Air Shut-Off Groups (3406B/C) {1078} Caterpillar

Gen Set Engine

3406 GEN SET (S/N: 75Z1-UP)

3406C GEN SET (S/N: 4ZR1-UP; 1LS1-UP)

Industrial Engine

3406 IND (S/N: 90U1-UP)

Introduction

Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.

Illustration 1	g06012407

Note: Put a small amount of clean engine oil or glycerine on the lip of seal (4) and in the bores for the O-ring seals at assembly.

1. Distance bearing is installed below pipe surface ... .25 ± 0.25 mm (0.010 ± 0.010 inch)

2. Diameter of shaft ... 15.80 ± 0.03 mm (0.622 ± 0.001 inch)

   Bore in bearings ... 15.88 mm (0.625 inch)

   Bore in pipe for bearings ... 18.263 ± 0.013 mm (0.7190 ± 0.0005 inch)

3. Valve assembly shown in the "run" (open) position.

   When the valve is closed a 0.08 mm (0.003 inch) feeler gauge must not fit between the valve and the bore in the pipe at any point.

4. Seal. Install the seal with the tip of the seal toward the outside as shown.

5. Diameter of shaft ... 9.60 ± 0.03 mm (0.378 ± 0.001 inch)

   Bore in the bearing ... 9.80 ± 0.03 mm (0.386 ± 0.001 inch)

   Note: Adjust shaft as needed to change spring tension until hold-in current consumption (draw) is less than 2A at shutdown.

6. 3N-9106 Torsion Spring (used with some 3406 Engines:

   Free length ... 63.5 mm (2.50 inch)

   Outside diameter ... 30.7 mm (1.21 inch)

   5N-2761 Torsion Spring:

   Free length ... 49.8 ± 0.5 mm (1.96 ± 0.02 inch)

   Outside diameter ... 30.7 ± 0.5 mm (1.21 ± 0.02 inch)

7. 3N-7848 Torsion Spring:

   Length under test force ... 22.86 ± 0.5 mm (0.90 ± 0.02 inch)

   Test force ... 4 N (1 lb)

   Free length after test ... 35.6 ± 0.5 mm (1.40 ± 0.02 inch)

   Outside diameter ... 18.8 ± 0.5 mm (0.74 ± 0.02 inch)

8. Bracket assembly. Bracket assembly must be adjusted so valve assembly (3) is parallel to pipe bore with 2°.

9. 4N-3889 Solenoid:

   Voltage rating ... 12V

   Current consumption (draw):

   Pull-in windings ... 21A at 12V

   Hold-in windings ... Below 1A at 14.3V

   4N-3890 Solenoid:

   Voltage rating ... 24V or 32V

   Current consumption (draw):

   Pull-in windings ... 10A at 24V

   Hold-in windings ... Below 1A at 28V

   4N-3889 4N-3890 Solenoids:

   Plunger travel ... 11.7 ± 0.3 mm (0.46 ± 0.01 inch)

   Distance from plunger face to flange face:

   with solenoid energized ... 9.6 ± 0.5 mm (0.38 ± 0.02 inch)

   Note: The hold-in current consumption (draw) on engine must take less than 2A at shutdown.

   with plunger extended ... 21.28 ± 0.13 mm (0.838 ± 0.005 inch)

10. Diode assembly. Diode assembly required to suppress the back EMF voltage spike generated when the solenoid is turned off.