2006 Johnson SD 30 HP 4 Stroke Outboards Service Manual, PN 5006592, Page 239Get this manual
POWER TRIM AND TILT OPERATION
Trim Tilt "UP" Circuit
The electric motor is operating in clockwise 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 left, opening the "down" pressure main check valve and returning oil from the upper cylinder chamber (and oil from the reservoir) to the pumpPressure built up by the pump will then open the "up" pressure main check valve and oil will enter the lower cylinder chamberWhen the trim motor stops, both the "down" pressure main check valve and the "up" pressure main check valve will close to retain tilttrim positionWhen full trimtilt "up" position is attained, sustained operation of the "up" relay will have no effect, as pump oil flow will be returned to the reservoir through the "up" relief valve