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| Illustration 1 | g01219617 |
Main Relief Valve (1) Drain (2) Pump Supply Oil (3) Line to Transmission Lubrication (4) Adjustment Screw (5) Spring (6) Spool (7) Slug Chamber (8) Slug | |
Pump supply oil enters the main relief valve through passage (2). This oil enters a hole in spool (6) and flows through an internal passage in the spool. The pressure of this oil is felt in slug chamber (7) .
The oil acts on slug (8). Slug (8) cannot move to the left. Therefore, the oil pressure will push spool (6) to the right. When the oil pressure in slug chamber (7) exceeds the force of spring (5), the spool moves to the right.
When the spool moves to the right, pump oil is allowed to exit through passage (3). This oil is used to lubricate the transmission.
When the pressure in passage (2) is no longer high enough to overcome the force of spring (5), spool (6) shifts back to the left.
The pressure setting of the main relief valve may be adjusted with adjustment screw (4).