How "Caterpillar" Fights World War II   War and Peace - Caterpillar 
Caterpillar Tractor Company in World War Two
Peoria, IL
1925 - Present (As Caterpillar)

This page updated 6-20-2023.

Caterpillar's main product line and its greatest contribution to the winning of World War Two was its crawler type tractors; the D2, D4, D6, D7, and D8.  Between 1942 and the end of 1945, the company produced 56,306 of these tracked vehicles. They were used extensively by US Army Engineering Battalions and the US Navy Construction Battalions, better known as the Seabees.  While Caterpillar contributed to the war effort with several other products, such as tank transmissions and gun carriages to name two.  If it had not produced them, it would not have affected the war effort in an appreciable way.  If Caterpillar had not produced the 56,306 crawler tractors, the war effort would have been severely hindered, and the war could have lasted longer than it did.

World War Two has been called the first war where air power made a huge impact.  Strategies by the American military revolved around seizing territory and building airfields and bases of operation for aircraft to attack deeper into enemy territory.  Then it moved forward and kept repeating the process, with the final goal being the invasions of Germany and Japan to bring unconditional surrender.  In order for World War Two to be an airpower war, it was first of all a construction war.  Caterpillar crawler tractors were instrumental in the US military's construction war, and the United States' not-so-secret weapon of World War Two. 

This vintage Caterpillar D7 tractor is on display in the early morning sun with a LeTourneau bulldozer on the front of the tractor and overhead cable system.  Caterpillar built 20,503 D7's during World War Two, which was 40% of the tractors it built from 1942-1945.  The Caterpillar D7 with a LeTourneau bulldozer but painted in olive-drab rather than Caterpillar yellow, was the iconic military crawler tractor-bulldozer combination of World War II.  Author's photo from the front of the Local 150 of the IUOE in Merrillville, IN.

Definition:  It should be noted that the vehicle in the photo is a not a bulldozer.  It is a crawler tractor with an attached bulldozer.  Technically the bulldozer is the blade attached to the front of the tractor.  During World War Two, Caterpillar built tractors.  Other companies, such as LeTourneau, built bulldozer blades and their control mechanisms, then installed them onto the Caterpillar tractors.  Both the US Army and US Navy list crawler tractors in their list of equipment, not bulldozers.  To most persons, including generals and admirals from World War Two, the entire tractor with the blade is a bulldozer.

Two of America's top military officers, General Eisenhower and Admiral Halsey, included the bulldozer in their respective lists of the most important weapons contributing to American military success during WWII. After World War II, each was quoted as having said the following:

A quote from "The Great Crusade" by General Dwight D. Eisenhower:  "Incidentally, four other  pieces of equipment that most senior officers came to regard as among the most vital to our success in Africa and Europe were the bulldozer, the jeep, the 2-1/2 - ton truck and the C-47 airplane."

Asked about the weapons used to win the war, Admiral Halsey offered:  "If I had to give credit to the instruments and machines that won us the war in the Pacific, I would rate them in this order:  Submarines first, radar second, planes third, bulldozers fourth."

Pre-World War Two:  The early history of Caterpillar is all about crawler type tractors.  While today's company produces a plethora of construction equipment and owns various other companies producing locomotives to gas turbines,  Caterpillar's main product lines going into World War II were tractors, road graders, and diesel-powered generator sets.  Caterpillar started making its own bulldozers in 1946. 

Between June 13, 2017, and June 20, 2018, the Caterpillar Visitor Center in downtown Peoria, IL displayed a collection of vintage tractors from the Veercamp Family Collection of California.  On display are the roots of the company, tractors with Holt and Best nameplates. Both companies produced crawler tractors in the early 20th Century; and were direct competitors.  In 1925, the two companies combined, resulting in the new company named the Caterpillar Tractor Company.   Author's photo.

The Mexican Punitive Expedition of 1916-1917:  Caterpillar may have one of the longest histories of providing equipment to the US military than any company currently still in business.  While the Mexican Punitive Expedition may be better known for the introduction of the airplane and the automobile for scouting purposes, the expedition was still primarily a horse cavalry operation.  Holt 75 crawler tractors pulled long wagon trains of hay to feed the horses.  This was the first use of crawler tractors for the US military, and the first for what in 1925 became Caterpillar.  

World War One:  World War One introduced the crawler tractor to the US Army on a mass scale, with 9,771 Holt tractors built by Holt and under license by five other companies.  Not only did the American forces use them, but England, France, and Russia also procured by them.

Historical note:  During both the Mexican Punitive Expedition and World War I, the Holt tractor was used in military service to pull wagons, artillery pieces, and other equipment behind the tractor.  At the time, both Holt and Best were suppliers of agricultural tractors, which pulled plows or other farm equipment behind the tractor.  It wasn't until the 1930's that Caterpillar switched from being an agricultural supplier to a construction equipment supplier when bulldozers were added to the front of tractor.

Best World War One Tractor Production:  A portion of 950 6-ton 1917 tanks.  Best Tractor shared production with Van Dorn Iron Works and Maxwell Motor for a contracted total of 4,440 tanks.  Then they were known as a Special Tractor, with production in 1918-1919.  With the end of the war, production ceased at 950. 

This 1917 6-ton tank is on display at Miller Park in Bloomington, IL.  It may very well have been built by Best Tractor.   Author's photo added 5-21-2018.

Holt World War One Tractor Production: 

This is a Reo-built Holt five-ton tractor.  The photo was taken at the former Ropkey Armor Museum.

The Holt T-35 was designed during World War One but did not begin production until after the war.  It was the last tractor designed by that company before it combined with Best to become Caterpillar.  This is the original prototype unit that is part of the year-long display at the Caterpillar Visitor Center.  When Caterpillar began business in 1925, this was its first product and in 1928 was renamed the Caterpillar Ten.  Author's photo.

Between the Wars:

This Best 1919 60 Tracklayer was on display until June 2018 at the Caterpillar Visitor Center in Peoria, IL.

The Caterpillar Twenty was the first new design of the new Caterpillar Company.  This particular unit was painted white instead of the normal Caterpillar gray; and was used as a sales and marketing tool at farm equipment expositions and state and county fairs.  Author's photo from the Caterpillar Visitor Center in Peoria, IL.

This Caterpillar 60 Logging Cruiser is in the gray and red trim paint the company was using in 1930.  Author's photo from the Caterpillar Visitor Center in Peoria, IL.

Caterpillar's Million Dollar Baby!  All of the tractors previously produced by Best, Holt, and Caterpillar had gasoline engines.  In the early 1930's, Caterpillar spent one million dollars ($15,892,558 in 2017 dollars) to develop the diesel engine.   By 1934 Caterpillar was the largest producer of diesel engines in the world.  This Model 65 was built in 1932 and was in the new Caterpillar yellow.  The company has revised the shade of yellow several times since 1932.  Today most construction equipment seen along the road, no matter the manufacturer, is painted some shade of yellow. Author's photo from the Caterpillar Visitor Center in Peoria, IL.

World War Two:

Three Caterpillar plants won the Army-Navy "E" Award during World War Two a total of seven times.

The East Peoria, IL Plant won the award on February 13, 1943, and added stars on May 24, 1944, November 25, 1944, and June 9, 1945.  This was Caterpillar's main plant.  The awards were for the timely production of crawler tractors.

The San Leandro, CA plant won the award on February 16, 1945, and added a star in August 1945.  This plant was the original plant operated by Daniel Best.  The plant made 37mm shells during WWII and was the supplier of diesel fuel injection components for Caterpillar's diesel engines.

The Caterpillar Military Engine Company, Decatur, IL plant won the award on June 26, 1945.  This plant was originally built to produce RD-1820 diesel tank engines.  In 1944 Decatur converted to D7 production, which was the product for which the plant won the award.

This Army-Navy "E" Award employee program and employee pin were on display for part of 2019 at the Caterpillar Visitor Center.  Author's photo added 11-4-2019.

Caterpillar had $570,578,000 in major war contracts during World War Two.

Caterpillar World War Two Products:  56,306 crawler tractors, wheeled tractors, road graders, 37 mm shells, carriages for 155 mm howitzers, M4 series tank transmissions and differentials, 120 RD-1820 radial diesel engines.

Crawler Tractors:  Caterpillar's most important contribution, as noted earlier, was its production of crawler tractors.  It was one of the few companies that continued its pre-war product during the war.  Its only change was to start painting the tractors olive-drab rather than Caterpillar yellow.

Uses:   The crawler tractor's versatility came from its different attachments.  Equipped with a bulldozer blade, it could push.  With a rear mounted winch, it could pull and tow.  With a hoist, it could lift.  By pulling a scraper, it could haul large amounts of dirt, coral, or rock.  It was able to fill bomb holes, push destroyed equipment off a road, clear rubble in bombed out towns, pull logs out of jungles and forests that were used to make bridges, knock down trees, build approaches to rivers for pontoon bridges, clear jungles and forests for airstrips, warehouses, tank farms, and barracks.  It was the construction equipment's  World War Two equivalent of the Swiss army knife. 

The Army Engineer Aviation Battalions Table of Organization and Equipment showed the following equipment list for tractors as of November 1942 consisted of:

Tractors:
Diesel, D-4, w/dozer   (3)
Diesel, D-4, w/dozer & trailer   (3)
Diesel, D-7, w/dozer    (3)  Later in the war another D-7 was added for a total of (4)
Diesel, D-8, w/dozer   (1)

Also listed is a:
Shovel:
Gasoline, 1/2 cu. yd.   (3)
push w/D-4 tractor       (3)  Apparently, the shovels were not able to move on their own power.

Interestingly, the tractors are being identified by their Caterpillar trade name, rather than their military nomenclature.
The D4 was a "Tractor, Light, M1," the D6 was a "Tractor, Medium, M1,", and a D7 was a "Tractor, Heavy, M1."  There was no military designation for the D2 or D8.

The US Navy Construction Battalions, or Seabees, in the Pacific built 400 varying types of naval bases during World War Two.  They also built 100 airstrips, 235,000 miles of roads, 700 acres of warehouses, housing for 1.5 million men, and storage tanks for 100 million gallons of gasoline.  Each Seabee Battalion was issued eight Caterpillar D8 tractors, which was one of the main tools to help them accomplish these huge achievements in just over three years.  Each Seabee Battalion also had four D7s, four D6s, and two D4s.  

Author's note:  Early Caterpillar tractors did not have electric cranking motors for starting the diesel engines.  Instead, they came equipped with a two-cylinder gasoline starting engine which was started by a pull rope or hand-crank.  The smaller D2s and D4s used pull ropes, while the larger D6s, D7s, and D8s used the hand-crank.  Once the gasoline engine was started, it would then engage the diesel engine to start it.  The gasoline starting engines were known as pony motors.  The use of the pony motors carried on with the Caterpillar tractors sold to the US military during WWII and into post war units.  This allowed the tractor to be started anywhere as long as gasoline was available to start the pony motor.  With the tractors working around the world in all sorts of environments, there was no need to worry whether the battery was dead and couldn't start the tractor.  Also, the pony motor would pre-warm the diesel in cold environments where diesels are hard to start.  Only the strong arm of a soldier or sailor was needed to pull-start or hand-crank the pony motor.  If the pony motor was well maintained and adjusted properly, it would start with one rope pull or one turn of the hand-crank.

Caterpillar started a new series of tractors when the serial numbers reached 9999. 

Author's Note and Disclaimer:  The Detroit Office of Ordnance of the U.S. Army was the primary purchasing entity for vehicles for the U.S. Army during World War Two.  It also purchased vehicles for the USMC, US Navy, and for Lend-Lease.  However, there were other organizations that also purchased vehicles including the Army Corps of Engineers, U.S. Army Air Force, U.S. Army Signal Corps, Navy Bureau of Ordnance, Navy Bureau of Aeronautics, and foreign countries making direct purchases.

*Starting in 1944, the Army Corps of Engineers became responsible for the purchase of low speed tractors which, until then, had been the domain of Army Ordnance.  Therefore, the totals for these types of tractors are incomplete.  At the same time, as noted above, other branches of the U.S. military were also making their own purchases, making the totals even more inaccurate.

Note the differences between the two above tables, indicating other parts of the U.S. Army and the U.S. Navy were also purchasing tractors.  Trying to determine how many units a company built for World War Two can be a challenge.

D2:  D3400 Diesel Engine with 25.5 hp

Photos below are of a Caterpillar D2 that served with the US Navy at its Dahlgren, VA proving ground.  Photos were taken at the 2018 World War Two Weekend at Reading, PA. 

The former Naval Proving Ground D2 has been repainted to represent a D2 used by the Seabees.  According to the information above, the Seabees did not use the D2 in their normal combat construction battalions.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

The brass tag on the D2 from the Naval Proving Ground shows it was serial number 76.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

The rope pull-starter for the two-cylinder gasoline pony motor can be plainly seen.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

Looking at the left side of the engine, the controls for the pony starting motor are visible along with its left side spark plug and spark plug wire.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

D4:  D4400 Four Cylinder Diesel Engine
Both of the Caterpillar D4s shown in this section are on display at Fort Leonard Wood, MO.  The first one is on Iowa Avenue in front of the First Engineering Brigade Headquarters building.  The second D4 is part of a diorama inside the Combat Engineer's Museum complex at Fort Leonard Wood.  US Army engineers utilized the D4 extensively during World War Two.

This D4 was built by Caterpillar in 1945 and is serial number 2T7307SP.  Author's photo added 6-19-2018.

This D4 is equipped with headlights for night operation.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

The generator for the headlights is at the front of the engine.  At the rear of the engine, one of the two spark plugs and spark plug wires can be seen on the pony starting motor.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

The pull rope pulley for starting the gasoline pony motor can be seen here.  Author's photo added 6-19-2018.

The four fuel injectors and the pony motor at the rear of the diesel can be seen.  Author's photo added 6-19-2018.

A Caterpillar D4 is seen pulling a load off of a Landing Craft, Medium, during a practice landing in the Pacific Theater.  This D4 does not have headlights for night operation. 

The diorama inside the Combat Engineer's Museum at Fort Leonard Wood depicts this Caterpillar D4 moving rubble out of the street.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

The headlights on this D4 have brush guards on them.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

This military D-4 was on display at the 2023 TBM Reunion and Salute to Veterans.  Several times during the day the owner used the gasoline-powered pony engine to start the diesel and then drove it around the airshow site.  Author's photo added 6-20-2023.  

The TBM Reunion takes place at the Peru, IL airport.  This D4 was photographed 52 miles from where it was built in Peoria, IL.  Author's photo added 6-20-2023.  

Author's photo added 6-20-2023.  

R4:  In theory, the U.S. Army did not have any R4 gasoline Caterpillar tractors, nor did Caterpillar produce any for the U.S. Army.  Research by Jeff Rowsam has found otherwise.  Below is one of several photos he found of a Cat R4 in use by the U.S. Army during World War Two.  In this case, the R4 is clearing ash from the eruption of the Mt. Vesuvius volcano in Italy.

This 1944 R4 is on display at the Seabee Museum in Davisville, RI.  It was built on 1-15-1944 and has a serial number of 604986.  While the Seabees had two D4s per battalion, it is unlikely that they would have been issued gasoline powered R4's when the rest of their tractors were diesel powered.  Caterpillar records don't show any R4's being built for the military during World War Two, and limited Army Ordnance records don't have any R4's included either.  However, photos like the one above show that the R4 was used by the U.S. Army.  The bulldozer blade is a LeTourneau Tiltdozer Model M.  Author's photo added 11-4-2019.


Author's photo added 11-4-2019.

Author's photo added 11-4-2019.

Author's photo added 11-4-2019.

Author's photo added 11-4-2019.

D6:  A total of 453 D6 tractors were modified in 1942-1943 as D6 High Speed Tractors, M1.  The modification allowed the D6 to function as a prime mover for artillery.  It could travel at 11 mph after changes to the engine governor and the gears in the transmission.

This post-WWII era Caterpillar D6 is on display at the U.S. Veterans Memorial Museum in Huntsville, AL.  It originally served with the US Army at the nearby Redstone Arsenal.  When retired, it was transferred to the Naval Mobile Construction Battalion (Seabees) located at Redstone.  It served as a static display with the Seabees until the unit was deactivated in 2013.  Author's photo added 3-22-2018.

This Caterpillar D6 was delivered to the US Army Corps of Engineers on October 4,1962.  Author's photo added 3-22-2018.

During World War Two each Seabee Battalion was equipped with four D6 tractors.  Author's photo added 3-22-2018.

D7:   D8800 engine 69 drawbar hp and 82 belt hp. 

The D7 in front of the Local 150 of the IUOE in Merrillville, IN is equipped with a LeTourneau straight dozer.  During World War Two, a large percentage of the Caterpillar tractors were fitted with LeTourneau bulldozers.  After being produced in Caterpillar's East Peoria plant, the tractors were transported across the Illinois River to the LeTorneau plant in Peoria, IL for outfitting with either a straight dozer, like the one installed on this D7, or an angle dozer.  The bulldozer on this D7 is a straight blade and cannot be angled.  The LeTourneau designation for this type of dozer is WEK7.  The designation for an angle dozer was WCK7.  The vintage of both the tractor and dozer are unknown, but both were probably built during or right after the war, because in 1946 Caterpillar began making and installing its own bulldozers on its tractors.  Author's photo.

 The overhead steel bar that carried the control cables from the rear control unit to the bulldozer was called the "headache bar" by the servicemen that operated the tractors.  During operations where bulldozer equipped tractors were pushing over coconut or other large trees in the Pacific, the "headache bar" offered the operator some protection when the tree fell back on the tractor.  Author's photo.

Mounted on the rear of the D7 is a LeTourneau R-7 power control with a double sheave assembly.  Author's photo.

This 1942 Caterpillar D7 is on display at the Seabee Museum in Davisville, RI.  Author's photo added 11-4-2019.

Author's photo added 11-4-2019.

Author's photo added 11-4-2019.

Author's photo added 11-4-2019.

Author's photo added 11-4-2019.


This 1951 Caterpillar D7 is on outdoor display at Fort Leonard Wood, MO.  It is shown pulling a J.D. Adams towed leaning wheel road grader.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

On the larger Caterpillar tractors like this D7, the pony starting motor was on the left side of the engine with the controls towards the rear.  The shaft coming down from the engine cover toward the front of the engine is part of the starting system for the pony motor.  The operator would get up the left track and insert the crank handle into the shaft through a hole in the engine cover.  The right-angle connection rotated the crank shaft of the pony motor.  The spark plugs and wires are visible on top of the pony motor.  Author's photo added 6-19-2018.

Author's photo added 6-19-2018.

The post-World War Two D7 series featured Caterpillar's own dozer attachments with the Caterpillar logo.  This one is a straight or "S" configuration.  Caterpillar also produced the front mounted No. 24 cable control.  The D7 has headlights with brush guards.  Author's photo added 6-19-2018.

This shows the right side of the engine on the D7.  Author's photo added 6-19-2018.

This tractor has a post-World War Two Caterpillar No. 25 double drum rear cable control.  Author's photo added 6-19-2018.

The serial number for this D7 is 3T 19549 and has a date of 6-28-1951.  Author's photo added 6-19-2018.

This Caterpillar D7E is on display at the Louisiana National Camp Beauregard Museum in Pineville, LA.  Author's photo added 3-22-2018.

 The D7E features a long stroke, low RPM, four-cylinder, turbo-charged engine.  This produces a very distinct sound when it runs.  This unit has a power shift transmission and standard hydraulics.  Author's photo added 3-22-2018.

 Caterpillar does not offer a heavy duty drag winch.  The Hyster Company supplied the winches for the Caterpillar D7 line of tractors.  The D7H is not the Caterpillar tractor model but the Hyster winch model number.  There was no Caterpillar D7H in this configuration.  Author's photo added 3-22-2018.

 The Roll Over Protection Structure or ROPS canopy was a post-production addition.  Most tractors supplied to the military did not have the ROPS when first issued.  Author's photo added 3-22-2018.

This post-World War Two armored D7F is on display at the Louisiana National Guard Museum at the Jackson Barracks in New Orleans.  Author's photo added 3-22-2018.

It was used by Company B, 527th Engineering Battalion of the Louisiana Army National Guard in Desert Storm.  Author's photo added 3-22-2018.

The Louisiana National Guard has an armored D7E on display at Camp Beauregard in Pineville, LA.  Author's photo added 3-22-2018.

Author's photo added 3-22-2018.

 Author's photo added 3-22-2018.

 Author's photo added 3-22-2018.

This Vietnam era Caterpillar D7 has a Rome Plow which was used for land clearing in the jungle.  Author's photo added 6-19-2018.

There was such a need for the D7 3T that Caterpillar shipped components to American Car and Foundry which then assembled the parts into approximately 1,000 tractors. 

D8:  In the southwest Pacific, each LST had a D8 with a bulldozer assigned to it.  Each was equipped with air intakes and exhausts that extended above the tractor to allow for deep water operation.  The D8s were placed at the front of the ship.  When the LST could not get all the way on to the beach to unload its cargo, the D8 would be first off and make a sand ramp to the ship.

I have been looking for a World War Two era D-8 ever since I started researching Caterpillar's contribution to winning World War Two in late 2017.  In September 2020, I finally I found the one below at a private owner's military vehicle collection located in Michigan.  I was there to look at several other of his vehicles, not knowing the D-8 was in his collection. 

Author's photo added 9-25-2020.


The original data plate is still on the D-8.  Author's photo added 9-25-2020.

D-8 Serial Number LH-9781 was built in 1942 and carried USA Registration Number 9176981.  Author's photo added 9-25-2020.

The gasoline starting engine can be seen in this photo.  Author's photo added 9-25-2020.

Author's photo added 9-25-2020.

Author's photo added 9-25-2020.

Author's photo added 9-25-2020.

Author's photo added 9-25-2020.

The D-8 was powered by a six-cylinder Caterpillar engine.  Author's photo added 9-25-2020.

Author's photo added 9-25-2020.

In 1942 instrumentation was sparse.  This only has oil pressure and water temperature gauges.  Author's photo added 9-25-2020.

The bulldozer blade has been removed and is sitting a few feet away from the tractor.  Author's photo added 9-25-2020.

Generator sets:  Industrial power units were introduced in 1939.  During World War Two Caterpillar built six different versions.

D13000:   

This 1940 Caterpillar D13000 is owned by Mike Schreiber of Winfield, IN.  Author's photo added 11-1-2020.

This sign is incorrect.  This is a D13000, not a D1300.  The data plate shown in the next photo confirms the identity of the engine.  The U.S. Navy's Torpedo Station in New Port, RI was responsible for the development and testing of the torpedoes used in World War Two.  Unfortunately, it is infamous for not properly testing its new detonator designs for World War Two.  This resulted in many duds and misses by American submarines and destroyers in the early part of the war.  However, the Cat D13000 no doubt performed just as it was expected and supplied backup electrical power when required.  Author's photo added 11-1-2020.

Author's photo added 11-1-2020.

Author's photo added 11-1-2020.


The D13000 has a two-cylinder gasoline engine to start the diesel.  The gasoline engine has a cranking motor to start it and a magneto to provide the spark.  Author's photo added 11-1-2020.

Author's photo added 11-1-2020.

Author's photo added 11-1-2020.

Author's photo added 11-1-2020.

D3400:

This 1947 D3400 Diesel Electric Set is on display at the Caterpillar Visitor Center.  It is similar to the D3400 sets that Cat produced during World War Two.  Author's photo.

This has been restored to mint condition.  The sparkplug and sparkplug wire for the two-cylinder pony motor can be seen at the right end of the engine next to the generator.  Author's photo.

 The second sparkplug and wire are visible on the other side of the engine.  Author's photo.

This is one of 6,047 34-15 generator sets produced between 1938 and 1947, when the engine was discontinued.  The electric generator produced 15 KW 3-phase or 13KW single phase at 60 hertz at 1,200 rpms.  During World War II, the 34-15 generator set was used as an auxiliary power generator on 534 American Victory ships.  Author's photo.

 Note the size of the unit compared to the eight-foot ladder against the building.   Author's photo.

  Author's photo.

  Author's photo.

Graders:  Caterpillar supplied some road graders to the US military in World War Two, but not on the scale of its tractor production. 
 

This 1940 Caterpillar Diesel No.12 grader was the model on which the company standardized and provided to American military engineering battalions during WWII.  Author's photo from the National Construction Equipment Museum in Bowling Green, OH.

Author's photo.

Author's photo.

Author's photo.

Author's photo.

Wheeled tractors: 
 

The DW10 wheeled tractor and the DW6 were introduced in 1941 in response to the LeTourneau Turnapull.  Production stopped in 1943 but resumed in 1945.  While the wheeled tractors did not serve with the military overseas, they were used in shipyards to move modular ship sections to the construction site.  This DW10 was built in 1949.  Author's photo from the National Construction Equipment Museum in Bowling Green, OH.

RD-1820 Radial Tank Engine:  This sounded like a good idea at the time.  In July 1941, US Army Ordnance approached Caterpillar about converting a Wright R-1820 Cyclone gas-powered aviation engine into a diesel-powered tank engine.  Caterpillar had established itself as the leader in diesel engine technology in the 1930s, so its involvement made sense.  Caterpillar formed a new company called the Caterpillar Military Engine Company, which built a new plant at US Government expense in Decatur, IL to produce the engines.  The plant was tooled for a build rate of 1,000 engines per month.  By January 1942, Caterpillar had a prototype engine.  By year's end, two prototype tanks were built using the engines.  These engines could not only run on diesel fuel, but other fuels including 100 octane aviation fuel.  In October 1943, Chrysler started production of the M4A6 Sherman tank in the Detroit Tank Arsenal.  Army Ordnance ordered 750 of the M4A6 Caterpillar RD-1820 powered Sherman tanks but cancelled the order after 75 units.  The last one was produced in February 1944.  Only 120 engines were produced in Decatur.

In the two years since Caterpillar started on the engine, the engine shortage had been reduced.  Chrysler, Ford, and General Motors all had engine technology available in 1942 for installation in M4 tanks.  Ford's 500 HP V-8 engine became the engine of choice for the US Army, and the RD-1820 was no longer needed.  As the Army started to move offensively in 1943 in the Southwest Pacific, North Africa, Sicily, and Italy, it learned that modern warfare required advanced bases, especially air-fields, to take the fight to the enemy.  The invasion of Europe, planned for 1944, would need a huge number of tractors.  The invasion of Japan was planned for late 1945 or early 1946.  What the US Army really wanted and needed for the rest of the war was more D-7 Tractors.  So, Decatur was converted to production of that vehicle. Caterpillar production of D-7 Tractors tripled from 1943 to 1944.

This is one of 75 M4A6 Sherman tanks produced with the Caterpillar RD-1820 engine.  Today, none of the tanks nor engines are known to exist.

M4 Transmissions and Differentials:  Caterpillar produced transmissions and differentials for many of the 49,234 Sherman tanks built during WWII. 

The Sherman tank had the engine in the rear of the tank.  The drive shaft ran from the back to the front of the tank, where the power was applied to the tracks.  The differential, or Final Drive Unit, is the cast piece on the front of this Fisher Body built M4A2 tank.  Author's photo.

Looking inside a cut-away tank at the Canadian War Museum in Ottawa, ONT, one can view the M4A2 Sherman transmission inside the tank.  This was located to the right of the driver's position in the background.  Author's photo.

The next two photos show the internal gears and brakes that Caterpillar manufactured before assembling them into the Final Drive Unit.  Author's photo.

Author's photo.

155mm Howitzer M114 Gun Carriage:

Caterpillar built complete carriages for the M114 155mm howitzer, like this one on display at the Indiana Military Museum in Vincennes, IN.  Author's photo.

37mm Shells:

Also, this 37mm round is on display at the Indiana Military Museum.  The San Leandro, CA Caterpillar plant produced the projectile portion of the round.  Author's Photo.

A female operator works on cylinder heads for the RD-1820 radial diesel engines at the Decatur, IL plant during World War Two.  Photo added 11-4-2019.

This photo shows the Caterpillar U.S. Army Training school for army mechanics, which ran in Peoria.  Photo added 11-4-2019.

Army engineers work at an Aleutian Island Army Air Forces base during World War Two.  In the background are the tents the soldiers lived in, P-40 fighters and OA-10 patrol aircraft.  Photo added 11-4-2019.

This Caterpillar D4 is also at the Aleutian Islands.  It is pulling skids containing 55-gallon barrels that have come ashore on the LCVs in the background.  Photo added 11-4-2019.

This Seabee D7 is pulling a Rhino dock onto the beach.  The Rhinos could provide direct access for vehicles to travel from an LST to the beach without having to go through the water.  This was extremely helpful when the LSTs could not get up on the beach.  Photo added 11-4-2019.

A Seabee operating a D8 waves at three B-29s on one of the Marianas Islands.  Photo added 11-4-2019.

This photo shows a Caterpillar D7 going ashore from an LST in the South Pacific in 1944.  However, the photo shows much more.  Firstly, it shows the versatility of the crawler tractor with the LeTourneau Model WCK7 Angledozer mounted to the front while it pulls a LeTourneau Model 18 Carryall.  Secondly it shows the close relationship of Caterpillar and LeTourneau during World War Two.

The story of the Caterpillar Tractor Company in World War Two cannot be told without telling the story of R.G. LeTourneau, Inc.
To learn more about LeTourneau's contribution to winning World War II, go to:

R.G. LeTourneau in World War II