Abstract: The present invention provides a capacitive sensing apparatus having utility in object detection security applications whereby the object detection field generated by the apparatus is made steerable. The apparatus includes a power source having a ground connection in communication with at least one sensing circuit operative to detect an object moving within the sensing field. At least one conductive element is provided in communication with electrical ground. To steer the direction of the sensing field, the relative position and distance between the conductive element and the sensing circuit is adjusted such that a desired sensing field pattern is obtained.

Abstract: The present invention discloses a rock bolt having a tendon (1, 201) which is able to yield and thereby control movement of unstable rock strata into which the bolt is installed. The tendon has a portion which is provided with a grout slippage mechanism, preferably in the form of a tube (8) which surrounds the tendon. A two part grout anchor (10, 100, 200) is clamped to the tendon. The grout anchor is embedded in grout and is therefore essentially immovable. The tendon passing through the anchor is worked and thereby dissipates energy. The tendon can be either a multi-strand cable (1) or a solid bar (200). Various forms of anchor (10, 200) are disclosed with either complementary recess(es) (14) and protrusion(s) (15) or opposed protrusions (115) which form pinch point(s). A one piece grout anchor (300) is also disclosed.

Abstract: A capacitive sensing system senses the presence of an object proximate to an antenna using a sensing field signal having a sensing field frequency. The capacitive sensing system can be used in security systems, to provide an alarm if a valuable object is removed from where it can be detected. The capacitive sensing system can also be used to provide an alarm when an object is detected near a moving member, such as a parking barrier gate, sliding gate, elevator door, garage door, or window. The sensitivity of the system may be adjustable according to one or more conditions, such as position of the moving member, time of day, or operator inputs (for example, to put the system into a maintenance mode having low sensitivity). Systems may also have a cut-out, in which alarms are suppressed.

Abstract: The present invention provides a capacitive sensing technique that is advantageously useful for security applications wherein digital technology is used to measure frequency shifts caused by a conductive or grounded object moving within a capacitive sensing field. The system includes a floating reference to compensate for drifting or offsets caused by electrical noise or other environmental conditions. The system also includes a CPLD integrated circuit or microprocessor and operative to monitor changes in a sensing field signal and digitally compare a reference signal to the sensing field signal such that when a difference between the two signals exceeds a predetermined threshold, an object detection signal is generated by the monitor circuit which causes the activation of an alarm signal.

Abstract: The present invention discloses a rock bolt having a tendon (1, 201) which is able to yield and thereby control movement of unstable rock strata into which the bolt is installed. The tendon has a portion which is provided with a grout slippage mechanism, preferably in the form of a tube (8) which surrounds the tendon. A two part grout anchor (10, 100, 200) is clamped to the tendon. The grout anchor is embedded in grout and is therefore essentially immovable. The tendon passing through the anchor is worked and thereby dissipates energy. The tendon can be either a multi-strand cable (1) or a solid bar (200). Various forms of anchor (10, 200) are disclosed with either complementary recess(es) (14) and protrusion(s) (15) or opposed protrusions (115) which form pinch point(s). A one piece grout anchor (300) is also disclosed.

Abstract: The invention relates to a rock bolt (1) and method of installing a rock bolt, particularly a hollow bolt. The method of installation utilises a chemical anchor, the components of which are provided in a cartridge (4) which is either injected through the bolt or removably attached to an end thereof. The bolt preferably includes a thread (40) formed by plastically deforming the walls (41) of the bolt so as to maximise tensile strength whilst minimising wall thickness.

Abstract: The washer is of frusto-conical shape as viewed externally and consits of a body (21) and a tapered flange (23) depending therefrom. When the lip (28) of the flange rests on a flat surface and the washer is subjected to a predetermined compressive load (26) the tapering of the flange leads to its deformation radially outward. This expansion acts as a visual indication that the predetermined load has been applied. The flattening of the flange which also accompanies its deformation increases the contact area of the washer with the underlying surface and thereby reduces contact stresses. When used in rockbolting, hole (22) receives a rock bolt and the void defined by the flange (23) can accommodate a raised portion of a load plate. The recess (30) receives a bearing assembly or a domed element (the latter compensates for misalignment of the bolt with the surface) so as to transmit tightening loads from the nut of the rock bolt to the washer, etc.

Abstract: A plate (1) for use in support of a mine roof comprising two interconnected parts (2, 3). The first part has a substantially frusto-conical projecting portion (6) which defines a first opening (7) and the second part (3) is fitted to the first part and has all associated second opening to allow for a rock bolt to pass through the plate. The two parts (2, 3) are interconnected by an interconnecting portion (20) of the second part, which is arranged through the opening (7) and is deformed such as by being swaged over to capture the projecting portion 6. The interconnecting portion is swaged over to form either a single continuous return portion (13) or individual return portions (23).