Eastern Railroad Discussion > What is the purpose of a rail anchor?

Anybody know the purpose of a rail anchor? While it's odviuos(spelled wrong) what the other track components are used for, when I see the rail anchors, it looks like it just wraps around the bottom of the rails and nothing else.

anchors or creepers or C Clamps are used next to ties to prevent rail from moving lenghtwise (sliding) this is needed to prevent kinks etc.

That is why, most of us Railroaders tell railfans to stay back.
In a derailment, if the wheel flange hits the creeper it will pinch it and it is like a spring. I have seen these fly several hundred feet.

Normally they are there to keep the rail from running as JAAP said.

Rail anchors clamp onto the base of the rail snug against both sides of the crosstie. This forces the rail to move the tie along the axis of the track if it tries to slide or expand or contract. Since expansion or contraction generally cannot exert enough force to move all the ties, the rail will expand or contract in the crossways direction instead of along the axis of the track. This is the primary way of limiting expansion in continuous welded rail. While this seems a bit incredible, you can see the principle at work if you take a block of rubber and squeeze it in a vise. It expands crosswise when compressed in the vice jaws. Steel rail will do the same thing, except the forces are immense. In track that sees predominantly traffic in one direction and also on grades, the rail tends to creep so anchors help restrain that too. In extreme cases of restrained contraction, the forces become so high that the rail fractures. This is called a "pull-apart" and can sometimes open a gap 12" or wider--dangerous but, fortunately, detected by track circuits in signalled territory. Worse, is the opposite where the rail is trying to expand so intensely (like on an exceptionally hot day) that the compressive forces finally force the ties to slide crosswise out of alignment forming an "s" shaped kink in the track. The bad thing about this "heat kink" as it is sometimes called, is that the rails stay intact so the track circuit doesn't detect the kink and the engine crew sees this ugly kink in the track with no way to stop before running over it, often resulting in a derailment. At the risk of getting too detailed, you will occasionally see rail anchors installed around special trackwork like switches, diamonds, and double slip switches. These are usually to minimize adjacent track expanding and contracting thus throwing the special trackwork out of alignment. It is for this reason that nice straight alignment thru a diamond (or especially thru two diamonds as when a double track crosses a single track) is so hard to acheive. The day you align it its nice and straight and the weather is 60 degrees and the next day its 88 degrees and it looks like you were drunk when you lined the diamond. Oh well, enuf on this subject! Merry Christmas!

Rail anchors were in use long before ribbon rail. The principal cause of rail slip is the longitudinal force exerted on the rails when brakes are applied on a train. The force is in the direction the train is travelling.

In the 1940s I lived near Montreal, close to the main lines of CN and CP. Both lines were double track with right hand running and ABS signalling. Since all trains on a track were travelling in the same direction, they applied rail anchors on one side of the ties only. On lines with two way traffic, or on ribbon rail, they are applied on both sides of the tie.

It seems that braking would apply force to the rails only if the brake shoes are "locked up" and the wheels are sliding, producing friction on the rail head. In normal braking virtually all the kinetic energy is shed as heat from friction between the brake shoes and wheels. The main longitudinal rail displacement from trains is due to tractive effort, where friction is necessary.