2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 240Get this manual
POWER TRIM AND TILT OPERATION
TrimTilt "DOWN" Circuit
The electric motor is operating in counterclockwise directionCheck valve "A" will open, allowing oil to flow from the reservoir to the pumpOil flow from the pump enters the spool valve and moves it to the right, opening the "up" pressure main check valveOil from the lower cylinder chamber will go through the "up" pressure main check valve to the pumpPressure built up by the pump will open the "down" pressure main check valve and oil will enter the upper cylinder chamberThe piston will retract (move inward), which will tilt the outboard downOil in the lower cylinder chamber is returned to the pump through the "up" pressure main check valveWhen full "down" position is reached, continued operation of the "down" relay will have no effect, as pump oil flow will be returned to the reservoir through the "down" relief valve