Servo-mechanism for variable pitch propellers

摘要

984,126. Variable pitch propellers. N. J. LIAAEN. Oct. 26, 1962 [Oct. 26, 1961], No. 40590/62. Heading B7V. In a servo-mechanism for variable pitch propellers wherein a couple of mutually oppositely directed rotational forces act on each blade base of the propeller, during rotation into forward movement position the forces of the couple act on either side of the axis of rotation of the blade whereas when effecting a rotation movement astern only one of the forces is operative. Each blade 3 is secured to a disc 4 provided with cranks 6 and 7. A piston 9 has a rod 10 carrying a slide means 11 comprising guide members 111, 112 for a slide block 12 on the crank 6. A piston 13 slidable on the rod 10 has a projection 131 with a face 132 engaging a slide block 15 on the crank 7. The piston rod houses a slide valve 16 but in another embodiment this valve is not in the propeller hub but is mounted inside the vessel. When the valve 16 is positioned so that pressure medium enters the space between the pistons 9 and 13 to move them apart, the piston 9 moves the member 111 to engage the block 12 to effect clockwise rotation of the crank disc 4, while the piston 13 moves so that the face 132 engages block 15 to move crank 7 and thus also rotate disc 4 clockwise. When the valve 16 is positioned to supply pressure medium to the head of the piston 9, the latter will move, via the rod 10, member 112, block 12 and crank 6, to rotate the crank disc anti-clockwise. The spaces on both sides of the piston 13 will be open to exhaust so that this piston is rendered ineffective.