CAT Generator SR4

NOTE: Use Cat Special Purpose Grease (SPG) 2S-3230 for ball bearings. This is a NLGl No. 2 Grade (without molybdenum disulfide) with thickener Polyurea, and a temperature range of [-29 to 177% (-20 to 351°F)]. Use NLGl No. 1 or 0 Grade for extremely low temperatures.

NOTE: Use Cat 108-861 1 Grease for spherical roller bearings. This is a NLGl No. 1 % Grade (without molybdenum disulfide) with thickener Clay, viscosity 32cST at 40°C (104°F) and 5 cST at 100°C (212°F).

Remove the louver assembly or rear plate from the rear of the generator housing.

Remove the top and lower grease pipe plugs.

Install a grease fitting in the top, threaded grease pipe.

Grease shielded ball bearings with 1.8 to 2.0 oz of 2S-3230 Grease at an interval of every 2000 hours. Grease spherical roller bearings with 1 oz of 108-8611 Grease at an interval of every 1000 hours. DO NOT MIX GREASES.

NOTE: Some two bearing generators have spherical roller bearings in the front bracket and ball bearings in the rear bracket. These units should use a common 2S-3230 Grease for front and rear bearings.

Wipe off excess grease. Remove the top grease fitting and install plug.

Operate generator for one hour. This allows the grease to expand, forcing the excess grease out of the cavity relieving the internal pressure. The generator should continue to operate until the grease stops purging. Grease may not purge until later grease intervals.

WARNING: Before working inside the generator, make sure that the starter motor can not be activated by any automatic or manual signal.

When the engine-generator is operating, voltages up to 600V are present in these areas near or on the regulator: 1. the regulator terminal strip. 2. the excitation transformer terminal strip (selfexcited generator only).

Donot short theseterminals to ground with any part of the body or any conductive material. Loss of life or injury could result from electrical shock or injury from molten metal.

An electrical shock can be received from the regulator capacitor (Cl) when the engine-generator is not in operation. To avoid possible injury, discharge the stored charge using an 100 ohm resistor across C1 terminals.

NOTICE: Electronic components in the regulator can be damaged during generator operation if contact is made between the part and ground.

Periodically generators should be inspected for cleanliness. Contaminants such as dirt, dust, grease, salt, or oil films should not be allowed to accumulate on the windings.

If moisture is allowed to remain in contact with an electrical winding, some of the moisture will eventually be retained in voids or cracks of the insulation. This will lower the resistance of the winding insulation. The insulation used on the windings of Caterpillar generators is moisture resistant, but constant exposure to moisture will gradually lower the insulation's resistance.

Dirt can make the problem worse because it can hold the moisture in contact with the insulation. Salt (from sea air) can also make the problem much worse. This is because salt tends to absorb moisture from the air.

When the salt and moisture combine, they form a good electrical conductor.

The following maintenance procedure for generator bearings should be followed at every major engine overhaul:

1. Remove bearing bracket. Inspect the bracket bore and bearing outer race and rolling elements. Standby Power units should have the bearing inspected and the grease replaced every three years. The bearing bracket bore should be inspected for out of roundness, excessive wear, and a bracket step less than 0.0762 mm (.003 in).

The bearing should be inspected for outer race damage, severe fretting, and smoothness of operation. If possible, the bearing elements should be inspected. Some double shielded ball bearings prevent visual inspection of the ball bearing elements. Other double shielded ball bearings have a retaining ring, that can be removed, to allow access for a visual inspection of the ball bearing elements.

NOTE: Bearings being removed for failure analysis should not be cut off with a torch.

2. Spherical Roller Bearing should be cleaned and re- '@ packed with 108k3611 Grease Pack the bearing and cavity to one-third to one-half of the cavity volume. (Approximately 3 - 4 oz. in the bearing and 4 - 5 02. in the cavity.) Refer to the chart that follows.

3. All ball bearings should be cleaned and the bracket cavity re-packed with 2.5-3230 Grease. The cavity should be filled to one-third to one-half of the cavity volume. Refer to the chart that follows.

4. Make sure the grease supply tube to the bearing is filled with grease.

5. Remove the bracket drain plug and operate generator for one hour. This allows the grease to expand, forcing the excess grease out of the cavity reliei/ing the internal pressure. The generator should continue to operate until the grease stops purging. Grease may not purge until later grease intervals.

6. Stop the engine. Install the bracket drain plug and wipe off excess grease.

Warning: This procedure requires trained personnel with PPE!

Megohmmeter available for testing?

If megohmmeter is not available, report to the maintenance team and stop the procedure

Select the situation for testing

Enter the megohmmeter test reading

Is the test reading above one megohm?

Note down any issues found during the test

Sign off on the resistance check

Warning: This maintenance check requires trained personnel with PPE!

Main Stator Winding Temperature