Avon Rubber P.l.c.

Avon Polymer Products Limited

Avon Rubber Company Limited

Iddon Brothers Limited

Donald M Turner

David Boast

Michael I Iddon

Richard Smith

In order to form a noise suppressor in a hose of e.g. a motor vehicle, modular portions are connected in series to define suppression chambers with particular noise suppression characteristics. Those characteristics are due to the volume of each chamber, to the size of the apertures from the chambers to the central duct of the suppressor, and optionally due to spacers which are inserted into at least one aperture of the chambers to alter the effective open area of that aperture. Such spacers may also be used in which the noise suppressor is not modular. Where modular portions are used, it is preferable that each chamber is bounded by parts of two modular portions. A wall of one modular portion may then close the chamber in another modular portion, making the manufacture of the modular portions easier. Also disclosed is the use of a mass acting as a damper, which may be a noise suppressor as previously discussed, within a hose. The mass is connected to the hose by resilient means, e.g. electrometric material.

Noise and vibration suppressors

An improved bush assembly for insertion into an aperture of a lug of a track part of a tracked vehicle is disclosed. An exposed outermost side wall of the bush has an extended surface length, so that when under design precompression the wall makes angles of approximately 90.degree. with the inner surface of the aperture and 70.degree.-80.degree. with the outer surface of the central pin. The wall may be concave and the bush may comprise a number of annular bush parts. The high tensile strains which develop on that wall of the bush are thereby minimized and bulging out of the bush beyond the end of the pin is discouraged.

Bush assembly for track of tracked vehicle

To make an underwater marker with indicia on it, an uncured or partcured base material of one color is prepared with the shape of the desired indicia cut out of it. The indicia are cut from uncured or partcured material of different color and are fitted into the cut-out in the base material to form a single layer. A transfer material bearing antifouling material is placed over the face of the layer and the assembly is pressed together to embed the antifouling material into the layer and to cure the contrasting materials together with each other and with an optionally underlying reinforcing layer. A backing sheet of the transfer material is stripped off to expose the particles.

Method of making underwater marker

Material having antifouling particles embedded in one surface is made by a transfer process. A sticky backing web is fed through a dip sticky side up. A charge of particles rolls in the dip, being unable to follow the web up a rise unless adhered to its surface in a layer. After coating the layer with a bonding agent a part cured elastomer sheet is brought into contact with the particles which are pressed into its surface, after which the backing web is stripped off to expose the particles.

Method of making anti fouling material

Apparatus and method for testing unvulcanized rubber or rubber-like materials can work at high shear rates (e.g. 100 sec.sup.-1) as a result of applying and maintaining pressure on the test sample as it is being sheared by a rotor in a test chamber. The rotor is smooth-faced. Both conditions simulate more accurately the forces acting on such materials in such operations as extrusion. The test material is transferred into the test chamber through transfer ports from a transfer chamber by a pressure member which continues to exert pressure on material in the transfer chamber, which may be a next test sample. Specific operating steps of the rotor at varying speeds and directions to assess various useful parameters of the test material (including not only viscosity but also elasticity) are described, together with a mathematical model for rationalizing the behavior of the material under these test conditions.

Testing rubber

A rotatable scroll for a rubber extruding machine comprising a series of vanes in the base of channels in the scroll to redirect the material into a surface layer and to direct lumps of material to one edge of the channel and a ramp or ramps over which the lumps flow with a small clearance between the ramp and the barrel.

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Bath, United Kingdom

Donald M Turner