Breather switch
Encyclopedia
A breather switch, expansion joint or adjustment switch is an intentional gap in lengths of railway tracks created to allow for expansion
in long sections of otherwise unbroken rail. They are placed either between very long sections of continuous welded rail (CWR), at the transition between CWR and jointed track, and commonly in the vicinity of bridges and aqueducts where the infrastructure and track may expand at different rates.
Unlike a butt (flat) joint between two lengths of railway, each section is tapered diagonally, allow for a smooth transition and high-speeds across the gap.
Breather switches have two advantages over traditionally joined track. Firstly, they eliminate or significantly reduce the noise and minor wheel damage created when a train
passes over the small gap between jointed rails, and secondly, where a section of CWR is particularly prone to expansion, these act as relief points to ensure that under extreme circumstances track does not warp out of shape or cause a sun kink
.
Expansion joint
An expansion joint or movement joint is an assembly designed to safely absorb the heat-induced expansion and contraction of various construction materials, to absorb vibration, to hold certain parts together, or to allow movement due to ground settlement or earthquakes...
in long sections of otherwise unbroken rail. They are placed either between very long sections of continuous welded rail (CWR), at the transition between CWR and jointed track, and commonly in the vicinity of bridges and aqueducts where the infrastructure and track may expand at different rates.
Unlike a butt (flat) joint between two lengths of railway, each section is tapered diagonally, allow for a smooth transition and high-speeds across the gap.
Breather switches have two advantages over traditionally joined track. Firstly, they eliminate or significantly reduce the noise and minor wheel damage created when a train
Train
A train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...
passes over the small gap between jointed rails, and secondly, where a section of CWR is particularly prone to expansion, these act as relief points to ensure that under extreme circumstances track does not warp out of shape or cause a sun kink
Sun kink
Sun kink refers to a condition that can occur on hot days in rail tracks. The phenomenon is caused by what is properly termed as buckling.The buckling force in the track due to warming up is a function of the rise in temperature only and is independent of the track length: F = E A \alpha_L \Delta...
.