Series 5A1-5A1808, 1931 - 1937

The Gas FIFTY was one of the last big Gas (Gasoline) tractors.

The well restored example below is in a collection in the UK.


Production began in 1931 and continued until 1937 with only 1708 tractors being built.

Tractors with serial numbers 5A1 to 5A757 had the fuel tank in front of the operator and the air cleaner under the bonnet. Later tractors had the fuel tank behind the driver’s seat and the air cleaner in front of the driver behind the dashboard.

The first few tractors were painted grey but the color changed to Highway Yellow on 7th Dec 1931.

The engine had individual crossflow cylinder heads and separate rocker covers.

Two widths were available, 60 inch gauge and 74 inch gauge, this being the width between the track centres.

FIFTY Details

7500G Spark ignition Engine 4 cylinders 5 ½ x 6 ½ inch (Bore / Stroke)
Overhead valvegear
52 D.H.P at 850RPM
Weight 17,900 lbs.

Below is a list of machines made by year and serial number. Note in 1933 a block from 5A544 to 5A644 was not used, we don’t know why

1931 1 54
1932 55 328
1933 329 543
1933 645 809
1934 810 1006
1935 1007 1579
1936 1580 1721
1937 1722 1808

Link toi a "walkround video of a Cat FIFTY by Squatch 253.

Caterpillar Fifty Tractor #5A476 - LaPlante-Choate RB-50 Bulldozer Blade - YouTube

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