Shuttle Valve Failure Causing Malfunction Of Main Hydraulic Pump Caterpillar

Shuttle Valve Failure Causing Malfunction Of Main Hydraulic Pump

Usage:

EXCAVATORS330 (9PJ1034-UP, 9WJ, 6ZK, 8RL179-UP, 2ZM),
330 L (6SK1034-UP, 8FK, 2EL, 9ML166-UP, 5YM),
330 LN (8CK) EXCAVATORS

Problem:

Malfunctions of the 128-9062 Main Hydraulic Pump Group have been traced to premature wear and/or breakage of the poppet-type shuttle valve used to monitor travel speed signal.

The failures have a greater chance of occurring in pumps with one shuttle valve. Pumps that have three shuttle valves for travel speed signal and pilot pump assist have not been reported having similar failures.

Solution:

The problems with the shuttle valves can be resolved by replacing the poppet-type shuttle valves with new ball-type shuttle valves.

A new ball-type shuttle valve consists of a 081-3959 Plug, 123-2020 Bush, 3G-0785 Ball, and a 123-2021 Seat. Refer to the illustration for location of the parts on the pump head group.

A new 166-3184 Cover will also come with the ball-type shuttle valve parts to replace the 115-3685 Cover currently in use. The new cover will make it possible for the pump head group to use the ball-type shuttle valve.

The new ball-type shuttle valve and cover is also being installed as part of the new 159-7781 Pump Head Group on the new 159-7779 Main Hydraulic Pump Group. The 159-7779 Main Hydraulic Pump Group replaces the former 128-9062 Main Hydraulic Pump Group.

159-7781 Pump Head Group

(1) 166-3184 Cover.

(2) 081-3959 Plug.

(3) 123-2021 Seat.

(4) 3G-0785 Ball.

(5) 123-2020 Bush.

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