Abstract: A pneumatic output signal limiting device utilizing a planar-type construction having a balance beam with a passage extending through the area of its pivotal axis to provide communication between side-by-side chambers and arranged so that the balance beam moves into contact with a valve in the output chamber to close the passage and further movement in the same direction open a vent. In operation, the output signal equals the input signal when the input signal is within one limit of a preselected output signal operating range. When the input signal equals the limit, the passage is closed and the output signal is maintained equal to the limit. The passage remains closed when the input is outside the limit and the output signal is maintained equal to the limit until the input signal is a preselected value outside the limit. Then the balance beam moves in the same direction to open the vent and reduce the output signal to the vent pressure.

Abstract: A fluid control valve has a port means across which a control element, mounted on a lever, is slidable. An input control arm rotates a cam which imparts linearly-related angular movement to a further lever. A roller is engaged between the two levers and is movable to vary the distances from the pivotal axes of the levers to their points of engagement with the roller. These distances are different on each lever. Movement of the roller thus varies the linear relationship between movement of the input arm and the control element.

Abstract: A pneumatic apparatus or relay which, in one embodiment, maintains the output pressure at a fixed level until the signal pressure obtains a predetermined value at which time the output pressure varies according to the signal pressure and, in a second embodiment, maintains the output pressure at a first level, which may be essentially zero, until the signal pressure obtains a predetermined value at which time the output pressure assumes a second level until the signal pressure reaches a second predetermined value and then the output pressure varies according to the signal pressure.

Abstract: A multiple low pressure selector relay having a housing provided with a plurality of low pressure relays each having an exhaust port. A movable selector is carried by the housing and has means for closing all of the exhaust ports except two thereof when the selector is in one position thereof, the selector having the means thereof opening other of the exhaust ports when the selector is moved to other positions thereof whereby the desired number of exhaust ports in addition to the two thereof can be opened.

Abstract: A condition responsive valve construction having a housing provided with a valve seat. A pair of metallic balls are secured together in abutting relation and are movable toward and away from the valve seat so that one of the balls acts to open and close the valve seat. A lever is movably mounted in the housing and acts between the balls to cause movement thereof upon certain movement of the lever caused by a condition responsive means sensing different conditions. Spring means are provided for tending to hold the balls in the valve seat closed position thereof and in a certain valve seat open position thereof so that the lever can have lost motion travel between the balls for creating a differential in the conditions required to open and close the valve seat.