DISC A. 4F1487 - Caterpillar

Rear Suspension Arrangement - (Early 6x4 arrangement illustrated) 12. Suspension Cylinder - rear axle16. Pivot Pin17. Pivot Pin18. A-Frame19. Spherical Bearing20. Panhard RodAccumulator - Early Type
Early Type AccumulatorAccumulator - Later Type
Later Type Accumulator 1. Nitrogen Charging Valve2. End Cap3. Nitrogen Chamber4. Cylinder Tube5. Piston6. Pressure Oil Chamber7. End Cap8. Port9. Restrictor/Check Valve10. HolesThe accumulator has a sealed piston (5) that moves along the bore of the cylinder tube (4). Chamber (3) is charged with nitrogen gas through the charging valve (1). The accumulator receives pressure oil through port (8) which compresses the nitrogen in chamber (3). During normal operation the compressed nitrogen acts as a source of stored energy to provide the necessary 'spring' and absorb shock.The accumulator is similar to the early type described previously except that the end cap (7) has an integral restrictor/check valve (9). When oil is flowing into the accumulator the restrictor/check valve lifts off its seat and allows free flow into the oil chamber (6). When oil is flowing out of the accumulator the restrictor/check valve is seated and oil can only escape at a controlled rate through the two holes (10).When the front wheels hit a bump the resulting high pressure in the suspension cylinders unseats restrictor/check valve (9) and allows free flow of oil into the accumulator. The suspension therefore reacts very quickly to the disturbing force resulting from the bump. When the disturbing force is removed the increased nitrogen pressure forces oil out of the accumulator. Restrictor/check valve (9) closes so that oil can only escape at a controlled rate through holes (10).Suspension Air Filter
Air Filter 1. Inlet Port2. Louvres3. Quiet Zone4. Element5. Valve6. Outlet PortThe air filter ensures a supply of clean pressurised air to the suspension rotary valve and control valve. The air flow from the truck main air system enters the filter through inlet port (1). The air flow passes through louvres (2) which force it into a whirling flow pattern. Liquid particles are thrown against the inside wall of the bowl by centrifugal force, and run down the wall into the bottom of the bowl into a 'quiet zone' (3). The air then passes through the sintered bronze element (4) where any remaining solid particles are removed. Air flow through the filter creates a pressure differential above and below the diaphragm of valve (5). After a period of time the difference in pressure is sufficient to cause the diaphragm to lift valve (5). Thus any liquid accumulated in the bottom of the bowl is automatically drained.External Restrictor/Check Valve
External Restrictor/Check Valve 1. Cap2. Body3. Spring4. Poppet5. Inlet PortWhen the suspension control valve is in the "raise" position oil flows into the suspension cylinders and accumulator through the external restrictor/check valve. Oil enters inlet connection at port (5) and lifts the poppet (4) off its seat allowing full forward flow. When the suspension valve is in the "lower" position oil flowing out of the cylinders and accumulator must pass through the hole in poppet (4). The poppet