PIN 1359292 - Caterpillar

Engine: 3508 (S/N: 6TJ) 3512 (S/N: 2WK) 3516 (S/N: 9KF)Introduction
This Special Instruction describes the procedure for the installation and cold alignment of two-bearing generators to locomotive engines. These units are permanently mounted on a Caterpillar base. This procedure for alignment relates to traction generators which are driven from the flywheel (rear driven). This procedure also relates to auxiliary generators that are driven from the front power take-off.Do not check the final alignment of the generators until the base is in the permanent position. In addition, the engine and generators must be permanently installed on the base. When the initial alignment of the generators is performed at the factory, the alignment is within the tolerance of the "new" category. Refer to the ""Specifications"" Section for details.Do not perform any procedure in this Special Instruction until you have read this information and you have understood this information.General Information
Cold Alignment
This section describes the recommended procedure for the cold alignment of two-bearing generators to Caterpillar diesel engines. This procedure must be performed with all of the components at ambient temperature.The following steps have taken into consideration several factors in order to achieve the correct operating alignment.
Illustration 1 g00588910
(1) Static clearance (2) Crankshaft (3) Running clearance (4) Bearing bore (A) Position of crankshaft during cold alignment (B) Position of crankshaft during operation
During the procedure for cold alignment, the crankshaft lies at the bottom of the bores of the main bearing. The following conditions tend to lift the crankshaft and these running conditions cause the crankshaft to rotate approximately around the center of the bores of the main bearing: firing pressures, centrifugal forces and engine oil pressure.
Illustration 2 g00588938
(5) Engine (6) Vertical Change In The Location Of The Crankshaft (7) Generator (8) Crankshaft (9) Vertical Change In The Location Of Generator Shaft (10) Rear (11) Front (C) The Location Of The Centerlines Of The Shaft For Cold Alignment (D) The Location Of The Centerlines Of The Shaft During Operation
The weight of the flywheel and the coupling causes a small deflection of the shafts during the procedure for the cold alignment.
Heat from the engine causes the expansion of metal in the engine and in the generator during operation. The result of this expansion is a change in the locations of the centerlines of the crankshaft and generator shaft. The thermal expansion of the engine is greater than the thermal expansion of the generator. This difference will cause the change in the horizontal centerline of the engine crankshaft to be greater than the change in the horizontal centerline of the generator shaft.
Due to these factors, the procedure for the cold alignment positions the horizontal centerline of the generator shaft above the horizontal centerline of the crankshaft. Refer to the specifications for cold alignment in the ""Specifications"" Section in order to correctly align the unit during operation.Hot Alignment
In the past, a check of the hot alignment may have been used to check the accuracy of the procedure for the cold alignment. However, tests have shown that the results of