- Mini Hydraulic Excavator
- 308E2 CR (S/N: EC21798-UP; MY21900-UP)
Introduction
This Special Instruction provides the installation procedure for adjustable auxiliary relief valves on certain 308E2 CR Mini Hydraulic Excavators with the 467-3072 Bank Valve Gp (Main Control Valve). This Special Instruction can only be applied for 308E2 CR Mini Hydraulic Excavators with the 467-3072 Bank Valve Gp (Main Control Valve).
Do not perform any procedure in this Special Instruction until you have read the information and you understand the information.
Safety Section
| NOTICE |
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Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products. Dispose of all fluids according to local regulations and mandates. |
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Hydraulic oil pressure can remain in the hydraulic systems after the engine and pump have been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic systems. To prevent possible injury, refer to the section, Testing and Adjusting, "Hydraulic System Pressure - Release" before any fitting, hose or component is loosened, tightened, removed or adjusted. When possible, the bucket or attachment must always be lowered to the ground before service is started. When it is necessary for the boom to be in the raised position while tests or adjustments are done, be sure that the boom, stick and bucket or attachment have correct support. The swing lock (if equipped) must be engaged before service is started. Always move the machine to a location away from the travel of other machines. Be sure that other personnel are not near the machine when the engine is running and tests or adjustments are being made. |
Required Parts
| Required Parts | ||
|---|---|---|
| Qty | Part Number | Part Name |
| 2 | Relief Valve Gp | |
Installation Procedure
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| Illustration 1 | g06027229 |
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Main Control Valve (1) | |
- Remove two plugs (1) from the main control valve auxiliary section.
- Install two 456-1861 Relief Valve Gp in place of the plugs (1). Tighten 456-1861 Relief Valve Gp to
44.5 ± 4.5 N·m (32.8 ± 3.3 lb ft) .
Adjustment Procedure
Relief valves are preset to
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| Illustration 2 | g06027245 |
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(2) Jam nut (3) Internal hex screw | |
- Loosen the jam nut (2).
- Adjust relief pressure by turning the internal hex screw (3). Turning the screw clockwise increases relief pressure. Turning the screw counterclockwise decreases relief pressure.
- When desired relief pressure is achieved, tighten the jam nut (2) to
13.5 ± 1.5 N·m (10.0 ± 1.1 lb ft) .