The two types of tram bars are rigid and tele-
scopic. The rigid tram bar is of fixed length and does
not allow for error. The telescoping feature of the tele-
scopic tram bar makes it more convenient and safer to
use. For this reason, this chapter discusses the tele-
scopic tram bar. Both, however, accomplish the same
As shown in view A of figure 3-13, the telescop-
ing tram bar consists of two parts, one bar sliding
within the other. The parts of the bars have a small
amount of movement with respect to each other and
are extended by an internal spring. A scribe mark on
the inner part is visible through an opening in the
outer part. Engraved on the edges of the opening is a
graduated scale that runs on each side of a zero mark.
When the inner scribe mark and the outer zero mark
are in line, the tram bar is at the correct length.
As shown in view B of figure 3-13, a gage is fur-
nished with the instrument to check that the zero line
and the scribe mark match when the length is correct.
bar. One block has a fixed pin, whereas the other has
a movable pin. After the blocks are welded in place on
the element, the movable pin can be adjusted so that
the scribe mark and the tram bar zero line match
exactly when the dials of the element are at some pre-
determined reading. The movable pin is then tack-
welded in place. To protect the ends of the pins from
damage and corrosion when the pins are not in use,
the pin ends are covered with grease-filled caps.
Tramming operations should be performed with
great care to prevent injury to personnel or damage to
The equipment power drives should not be used
unless it is absolutely necessary.
The equipment should be positioned to the
approximate tram position and the bar inserted with
the heavier end down.
The bar should not be held in place while the
tram blocks are moving with respect to each other.
As shown in view C of figure 3-13, the block has
pins with cupped ends that fit the rounded ends of the
However, if necessary, holding should be done only
while the blocks are moving away from each other.