a plate is added to suspended joint, this type of joint is referred to as a bridge joint, as shown in
figure 3.20C, in which the plate is labeled (1) .
(3) Three ties. A joint that extends across three ties is used a great deal in main-line
tracks. The ties are laid close together--6 to 8 inches, and the rail ends rest on the middle tie. An
example is seen in figure 3.20D.
b. Location. The terms broken joint and square joint describe the location of a joint in a
rail. A broken joint is one which appears across from the center of the opposite rail. An
allowance of from 12 to 24 inches from the center is made on most roads. A square joint refers
to one that is directly across from another in the opposite rail.
On North American lines, the broken joint is found more often than the square one. It
has never been determined that one provides a safer track than the other; however, alternate
(broken) joints seem to be the more desirable especially for track carrying heavy traffic.
Standard military practice is to use the broken joint. Its location should not exceed 30
inches from the center of the opposite rail, preferably not more than 18.
3.28. INSTALLATION
You have the parts of the joint assembly--the two bars and the four or six bolts, nuts, and
washers--ready to install. All parts have been well lubricated; even slight rust on the threads
may prevent the correct tension from being reached in tightening the bolts or may cause the
threads to be stripped. What procedure do you follow in installing the assembly? The
subparagraphs following take you through the steps.
a. Allowing space for expansion. The rail ends are in place on or between the ties as
standard practice for your road dictates. But how far apart must the ends be? When joint bars are
applied, rail expansion and contraction caused by temperature changes must be provided for.
Rails laid in hot weather are placed close together so that when they contract in cold weather the
space (rail gap) will not be too large. Similarly, rails laid in cold weather have a space between
length ends so that there is room to expand. Joint bars and bolts are made so as to allow the rail
to move a small amount within
66
Previous Page
