2004/05/03 Caterpillar

Off-Highway Truck/Tractor:

777D (S/N: 2YW1-UP; AGY1-UP)

789C (S/N: 2BW1-UP)

793 (S/N: 3SJ1-UP)

793B (S/N: 1HL1-UP)

797 (S/N: 5YW1-UP)

797B (S/N: JSM1-UP)

785C (S/N: APX1-UP; 5AZ1-UP)

793C (S/N: 4AR1-UP; ATY1-UP; 4GZ1-UP)

Service Magazine, SEPD0729, 12 April 2004, "Use The Correct Stub Shaft for the Crankshaft". Disregard this article. Refer to the following article.

A stub shaft was manufactured with two different methods in order to cut the keyway. One method used a cutting wheel. The other method used an end mill. The stub shaft that has the keyway that is cut by using an end mill may fail if the stub shaft is used on a 3500B High Displacement Engine.

Inspect the keyway of the 7N-7057 Stub Shaft during a conversion of a 3500B Engine from a standard stroke to a high displacement. Inspect the keyway of the 7N-7057 Stub Shaft at an overhaul of a 3500B High Displacement Engine.

Ensure that the keyway of the stub shaft is cut with a cutting wheel if the stub shaft is used on a 3500B High Displacement Engine. Either keyways on the stub shaft may be used on a 3500B Standard Stroke Engine. All new 7N-7057 Stub Shafts will have a keyway that is cut with use of a cutting wheel.

Illustration 1	g01064719
Keyway that is cut with an end mill

Illustration 2	g01064720
Keyway that is cut with a cutting wheel