Spring Isolator Group Installation and Adjustment Procedure {7060} Caterpillar

Engine

All 3600

All C280 Engines

Introduction

Do not perform any procedure in this Special Instruction until the information has been read and understood.

Spring isolators are used to reduce vibration and noise.

This Special Instruction provides the necessary information that is required for installing and adjusting the 7C-0533 Generator Base Mounting Group and the 7C-6537 Generator Base Mounting Group.

Note: A generator base mounting group is commonly called the spring isolator.

The 7C-0533 Generator Base Mounting Group is used more frequently than the 7C-6537 Generator Base Mounting Group for most applications.

The 7C-6537 Generator Base Mounting Group has a vertical restraint of ±2 G and a horizontal restraint of ±3 G under low cycle conditions. The spring isolators are primarily used in seismic sensitive areas.

Installation Procedure

Illustration 1	g00287371
7C-0533 Generator Base Mounting Group. (1) Isolator mounting holes (2) Base mounting holes (3) Isolator top plate (4) Leveling nuts (5) Snubber blocks (6) Snubber compression plate (7) Locknut (8) Snubber bolt (9) Flat steel washer (10) Isolator bottom plate (11) Fabric reinforced washer (A) 45 mm (1.8 inch) Initial clearance (B) 3 mm (0.1 inch) Tolerance at operating load

1. The spring isolators are shipped fully assembled. Space the isolators and arrange the isolators in accordance with recommendations from your Caterpillar dealer.

   Note: Spring isolators do not use shipping blocks. Do not remove any internal components from the spring isolators.

2. Use shims or grout in the foundation to provide a flat surface for the spring isolators. The maximum difference in elevation that can be tolerated is 6.35 mm (0.250 inch). Isolator base plates must rest on a flat surface. Use the correct size of anchor bolts and type of anchor bolts for isolator mounting holes (1).

3. Fabric reinforced washers (11) are included with each spring isolator. The washers are wired to the spring isolators. Remove the fabric reinforced washers. Save the washers for later use. Do not discard the washers.

4. Loosen both locknuts (7) and loosen snubber bolts (8) until the snubber compression plate (6) does not bind with the snubber blocks (5).

5. Place the engine base onto the spring isolators. Top plates (3) will deflect approximately 13 mm (0.5 inch). Bolt the engine base to top plate (3) through base mounting holes (2).

   Note: The cap screws must not project more than 3 mm (0.1 inch) below the lower surface of isolator top plate (3).

6. Install the anchor bolts or nuts through mounting holes (1). Install one fabric reinforced washer (11) and one flat steel washer (9) for each bolt. The fabric reinforced washer (11) is located between the isolator bottom plate (10) and the flat steel washer (9). Tighten the bolts or nuts to 109 N·m (80 lb ft). (Steel washers are not supplied.)

Note: Tightening snubber bolt (8) greater than finger tight reduces the efficiency of the isolator. Only tighten the snubber bolt further if absolutely necessary.

It is normal for the motion of the engine to increase while you are starting or stopping the engine. If the motion should become unsatisfactory, tighten snubber bolt (8) slightly.

Illustration 2	g00287237
7C-6537 Generator Base Mounting Group. (1) Isolator mounting holes (2) Base mounting hole (3) Isolator top plate (4) Leveling nuts (5) Snubber blocks (6) Snubber compression plate (7) Locknut (8) Snubber bolt (9) Flat steel washer (10) Isolator bottom plate (11) Fabric reinforced washer (A) 45 mm (1.8 inch) Initial clearance (B) 3 mm (0.1 inch) Tolerance at operating load

Adjustment Procedure

1. For these isolators, initial clearance (A) is approximately 45 mm (1.8 inch) at free height. If the clearance is less than 25 mm (1.0 inch) on any isolator, contact your Caterpillar dealer.

2. Check the engine level. If the engine is not level, turn both leveling nuts (4) of all isolators that are on the low end of the engine. Turn each of the leveling nuts clockwise in even increments until the engine is level. The adjustment of the isolator is now complete. The operating height can be increased by repeating Step 2 on all the isolators. Do not exceed the free height of the isolator. When the required height is achieved, recheck the engine level.

   Note: Due to the large load capacities of these isolators, lifting the engine base slightly may be easier to facilitate the adjustment of the isolator.

3. Providedthat the floor is level under each isolator "cluster", all the isolators that are within that cluster should be within approximately 3 mm (0.1 inch) (B) of each other. This dimension is required to ensure equal loading on each isolator within the cluster.

Horizontal Snubber Adjustment

Note: Efficiency will be obtained if the snubber compression plates are barely contacting snubber blocks (5). Only use the snubber blocks to help prevent excessive movement of the engine due to excessive dynamic loads. Excessive use of the snubber blocks will result in an increase in vibration.

1. Tighten snubber bolts (8) at each end of all isolators until the isolators are finger tight. Operate the engine.

2. Additional motion of the engine is normal while you are starting and stopping the engine as the speed passes through resonance frequency. The motion should quickly decrease when the operating speed is reached. If the movement becomes excessive, tighten snubber bolts (8) on each end slightly until the movement is reduced to an acceptable level.

3. Tighten locknuts (7) to complete the installation.