ENGINE AR 7E3421 - Caterpillar

Required Tools
Table 1
QTY Part Number Description
1 448-0722 Probe
1 448-0723 Probe
1 448-0724 Tool Gp
1 448-0725 Tool Gp General Care
The following factors will accelerate deterioration of rubber:
Age
Repetitive Starting and Stopping of Generator Set
Harsh Electrical Events (such as loss of synchronism) when paralleled with utility
Heat
Ultraviolet light (UV light)
Petroleum products
Solvents
Anaerobic adhesives (thread lock compound)
OzoneAnaerobic adhesives can also deteriorate the bond between rubber elements and the steel flange or the hub.In an environment that is free of an aggressive chemical and light related agents, the main cause of an accelerated deterioration of the rubber is heat.There are five causes of heat buildup in rubber coupling elements:
High ambient temperature
Damping of torsional vibrations
Compensation for angular misalignment
Compensation for radial misalignment or for offset
Compensation for axial misalignment or for movementIn a controlled environment, the destructive conditions can be minimized. The rubber couplings can have a long useful life.
Illustration 1 g01322929
Flexible coupling
(1) Hardness stamp
(2) Outer coupling
(3) Rubber elementPreventive Maintenance Schedule
Maintenance for the Rubber Flexible Coupling consists of four activities:
Keep the coupling free of excessive heat, UV light, petroleum products, solvents, anaerobic adhesives, and ozone.
Periodically inspect the rubber and the metal components for any imperfections, for stress, and for wear.
Check the torque for the fasteners periodically.
Check the alignment periodically.
Illustration 2 g01323258
(1) Rubber areas that are peeling away from the steel hub
(2) Wear at the loaded side of the teeth
Illustration 3 g01323319
Detail A
Cracks in the rubber
During visual inspection of the rubber element, note any rubber areas that are peeling away from the steel hub. A wear of 3 to 4 mm (0.118 to 0.157 inch) at the loaded side of the teeth is allowable. Refer to Illustration 2.During visual inspection of the rubber element, note any tears or cracks in the center of the rubber element. Refer to Illustration 3.Inspection Schedule
Every 2,000 Hours
Inspect all externally visible surfaces and check the torque of accessible bolts. Refer to the "Inspection" section.At Top End Overhaul (8000 to 22000 Hours)
Unbolt the drive ring from the flywheel. Slide the drive ring away from the flywheel over the rubber element. Inspect the surfaces of the drive of the rubber element and the back side of the rubber element. A borescope can be used to check for cracks on the flywheel side of the rubber element.Inspection
Torsional Set
Illustration 4 g01323355
Torsional set of rubber coupling
(X) Distance of torsional set
(Y) Diameter of molded edgeUse the following steps to determine the amount of torsional set of a rubber coupling. Refer to Illustration 4.
Use a straight edge and the centerlines of the holes on the inner hub. Put a mark on the edge of the mold line of the rubber element.
Use a straight edge and the centerline of a tooth space. Put a mark on the edge of the mold line that is on the rubber element.
Measure the distance between the marks. Replace an element when the torsional set (X) exceeds 25 mm (1 inch).Cracks
Examine all rubber surfaces for cracks. Refer to Illustration 3.Length - Acceptable hairline cracks are random and short. Cracks that radiate diagonally from the center of the rubber