Abstract: The excitation winding of an alternator is energized through a silicon controlled rectifier (SCR) from the output of the alternator. The SCR is bypassed by a constant current network to allow the alternator to start up; even with no excitation current, when the alternator output voltage is due to residual magnetism alone, this network can pass a current into the excitation winding, and build the current up gradually to a value above the latching current of the SCR. When this has happened, the SCR can latch on after being fired, and takes over control of the excitation current. Because the network is a constant-current network rather than a purely resistive network, it can be designed to pass sufficient current at low alternator output voltages, without having to dissipate excessive power at higher output voltages. Also, when the output voltage is at its normal operating value, the constant-current network is rendered non-conductive, to avoid the excessive power dissipation which might occur at full voltage.

Abstract: The excitation winding of an alternator is energized through a silicon controlled rectifier (SCR) from the output of the alternator. The SCR is bypassed by a constant current network to allow the alternator to start up; even with no excitation current, when the alternator output voltage is due to residual magnetism alone, this network can pass a current into the excitation winding, and build the current up gradually to a value above the latching current of the SCR. When this has happened, the SCR can latch on after being fired, and takes over control of the excitation current. Because the network is a constant-current network rather than a purely resistive network, it can be designed to pass sufficient current at low alternator output voltages, without having to dissipate excessive power at higher output voltages. Also, when the output voltage is at its normal operating value, the constant-current network is rendered non-conductive, to avoid the excessive power dissipation which might occur at full voltage.

Abstract: Marine propulsion equipment for installation in a ship or boat comprises a screw propeller with variable-pitch blades, mounted on one end of a propeller shaft whose other end is coupled to the output flange of a reversible speed-reduction gearbox. A pitch control rod is connected at one end through a linkage to the blades and extends within an axial bore in the shaft, the rod being longitudinally movable by a hydraulic actuator between predetermined limiting positions corresponding respectively to a coarse-pitch setting and a fine-pitch setting of the screw blades. The actuator is of piston-and-cylinder type interposed between the output shaft of the gearbox and the adjacent end of the propeller shaft as a part of the drive train. The actuator cylinder is formed either in a half-coupling which connects the shaft to the gearbox output flange, or in a separate tubular capsule which is itself connected between the half-coupling and the gearbox output flange.