Suzuki DF25/DF30 Four Stroke Service Manual, Page 222Get this manual
POWER TRIM AND TILT
SHOCK ABSORBER CIRCUIT) Shock valve Should the lower unit strike an underwater object whilst in motion, the piston will rise abruptly, creating sudden high impact pressure in the upper cylinder chamberThe shock valve will then open, allowing oil to flow into the area between the tilt ram piston and the free piston, thereby dampening (absorbing) the impact(Return valve When the point of impact has passed, propeller thrust and motor weight will force the tilt ram piston back downwardsThe oil from between the ram piston and the free piston is then expelled through the return valve before flowing into the upper cylinder chamber