PUMP GP-AUX-S 4917734 - Caterpillar

Caterpillar MachinesSome 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.
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.
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.