| 摘要 |
A high intensity optical unit for projecting sharp images of a lantern slide scale and a pointer onto a screen which images are easily visible during daylight hours. The optical unit cooperates with and is positioned a predetermined distance from a mirror which is mounted on a wheel being tested in a plane substantially normal to the axis of the wheel. A single low intensity lamp is used to project a cross hair target light beam and a locator light beam at different angles against the wheel mounted mirror and other mirrors in the optical unit for reflection onto the screen such that when the optical unit is moved to a position wherein the target and locator images lie in a common vertical plane on the screen the optical unit is properly spaced from the wheel mounted mirror. Stop means preset the lowermost positions of the lantern slide and the pointer such that the zero line of a lantern slide camber scale image, the pointer image, and the target image will all lie on the same horizontal line when projected on the screen and when the target image has been reflected off the surface of a wheel mounted mirror that is perfectly normal to the axis of rotation of the wheel. The lantern slide and pointer may be adjusted vertically and reset to compensate for wheel run out due to imperfect wheels and mirror mounting errors, and the reset pointer image will retain the corrected camber zero allowing movement of the lantern slide to make other tests between the initial and final camber tests.
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