BALL BEARING 0950990 - Caterpillar

D379 ( 68B5682-Up ),
D398 ( 66B7444-Up ),
D399 ( 35B4702-Up ) Industrial Engines;
D379 ( 34Z478-Up ),
D398 ( 35Z507-Up ),
D399 ( 36Z469-Up ) Generator Set Engines So EquippedSeveral improvements have been made to the hydramechanical shutoffs for the above models. These improvements were made for better, more positive shutoff operation and longer component service life. A complete list and explanation of the changes which have been made is given in the topic "Shutoff Improvements".
To make sure the shutoff operates correctly and will stop the engine when necessary, test operation at specific intervals is very important. This is the reason for the recommendation in Operation And Maintenance Guides to test the shutoff operation every 500 SMU (Service Meter Units). The topic "Test Procedures" tells how to make the regular maintenance test, and how to check specific circuits and components for correct operation. An important component to check is the drive coupling, because a failure of the coupling will prevent operation of the complete system. The drive coupling test can be made during normal engine operation under full load conditions; it is not necessary to slow down or stop the engine for this test.
Shutoff Improvements
Air Inlet Shutoff Group
1. A new 5N8963 Cylinder (Hydraulic) is used in place of the former 5N3089 Cylinder. In comparison with earlier 5N3089 Cylinders, these improvements have been made: ...A different spring is used in the new cylinder, and in later 5N3089 Cylinders. The new spring is cadmium plated (has a layer of cadmium) to prevent rust. With the former spring, particles of rust fell from the spring to the surface of the seal and caused seal damage. Later 5N3089 Cylinders that use the new spring have an identification mark which is a square with a letter N or later letter inside the square.
...The head of the new cylinder is both longer and larger in diameter than the head of earlier 5N3089 Cylinders. Later 5N3089 Cylinders have a head which is larger in diameter, but not longer. See Illustration 1. The larger head diameter prevents possible contact between fitting connections and the cylinder plunger, which can prevent operation of the cylinder. This contact was possible in some earlier cylinders, if fittings were tightened too tightly. The longer head used on the new cylinder gives more clearance so the fittings can be removed or installed without removal of the cylinder from the mounting flange. Also, the increased clearance makes it easier to remove or install the flange bolts.
Illustration 1. Air inlet shutoff cylinders.2. A new 5N9202 Flange is used in place of the former 5N3084 Flange, which is canceled. The new flange is 6.00 mm (.236") thick in comparison with the 3.00 mm (.118") thickness of the former flange, and has a machined groove for an O-ring seal (see paragraph "3", which follows, and Illustration 2). The thicker flange gives a more rigid mounting for the hydraulic cylinder. Formerly, it was possible for distortion of the flange to prevent free movement of the cylinder plunger. In addition to the