Abstract: A mechanism for use in a reel type lawn mower for maintaining a controlled constant uniform pressure between V-shaped reel blades and a bedknife. The blades are arranged to maintain continuous contact with the bedknife on both sides of the center of the reel. A biasing unit acts between the reel unit and the bedknife unit to apply a regulated pressure on both sides of the reel center in response to a feedback signal such as a temperature signal at the reel/bedknife interface.

Abstract: A mechanism for use in a reel type lawn mower for maintaining a constant uniform pressure between V-shaped reel blades and a bedknife. The blades are arranged to maintain continuous contact with the bedknife on both sides of the center of the reel. A biasing unit acts between the reel unit and the bedknife unit to apply a regulated pressure on both sides of the reel center.

Abstract: A method of making interlocked metal tube from a strip of the metal of generally S-shaped cross-section by which the shaped strip is formed into a helix without interengaging adjacent coils of the helix, passing the helix without rotation through a rotating driving means to move the non-rotating helix axially, interengaging adjacent coils of the helix and then performing an operation to prevent subsequent disengagement of the adjacent coils, thereby to form an interlocked metal tube. The driving means for the helix is a rotatably-driven mandrel around which the open helix is placed. The mandrel has intermediate its ends a radially-outwardly extending integral portion in which there is a helical passageway forming a tunnel through which the helix is passed and from which the helix is delivered to move without rotation axially along the remainder of the mandrel.

Abstract: A shelf unit (3, FIG. 1) for a refrigerator cabinet includes an air flow passageway (6) connectible to a duct (1) located at the rear of the refrigerator. The flow of air through the passageway (6) is regulated by a flap whose movement is controlled by a thermostat (9) also mounted upon the shelf. The shelf unit, when in position in a refrigerator, enables a user to preset the temperature of the zone in the refrigerator cabinet beneath the unit.

Abstract: A control unit for a gas-fired water heater comprises a resiliently-loaded main valve for controlling gas flow to a gas burner of the heater, the main gas valve being opened and closed by a flexible diaphragm exposed to pressure of water flowing through the water heater. A subsidiary gas valve located upstream in the gas supply of the main gas valve has a permanently open by-pass and is actuable by a user operated control which also adjusts the resilient loading of the main gas valve in such manner as to adjust the rate of water flow and the rate of gas flow to provide hot water of a required temperature and at a required rate of flow.

Abstract: A flame failure device has a hollow, tubular, heat-resistant, temperature sensitive member to be directly heated by a flame and so arranged that the member will expand or contract along a generally rectilinear axis as it is heated or cooled. The temperature-sensitive member is connected to a mount in a manner which permits or permitted at least initial adjustment of the relative position of the mount and temperature-sensitive element along the generally rectilinear axis and has an abutment which will move relative to the mount as the temperature-sensitive member is heated or cooled. A main valve for controlling supply of fuel to a burner has a fuel inlet, a fuel outlet, a chamber having a diaphragm defining a wall of the chamber, a main-valve member operatively connected to the diaphragm and movable therewith, and a supply passage for restricted fuel flow to the chamber.

Abstract: In a container assembly for an exhaust emission control catalyst for internal combustion engines, of the kind comprising a cylindrical substrate body carrying the catalyst and mounted within a sheet metal casing with the interposition of a compressible cushioning layer of refractory material, an open-seam sheet metal shroud of variable circumference is used to enclose the compressible layer and to compress it prior to, or simultaneously with, endwise insertion into the casing. The shroud or the casing may have elongated ribs pressed in it, the ribs tapering at their ends to facilitate entry.

Abstract: A superplastically deformable aluminium base alloy contains 2-8.5% by weight of magnesium and 0.4-1% by weight chromium. It may also contain minor alloying elements.

Abstract: An internal member for supporting a hollow body during shearing in the form of a close-fitting solid body. The body comprises at least portions meeting in the shearing plane and each portion including at least one split ring having a single gap in its periphery to allow it to expand to fit the hollow body. Expansion may be effected by axial movement of frusto-conical plugs corresponding to and co-operating with frusto-conical inner surface in the rings. Each ring may either comprise a single component, preferably notched on its inner face to increase flexibility, or be in the form of a thin split cylindrical shell surrounding a plurality of inner segments.

Abstract: Improved optical means for automatically controlling or monitoring the position of a relatively moving member such as a tool tip in a numerically controlled machine tool has an image of a region of a datum line projected on to a slit in an optical system. Light passing through the slit falls on to a photoelectric detector device which comprises an array of discrete elements. The elements are electronically scanned sequentially and an electric circuit is provided to produce an output signal when a preset change in incident light intensity is detected by any of the photoelectric elements thus indicating the presence of the movable member at the datum line. There may be two slits projecting images of the region around two transverse datum lines on to two separate arrays so that the movable member can be controlled in two dimensions. Alternatively, in place of two separate arrays and two slits a single two dimensional array may be provided suitably masked.

Abstract: In the shaping of ductile metal sheet, especially superplastic alloy sheet, by the application of pressure differentials, the peripherally clamped sheet is first urged, by pressure differential in one direction, against a female molding surface to form a partially shaped bubblelike preform and then a male mold is advanced towards the sheet from the other side and a reverse pressure differential is applied to cause the pre-form to conform to the shape of that mold. The active area forming the pre-form may be restricted by an apertured plate adjacent the clamping plane, matching the overall outline of the body, and a plate the other side matching closely the profile of the body may confine the action of the reverse pressure only to that part of the sheet that engages the progressively increasing part of the male mold that extends through the clamping plane so that the sheet locks progressively onto the sides of the male mold to obtain an approximately uniform wall thickness in the finished body.

Abstract: In tube-shearing apparatus of the kind employing relatively transversely moving apertured dies and an internal supporting mandrel, the mandrel comprises an elastomeric body which is compressed axially with the high force to expand it radially against the tube wall such as to form not merely an internal support but effectively a supporting shear blade inside the tube. This allows clean shearing also of tubes having internal protuberances such as welding seams.