Ships steering gear

Claim 2

In a pressurised-fluid operated steering gear system for a ship comprising four pressurised-fluid actuators disposed in opposed pairs to control a common tiller arm, two pumps adapted selectively to supply pressurised fluid to actuators which are diametrically opposite across the rotary axis of the tiller arm while fluid is vented from the other two actuators, each said actuator comprising a chamber and means defining opposite end walls of the chamber relatively movable in response to variations of fluid pressure in the chamber and two supply lines opening into each chamber in spaced relation therealong between said end wall defining means and respectively connected to the pumps, the modification which comprises inserting in each chamber between the end wall defining means thereof an element forming a barrier between said supply line openings of the chamber which barrier element is movable in the chamber to close one or the other of said supply line openings in response to a pressure difference across said barrier element and the barrier elements collectively serving to isolate the pumps from one another so that failure of one pump or the pressurised-fluid circuitry associated therewith will not prevent operation of the steering gear solely by the other pump.

Claim 3

A steering gear system as claimed in claim 1, wherein valves are provided which are selectively operable to control the supply lines associated with each said pump, each valve being movable between a first position communicating said supply lines with said pump, a second position isolating said supply lines from said pump and venting said supply lines and a third position closing said supply lines, there being associated with each valve a mechanism responsive to the other pump such that said mechanism permits movement of said valve to said third position thereof only when said other pump is inoperative.

Claim 4

A steering gear system as claimed in claim 2, wherein means is provided automatically to move said valve from said first to said second position thereof in response to cessation of the pump associated with said valve and from said second to said third position thereof in response to cessation of said other pump.

Claim 5

A steering gear system as claimed in claim 1, wherein each pressurised fluid supply line is in communication with a reservoir for pressurised fluid adapted to provide the required supplement to the volume of fluid in the said other fluid supply line when said barrier element moves to close said one supply line.

Claim 6

A steering gear system as claimed in claim 4, wherein means is provided for maintaining fluid in the reservoir under pressure.

Claim 7

A steering gear system as claimed in claim 1, wherein the pressurised fluid is hydraulic fluid.

Claim 8

A pressurised-fluid operated steering gear system for a ship comprising a tiller arm having a rotary axis, four cylinders each having a closed end and an open end, the cylinders being disposed in pairs on opposite sides of the rotary axis of the tiller arm with the open ends of the cylinders of each pair opposed to one another, two rams articulated to said tiller arm on opposite sides of said rotary axis thereof, the opposite ends of each ram entering and being movable within the open ends of a respective said pair of cylinders, two pumps having respective supply lines to each cylinder, the supply line of one pump opening to each cylinder at a position spaced therealong from the supply line opening of the other pump and a barrier element extending across and slideable along each cylinder between the closed end thereof and the ram end entering the same in response to a pressure difference across said element so as to close one or the other of said supply line openings, the arrangement being such that pressurised fluid can be introduced from one or both of the pumps into two of the cylinders which are diametrically opposite to one another across said tiller arm rotary axis while fluid is vented from the other two cylinders thereby producing an opposite longitudinal displacement of said rams which will rotate the tiller arm, said barrier elements serving to isolate the pumps from one another so that operation of the steering gear by one pump only will not be prevented by failure of the other pump or pressurised fluid circuitry associated therewith.

Claim 9

A pressurised-fluid operated steering gear system for a ship comprising a tiller arm having a rotary axis, four cylinders each having a closed end and an open end, the cylinders being disposed in pairs on opposite sides of the rotary axis of the tiller arm with the open ends of the cylinders of each pair opposed to one another, two rams articulated to said tiller arm on opposite sides of said rotary axis thereof, the opposite ends of each ram entering and being movable within the open ends of a respective said pair of cylinders, two pumps having respective supply lines to each cylinder, the supply line of one pump opening to each cylinder at a position spaced therealong from the supply line opening of the other pump and a barrier element extending across and slideable along each cylinder between the closed end thereof and the ram end entering the same in response to a pressure difference across said element so as to close one or the other of said supply line openings, the arrangement being such that pressurised fluid can be introduced from one or both of the pumps into two of the cylinders which are diametrically opposite to one another across said tiller arm rotary axis while fluid is vented from the other two cylinders thereby producing an opposite longitudinal displacement of said rams which will rotate the tiller arm, said barrier elements serving to isolate the pumps from one another so that operation of the steering gear by one pump only will not be prevented by failure of the other pump or pressurised fluid circuitry associated therewith.

Claim 10

A pressurised-fluid operated steering gear system for a ship, comprising a rotary actuator for rotating a tiller, a plurality of arcuate chambers for pressurised fluid in said actuator defined between rotor vanes and stator vanes thereof, two pumps having associated supply lines which communicate each pump with each chamber, said supply lines opening to each chamber at positions arcuately spaced therealong from one another and a free vane in each chamber interposed between the rotor vane and stator vane defining the same and movable in response to a pressure difference across said free vane to a position closing one or the other of said supply line openings of the chamber, the arrangement being such that the tiller can be rotated by introducing from either or both of the pumps pressurised fluid into a pair of said chambers which are diametrically opposite across the rotary axis of the actuator while venting fluid from other chambers and such that said free vanes isolate the pumps from one another so that operation of the steering gear by one pump only will not be prevented by failure of the other pump or pressurised fluid circuitry associated therewith.

Claim 11

A pressurised-fluid operated steering gear system for a ship, comprising a rotary actuator for rotating a tiller, a plurality of arcuate chambers for pressurised fluid in said actuator defined between rotor vanes and stator vanes thereof, two pumps having associated supply lines which communicate each pump with each chamber, said supply lines opening to each chamber at positions arcuately spaced therealong from one another and a free vane in each chamber interposed between the rotor vane and stator vane defining the same and movable in response to a pressure difference across said free vane to a position closing one or the other of said supply line openings of the chamber, the arrangement being such that the tiller can be rotated by introducing from either or both of the pumps pressurised fluid into a pair of said chambers which are diametrically opposite across the rotary axis of the actuator while venting fluid from other chambers and such that said free vanes isolate the pumps from one another so that operation of the steering gear by one pump only will not be prevented by failure of the other pump or pressurised fluid circuitry associated therewith.