GB857021A - Improvements in or relating to pest scarers - Google Patents

Abstract

857,021. Scare signals and detonator apparatus. BLANCH & CO. Ltd., A. B. Jan. 16, 1957 [May 10, 1956; July 13, 1956; Aug. 7, 1956], Nos. 14609/56, 21767/56 and 24226/56. Class 118 (2). A pest scarer of the type wherein a repetitive detonation is produced automatically is combined with a timing mechanism for stopping and/or starting the repetitive detonation. Fig. 1 shows an apparatus producing detonations by igniting an explosive gas mixture together with timing mechanism for controlling the flow of gas to the ignition chamber. A generator 5 contains calcium carbide and water to produce acetylene gas which passes through tubes 6 and 8 to control mechanism 9. When sufficient pressure has been built up inside the mechanism 9 a piston or diaphragm is operated by the said pressure to cause release of the gas into ignition chamber 13 where it is fired by a flint sparking device actuated by the spring-biased return movement of the piston or diaphragm. This part of the apparatus may be as described in Specification 734,175. To prevent detonations continuing throughout the night a timing mechanism 11 is adapted to allow the acetylene gas to escape into the atmosphere when detonations are not required. The timing mechanism 11 comprises clockwork 18 (Fig. 3) mounted on a plate 19 welded to a lid 20 of a weatherproof casing 21. The lid 20 carries a spike 17 for insertion in the ground to support the timing mechanism near the detonation apparatus. The casing 21 is removably held in place by a wing- nut 24. The clockwork 18 drives a twenty-four hour clock dial 33 through gearing 26, 27. Above the clock dial 33 are mounted two independently-adjustable cam segments 32 which can be clamped relative to the clock dial 33 by means of a knurled nut 30. These cams 32 engage a follower 34 to open a spring-loaded valve 37 and allow a tube 10 to communicate with the atmosphere via a port 39. The tube 10 is connected to a T-piece 7 between tubes 6 and 8 such that while cams 32 hold valve 37 open gas from the generator 5 escapes to the atmosphere instead of passing along tube 8 to build up operational pressure in the mechanism 9. In a modification (Fig. 4, not shown), the timer cams operate a pivoted lever which carries a rubber cup normally sealing a gas exit to the atmosphere. The third Provisional Specification also discloses several valve modifications including two arrangements where the gas pressure assists in lifting the valve which therefore also acts as an excess-pressure relief valve. The first Provisional Specification also discloses a rotary valve operated by a ratchet controlled by timing cams. The timing mechanism may alternatively control the generation of gas in the generator 5 by regulation of the water supply thereto, or it may control the ignition means. The first Provisional Specification states that the ignition may be electrical by means of a hot wire or spark, in which case the timer controls a switch in the circuit, or ignition may be by flint in which case the timer may remove the flint from the friction-wheel or disconnect a drive to the friction-wheel. Specification 857,022 also is referred to.