3.0
General Description
The Abtus ABT4060 Sighting Board Set is a popular, quick and accurate way to measure vertical alignment,
particularly suitable for repairing and lifting in these areas of subsidence. The boards are constructed from Nylon,
Acetal and GRP, ensuring they are electronically non-conductive, lightweight and robust.
3.1
Measured Packing
In measured packing, the amount of packing a particular sleeper requires is determined by measuring how much
the unloaded rail is below the desired level and how much the sleeper is depressed when traffic passes over it.
When these measured quantities added together are placed under the sleeper the loaded rail is at the correct
level.
4.0
Use of Gauge
4.1
Description of parts
The three boards have heavy-duty spring grip rail feet and integral spirit levels for vertical accuracy. The
intermediate board is adjustable up to 24mm of lift in 0.25mm increments and a spring indexed system allows
further measurement up to 160mm in 5mm increments. The target board is translucent allowing visibility in all
daylight conditions, with the option of fitting in a backlight for use at night or in tunnels.
4.2
The Sighting Board
The sighting board cross head is provided with a slit through which the Intermediate and Target boards are
sighted. On a level rail, and with the intermediate board adjusted to zero on the scale plate, the slit on the top
edge of the intermediate board and the sighting line on the target board are at the same line of sight.
4.3
The Intermediate Board
The intermediate board cross head can be adjusted for height by one of two methods.
i.
Coarse adjustment from 0-160mm in 5mm increments
ii.
Fine adjustment from 0-24mm in 1mm increments
Coarse adjustment
If the rail section has a void deeper than 24mm and a considerable amount of packing is required, the coarse
adjustment should be used.
The knurled hand nut at the top of the pole should be screwed down to zero.
Check that the pointer is visible through the scale window. If this is not the case, twist the crosshead until the
inner shaft clicks into alignment with the outer pole. The pointer should now be visible in the scale window.
Fine adjustment
If the void to be measured is less than 24mm, the fine adjustment screw should be used. This is the knurled nut
positioned at the top f the pole.
