By 1936, Caterpillar produced nearly half of all diesel engines in the United States.


Auto Patrols were first manufactured in gray before Caterpillar switched to classic highway yellow.


Caterpillar's diesel development program was overseen by Art Rosen.


Although our machines officially became yellow at the end of 1931, you could still special order gray to suit your fancy.


The Caterpillar Sixty Track-Type Tractor was used on this job.


Here you can see Caterpillar track-type tractors at work pulling scrapers on the north approach to the Golden Gate Bridge.

Video of photos of Caterpillar in the 1930s
1930s, diesel engine photography video
Auto Patrols video an transition to classic highway yellow.
Two men with tractor
Man servicing equipment in service bay
Tractor entering mine
Caterpillar photos buidling the Golden Gate Bridge

It was the decade we turned yellow. “Hi-Way Yellow” to be specific. The 1930s saw our company on a path of innovation, customer commitment and industry leadership – things that are still in our DNA today.

While many were feeling the deep impact of the Great Depression, innovation kept Caterpillar alive and thriving. The Auto Patrol (the industry's first true motor grader) hit the scene. Another major innovation? Adding the diesel engine to our machines. Our first diesel tractor model – the Cat Diesel Sixty – was introduced in 1931.

The diesel engine itself was hardly a new concept,but having the first diesel engine specifically made for a tractor was an impressive demonstration of the value of research and development efforts. Two years after its manufacture, Caterpillar diesel engines produced half the diesel horsepower in the United States. By the end of the 1930s, Caterpillar was the largest diesel engine manufacturer in the world. These powerful machines made work easier for our customers who used them to complete construction on the Hoover Dam, the Golden Gate Bridge and other incredible projects around the world.

1931 Caterpillar releases the industry's first true motor grader - the Auto Patrol.
1931 Caterpillar begins producing its first diesel tractor model - the Caterpillar Diesel Sixty Tractor.
1931 Caterpillar changes the standard paint color of its machines from gray with red trim to “Hi-Way Yellow” with black trim. 
1936 Caterpillar track-type tractors help complete the construction of the Hoover Dam.  
1937 Caterpillar machines help complete the construction of the Golden Gate Bridge. 


Meet the People

Art Rosen receiving service pin
Meet Art Rosen – The Inventor

Art Rosen, a brilliant engineer, is credited as the architect of one of the most significant inventions in the earthmoving industry – the Cat diesel engine. Hired directly by Caterpillar Chairman C.L. Best, Rosen worked in our San Leandro research and development facilities. The challenges he faced were many. The great problem lay in adapting the diesel idea for a purpose far from its primary use, heavy stationary and marine installations, to make it work on a tractor. This was far easier said than done, as stationary diesels were bulky and expensive.

Rosen overcame those obstacles, and less than four years later the first prototype, “Old Betsy,” was successfully tested. The first production model was installed in the legendary Cat Sixty tractor, creating the new “Diesel Sixty” machine, leading the U.S. and the world into the fabulous diesel upsurge of the thirties and forties. The Diesel Sixty cemented our legacy and paved the way for an industry that today runs almost completely on diesel fuel.

Rosen would later go on to lead Caterpillar’s research and development team. His team’s later successes would include both the Caterpillar dozer blade and new wheeled equipment, just to name a couple. Rosen once said, “Research at Caterpillar is not merely a splendid physical building – containing superior equipment – staffed by competent personnel – but within these walls pervades the spirit of the founders of the Company – the backlog of Caterpillar experience.” Rosen retired from Caterpillar in 1949.

Lillian Cutt McCoy with members of credit union
Meet Lillian Cutt McCoy – The Innovator

Lillian Cutt McCoy started her Caterpillar career in East Peoria, Illinois, in the early 1930s. Lillian worked in the Accounting department, but she also had a flare for writing, and it wasn’t long before she joined the editorial team for the company’s newsmagazine, News & Views.

Her former days as an athlete had opened the door for her to manage some of Caterpillar’s sports league teams, including the women’s softball and basketball teams. Lillian said it was a way for her to put her organizational skills to work. The Caterpillar Dieselettes softball team would go on to become one of the most successful amateur teams in the world.

She had a remarkable career and coaching efforts, yet her lasting legacy was her work as a founder of the Caterpillar Employees’ Credit Union in 1937. Membership was limited to regular employees of Caterpillar, and every employee was eligible to purchase shares. The money obtained was used to make loans to members. The purpose of the Credit Union was to help employees save money, while also enabling them to obtain loans at a reasonable rate of interest.

Lillian was a member of the original member committee and held many different positions including the role of vice pPresident. Although the credit union separated from Caterpillar long ago, “CEFCU” is still around today as the Citizens Equity First Credit Union. We think she would be proud to know her legacy lives on.

Ollie Sleeter shaking hands with others
Meet Ollie Sleeter – The Maker

Ollie Sleeter saw quite a bit of history during his time. Starting in 1910 when he witnessed the first Holt Caterpillar tractor roll off the assembly line in East Peoria, Illinois, to the merger that made modern-day Caterpillar in 1925.

Ollie was particularly proud of one historic experiment that changed the look of Caterpillar machines forever in 1930. Until then, our products were “battleship gray” with red detailing but the new decade brought a call for change.

Ollie worked directly with engineers on tests to determine a paint color for our products. Tests narrowed down the choices to three colors: yellow, red and white. With safety in mind, the aim was to find the color that would be visible at the greatest distance both day and night, and yet be pleasing to the eye. When the tests were over, yellow was chosen, and paint specialists devised the distinctive Caterpillar Hi-Way Yellow for exclusive identification of Cat machines.

When Ollie retired in 1949, he proudly wore his Caterpillar 45-year service pin – one of only a handful in the entire company. He beamed when he talked about his long association with Caterpillar. He said, "They proved in my lifetime they could run a tractor without wheels, they could turn the huge machine around on a dime, and they could run an engine without gas." Ollie went on about Caterpillar’s future: "I’d say they'll have a product none of us can conceive of today because of the vast improvements on it.”

Leonard Fletcher and coworker infront of tractor
Meet Leonard Fletcher – The World Changer

Leonard Fletcher joined Caterpillar in 1927, bringing with him 12 years of valuable experience in the agricultural field. Hear in his own words how he first headed agricultural sales and was then sent to represent the company in Europe, particularly Russia.

By late 1929, worldwide sales had begun to stagnate due to the Great Depression. New markets needed to be opened up. Fletcher personally negotiated several large orders for tractors and combines for large grain farm operations in what was then the Soviet Union. More orders followed, and both Caterpillar track-type tractors and combines were purchased in large numbers. Those global sales helped the company stabilize output of factories adversely affected by the Great Depression. Caterpillar was able to earn a profit while reducing the prices customers paid for tractors.

Fletcher’s success led to him becoming a Caterpillar vice president before retiring in 1954.

See the Artifacts

1930s Parts video
1930s Parts

c. 1935 - Caterpillar employees manufacture parts for the track-type tractor line in the 1930s.

Watch Video

Man with Caterpillar engine
The Day We Went to Sea

1938 - Cat® diesel engines have been famous on land for their dependability and economy since 1931. Seven years later, we decided to head off to sea.

Full Story

People looking at engine on assembly line
Cat® D17000 Engine

1935 - Caterpillar took advantage of a growing market and introduced the first diesel engine designed specifically for non-tractor applications.

Full Story

Video of operator on D8

Big and Small

1938 - Caterpillar customers come in all sizes. Watch a young man operate a Cat® RD8 Track-Type Tractor.

Watch Video