| 摘要 |
1287981 Surveying GEWERKSCHAFT EISENHUTTE WESTFALIA 25 Feb 1970 [5 Nov 1969] 9035/70 Heading G1F In apparatus for determining deviation from a predetermined path defined by a beam of electromagnetic radiation in an underground tunnel installation, a target plate 4 receives the radiation and indicates deviations from the predetermined path, the target plate 4, Fig.2, being carried by a ring 5 mounted for rotation about the axis 7 of the tunnel on rollers 6 in a channel-section guide piece 8, the ring also carrying a weighted body 9 so as to maintain the plate 4 in the same vertical position in spite of rotation of the tubular section tunnel member 1a which can occur during a driving operation and which would otherwise misalign the plate 4 with the beam of radiation. In an alternative embodiment, Fig.3, the plate 4 is carried by an arm 18 mounted on a carriage 13 freely movable round a guide piece 10 fixed with respect to the tunnel section 1a. A hinge 19 allows the arm 18 to be pivoted to a position parallel to the walls of the tunnel to allow access to the tunnel face. In another alternative construction, Fig.5, the target plate 4 is carried by a pendulum member 21, 22 pivotally mounted on a pivot 23 coincident with the axis 7 of the tunnel on a support arm 25 secured to a suitable one of a number of mounting straps 26. The arm 25 may be hinged to allow access to the tunnel face. In a further embodiment the support arm 25 is telescopic and the straps 26 are replaced by a perforated mounting ring to which the support arm may be affixed. (For figure see next page) |
