Gas-cushion load-supporting apparatus

Claim 2

A gas-cushion load-bearing apparatus including gas curtain forming means for forming a curtain of moving gas for peripherally containing, at least in part, a load-bearing gas cushion formed between the apparatus and a cooperating surface, gas supply means for supplying pressurized gas to the curtain forming means, the curtain forming means comprising a first, inner, member and a second, outer, member carried by and spaced apart generally radially of the apparatus and defining therebetween a gas outlet port through which gas issues to form the gas curtain, the said first member being mounted for limited rotation about an axis which is orientated generally peripherally of the apparatus and having a first surface exposed to the gas cushion pressure which pressure produces a turning moment about the said axis in one direction, and biassing means biassing the first member in the opposite direction against the turning moment and effective to cause the first member to adopt a predetermined angular position about the said axis when the gas cushion pressure has a predetermined value, the first member having a second surface partly defining the gas outlet port and movable relatively to the second member in a manner to vary the mass flow of the curtain forming gas through the gas outlet port when a variation in cushion pressure from the said predetermined value causes a corresponding rotational movement of the first member about the said axis, the variation in the mass flow of the curtain forming gas being in a sense to increase the variation in cushion pressure.

Claim 3

A gas-cushion load-bearing apparatus including gas curtain forming means for forming a curtain of moving gas for peripherally containing, at least in part, a load-bearing gas-cushion formed between the apparatus and a cooperating surface, gas supply means for supplying pressurized gas to the curtain forming means, the curtain forming means comprising a first, inner, member and a second, outer, member carried by and spaced apart generally radially of the apparatus and defining therebetween a gas outlet port through which gas issues to form the gas curtain, the said first member being mounted for limited rotation about an axis which is orientated generally peripherally of the apparatus and having a first surface exposed to the gas cushion pressure which pressure produces a turning moment about the said axis in one direction, and biassing means biassing the first member in the opposite direction against the turning moment and effective to cause the first member to adopt a predetermined angular position about the said axis when the gas cushion pressure has a predetermined value, the first member having a second surface partly defining the gas outlet port and movable away from the second member in a manner to increase the mass flow of the curtain forming gas through the gas outlet port when an increase in cushion pressure above the said predetermined value causes a corresponding rotational movement of the first member about the said axis.

Claim 4

A gas-cushion load-bearing apparatus including gas curtain forming means for forming a curtain of moving gas for peripherally containing, at least in part, a load-bearing gas-cushion formed between the apparatus and a cooperating surface, gas supply means for supplying pressurized gas to the curtain forming means, the curtain forming means comprising a first, inner, member and a second, outer, member carried by and spaced apart generally radially of the apparatus and defining therebetween a gas outlet port through which gas issues to form the gas curtain, the said first member being mounted for limited rotation about an axis which is orientated generally peripherally of the apparatus and having a first surface exposed to the gas cushion pressure which pressure produces a turning moment about the said axis in one direction, and biassing means biassing the first member in the opposite direction against the turning moment and effective to cause the first member to adopt a predetermined angular position about the said axis when the gas cushion pressure has a predetermined value, the first member having a second surface partly defining the gas outlet port and movable away from the second member in a manner to increase the mass flow of the curtain forming gas through the gas outlet port when an increase in cushion pressure above the said predetermined value causes a corresponding rotational movement of the first member about the said axis.

Claim 5

A gas-cushion load-bearing apparatus including gas curtain forming means for forming a curtain of moving gas for peripherally containing, at least in part, a load-bearing gas cushion formed between the base of the apparatus and a cooperating surface, gas supply means for supplying pressurized gas to the curtain forming means, the curtain forming means comprising a first, inner, member and a second, outer, member carried by and spaced apart generally radially of the apparatus and defining therebetween a gas outlet port through which gas issues to form the gas curtain, the Said first member being mounted for limited rotation about an axis which is orientated generally peripherally of the apparatus and having a first surface exposed to the gas cushion pressure which pressure produces a turning moment about the said axis in one direction, and a second surface exposed to a different gas pressure which pressure produces about the said axis a second turning moment opposing the first turning moment, and spring biassing means producing a third turning moment of the first member about the said axis such that the first member adopts a predetermined angular position about the said axis when the gas cushion pressure has a predetermined value, the first member having a third surface partly defining the gas outlet port and movable away from the second member in a manner to increase the mass flow of the curtain forming gas through the gas outlet port when an increase in cushion pressure above the said predetermined value causes a corresponding rotational movement of the first member about the said axis.

Claim 6

A gas-cushion load-bearing apparatus including gas curtain forming means for forming a curtain of moving gas for peripherally containing, at least in part, a load-bearing gas cushion formed between the base of the apparatus and a cooperating surface, gas supply means for supplying pressurized gas to the curtain forming means, the curtain forming means comprising a first, inner, member and a second, outer, member carried by and spaced apart generally radially of the apparatus and defining therebetween a gas outlet port through which gas issues to form the gas curtain, the Said first member being mounted for limited rotation about an axis which is orientated generally peripherally of the apparatus and having a first surface exposed to the gas cushion pressure which pressure produces a turning moment about the said axis in one direction, and a second surface exposed to a different gas pressure which pressure produces about the said axis a second turning moment opposing the first turning moment, and spring biassing means producing a third turning moment of the first member about the said axis such that the first member adopts a predetermined angular position about the said axis when the gas cushion pressure has a predetermined value, the first member having a third surface partly defining the gas outlet port and movable away from the second member in a manner to increase the mass flow of the curtain forming gas through the gas outlet port when an increase in cushion pressure above the said predetermined value causes a corresponding rotational movement of the first member about the said axis.

Claim 7

A gas-cushion load-bearing apparatus according to claim 3, wherein the second surface of the first member is exposed to atmospheric pressure.

Claim 8

A gas-cushion load-bearing apparatus according to Claim 3, including a rolling diaphragm connected to the base of the apparatus and to the first member between the first and second surfaces thereof for providing a movement-accommodating gas seal separating said first and second surfaces.