b. The bolts. The strength and
tightness of the bolts securing the bars to the
rail contribute greatly to the efficiency of the
rail joint. The bolts used to splice light rail
are either 7/8 or 1 inch in diameter; those for
heavy rail, 1 1/4 inches. Typical bolts,
shown in figure 3.18A and 3.18B, have
either hexagonal or square nuts, and the
boltheads are either hexagonal or square.
Figure 3.18C shows one type of spring lock
washer that is placed between the nut and
the bar, to prevent the nut from working
loose. The section of the bolt directly under
the head is oval. Alternate holes in the bar
are also oval while the remainder are round.
When the oval section of the bolt is fitted
into the oval bolthole, the bolt is prevented
from turning because of jarring or vibration.
The oval holes also serve another
Figure 3.18. Typical Rail Joint Bolts, Nuts,
purpose. Rails, 75 pounds and up, are
and Spring Lock Washer.
bolted so that the nuts alternate
between the inside and outside of the rail. Looking at the outside of the rail, for example, you
would see a bolthead, a nut, a bolthead, and a nut; looking at the inside, you would see the
opposite sequence. The sketch given here
views a rail joint from above; R indicates
round hole; O, oval.
You may ask, Why are the bolts
staggered? They are staggered for a good
reason: the wheel rim of a derailed car
could shear off all the nuts if they were all installed on one side. To insure, then, that the bolts
will be staggered when installed, the bars are manufactured with the alternate round and oval
holes and the bolts are made with the oval neck section. For low rail and that