Set and Test the Overspeed Verification Switch{7410, 7427, 7490} Caterpillar

Engine:

3508B (S/N: S2A1-UP; S2B1-UP)

3512B (S/N: S2G1-UP; S2H1-UP)

3516B (S/N: S2P1-UP; S2R1-UP)

Introduction

ReferenceOperation and Maintenance, SEBU7845-04, "3500B Series II Marine Auxiliary Engines"

ReferenceSystems Operation, RENR5078-03, "3500B and 3500C Marine Engines"

ReferenceSystems Operation, SENR5002-07, "Installation Guide for Marine Engine Electronic Displays"

This Special Instruction provides the procedure that is necessary to set the Independent Overspeed Verification Switch. Do not perform any procedure that is outlined in this Special Instruction until the entire Special Instruction has been read and understood.

The 234-8717 Switch is included in the following Engine Instrument Panels:

• 280-7519 Instrument Panel Box Group

• 280-7515 Instrument Panel Box Group

• 231-9903 Instrument Panel Box Group

• 231-9902 Instrument Panel Box Group

Procedure

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Illustration 1	g01282060
Adjustment of Speed Switch (1) Adjusting Wheel for Speed Switch (2) "85% Overspeed Verify" Activation Button

1. With the engine stopped, turn the adjusting wheel (1) for the speed switch up to "100".

2. Locate the engine "Rated RPM" and the "85% Verify RPM" for your engine in Table 1.
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   Table 1

   Rated RPM	Overspeed RPM 118%	85% Verify RPM
   1000	1180	1003
   1200	1416	1204
   1770	1770	1505
   1600	1888	1605
   1800	2124	1805

3. To adjust the speed switch (2), perform Step 3 through Step 3.e.

   1. Operate the engine at the 85 % Verify RPM. Refer to Step 2.

   2. Depress the 85 % "Overspeed Verify Activation" button.

   3. Hold the button in and slowly turn the "Speed Switch Adjusting Wheel" toward the lower number.

      Note: The engine should shutdown.

   4. Cycle the Engine Instrument Panel switch to the "Off/Reset" position and back to the On position.

   5. Setup of the Overspeed verification with the independent switch is complete.

4. To verify the independent speed switch is correctly set perform Step 4 through Step 4.d.

   1. Restart the engine.

   2. With the engine running, depress the 85 % Overspeed Verification Activation button and slowly elevate the engine RPM.

   3. The engine should shutdown when it reaches the 85 % Verified RPM that was set in Step 3.a through Step 3.e.

   4. The verification of the overspeed verify with the independent switch is now complete.