1999/02/08 Caterpillar

Correct Seal Usage Improves Service Life {7555}

Usage:

All Caterpillar Machines

Some earlier Caterpillar machines built in the 1970's and early 1980's used metal backed seals with tubes, hose couplings and fittings. Later, new tubes, hose couplings and fittings were introduced. The new tubes, hose couplings and fittings were designed to use rectangular seals and O-rings. The rectangular seals and O-rings provide better sealing than the metal backed seals.

Metal backed seals will not fit in components designed to use rectangular seals or O-rings. Rectangular seals or O-rings may fit in components designed to use metal backed seals, however, they WILL NOT adequately seal components designed to use metal backed seals, particularly under high pressure.

NOTE: Components designed to use metal backed seals do not have grooves necessary to prevent rectangular seals or O-rings from distorting under pressure.

Metal backed seals are no longer serviced. Some earlier Caterpillar machines may still be equipped with tubes, hose couplings and fittings designed to use metal backed seals. These earlier tubes, hose couplings and fittings should be replaced with new components that either use rectangular seals or O-rings.

NOTE: Disregard NPR information that calls for rectangular seals or O-rings as direct replacements for metal backed seals. DO NOT use rectangular seals or O-rings to replace metal backed seals in components designed to use metal backed seals.

Caterpillar Information System:

1999/02/08 New Engine Pressure Sensors Available {1916,1917,1922,1923,1924}

1999/02/08 Valve Bodies Now Stress Relieved To Improve Service Life {3167}

1999/02/08 Special Instruction, "Installation Instructions For Improved Ride Control System", Now Available {0374,1408,4812,5051,5057,5077,5479,7332}

1999/02/08 Correction To Testing And Adjusting Manual, RENR2146-01 {0374,1435,5700}

1999/02/01 Procedure For Assembly And Installation Of Conventional Duo-Cone Seals Is Now Available{7561}

1999/02/01 Bearing Specifications For 3408E And 3412E Hydraulically Actuated Electronically Controlled Unit Injector (HEUI) Hydraulic Drive Group{1714}

1999/02/01 Correct Assembly Of Bulldozer Trunnion Bearings Prevents Failures{6069}

1999/02/01 Special Instruction, REHS0224, Available For Brake Rework{3066,3154,4101}

1999/01/25 Improved Solenoid Valve Group Available {5479}

1999/01/25 Correction To Power Train Disassembly And Assembly Manual SENR1381-01 {0600,0722,3254,3258,3260}

1999/01/25 Correction To Hydraulic System Specification Manual SENR6672 {5104,7568}

1999/01/25 Fuel Level Senders Improved To Prevent Open Circuit Conditions {1273,1408,7481}

1999/02/08 New VIMS Application Guide Available {7601,0374}

1999/02/15 Electrical System Schematic, SENR1864, Available {1400}

1999/02/15 Bolts, Washer, And Spacers Grouped Into Fastener Groups In Engine Cylinder Head Groups {1100}

1999/02/15 Correction To Operation & Maintenance Manual SEBU6955 {0374,0375,7560}

1999/02/15 New Thrust Washer Improves Service Life Of Differential Group {3258}

1999/02/15 Correction To Operation & Maintenance Manual, SEBU6492-02 {0374,0375,7490}

1999/02/15 Correction To Disassembly And Assembly Manual, RENR2116 {0374,1387}

1999/02/15 New Auxiliary Drive Coupling Group Improves Service Life {3252}

1999/02/15 100 cm Of 5P-1471 Hose Required For each 994 Wheel Loader Dust Ejector {1068}

1999/02/15 New Weld Procedures On 994 Wheel Loader Buckets Increase Service Life {6101}

1999/02/15 Rework Procedure Available To Upgrade Differential Case Assembly {3258}

1999/02/15 Air Conditioning And Heater System Updates Improve Operation And Reliability {7304,7309,7337,7343}