Foif J2-2, Инструкция по эксплуатации

Страница: 11 / 28

11
The outstanding advantages of this type of axis system are small friction torque,
good abradability. If the bush has been weared, it will still remain serviceable after
renewal of ball bearing, and the change of temperature has little effect on the
standing axis.
Reading System:
In order to eliminate the erroneous influence of an eccentricity of the circle, it is read
at two diametrically opposed graduation lines by means of two prisms cemented
into the alidade. The optical wedge is employed as the micrometer
The principle of the optical wedge micrometer is that when a single ray traverses the
optical wedge, it emerges in an angle to its original direction, but with a lateral
displacement of the optical wedge, this angle of deviation remains unchanged,
therefore the purpose of micrometer can be realized.
Automatic Vertical Index
The effect on the vertical circle reading of any residual error in levelling up is
eliminated by the automatic index. The principle is that when the standing axis
Inclines slightly, the pendulum will swing through an angle in the opposite direction
correspondingly, therefore the light rays emerging from pendulum deviate so that