satellite using a huge artillery piece, to which end he designed the Project Babylon "supergun" for the Iraqi government...
's Space Research Corporation
Space Research Corporation
Space Research Corporation was a corporation founded by Gerald Bull, after the budget for his research at Project HARP for the United States and Canadian federal governments was cut in 1967, in order to commercialize the technology of long-range artillery. Project HARP's assets were then given to...
. This allowed operations over 50 km with increased accuracy.
The M107 was retired from the U.S. Army in the late 1970s but it continues to see use in many armies around the world.
Users
: Belgian Land Component. 8 M110's used by the 20th Artillery from 1979 and out service since 1993 because termination of the unit.: Islamic Republic of Iran ArmyIslamic Republic of Iran Army
The Islamic Republic of Iran Army is the ground force of the Military of Islamic Republic of Iran. In Iran, it is also called Artesh, which is Persian for "army." As of 2007, the regular Iranian Army was estimated to have 465,000 personnel plus around 350,000 reservists for a total of 815,000...
.: Israel Defense Forces
Israel Defense Forces
The Israel Defense Forces , commonly known in Israel by the Hebrew acronym Tzahal , are the military forces of the State of Israel. They consist of the ground forces, air force and navy. It is the sole military wing of the Israeli security forces, and has no civilian jurisdiction within Israel...
.: Republic of Korea Army
Republic of Korea Army
The Republic of Korea Army is the largest of the military branches of the South Korean armed forces with 520,000 members as of 2010...
. Out of service since 2008.: Turkish Army
Turkish Army
The Turkish Army or Turkish Land Forces is the main branch of the Turkish Armed Forces responsible for land-based military operations. The modern history of the army began with its formation after the collapse of the Ottoman Empire...
.: Spanish Army
Spanish Army
The Spanish Army is the terrestrial army of the Spanish Armed Forces responsible for land-based military operations. It is one of the oldest active armies - dating back to the 15th century.-Introduction:...
. 12, converted to M110A2 in the early 1990s.: United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...
and United States Marine Corps
United States Marine Corps
The United States Marine Corps is a branch of the United States Armed Forces responsible for providing power projection from the sea, using the mobility of the United States Navy to deliver combined-arms task forces rapidly. It is one of seven uniformed services of the United States...
.: Royal Artillery
Royal Artillery
The Royal Regiment of Artillery, commonly referred to as the Royal Artillery , is the artillery arm of the British Army. Despite its name, it comprises a number of regiments.-History:...
.
See also
- G-numbers (SNL G295)
- List of U.S. military vehicles by model number