Why Are There Two More Tracks Between The Incoming Train Tracks?

At the moment of the train roaring past, a special set of steel components beside the track are silently performing a critical task – the rail protection system. As the last defense line to prevent derailment in track engineering, this device guards the safety of train operation in millimeter-level control through precision mechanical design.

The Function of The Rail Guard

The essence of rail protection is a set of guiding devices parallel to the basic rail, and its core function is to build a physical constraint space. When the train wheelset deviates from the track due to abnormal conditions, the guard rail forms a geometric limit through the principle of “three-point contact”: the wheel rim first contacts the guide surface of the guard rail, and then the outside of the wheel hub produces friction damping with the guard rail web, and finally the special surface of the guard rail head is used to guide the wheel back to the right track. The graded energy dissipation mechanism can reduce the lateral impact force by more than 60%. Modern guardrail modular composite structure by forging steel body, high polymer damping pad and intelligent monitoring units. Taking China’s mainstream HG-60 guard rail as an example, its section presents a unique “eagle beak” shape: the guide bevel at the top of 38° inclination can reduce the contact stress of the rim, the wear-resistant alloy layer in the middle of 16mm thick can withstand more than 5 million friction shocks, and the bottom trapezoidal slot and the sleepers reserve 2-5mm thermal expansion and cold shrinkage gap. This bionic structure makes the service life of the guard rail three times longer than that of the traditional model.

Types of Rail Guard

The guard rail is an important part of the fixed frog. It is located on both sides of the fixed frog. It is an important equipment to control the running direction of the wheel, prevent it from impacting on the harmful space of the frog or climbing on the center rail tip of the frog, and ensure the running safety.

In the frog of movable core rail, the guard rail is generally installed only on the side strand to prevent the side wear of the core rail. At present our country switch between iron guardrail types have mainly rail type, H type and trough type 3 kinds.

1.Rail separation iron guard rail structure

Rail type iron guardrail structure between rail interval type iron guardrail is shown in figure 1, using common rail as a guardrail, use interval iron keep inlet flange groove width, guardrail inside set four rail brace in order to preserve the position of the guardrail, using step bolt connection, is the main form of “75” type switch guard rails. Interval type iron guardrail, for both open structure, guard rails and basic rail connection is firm, but the scene, adjust the inconvenience guardrail plate specifications. At present, except for the “75” type switch, it is no longer used.

2.H-type guard rail structure

H-type guard rail, as shown in Figure 2, is composed of “H” shaped guard rail processed by ordinary rail, guard plate, adjusting plate and connecting bolt. The guard rail is not directly connected with the basic rail, so it is also called the separate guard rail structure. Check the spacing, backguard distance and flange groove width can be adjusted using the adjustment plate between the guard rail and the brace, without adjusting the gauge. H guardrail materials easy, convenient adjustment, high safety, defect is guardrail processing capacity is larger. In order to improve the safety of the train when passing, the top of the protection rail is 12mm higher than the top of the basic rail.

3.Trough type guard rail structure

Trough the guardrail guardrail structure groove as shown in figure below, the trough steel guardrail, guardrail plate and gusset plate, adjust and connecting bolts, etc, is separated type structure, not only can adjust the spacing for compliance and back support distance, when using basic guardrail side rail fastener withhold, still can adjust the gauge, is currently widely used form of a guardrail. Trough steel weight of the guardrail, at least good economy, processing is simple. The disadvantage is that special rolling groove rail is required, and the force of the guard plate is also large.