Bolts: consisting of the head and screw (with male cylinder) of a class
of two parts fasteners, be with the nut for fastening two parts
with a hole. This connection form called bolting.
As to unscrew the nuts from the bolts, they can make the two parts
separately, it is part of a removable bolted connection. Because a
bolt is railway accessories, railway accessories are part of the
railway line, the track referred to here include rails, sleepers,
connecting parts, track bed, anti-climbing devices, such as rail
support and turnout.
As a holistic engineering structures, track laying on the roadbed,
plays the role of guiding trains, locomotives and direct withstand
enormous pressure loads.
Under the dynamic action of the train, its various components must
have sufficient strength and stability to ensure that the train in
accordance with a predetermined maximum speed, safe, stable and
General classification and special bolts
Force by way of connection points: points common and have reamed
hole with. Articulation hole bolt hole size and fit to be used at
the time by the lateral force.
Divided by head shape: hexagonal head, round, square head,
countersunk head and so on. Wherein the hexagonal head is the most
Shen head with a general requirement in place after the connection
is not a smooth surface projections because countersunk head can be
screwed into the parts inside.
Can also be screwed into the round parts inside. Tighten the square
head of the force may be bigger, but the size is large.
In addition, to meet the needs of the lock after installation,
there is a hole in the head, the stem portion has a hole, the holes
do not allow the bolt to loosen when subject to vibration.
Some did not bolt threaded rod to be meticulous, called the waist
bolts. This bolt is conducive to change by force coupling.
There are special high strength bolts, the head will be bigger and
more, there are changes in the size of the steel.
Another special use of: T-shaped slot bolts, jigs and fixtures used
on most special shape, side of the head to be cut off. Anchor bolts
for machines and stationary ground connection, there are a variety
of shapes. U-bolts, as previously described. And so on.
There are special welding studs, threaded one end a head not, parts
can be welded on the other side of the nut screwed directly
Bolts performance levels meaning
Steel bolted performance rating
3.6,4.6,4.8,5.6,6.8,8.8,9.8,10.9,12.9 more than 10 levels,
including 8.8 and above bolts made of carbon steel or carbon steel
and heat treatment (quenching and tempering), commonly known as
high strength bolts, and the rest is known as ordinary bolts. Bolt
performance rating label has two parts numbers, respectively, said
male bolt material tensile strength and yield strength ratio. For
Performance rating 4.6 bolts, its meaning is:
1, the bolt material nominal tensile strength up to 400MPa grade;
2, bolt material yield strength ratio is 0.6;
3, bolt material nominal yield strength of 400 × 0.6 = 240MPa grade
Performance rating 10.9 high strength bolts, the material after
heat treatment, can be achieved:
1, the bolt material nominal tensile strength up to 1000MPa level;
2, bolt material yield strength ratio is 0.9;
3, bolt material nominal yield strength of 1000 × 0.9 = 900MPa
Bolt performance rating is the meaning of international standard,
the same performance level of the bolt, regardless of the origin of
the difference between the material and its performance is the same
design on the level of performance you can use only.
The so-called strength grade 8.8 and 10.9 refers bolt shear stress
level is 8.8GPa and 10.9GPa
10.9s s representation of steel