What Types of Rail Fastening Systems Are There?

How Rail Fastening Systems Are Classified

Every rail fastening system has the same job: hold the rail down, hold the gauge, transfer the wheel load into the sleeper, and control longitudinal movement, while allowing enough elasticity for the rail to breathe with temperature. Systems are classified by their primary working element. Elastic clip systems press the rail base against the pad with the spring force of a steel clip. Bolted clamp systems use a clamp element tightened by bolts and nuts, and transmit the clamping force through a rigid lever. Spike systems anchor the rail through a tie plate into the sleeper with dog spikes or screw spikes. High-speed systems combine these elements with insulation, gauge adjustment and elastic pads for the tight tolerances of ballastless track. Within these families, specific configurations are known by their designations, and the tables below give the component list for the common ones.

Elastic Clip Fastening System

Elastic clip systems are the most widely used family on main lines. The clip is made of spring steel, its toe presses on the rail base, and its legs bear on cast shoulders or guide plates. The standard configuration for this family uses two tension clips per sleeper, two screw spikes, flat washers, plastic dowels, guide plates and one rail pad.

The omega-type elastic clip system is a very common variant, recognized by the omega shape of its clip. It is used on ballasted track for general freight and passenger service and is quick to install and maintain: the clip is driven over the shoulder with a standard tool, and the toe load is set by the clip design, not by tightening torque.

Bolted Clamp Fastening System

The bolted clamp system transmits the clamping force through a rigid clamp element that is tightened by bolts and nuts, which gives a high clamping force and makes it suitable for heavy-duty and corrosive environments. The clamp bears on the rail base on one side and is anchored by screw spikes on the other, with a double coil spring washer under the nut to hold the preload.

Spike Fastening Systems

Spike systems are the traditional solution for timber-sleeper track. A tie plate sits between the rail and the sleeper, distributing the load and holding the rail base, and dog spikes or cut spikes are driven through the plate holes into the timber. The same family includes screw spike systems, in which the spike is screwed into a plastic dowel or a pre-drilled hole, giving a defined clamping force and easier removal.

High-Speed Rail Fastening Systems

High-speed lines need fastening systems with tight gauge tolerance, electrical insulation, and elastic elements that damp the impact of high-speed wheels. The WJ-7 and WJ-8 systems and the Type V system are the dedicated configurations used for this duty. Their component sets are similar in principle: rail clips of spring steel, screw spikes, rail insulators, guide plates, rail pads and plastic dowels, arranged for fast, accurate installation on ballasted or ballastless track.

In addition, a fist-shaped clip system is widely used in southern African railway networks and neighbouring countries, consisting of three parts: rail clips, base plates and insulating steel pins. It is a simple, robust design for moderate speed freight and passenger lines.

Selection Guidance

Line class: high-speed lines use the dedicated WJ or Type V configurations; conventional lines use elastic clip systems.

Axle load: heavy-haul and corrosive environments favour bolted clamp systems with high clamping force.

Sleeper type: timber sleepers use spike systems; concrete sleepers use clip systems with cast-in shoulders or dowels.

Insulation: track-circuited lines need systems with PA66 insulators and insulating rail pads.

Maintenance: choose systems whose clip toe load does not depend on precise bolt torque, to simplify field installation.

Frequently Asked Questions

Q1: What is the difference between an elastic clip system and a bolted clamp system?

An elastic clip system holds the rail with the spring force of a steel clip, so the clamping force is set by the clip design. A bolted clamp system uses a rigid clamp element tightened by bolts, so the clamping force is controlled by torque and is generally higher.

Q2: Which fastening system is used for timber sleepers?

Timber sleeper track typically uses spike systems: a tie plate under the rail and dog spikes or screw spikes driven into the timber. Screw spikes are preferred where removal and re-tightening are expected.

Q3: What is the role of the plastic dowel in a clip system?

The plastic dowel is cast or glued into the sleeper and receives the screw spike. It protects the concrete from cracking, provides thread anchorage, and can be replaced if the thread is damaged.

Q4: Why do high-speed systems use insulators and rail pads?

Insulators and pads form the electrical insulation chain between the rail and the sleeper for track circuits and stray current control, while the elastic pad damps impact and protects the slab from high-frequency vibration.

Q5: Can a fastening system designed for one rail section fit another?

Not without a compatibility check. The clip toe and rail base contact depend on the rail base width and profile; a system matched to a 150 mm base rail will not seat correctly on a narrower section.