Rail pads are elastic polyurethane mats which are interposed between steel rails and railway sleepers to protect the sleeper top from wearing and impacting.
The starting stiffness of a rail pad is designed to not be high so that their relative deformation under the spring clip toe loads is greatly substantial. In this way, it can guarantees the rail pad maintaining in close contact with the rail despite of any vertical movements of the latter. In addition, the reason why rail pads made up of rubber or plastic is to dampen the shocks of vibration of a passing train.
The rail pad laid under the rail is used to guarantee
- The load distribution covering a larger surface area
- Reducing load concentration and usage fatigue stress
- Even contact area between the rail and supporting components
- Reducing noise and structural vibrations
- Sealing function between the top support and rail bottom
- Reducing rail wearing and relevant supporting components
How does a railway pad protect the track rail from impacts?
Railway pads protect rails from impacts by acting as a cushioning buffer between the rail and sleeper, absorbing shock, distributing wheel loads over a larger area, and dampening vibrations, which reduces stress, prevents sleeper damage (abrasion/crushing), and extends track life. They work by deforming slightly under load to soak up energy, then slowly releasing it, softening the harsh jolts from trains and minimizing noise.
- Impact Absorption: The pad's elastic material (like rubber or cork-rubber) deforms under the wheel's weight, soaking up sudden impact energy instead of letting it transfer directly to the sleeper.
- Load Distribution: By spreading the concentrated force from the wheel across a wider surface of the sleeper, pads prevent high-pressure points that cause wear and deformation.
- Vibration Damping: They reduce resonant vibrations and high-frequency jolts (like those around 1000 Hz), which lessens noise and structural fatigue on the track components.
- Abrasion Prevention: The cushioning effect stops the rail from rubbing directly against the sleeper, preventing wear (abrasion) and crushing of the sleeper's surface.
- Enhanced Stability: The pads provide a more consistent contact surface, absorbing minor irregularities and improving overall track stability.
How to determine the aging of rail pads?
Through visual inspection (cracks, discoloration, wear) and physical property testing, measuring changes in hardness, thickness, and stiffness (spring constant), often comparing results to baseline data or standards, and sometimes using accelerated lab tests (heat, oil) or on-site dynamic measurements (vibration reduction) to predict performance degradation and replacement needs.
What Changes with Aging?
- Softer: Aged pads often become softer, reducing their stiffness and damping capacity.
- Increased Contact Forces: Softer, degraded pads can increase rail/sleeper contact forces, affecting track stability.
As a professional rail fastener manufacturer, GNEE RAIL can produce various types of rubber rail pads with different materials, such as natural rubber, EVA, HDPE and so on. In railway fastening system, rubber rail pads are often installed between the rail tracks and the concrete railway sleepers.