452 
Besides, the z spindle is mounted on the x carriage and the 
model carriage simultaneously serves as stylus carriage for the 
internal plotting table, 
The internal plotting table consists of a luminous surface of 
400 mm x 450 mm and permits a ratio of 1:2 between photo and 
model scale. In the basic design variant the drawing head is 
manually operated while in a second variant operation of the 
electromagnetic lifting magnet is by & foot switch. Lead 
holders, ball-point refills, ink pens and scribers can be used 
as drawing sheets. 
The x-, y-movement is made by freehand guidance on the 
x-modei carriage in the basic design variant.It can be 
extended by handwheels. Via synchros, which with regard 
to long life and accuracy proved to be of excellent value in 
the STEREOMETROGRAPH precision plotting machine transmission 
is made to belt drives attached to rollers in order to prevent 
slippage. Incremental shaft encoders can additionally be 
atteohed £o the rollers for digital output, The direction 
of rotation of the handwheels is reversible. 
Motion of the z-coordinate is performed by a foot disk, 
Transmission to z-spindle and height counter is likewise 
effected via synchros. An incremental shaft encoder can be 
attached to the z-spindle for digital output. 
The height counter is an independent module connected via 
cable to the distribution box. With a variable gear 10 
different scales can be selected readable in meters or feet. 
The least count on the digital counter is 0.01 m or 0.1 
foot. When the Digital Plotting Table is connected the 
heights are displayed on the counter of the control desk 
of DZT 90 x 120. According to the transmission ratio between 
0.01 $09.99 fromthe plotter to DZT 90 x 120 model scales 
can be selected in steps of 100 units between 1:100 to 
1:100000, 
For the output of the coordinstes x, y and z, electrically 
via synehros anc digitally by incremental encoders, recep- 
tacles are available permitting 4 peripheral devices to be 
connected electrically and two digitally. The coordinate 
ranges in the plotter are safeguarded by microswitches 
delivering acoustic signals when the end stop of the range 
is reached, 
The following elements are available for orie 
absolute orientation is essentially simplified and relative 
orientation not disturbed. By means of the by setting it 
is possible to measure vertical parallaxes in numerical 
orientation techniques and to ascertain more conveniently 
residual errors in relative orientation, The same elements 
of orientation are available as in precision plotters and 
the same methods of orientation can be applied.