CORE AS-EVAPORATOR 1474812 - Caterpillar

Illustration 3 g06297602
(D) Ring-Resistor Ring-Terminal
Disconnect one of the two main-rotor (field) and ring-resistor connections (B) from rotating rectifier.Separate larger main-rotor (field) lug from smaller ring-resistor ring terminal. Check resistance of the ring-resistor (D).Connect one lead of the ohmmeter to ring-resistor ring terminal and other lead to the second DC connection on the rotating rectifier. The resistance should be approximately 5 Ohms.
If resistance of the ring-resistor is far greater than 5 ohms or open circuit, disconnect the other main-rotor (field) and ring-resistor connection from the rotating-rectifier.Separate the larger main-rotor (field) lug from the smaller ring-resistor ring terminal. Check the crimp of the ring terminals on the ring-resistor leads.Measure resistance of the ring-resistor again directly across the ring terminals. If the ring-resistor is greater than 5 Ohms, contact Caterpillar Product Support.
Check that the cord wrap (C) that secures the three exciter armature AC leads to the rotor is still in place. The lacing is required to prevent damage to the leads during operation.Rework Procedure
Table 2
Diode usage
Generators with serial number S/N:M4N00001-00449 488-9244 Standard Diode 488-9245 Reverse Diode 488-9246 Sleeve
Generators with serial number S/N:M4N00450-99999 459-0221 Standard Diode 459-0222 Reverse Diode - Note: For Generators given a new serial number after being reworked through Caterpillar Reman, use 459-0221 Standard Diode and 459-0222 Reverse Diode.Note: Generators with serial number S/N:M4N00001-00449 will always need 488-9246 Sleeve, even after undergoing Caterpillar Reman updates.
Illustration 4 g06297777
(1) 488-9246 Sleeve
Install threaded sleeve (1) on all diodes for generators with serial number S/N:M4N00001-00449 even after undergoing Caterpillar Reman updates. The sleeve must bottom out on the base of the diode as shown in Illustration 4. The purpose of the sleeve (1) is to center the smaller studded diode in the oversized hole.
Illustration 5 g06297839
(D) AC connection point
(E) Diode mounting base
Rotate the rectifier to access one of the three AC connection points (E).Remove and discard all hardware that secures the two diode flying leads and armature lead.
Rotate the rectifier to access the base connection (F) of one of the diodes that has the flying lead disconnected.Remove and discard all hardware mounting the diode, and discard the diode.
Illustration 6 g06297803
(2) 5B-9079 Jam Nut
(3) 264-3617 Lockwasher
(4) 7X-0623 Washer
Install one of the new diodes of the same polarity as the removed diode. Ensure sleeve is in place as the stud is inserted through the hole in the rectifier plate.Orient diode base, so that the flying lead connection can be made with minimal twist.For 488-9244 Standard Diode and 488-9245 Reverse Diode (Illustration 6) :
Secure diode with hard washer (4), lock washer (3) and nut (2). Tighten the nut (2) to 13.5 1.0 N m (119.5 8.9 lb in).For 459-0221 Standard Diode and 459-0222 Reverse Diode (Not pictured) :
Secure diode with lock washer (3) and nut (2). Tighten the nut (2) to 10.0 1.0 N m (88.5 8.9 lb in).Note: Stud on the diode is plated copper. Do not overtighten the nut or diode can be damaged.
Rotate rectifier to access base connection of other diode that has flying lead