| 摘要 |
<p>The mechanism consists of a threaded spindle (1) onto which is mounted the carrier (20) for the photogram. On a trunnion (2) are mounted a driven wheel (4) and two gear wheels (5, 6). On a shaft (9) are assembled two other gear wheels (11, 12) which can be displaced along the shaft to give two speeds to a disc (23). Another disc (14) can be driven by friction by the first disc (13) and can be displaced radially with respect to it to give a method of varying continuously the rotating speed of spindle (17) which is connected to a revolution counter (18). Wheel (4) which is driven by a device, not shown in the figure, can thus displace the photogram carrier as shown by the double arrow, and the revolution counter (18) gives a measurement of the revolutions of spindle (1). Calibrated heights of the photogram relative to the stereoscopic device can then by established.</p> |
