Bolt (fastening)

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protruding end of a bolt,
axially secured with a spring pin in the transverse hole.
Partially threaded screws are also known as bolts . There is no clear distinction between the two.

The machine element bolt is a cylindrical connecting element .

In contrast to a pin and rivet , a bolt is usually inserted into the mounting hole with radial play so that it can be easily removed.

A simple bolt is used when there is only transverse loading from shear (and, to a lesser extent, bending ) (see shear hole reveal screw connection ). For axial, i.e. H. Longitudinal loads due to tensile force are often used with threaded bolts (for nuts ), which are then also referred to as screws . Alternatively, additional shaped elements such as head (collar bolt), transverse hole (for split pins , less often dowel pins ), transverse groove for axle holders or circumferential groove (for retaining ring / adjusting ring ) can be provided to create a positive fit between the bolt and the parts to be connected and to prevent the bolt from falling out to secure.

Bolts are recorded in the standards EN  22340 (without head) and EN 22341 (with head), and in Germany in DIN  1445 (with head and thinner threaded pin).

Bolts are often used for connections that are quick and often to be released, for example:

Screws are used for connections that need to be loosened less often. Shear force connections, which do not have to be released again, used to be made by rivets (mostly solid rivets ), today mostly by welding .


  • Fitting bolts with little play (fitting bolts without play or with a press fit are more likely to be referred to as a pin )
  • Hinge pins can be part of a swivel joint , e.g. B. in door hinges , link chains or rod connections.
  • Screws with a partial thread or larger-sized grub screws are sometimes referred to as threaded bolts or screw bolts .
  • Studs are firmly connected to a larger component. They are not typical bolts in that they cannot be easily removed and, as threaded stud bolts, also absorb longitudinal forces rather than shear forces. Stud bolts are fastened at one end, for example, by riveting (riveting bolts ) or pressing, splinting, gluing, welding or by a threaded connection in a blind hole . A typical application is the mounting of the cylinder head of internal combustion engines on the crankcase .
  • Collar bolts have a collar or head at one end
  • Countersunk bolts have a countersunk head and, like bolts with threaded pins, are used as fixed bearing and axle bolts ( stud bolts ), e.g. B. for rollers and door hinges.
  • Spring bolts with feather keys according to DIN 37082 C. In addition, a large number of bolts that contain a spring, are connected to a spring or are used to fasten (leaf) springs are referred to as spring bolts .
  • Shear pins are used to secure against overload. They can contain a predetermined breaking point to tear off in the event of overload, or they have a hollow axle with an internal axle and shear off when a certain torque is exceeded.
  • Force measuring bolts are used to measure the transverse forces that occur in the bolt, for example using strain gauges or magnetic coils.
  • Pyrobolts contain an explosive charge inside so that they can be cut through in a targeted manner.
  • Ball lock pins are used to quickly separate components. They are secured in their position by a spring-loaded ball.
  • Firing pin , a component of firearms .

Individual evidence

  1. We recommend tolerance h 11 for fitting bolts and H 8 to H 11 for bores.
  2. ^ A b Alfred Böge, Wolfgang Böge: Manual of mechanical engineering: Basics and applications of mechanical engineering , p. 810, Springer-Verlag

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