VALVE AR-LOAD CONTROL 4195124 - Caterpillar

Air Dryer
Glossary
To better understand the operation of the air dryer, a glossary of words and definitions is provided.Absorption: To collect molecules (small particles) of a gas or substance (foreign material) on micro-crystalline particles (very small crystal-like particles).Desiccant: A drying material for the air dryer (drying bed).Purge Valve: The drain valve to let the moisture and other foreign material, taken from the air, go out of the air dryer.Condensation: Moisture in the air that has changed into water.Introduction
Typical Air Circuit Schematic
(1) One-way check valve (two). (2) Air reservoir. (3) Inlet line from air compressor. (4) Air compressor governor. (5) Air compressor. (6) Outlet line to air reservoir. (7) Air dryer. (8) Unloader line from air compressor governor.The air dryer (7) is used to remove moisture, carbon and oil from the compressed air before it gets to the air reservoir (2). Clean, dry air is very important for safe operation and performance of brake systems that use compressed air. Clean, dry air will also prevent corrosion of parts.The air dryer (7) is installed in a vertical position. It is in the air system between the air compressor (5) and the air reservoir (2).With the use of the air dryer, it is not necessary to drain the air reservoir daily. The cartridge (canister) of the air dryer can be removed and replaced as a unit. The parts of the cartridge (desiccant beads and filter) can also be removed and replaced separately.During cold weather, the heating element in the air dryer keeps moisture from freezing in the bottom of the air dryer housing.Compression Cycle
Flow Of Air During Compression Cycle (Compressor Loaded)
(1) Cap. (2) Outlet passage. (3) Inlet passage. (4) Cartridge. (5) Housing. (6) Desiccant. (7) Filter.Moisture, carbon and oil is removed from the compressed air in three steps:* cooling* filtering* absorptionCooling
With the air compressor in its loaded or compression cycle, warm, moist air from the air compressor goes through inlet passage (3). The air goes down between housing (5) and cartridge (4). The air is cooled on the way down. This cooling changes the oil and water vapor to a liquid (condensation).As the air turns to go up through the cartridge (4), much of the oil and water drops to the bottom of housing (5).Filtering
When the air goes into cartridge (4), it goes first through filter (7). The filter removes additional dirt particles, oil and water mist.Absorption
From filter (7) the air then passes up through desiccant (6). The desiccant is a "drying bed" that removes additional moisture from the air by absorption.The "dry" air now goes out of cartridge (4) through outlet passage (2) in cap (1) to the air reservoir.Purge Cycle
Flow Of Air During Purge Cycle (Compressor Unloaded)
(1) Outlet passage. (2) Inlet passage. (3) Cartridge. (4) Housing. (5) Desiccant. (6) Spring. (7) Purge valve. (8) Filter. (9) Heater passage. (10) Purge passage. (11) Unloader passage.For the unloaded or purge cycle, the air flow through cartridge (3) of the air dryer is the reverse of the compression cycle.When the air system gets