240mm Caterpillar Mark IV

1920 SELF-PROPELLED ARTILLERY WORLD WAR 2

• 1 History of the 240mm Caterpillar Mark IV
• 2 240mm Caterpillar Mark IV Specification
  • 2.1 Basic
  • 2.2 Roles
  • 2.3 Dimensions
  • 2.4 Performance
  • 2.5 Performance
  • 2.6 Armor
  • 2.7 Changes

History of the 240mm Caterpillar Mark IV

During World War I, U.S. Army authorities concluded that towed guns fit their current battlefield doctrine.

However, large howitzers and similar artillery systems require several "mobile" vehicles (tractors or large trucks) to transport them, and the operator requires a lot of time to prepare these weapons, which negates most of their tactics in a sense value. Making the artillery system self-propelled is the main solution, as it requires less personnel and time to transport and set up the artillery firing position.

One such machine is the Caterpillar Mk IV, born as a single-person vehicle to power a large-caliber 240mm howitzer.

The 240 mm, 9.5 inch M1918 Schneider Howitzer of French origin was the largest field gun used by the U.S. Army Field Artillery during World War I and was a huge success.

Originally a towed artillery piece, the gun was originally designed during World War I and has since been updated several times to improve effectiveness and keep the type modern to meet the needs of the current battlefield. The 9.5-inch barrel fires a 356-pound shell, powered by a 49-pound TNT bag, with a range of up to 14,000 yards (about 10 miles) when fired.

The M1918 gun was towed by no less than 6 tractors in separate major components and required a crew of 20 to transport, install and operate. In a combat situation, the crew must set up the artillery system under cover of darkness, which also requires reconnaissance and extensive training on the ground, such as the use of six tractors and the many hours it takes to set up the artillery during the general day can cause enemy artillery fire.

Lots of attention. When the exact firing location was found, a seven-person management team first used surveyor rounds on site to plan the battery pit. Then, if the soil proves to be fair, crews use traditional picks and shovels to dig a 7-by-6-by-3-foot pit within three hours.

It took another 12 hours and a crew of 20 to complete the weapon setup.

First, place a metal base into the prepared pit and install steel ramps on both sides of the pit to spread the weight of the system. Next came the tractor towing the target mount, then another tractor that brought the recoil mechanism, and finally another transporter towing the 11,000-pound barrel. The gun wheels alone weigh 1,000 pounds each.

When complete, the entire weapon system weighs an impressive 39,920 pounds. As can be seen, the huge expense makes the self-propelled version very popular.

The Caterpillar Mark IV developed in 1920 did not use a "real" tank chassis, but instead relied on a tractor chassis weighing approximately 31,580 pounds with an 11,000-pound barrel and a suitable firing system. This tractor is based on the French design of the Saint-Chamont company. All told, the finished Caterpillar vehicle is over 71,500 pounds. A 150-horsepower engine drives a 400-volt, 70-kilowatt alternator, which in turn drives the 70-horsepower electric motor needed to move the rail system. Cranes attached to the rear of the artillery platform help lift each 356-pound shell from the waiting ammunition cart.

The arm then rotates the projectile into position on the loading tray. The main tractor can transport a crew of seven. The test took place at the Aberdeen Proving Ground in Maryland in 1921.

As a pusher, the engine/engine arrangement of the tractor chassis proves underpowered, with a top speed of just 9 mph and only under ideal conditions. A second tractor (without gun and stand), called "Mark IV-A", was mounted on the rear of the prime mover to increase speed on open terrain. While towing the vehicle itself is an option, it defeats the purpose of its "self-propelled" nature.

As such, the Mk IV concept was ultimately deemed insufficient and was later removed from the US Army's requirements after six were completed.

The concept of a large-caliber self-propelled gun was tested again during World War II, with a 240mm howitzer mounted on the tracked chassis of the T26E3 heavy tank in 1944. Due to the excessive weight, an additional wheeled bogie had to be installed on each side of the track. Although the war ended in September 1945, this new variant became the "T92 Howitzer Carriage".

The T92 HMC was never used in combat and was later scrapped with the US Army's dream of a large caliber SPG. Similar weapons concepts within Germany and the Soviet Union also failed during the war.

240mm Caterpillar Mark IV Specification

Basic

Roles

Dimensions

Performance

Performance

Armor

Depends on the ammunition carrier. 345 lb HE round and 40 lb TNT charge.

Changes