HOOD AS 3951853 - Caterpillar

Crankshaft Measurement
See the chart, "Crankshaft Measurement Specifications," on pages 9 through 12. Under the column "Radius," make a note that all minimum radii for BOTH main and rod journals must be checked at a radius SMALLER than that shown. For radii smaller than 1/4", the minimum radius gauge must be 1/64" less than the present dimension. See Example A.
For radii 1/4" or larger, the minimum radius gauge must be 1/32" less than the present dimension. See Example B.
Example A: With the change, the main journals of the first forging number in the chart, 5F1099, will read: minimum radius 13/64" (was 7/32")maximum radius 15/16" (not changed)
The rod journals will read: minimum radius 13/64" (was 7/32")maximum radius 15/16" (not changed)
Example B: With the change, the main journals of the seventh forging number in the chart, 7H7008, will read: minimum radius 1/4" (was 9/32")maximum radius 19/64" (not changed)
The rod journals will read: minimum radius 7/32" (was 15/64")maximum radius 1/4" (not changed)
The change is needed because the smaller fillet radius gauge gives a better indication of the acceptable fillet radius on new crankshafts.
Visual Inspection Of Crankshafts
1. Change Illustration 36, on Page 20, as shown on the corrected illustration in this article. This correction shows a VERY SMALL dip (or an area with a small radius) at the point where the journal surface and fillet meet. This small dip is acceptable. (This dip can some times be seen if you use a radius gauge.)The dip must be very small and must blend smoothly with the journal (straight line) and the main part of the fillet as shown. No ridges, peaks or high points are acceptable in the lower one-half section of a fillet.
During the procedure to grind, do not make any sudden changes in the radius; keep the fillet area as smooth as possible and be sure that it blends smoothly with the journal surface. The most important area is between 20° and 45° from the point where the fillet and journal meet. See the illustration. If you check the radius size with a gauge, use the gauge in the center of the fillet, shown as "X" in the illustration, instead of toward the sidewall or the straight journal.
2. On page 25, under Illustrations 45, 46 and 47, the caption presently reads: "Typical grinder burns in the sidewall", "DO NOT USE AGAIN" and,
"Use again only after the crankshaft has been thoroughly inspected according to Guideline For Reusable Parts - Inspection Of Crankshafts For Cracks, Form No. SEBF8043."
In relation to the above information, if grinder burns are found on new crankshafts, it is NOT necessary to inspect them with magnetic particle inspection equipment. All new and remanufactured Caterpillar crankshafts are inspected at the factory, by this method, before shipment. Caterpillar crankshafts which come from the factory with grinder burns are acceptable, if the grinder burns are in areas other than the journal or fillet.
This information will be in the next revision to these publications and has application to all Caterpillar crankshafts.
Use a fillet radius