Patent GB-741967-A (GB)
Title: Deep well surveying instruments
IPC: E21B47/022
Filed: 1953-09-09
Abstract: 741,967. Clinometers. MURATA, I. Sept. 9, 1953, No. 25007/53. Class 97 (2). A borehole clinometer comprises a freely suspended pendulum, means for clamping the pendulum in its central position, a magnetic compass card supported for free rotation on a pin and means for clamping it with the pin withdrawn, and (e.g. clockwork) driving mechanism which, when the instrument is at a desired depth, releases the pendulum and compass card and, after a time sufficient for the pendulum and compass card to come to rest, clamps the compass card in position and causes the pendulum to impress a record on a chart carried by the compass card at a distance from the centre representing the inclination and in a direction from the centre representing the orientation. As shown in Fig. 5, a plumb bob 4 is suspended in gimbals 5 in the upper part 1 of the casing, which is screwed to the main casing 2. A sleeve 8 sliding in casing 1 is pressed down by a spring 9, and also acts on arms 6 which hold the plumb bob in its central position. An inner casing 10 in casing 1, urged downwardly by a spring 11, carries a sleeve 16 with a flange 17 supporting a disc 12 carrying magnets 13. A needle 15 is mounted by a spring in a holder 19, the head of which engages a depending part of disc 12 to hold it down. Clockwork mechanism 30 in the base of casing 2 is driven by a spring 32 to turn a shaft 33 slowly. Shaft 33 is surrounded by a fixed sleeve 37 carrying cam arms 35, 36 operated by a recess 34 in shaft 33, and having shoulders one of which holds a sleeve 38 surrounding sleeve 37 in its lowermost position, against action of a spring 39. Sleeve 38 is keyed to shaft 33 to turn with it, but is free to slide axially on sleeve 37. The spring 32 may be wound by an outer ring 46. The instrument is enclosed in a protective container and lowered into a deep well. The clockwork is previously adjusted so that, when the required depth has been reached, shaft 33 has turned to a position wherein the cam arm 35 enters recess 34 in shaft 33, releasing sleeve 38 which moves upwards until arrested by the shoulder on cam arm 36. This raises inner casing 10 and sleeve 8, and movement of sleeve 8 rocks arms 6 to release plumb bob 4. The movement of sleeve 38 also raises a spring-loaded rod 28 slidable in inner casing 10, which through a leaf-spring 27, rocks an arm 25 to release a second clockwork mechanism 5, which drives a pinion 23 engaging a rack 21. A bell-crank lever 44 pivoted on the rack engages a spring-urged lever 42, the end of which bears on the inside of a cup-shaped part 40 on the end of shaft 33. The rack pushes the needle holder 19 upward against action of a spring 20, as shown in Fig. 2, so that the disc 1 is supported freely on needle 15. When this position is reached, lever 44 engages lever 25 and rocks it against action of spring 27 to stop the mechanism 5. This enables the disc 12 to settle with the magnets 13 in N-S position. After sufficient time has elapsed, rotation of shaft 33 carries a notch 41 in the part 40 into register with lever 42, the lower end of which drops into the notch so that the other end rocks lever 44, releasing lever 25 and starting the mechanism 5 again. Disc 12 is raised until its bevelled edge b contacts a complementaryshaped ledge a on the inner casing 10. Continuing movement of rack 21 pushes sleeve 16 upwards against action of a spring 18, until the flange 17 engages the underside of the edge of disc 12, which is thus clamped firmly. Meanwhile shaft 33 is turned until cam arm 36 enters the recess 34 to release sleeve 38, causing.the inner casing 10 to rise quickly so that a needle 41 on bob 4 marks a chart carried by disc 12. The instrument is drawn up, and the mark on the chart, which is marked with concentric circles and the points of the compass, indicates the inclination of the well shaft and the direction of inclination at the depth to which the instrument was lowered.