GASKET-COVER 8N9885 - Caterpillar

All SR4 generators have the same basic design. The following list displays some differences that may occur between SR4 generators:
Power for the exciter field is provided by either the permanent magnet pilot excited (PMPE) method or the self-excited (SE) method.
The location of the bearing can be inboard or outboard from the exciter rotor. The following factors determine the location of the bearing: vibration characteristics of the engine, vibration characteristics of the generator, the size of the engine and the size of the generator.Note: Some larger generators have two bearings. When a generator has two bearings, there is a bearing at each end of the generator shaft.
Illustration 1 g00611851
SE Type Components with Outboard Bearing (1) Bearing (2) Exciter Armature (Rotor) (3) Exciter Field (Stator) (4) Rotating Rectifiers (5) Main Field (Rotor) (6) Main Armature (Stator) (7) Rotor Shaft (8) Fan
Illustration 2 g00611845
SE Type Components with Inboard Bearing (1) Rotating Rectifiers (2) Exciter Field (Stator) (3) Exciter Armature (Rotor) (4) Bearing (5) Main Armature (Stator) (6) Main Field (Rotor) (7) Rotor Shaft (8) Fan
Illustration 3 g00851614
PMPE Type Components with Inboard Bearing (1) Rotating Rectifiers (2) Exciter Field (Stator) (3) Exciter Armature (Rotor) (4) Bearing (5) Main Armature (Stator) (6) Main Field (Rotor) (7) Rotor Assembly (8) Fan (9) Heat sink Assembly (10) Pilot Exciter Armature (PM Armature) (11) Pilot Exciter Field (Permanent Magnet (PM)) (12) Seal (13) SealRotating Field Assembly (RFA)
Illustration 4 g00851687
Rotating Field Assembly (RFA) Components (SE Inboard Bearing Type Shown) (1) Heat Sink and Rotating Rectifier Block (2) Exciter Armature (Rotor) (3) Bearing (4) Main Field (Rotor) (5) Rotor AssemblyThe RFA components attach to rotor assembly (5), which is supported by the engine flywheel and bearing (3). The pilot exciter field (permanent magnet (PM)) is also an RFA component on PMPE generators.Main Armature (Stator)
Illustration 5 g00637295
Main Armature (Stator)The generator main armature is stationary and the generator main armature contains the stator windings.Main Field (Rotor)
Illustration 6 g00851688
(1) Main Field (Rotor)Generator Main Field (1) is part of the rotating field assembly. The generator main field rotates with the rotating field assembly.Exciter
Illustration 7 g00637298
Exciter Armature (Rotor)
Illustration 8 g00637297
Exciter Field (Stator)Pilot Exciter
Illustration 9 g00851689
Pilot Exciter Armature
Illustration 10 g00851690
Pilot Exciter Field (Permanent Magnet (PM))A pilot exciter is used on permanent magnet pilot excited (PMPE) type generators. The pilot exciter consists of the stationary pilot exciter armature. Refer to Illustration 9. The pilot exciter also consists of the rotating pilot exciter field. Refer to Illustration 10. The pilot exciter field is also referred to as the permanent magnet (PM). Rotating Rectifier Blocks
Illustration 11 g00610186
Two Diode Rectifier Block
Illustration 12 g00611973
6 Diode Rectifier BlockThe rotating rectifier blocks are part of the rotating field assembly (RFA). There are two types of rotating rectifier blocks that are used. The size of the generator determines the size of the rotating rectifier block that is used.
The two diode rectifier block contains two diodes. Three identical blocks are required.
The six diode rectifier block contains six diodes. One block is required.Note: For additional information, refer to "Rectifier Circuits" within the Systems Operation Section, "Generator Operation". Note: Early SR4 generators were provided with six individual