MUFFLER GP 3872646 - Caterpillar

Off-Highway Truck:
797 (S/N: 5YW1-UP)
797B (S/N: JSM1-UP)
Reference: Special Instruction, REHS1768, "A Procedure to Update the Hydrualic Lines for the Hoist Pump"Description of Change: The hydraulic lines for the hoist pump have changed. The change improves the routing of the hydraulic lines. The change also simplifies the installation of the transmission and the removal of the transmission. The hose routings resulted in changes to the flow of oil from the hoist pump. In previous models, the flow of oil from the front two sections of the hoist pump was routed to the right side of the hoist valve. If the hoist pump was not activated, the oil would be bypassed to the front brake cooling circuit. The rear two sections of the hoist pump were routed to the left side of the hoist valve and then bypassed to the rear brake cooling circuit. With the new routing of the lines, oil flow from the two front sections of the hoist pump is now directed to the left side of the hoist valve and the oil flow from the rear two sections of the hoist pump are now directed to the right side of the hoist valve. These changes do not affect the performance of either the hoist system or the brake cooling system.Adaptable To: The updated 149-3063 Hoist Oil Lines Gp is effective with 797B (S/N: JSM147-UP) Off-Highway Truck. Refer to Special Instruction, REHS1768, "A Procedure to Update the Hydrualic Lines for the Hoist Pump" for the procedure to adapt the updated 149-3063 Hoist Oil Lines Gp to the following machines: 797 (S/N: 5YW1-UP) and 797B (S/N: JSM1-146).