Today in WW II: 25 May 1940 Boulogne, France is captured by the Germans.  More 
25 May 1941 King George of Greece abandons Crete, relocating to Cairo in a narrow escape from German forces.
25 May 1942 Japanese attack force leaves Hokkaido for invasion of the Aleutians Islands, Alaska.
25 May 1945 Chiefs of Staff of US military set 1 November 1945 as start date for invasion of Japan [Operation Downfall]. The huge casualties of Downfall avoided by use of Atomic Bombs in Aug 1945.
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.

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