Patent ID: 8801480

Claim:
The trim/tilt apparatus for a marine vessel propulsion machine, comprising: a cylinder apparatus interposed between a hull and a marine vessel propulsion machine which is supported to the hull so as to be tiltable, the cylinder apparatus being extended and retracted so as to make the marine vessel propulsion machine carry out a trim motion and a tilt motion, by controlling to supply or discharge a working fluid from a working fluid supply/discharge apparatus to the cylinder apparatus, the cylinder apparatus comprising: a housing which is used by being connected to one of the hull and the marine vessel propulsion machine and forms a large-diameter trim chamber; a cylinder which is inserted into a trim chamber of a housing so as to be extensible and retractable, and forms a small-diameter tilt chamber; wherein the cylinder is inserted into the trim chamber from a cylinder guide which is provided in an open end of the housing so the cylinder is extensible and retractable, at a time of a trim up and down operation in a trim region, and the cylinder guide is threadably attached to the open end of the housing, and is provided with a seal member which comes into close contact with the trim chamber, and a seal member which comes into slidable contact with an outer surface of the cylinder, a large-diameter trim piston which is fixed to the cylinder inside the trim chamber of the housing, and divides the trim chamber into a first trim chamber on a side which accommodates the cylinder, and a second trim chamber on a side which does not accommodate the cylinder; a piston rod which is used by being connected to either other of the hull and the marine vessel propulsion machine, and is inserted into the tilt chamber of the cylinder so as to be extensible and retractable; and a small-diameter tilt piston which is fixed to a piston rod end portion inside the tilt chamber of the cylinder, and divides the tilt chamber into a first tilt chamber on a side which accommodates the piston rod and a second tilt chamber on a side which does not accommodate the piston rod, wherein the large diameter trim piston is provided with a communication passage which communicates the second tilt chamber with the second trim chamber, thereby enabling the second tilt chamber between the large diameter trim piston and the small diameter tilt piston to be normally directly communicated with the second trim chamber, and the small diameter tilt piston is provided with a shock blow valve which is opened so as to transfer the working fluid in the first tilt chamber to the second tilt chamber, when the working fluid in the first tilt chamber reaches a set pressure.