CYLINDER BLOCK GP 7E5311 - Caterpillar

--------------- END SUPPLEMENT ---------------Description of Change: A new hoist cylinder is used on D550B Trucks. The new cylinder is stronger than the former hoist cylinder. The former cylinder can also be upgraded if required.Adaptable To: The new 7U417 Hoist Cylinder is a direct replacement for either the 5U2379 Cylinder or the 3U6770 Cylinder (DJB part numbers DH2379 and DB6770 respectively). Machines built with 5U2379 Cylinders are listed in Chart A. These cylinders can be fully or partly upgraded if required. Parts required to fully upgrade a 5U2379 Cylinder are listed in Chart B. Note that some of these parts can be made from existing parts. If all the parts listed are installed, then the cylinder will be fully upgraded to 7U417.
Procedure For Disassembly Of 5U2379 Cylinder
Use Illustration 1 to identify the components of the 5U2379 Cylinder.
Illustration 1. Components of 5U2379 Cylinder.1. Remove the cylinder from the machine. Cleanliness is essential during disassembly and assembly of hydraulic system components. Move the cylinder to a clean area before starting the upgrade. Allow sufficient floor and/or bench space for disassembly. The cylinder is very long when extended.2. Anchor the cylinder at the outer tube spherical bearing end and slowly extend the cylinder until the first stage is extended 400 to 500 mm (15 to 20"). There could be a lot of oil inside the cylinder which will be forced out.3. Remove screw (14) with lockwasher. Unscrew retaining ring (15). Then continue to SLOWLY extend the cylinder until the first stage components are fully withdrawn.4. Remove screw (4) with lockwasher. Unscrew nut (5) and remove piston (6), bearing (12) and retaining ring (15). Discard nut (5). Keep bearing (12). Keep piston (6) and rod (16) if they are going to be reworked as shown in Illustrations 3 and 4. Keep retaining ring (15) if the later part (7U1162) is not to be installed.5. Temporarily screw retaining ring (15) onto inner cylinder (9). This will allow the inner cylinder to be used to pull out the second stage components.6. If necessary extend the second stage 400 to 500 mm (15 to 20").7. Remove screw (11) with lockwasher. Unscrew retaining ring (13). Then continue to slowly extend the cylinder until the second stage components are fully withdrawn.8. Remove screw (2) with lockwasher. Unscrew nut (1) and remove piston (3).9. Remove screw (7) with lockwasher and remove spacer (8).10. Remove retaining rings (13 and 15) and bearing (10). Discard nut (1), spacer (8) and piston (3). Keep inner cylinder (9) if it is to be reworked as shown in Illustration 2. Keep retaining ring (13) if the later part (7U1163) is not to be installed.11. Carefully inspect all remaining parts before assembly. Remove all of the old seals and discard.12. Rework inner cylinder (9) as shown in Illustration 2 or use new 7U1192 Inner Cylinder.
Illustration 2. Dimensions for reworked 2U1293 Inner Cylinder.13. Rework rod (16) as shown in Illustration 3 or use new 7U1193 Rod Assembly.
Illustration 3. Dimensions for reworked 2U1294 Rod. The only difference