Structure And Operation: PPMU

• PPMU stands for Passive Pressure Maintenance Unit.
• System pressure increases according to increase of oil volume due to oil temperature increase. Sudden rise in system pressure can be controlled by feeding the increased oil into the PPMU.
• Oil flows into oil chamber via PPMU pipe A and PPMU pipe B by influence of pressure change, pushes gas spring of nitrogen gas, and pools.

When system pressure decreases, influent oil is distributed to both pipes by gas spring reaction force of nitrogen gas via PPMU pipe A and PPMU pipe B to control sudden decrease in system pressure.

Fig 1: Identifying PPMU Oil Chamber, Bellows And Gas Chamber

Courtesy of NISSAN MOTOR CO., U.S.A.