WINDOW-DOOR 2907173 - Caterpillar

Illustrations 1 and 2 show the former numbering scheme and new numbering scheme respectively. These illustrations show that the counterweights are numbered with a "1" at crankshaft front end and either a "8", "12", or "16" at the crankshaft rear end, depending on the size of the engine.
Illustration 1. Former crankshaft numbering scheme on a typical 3500 engine crankshaft.
Illustration 2. New crankshaft numbering scheme on a typical 3500 engine crankshaft.The front end of the crankshaft can be identified by the letters "FRT STD" stamped on the front face of the crankshaft. See Illustration 3. The letters "FRT STD" go toward the frontof the engine on a standardrotation engine (standard rotation is counterclockwise when viewed from the rear of the engine).
Illustration 3. Front face of a typical 3500 engine crankshaft.The rear end of the crankshaft can be identified by the two locator pads (X) on the flange at the rear end of the crankshaft. A pair of three digit numbers that make up the crankshaft sequence number can be found on these two locator pads. The rear end of the crankshaft can also be identified by the letters "FRT REV" stamped on the rear face of the crankshaft. See Illustration 4. The letters "FRT REV" go toward the frontof the engine in a reverserotation engine (reverse rotation is clockwise when viewed front the rear of the engine). This means that the rear end" of the crankshaft goes toward the frontof the engine in a reverserotation engine.
Illustration 4. Rear face of a typical 3500 engine crankshaft. Locator pad (X). Whether the "FRT STD" end of the crankshaft goes toward the front or rear of the engine, the number one counterweight must always go on the "FRT STD" end of the crankshaft and the last counterweight must always go on the "FRT REV" end of the crankshaft.