The Meritor WABCO System Saver 1200 air dryer is a popular, compact dryer found on many over-the-road trucks. It features a spin-on desiccant cartridge.

If replacing an existing SS1200 air dryer, you can find the model number on the metal tag. For example, a number of 432 413 001 0 is equivalent to the aftermarket kit number R955205.


WABCO System Saver 1200 Repair Kits WABCO System Saver 1200 Repair Kits

How the Meritor WABCO 1200 air dryer works

During system pressure build-up, compressed air passes into the air dryer where the filter system removes contaminants and passes the air into the drying stage.

Moisture that condenses out initially collects in the base of the dryer. Moisture-laden air passes through the desiccant bed in the air dryer cartridge and is dried. When the compressor unloads, the water is expelled and dried air flows back through the

A Typical Meritor WABCO Air Dryer Cycle:

  1. The governor turns the compressor on when supply tank pressure drops below cut-in pressure (approximately 100 psi).
  2. Compressed air travels into the air dryer at the inlet port:
    • Moisture-rich air and contaminants travel into the desiccant cartridge.
    • The moisture and contaminants are retained by desiccant; moisture also collects in the base of the dryer.
  3. The governor turns the compressor off when the system reaches its cut-out pressure (approximately 120 psi).
  4. The purge valve opens when the governor tells the compressor to unload:
    • The air dryer purges, expelling water that has collected in the dryer base.
    • Then the regeneration valve opens:
      • Dry system air flows back through the dryer. 10 psi is taken from supply and secondary tanks.
      • This back flow dries the desiccant, preparing it for the next cycle.