The American Automobile Industry in World War Two
An American Auto Industry Heritage Tribute
By David D Jackson

Overview      The U.S. Auto Industry at the Normandy Invasion, June 6, 1944    The U.S. Auto Industry and the B-29 Bomber   U.S. Auto Industry Army-Navy "E" Award Winners   The Complete listing of All Army-Navy "E" Award Winners   Sherman Tanks of the American Auto Industry   Tank Destroyers of the American Auto Industry    M26 Pershing Tanks of the American Auto Industry   Serial Numbers for WWII Tanks built by the American Auto Industry

    Automobile Manufacturers:  American Bantam Car Company   Checker   Chrysler   Crosley   Ford   General Motors   Graham-Paige   Hudson
   Nash-Kelvinator   Packard      Studebaker    Willys-Overland

General Motors Divisions
(Undergoing development) Aeroproducts   Brown-Lipe-Chapin   Buick   Cadillac   Chevrolet   Cleveland Diesel   Delco Appliance   Delco Products   Delco Radio   Delco-Remy   Detroit Diesel   Detroit Transmission   Electro-Motive   Fisher Body   Frigidaire   GM Proving Grounds   GM of Canada   GMC   GMI   Guide Lamp   Harrison Radiator   Hyatt Bearings   Inland   Moraine Products   New Departure   Oldsmobile   Packard Electric   Pontiac   Saginaw Malleable Iron   Saginaw Steering Gear   Southern California Division   Rochester Products   United Motors Service

Truck and Implement Manufacturers:   American LaFrance   Autocar  Diamond T   Caterpillar   Clark Equipment Company   Cleveland Tractor Company   Federal Motor Truck   International Harvester    Mack Truck
   Marmon-Herrington Company   Massey-Harris   Pacific Car and Foundry  Reo Motor Car Company   R.G. LeTourneau   Seagrave Fire Apparatus   Ward LaFrance Truck Corporation   White Motor Company

Automotive Tire
   B.F. Goodrich    Firestone Tire and Rubber Company
 Updates and Additions  


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 added 1-22-2018.

Caterpillar's main product line and its greatest contribution to the winning of World War II was its crawler type tractors; the D2, D4, D6, D7, 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 have not 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 II 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.  But World War Two, to be an airpower war, was first of all a construction war.  Caterpillar crawler tractors were instrumental in the US military's construction war, and America's not-so-secret weapon of WWII. 

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 WWII, 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 in 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 WWII 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.  But to most persons, including generals and admirals from WWII, 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 IIThe 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 has on display a collection of vintage tractors from the Veercamp Family Collection in California.  On display are the roots of the company, which are 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 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 on a mass scale to the US Army, with 9,771 Holt tractors built by Holt and under license by five other companies.  Not only did the American forces use them, but they were also procured by England, France and Russia.

Historical note:  During both the Mexican and World War I, the Holt tractor in military service was used 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 construction equipment supplier that bulldozers were added to the front of tractor.

Holt World War One Tractor Production Statistics:  (3) 18 HP, (407) 45 HP, (2,103) 55 HP, (63) 60HP, (1,810) 70HP, (676) 120 HP for a total of 5,082 tractors.

Licensed Holt World War One Tractor Production Statistics: 
Chandler Motor Car Company:  (700) 10-ton tractors,
Federal Motor Truck Company:  (87) 2.5-ton tractors,
Interstate Motor Company:  (7) 2.5-ton tractors,
Maxwell Motor Car Company:  (225) 6-ton tractors,
Reo Motor Car Company:  (1,477) 5-ton tractors
Total of 4,689

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 WWI, 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 was renamed in 1928 the Caterpillar Ten.  Author's photo.

Between the Wars:

This Best 1919 60 Tracklayer is 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, 1945 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 originally was 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.

Caterpillar World War Two Production Statistics:   (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.  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 equivalent of the Swiss army knife in WWII. 

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

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

What is interesting about this is that 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 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.  

Caterpillar World War Two Tractor Production (Courtesy of Caterpillar Archives)

In April 1942 the War Production Board assigned 85% of crawler for military, which included Lend Lease, most of which went to Britain.  With the war production being stopped no later than the end of September 1945, a certain percentage of 1945's numbers include civilian output.
  1942 1943 1944 1945 Totals  
D2 1,556 0 1,192 1,247 3,995 D2
D4 2,456 3,305 4,918 5,299 15,978 D4
D6 1,326 1,165 1,822 1,802 6,115 D6
D7 1,878 2,255 7,885 8,485 20,503 D7
D8 2,390 2,338 2,376 2,611 9,715 D8
Yearly totals 9,606 9,063 18,193 19,444 56,306 Grand Total

 D2:  D3400 Engine with 25.5 hp

This 1956 Caterpillar D2 is on display at the National Construction Equipment Museum in Bowling Green, OH.  One significant difference in this model from the D2s used by the military in WWII is its battery and electrical starter.  During WWII a two-cylinder gasoline engine would be located at the rear of the D3400 engine, which would start the diesel.  The gasoline engine was known as a "pony engine," and was hand started.  Author's photo.

Author's photo.

D4:  D4400 Four Cylinder Diesel Engine

This 1940 Caterpillar D4 is also on display at the National Construction Equipment Museum in Bowling Green, OH.  It is one of the oldest still in existence, as production started in 1939.  It has a LaPlant-Choate hydraulically activated bulldozer on the front and a Hyster D2 winch on the rear.  LaPlant-Choate supplied around 30% of the bulldozers for Caterpillar tractors during WWII.  LaPlant-Choate was a leader in using hydraulics for the movement of the blade.  Author's photo.

The D4400 four-cylinder diesel engine is typical of the era, as it has a two-cylinder gas pony starter engine.  The spark plug wire and plug are visible at the rear of the engine.  Author's photo.

The Hyster D2 winch on the rear of the tractor.  Author's photo.

D6:  A total of 453 D6 tractors were modified in 1942 and 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 miles an hour after changes to the engine governor and the gears in the transmission.

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 WWII 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 straight dozer like the one installed on this D7, or an angle dozer.  The bulldozer on this D7 is a straight blade and can not be angled.  The LeTourneau designation for this type dozer is WEK7.  For an angle dozer the designation 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 1950 D7 3T with Balderson inside mount cable dozer is serial number 3T15640.  Author's photo from the National Construction Equipment Museum in Bowling Green, OH.

This D7 3T served with the Army Corp so Engineers.  Author's photo.

Author's photo.

Author's photo.

Caterpillar World War Two D7 Tractor Models - D8800 Engine

  Years Number produced Comments
D7 7M 1940-1944 10,000??? D8800 engine 74 inch track gauge
D7A 1T1001 1943 138 Armor plated version of the D7 7M, blade operated by twin hydraulic cylinders and equipped with a Hyster D7N winch on the rear
D7 3T 1944-1955 28,000 This was built to military specifications to accommodate the conditions for use in the hostile conditions on the battle front.
D7 4T 1944-1945 Unknown This was built to military specifications to accommodate the conditions for use in the hostile conditions on the battle front.
D7 6T 1945 1,054 This model was built for the US Navy and had six rollers rather than the five on other model D7s. 
D7 High Speed 1942-1943 310 D7 High Speed Tractor M1 - This was modified to function as a prime mover for artillery.  The tractor was modified to travel at 11 miles an hours by modifying both the engine governor and the gears in the transmission.

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. 

Caterpillar World War Two D7 Tractor US Military Deliveries
From the numbers below it can be seen that the US Army took 85% of the D7 production over the course of WWII.  In 1945 the Army and Navy took 97% of the production of the D7.  This is in spite of the fact that the military was only allocated 85% of production.

  1942 1943 1944 1945 Totals
D7 Yearly Production 1,878 2,255 7,885 8,485 20,503
D7 Yearly US Army Deliveries 1,150 (61%) 1,961 (86%) 7,094 (90%) 7,239 (85%)

17,444 (85%)

D7 Known US Navy Deliveries      

1,054 (12%)


D8:  In the southwest Pacific each LST had a D8 with a bulldozer assigned to it that were equipped with air intakes and exhausts that were extend above the tractor to allow for deep water operation.  The D8s were placed at the front of the ship, and 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.


Generator sets:  Industrial power units were introduced in 1939 and during WWII Caterpillar built six different versions.


On display at the Caterpillar Visitor Center is this 1947 D3400 Diesel Electric Set.  It is similar to the D3400 sets that Cat produced during WWII.  Author's photo.

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

On the other side of the engine the second sparkplug and wire are visible.  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.

D13000:  The largest of the four generator sets Caterpillar produced during WWII was powered by the D13000 engine.  It produced 75 KW of three phase electrical power at 220/440 volts.  This generator produced the electrical power for airfield runway lighting, allowing air operations at night.  Surgical rooms and hospitals, refrigeration for fresh meat and produce, and many other pieces of equipment could be powered by D13000 generators.  While inconsequential to the waging of a war, but most important to the morale of troops, D13000s provided the energy to refrigerate the two cans of beer a serviceman was allocated each day while in and Rest and Recreation area.  Having a cold beer in the tropics was important!

The unit below, serial number 2V2760, was accepted by the US Navy on April 6, 1951.  It weighs 12,255 pounds.  It is very similar, if not identical, to those produced by Caterpillar for the US Navy in WWII.

 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 WWII, but not on the scale of its tractor production. 

Allocation of Graders to Military Units
Type of Grader  Number in a US Army Engineer Aviation Battalion Number in a US Seabee Battalion
Leaning Wheeled, Towed 1 0
Motorized, Diesel 6 3


Caterpillar World War Two Grader Production
Five of the six models were terminated early in the war to standardize on the Diesel No. 12.

Model Years produced
No. 212 1939 to 1942
Diesel No. 212 1939 to 1943
No. 112 1939 to 1942
Diesel No. 112 1939 to 1942
No. 12 1939-1942
Diesel No. 12 1938-Present

 This Caterpillar 44 puller road grader from the 1930s is on display at the National Construction Equipment Museum in Bowling Green, OH.   Author's photo.

 Author's photo.

 Author's photo.

This 1940 Caterpillar Diesel No.12 grader was the model that the company standardized on, 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 and resumed in 1945.  While the wheeled tractors did not serve with the military overseas, they were used in shipyards for moving 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, the 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 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 base; especially air fields to take the fight to the enemy.  The invasion of Europe, planned for 1944, would need a huge amount 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.

One of 75 M4A6 Sherman tanks produced with the Caterpillar RD-1820 engine.  Today, none remain of the tanks or engines are known to exist.

M4 Transmissions and Differentials:  Caterpillar produced of 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, and a drive shaft that ran 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 on display at the Indiana Military Museum is this 37mm round.  The San Leandro, CA Caterpillar plant produced the projectile portion of the round.  Author's Photo.

A Caterpillar D7 going ashore from an LST in the South Pacific in 1944.  The photo shows two things.  The first 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.  The second is the close relationship of Caterpillar and LeTourneau during World War II.

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




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