Abstract: A communication apparatus includes a support structure (41) that is fastenable to a safety helmet (58). A vibration conduction microphone (54) is carried by the support structure. The vibration conduction microphone and the speaker enclosure (43) are positioned so that, when the support structure is fastened to the safety helmet, the vibration conduction microphone and the speaker enclosure come into contact with a rear of the wearer's head.

Abstract: A fluid mixer includes an elongate mixing chamber having an inlet system at one end for admission of liquid and gas to be intimately mixed by passage through the chamber and an outlet for the mixture at the opposite end, wherein opposed longitudinal sides of the chamber are each defined by a surface of scallop shape having peaks and troughs, with the peaks of the two surfaces being relatively offset so as to cause the liquid and gas entering the chamber to flow along a generally sinuous path through the chamber to create a turbulent flow which promotes intimate mixing. Advantageously a UV source extends within the chamber to sterilize the liquid flowing through the chamber.

Abstract: A mobile frame (10) for supporting an elongate flexible structure (11) such as a ground working tool assembly, the mobile frame (10) is foldable between a first position in which the elongate flexible structure (11) is supported in a working condition in relation to the ground, and a second position in which the elongate flexible structure (11) is supported in a stored condition in relation to the ground. The mobile frame comprises a first frame portion (31) supported for movement over the ground and a second frame portion (32) for supporting one end of the elongate flexible structure. The second frame portion is mounted on the first frame portion for folding movement with respect thereto about a pivot axis inclined to the fore-and-aft axis of the mobile frame such that the spacing between the ends of the elongate flexible structure (11) increases as the elongate flexible structure is moved from the first position to the second position.