Today in WW II: 20 Feb 1942 Navy Lt. Cdr. Edward 'Butch' O'Hare of Chicago becomes America's first World War II flying ace. Chicago expanded old Orchard field in 1946, renaming it for O'Hare.  More 
20 Feb 1944 Operation Argument aka 'Big Week' begins; American bombers concentrate on German aircraft manufacturing to lure the Luftwaffe into a decisive battle.
Visit the Olive-Drab.com World War II Timeline for day-by-day events 1939-1945! See also WW2 Books.

R-4 Caterpillar Bulldozer / Tractor

Caterpillar introduced the R4 (6G series) in 1938, based on the earlier Caterpillar Thirty, and the R4 was produced until 1944. It was powered by a 4 cyl. gasoline engine and had both a 44 inch and a 60 inch track gauge (width). The R-4 had only one upper track roller, compared to two rollers on the Cat Thirty. The later D4 Caterpillar tractor was based on the R-4.

The rear winch was a Hyster D4 while the power control unit was by LaTourneau.

The dataplate states that the maximum drawbar pull is 7,332 lbs. and the maximum ground speed is 5.4 mph.

Thanks to Stephen A. Sarkany for help with this page.

USN Seebee R-4 Caterpillar Tractor with bulldozer blade, Carswell Strategic Air Command Base, Ft. Worth, TX.  Photographed 10 November 2006. Photo: Courtesy of Bob Pettit
USN Seebee R-4 Caterpillar Tractor with bulldozer blade, Carswell Strategic Air Command Base, Ft. Worth, TX. Photographed 10 November 2006. Photo: Courtesy of Bob Pettit.

USN Seebee R-4 Caterpillar Tractor with bulldozer blade, Carswell Strategic Air Command Base, Ft. Worth, TX.  Photographed 10 November 2006. Photo: Courtesy of Bob Pettit
USN Seebee R-4 Caterpillar Tractor with bulldozer blade, Carswell Strategic Air Command Base, Ft. Worth, TX. Photographed 10 November 2006. Photo: Courtesy of Bob Pettit.

USN Seebee R-4 Caterpillar Tractor with bulldozer blade, Carswell Strategic Air Command Base, Ft. Worth, TX.  Photographed 10 November 2006. Photo: Courtesy of Bob Pettit
USN Seebee R-4 Caterpillar Tractor with bulldozer blade, Carswell Strategic Air Command Base, Ft. Worth, TX. Photographed 10 November 2006. Photo: Courtesy of Bob Pettit.

Data plate of USN Seebee R-4 Caterpillar Tractor with bulldozer blade, Carswell Strategic Air Command Base, Ft. Worth, TX.  Photographed 10 November 2006. Photo: Courtesy of Bob Pettit
Data plate of USN Seebee R-4 Caterpillar Tractor with bulldozer blade, Carswell Strategic Air Command Base, Ft. Worth, TX. Photographed 10 November 2006. Photo: Courtesy of Bob Pettit.