LINER 4536729 - Caterpillar

Illustration 1. Location of the drilled oil galleries.Cylinder blocks have increased wall thickness in key locations to make the block stronger. The oil galleries are now drilled rather than cast. These improvements have increased the fatigue limits of the block. This allows the block to be used at higher ratings without decreasing the reliability of the block.
Crankshafts used in 3512 and 3516 Engines have improved heat treating. The manufacturing process for the crankshaft oil supply holes has been changed to reduce stress concentrations. These changes will result in stronger crankshafts.
Illustration 2. Former and new camshaft drive gear retainers.Camshaft lift, duration and profile have been refined to provide increased efficiency. The camshaft drive train has been improved to carry more load, as shown in Illustration 2. One larger bolt is now used, rather than two smaller bolts to fasten the camshaft drive gear on the end of the camshaft. This provides a stronger gear-to-camshaft joint and is simpler to assemble.
Illustration 3. Cross sections of the forged piston and the cast piston.
Illustration 4. Forged piston and cast piston.
Illustration 5. Bottom view of the forged piston and the cast piston.Two types of pistons are now used. One type piston is of all cast construction and is used in lower and intermediate rated engines. The other type piston has two parts; a forged skirt, pin boss and central crown with a cast outer crown. These two piston parts are electron beam welded together. This welded type piston is used in the new uprated engines.
Illustration 6. Connecting rod used with the welded piston and the connecting rod used with the cast piston.Due to the increased piston crown thickness, a new connecting rod with a different small end balancing boss is used. This will provide sufficient clearance between the top of the rod and the undersize of the piston crown.
Piston pins have been improved but the difference is hardly discernible to the naked eye. The improved piston pin is required for proper break-in and satisfactory performance under the increased load. The former pin is not to be used with the welded pistons.
Illustration 7. New and former intake and exhaust valves.
Illustration 8. New and former rocker arm shafts.
Illustration 9. New and former injector rocker arms.
Illustration 10. New and former rocker bases.
Illustration 11. New and former valve covers.Many new, improved valve train components are used with the uprated 3500 Series Engines. The intake and exhaust valves now have thicker head and face areas. The rocker arm shafts have improved hardening techniques and thicker mounting spades. Push rods have improved heat treat techniques. The injector rocker arm is stronger and has a longer adjusting screw. The aluminum rocker bases have been changed to provide additional strength. The valve cover height has been increased to provide clearance for the stronger injector rocker arm.
Illustration 12. Cross section of new and former cylinder heads.
Illustration 13. New and former cylinder heads.New cylinder heads have increased strength through the use of internal gussets which reduce cyclical deck distortion. This increases the strength