Begin by screwing the hand nut anti-clockwise, so that it rises up to the cross head. The arrow at the top of the
scale window should line up with the 0mm mark on the ring scale. Ensure that the inner pole is pushed fully
down. The hand nut should rest on top of the black plastic ferrule.
The intermediate board is now setup for fine adjustment. Rotate the hand nut clockwise and the cross head will
rise up. One complete turn of the nut will move the cross head up 12mm. The bottom row of numbers on the ring
scale should be used to read 0-12mm displacement. The second turn of the hand nut will raise the cross head a
further 12mm. The top row of numbers on the ring scale should be used to read 12-24mm displacement.
4.4
The Target Board
The target head is fitted with a laminated plastic target plate (black and white) which can be kept clean by wiping
over from time to time.
5.0
Procedure
Before a length of track is measured packed it must be examined and the components replaced or repaired as
necessary. It is essential that all fastenings are tight and that baseplate or chair
seating’s
are hard up to the rail.
Bull head rails should be properly locked up. Sleepers that are end or centre bound and faulty top in excess of
19mm (3/4”) must be ordinarily
shovel packed. Hollow sleepers are then detected by sounding at the ends near
the baseplates or chairs with a pick shaft or hammer. A void meter should be applied where any sleeper is found
hollow, or there is any doubt about it. The readings are chalked on the rail or sleeper accordingly.
The sighting boards are next brought into use to measure slacks in the rail top. Both rails are eyed for top and
where possible the one needing least attention is selected for boning through with the sighting boards. If however
one rail is “generally” higher than the other (allowance being made for cant) it should be selected,
even if it
requires attention. FOR THIS PURPOSE THE SELECTED RAIL IS KNOWN AS THE SIGHTING RAIL, AND
THE OPPOSITE ONE AS THE CROSS LEVEL RAIL.
The sighting rail is then eyed for high spots about 30 metres apart and they are marked. At these points the cross
level of the rails is checked. (On curved rails the correct required cant must be known and the cant slide set
accordingly.)
Figure 2 Intermediate Board
