Switches are at the heart of flexible railroad infrastructure. They enable changes of direction in the track network, create connections and determine the speed, safety and efficiency of rail operations. But what at first glance appears to be a simple rail branch is actually a highly complex technical system.
The construction of a turnout requires millimeter-precise production, coordinated components and the highest material quality. This is because every journey, every change of direction, every braking and acceleration maneuver has a direct effect on the components. It is therefore all the more important that these components function reliably – even under high loads and extreme weather conditions.
In this article, we analyze the complete components of a turnout. We show which components play a role, how they interact – and why the quality of the installed parts, as supplied by Bharat Forge CDP Railsystems, is essential for safe and long-lasting operation.
A brief overview: Types of switches
Before we look at the technical structure in detail, it is worth taking a brief look at the different types of turnouts. Depending on the track geometry and operational requirements, turnouts differ not only in their length or curvature, but also in their function:
- Single points: classic change of direction between two tracks
- Crossing switches: Combination of turnout and crossing, often for space-critical track connections
- Double crossing points (DKW): enable four travel options in a compact space
- Outside curve turnouts: especially for curved routes
The choice of design has a direct influence on the turnout structure – especially for the frog, wheel guide and setting mechanism.
👉 You can find a comprehensive introduction in our article “What is a switch?”.
Technical overview: How the components of a turnout interact
The design of a turnout does not follow a random arrangement – it is the result of many years of engineering experience, standardized requirements and safety-critical functions. Each turnout consists of a defined combination of mechanical components that together enable what is indispensable in rail operations: the safe and precise switching of tracks.
The focus here is on the interplay between moving and fixed components. The switch blades actively steer the wheel in the desired direction. The frog ensures an uninterrupted transition across the crossing rails. Wheel guides ensure the correct wheel alignment. Locking systems and adjusting mechanism guarantee the clear and safe position of the turnout – even under high loads and changing environmental conditions.
To ensure that all these functions interlock reliably, the components must be precisely matched to each other. Incorrect tolerances, inadequate materials or a lack of maintenance have a direct impact on operational safety. This is why the technical components of a turnout are not just a question of design – they are a key prerequisite for safe, low-maintenance and efficient rail traffic.
In the following sections, we look at the key components in detail – with a focus on the high-quality solutions from Bharat Forge CDP Railsystems and their specific advantages in use.
The central components in the structure of a switch
The technical structure of a turnout follows a clearly defined system: each element fulfills a precise task in the interplay of track switching, track guidance and safety. High mechanical loads, changing environmental conditions and safety-related requirements have a direct impact on the components.
How these components interact and what functions they perform is shown below – the associated switch sketch provides an initial overview of the most important elements.
A faulty design or inferior material quality can lead to travel interruptions – therefore, attention should be paid to durable, standard-compliant solutions right from the procurement stage.
Switch blades – Movable direction changer with safety-critical function
The switch blade is the central control element of a railroad switch. As a movable rail track, it decides whether the train follows the straight track or crosses over to the branching track. During operation, one of the two switch blades is always in contact with the adjacent stock rail – the route is thus clearly defined and is often confirmed by an associated switch signal.
From a mechanical point of view, the tongue is a flexible but dimensionally stable component. The area of the tongue tip where it makes exact contact with the stock rail is particularly critical. This is where it is crucial whether the travel path is set correctly – and whether the transition takes place without any impact or gap.
Numerous forces act on the tongue:
- Vertical load due to the wheelsets rolling over
- Lateral forces during the positioning process and due to cornering
- Temperature-related linear expansion over the course of the day
- Abrasion and corrosion due to environmental and weather influences
In order to withstand these challenges in the long term, high-quality support and precise movement of the tongue are essential. This is precisely where the tongue rolling device from CDP comes into play. Your advantages at a glance:
- Low-friction movement for a smooth tongue position
- Low wear due to targeted force distribution
- Robust construction, designed for temperature changes and high loads
- Compatibility with various switch shapes and installation positions
The CDP solution offers decisive added value, especially for systems with a high setting frequency – such as in railroad stations or industrial tracks: fewer failures, reduced maintenance and a consistently safe turnout function.
The switch blade is therefore not simply a moving component – it is a precise guide element with a direct influence on the safety, reliability and service life of the entire switch construction.
Stock rail – Stable guide and reference point for the switch blade
Together with the switch blade, the stock rail forms the central pair in the setting mechanism of a turnout. Unlike the movable switch blade, the stock rail is a fixed rail section that serves as a reference surface for the switch blade position. Clear and safe track guidance is only guaranteed if the switch blade makes positive and powerful contact with the stock rail.
In detail, the stock rails perform several essential functions:
- Mechanical guidance of the wheel via the tongue area
- Stop surface for the movable tongue
- Force absorption when rolling over the tension wheel
- Shaping the seamless transition to the adjoining rail
The geometry in the stop area is particularly important. Even small manufacturing tolerances or wear and tear can lead to problems, for example:
- Impacts when rolling over, which have a negative effect on the track position and ride comfort
- Tracking errors that can cause derailment in extreme cases
- Wear on wheel set profiles and tongue edge due to poor fit
To prevent these risks, the stock rail is usually made of particularly resistant steel and precisely matched to the geometry of the tongue. In conjunction with the tongue rolling device from CDP tongue roller device, the result is a low-friction and permanently reliable rail contact.
In addition, the stock rail must:
- Compensate for temperature changes without deforming
- be mechanically stable and anchored in the substrate
- be installed with corrosion protection – especially outdoors
In the context of the entire turnout structure, the stock rail therefore not only functions as a “silent” component, but also as a fundamental prerequisite for safe track changes. Its condition directly influences the function of the switch – and therefore the entire setting process.
Tongue roller device – low friction, low maintenance, safety-relevant
The switch blade roller device is one of those components of a switch that may seem inconspicuous at first glance – but is essential for its function. It supports the mobility of the switch blade by allowing it to move along the sliding surface with little friction. Without a functioning roller device, the actuating forces would be significantly higher, the mechanical stress greater – and the wear of all adjacent components correspondingly accelerated.
During operation, the tongue rolling device performs a number of critical tasks:
- Reduction of friction between tongue and sliding chair plate
- Stabilization of tongue movement with changing loads
- Protection against jamming due to temperature changes, ice, dirt
- Avoidance of material removal on the tongue and plain bearing
The tongue rolling device from CDP has been specially developed for these requirements. Its design principle is based on the following properties:
- Rolling instead of sliding principle: The movement takes place via rollers or ball bearing elements – with significantly less friction than with classic plain bearings.
- Weather-independent function: smooth operation is maintained even in wet, icy or hot conditions.
- Robust design: Suitable for high wheelset loads, frequent shifting and long downtimes.
- Easy maintenance and interchangeability: Ideal for modernization and maintenance cycles.
The use of a high-quality rolling device brings tangible benefits, particularly in older switch systems or in areas of the line that are subject to high climatic stress (e.g. mountains, industrial environment, coastal region):
- Less wear on tongues and guide rails
- Reduced actuating forces → Protection of interlocking and drive
- Prevention of failures due to blocked tongue movement
The switch roller device therefore works behind the scenes – but is crucial for trouble-free, safe operation. In combination with the tongue and the slide chair plate, it forms the dynamic center of every functional switch.
Sliding chair plates – base layer for movement and precision
Slide chair plates form the bearing and guide surface for the movable switch blades. They are anchored in the track bed and ensure that the switch blades can be moved in a controlled, uniform manner and with defined friction. As the contact surface between the switch blade and the substructure, they have a direct influence on the setting process – and are also a highly stressed component in continuous operation.
Sliding chair panels fulfill the following key functional tasks:
- Load absorption of the vertical forces by the wheelset weight
- Guiding the tongue in its lateral movement
- Distribution of frictional forces in the direction of the sleeper and substructure
- Noise reduction and damping when rolling over due to elastic supports (optional)
The sliding chair plates from CDP Railsystems are designed for high mechanical load capacity and long service life. Your advantages in use:
- Precise fit to the tongue for defined, smooth movement
- Durable materials, suitable for intensive use and outdoor use
- Maintenance-friendly design, compatible with existing installation situations
In conjunction with the tongue rolling device, the sliding chair plates act as a functional guide layer. Faults or wear in this area can lead to:
- imprecise tongue position,
- Blockage of the positioning movement or
- increase the actuating force.
Smooth, low-friction sliding is essential, especially for turnouts with electric or hydraulic drives – to avoid overloads in the interlocking and to keep the operating times constant.
CDP also offers system-compatible variants that can be integrated into existing track systems – a decisive advantage for retrofitting or as part of maintenance programs.
Centerpiece switch – transition nodes for wheels, forces and precision
The frog is a central element in the switch structure, especially in the area where two rail tracks cross. Here, the wheel of the vehicle is specifically guided over a short interruption – the so-called frog gap. This area is relevant to safety, as the wheel does not have full contact with the rail for a short time.
The centerpiece fulfills several critical tasks:
- Guiding the wheel arch over the crossing of two track lines
- Bridging the frog gap using wing rails and wheel guides
- Load absorption at maximum force – especially on the frog tip
- Ensuring a safe transition at different speeds
Enormous point loads occur in the area of the frog tip in particular – caused by the concentrated overrolling of the train wheel sets. The demands on material quality, geometry and wear resistance are correspondingly high.
In conjunction with the wheel control arms, the wheel is guided through the frog without hitting the frog gap – a safety-critical passage in the entire track. A worn or poorly adjusted frog can lead to:
- impacts and imbalances in the wheel arch,
- Tracking errors or even
- lead to material fractures.
Setting rod / coupling rod – Mechanical connection for safe switch setting
The safe position of a turnout is not only based on electronic or hydraulic control, but above all on reliable, mechanical power transmission. A central role in this is played by control rods and coupling rods – they are the connecting links between the actuator, the point lock and the switch blades.
They take on several important functions at the same time:
- Synchronization of the tongue movement so that both tongues switch evenly
- Power transmission from the point machine to the switch device
- Positioning lock, even with vibrations or load
- Prevention of mechanical blockages due to torsion or displacement
CDP offers coupling rod solutionsthat are designed for high precision and stability:
- Torsionally rigid design for even force distribution
- Weather-resistant materials, corrosion-protected and durable
- System compatibility for different switch types
- Easy to install and adjust, ideal for new builds and retrofits
Malfunctions in this area can have serious consequences:
- Asymmetrical tongue position → Risk of misrouting
- Blocked signal box → Operational failure
- Mechanical overload of the drive due to incorrect force application
Wheel control arm – invisible guard in the centerpiece area
The wheel guide is an often overlooked but safety-critical component in the design of a turnout. Its task is to guide the wheel of a rail vehicle in a targeted manner – especially when crossing the frog gap, i.e. the short area in which the wheel has no continuous rail contact.
Without the wheel guide, the wheel would possibly deviate from the intended running surface – with potentially serious consequences such as:
- Track misalignment or derailment
- Material damage to the frog or wheelsets
- Heavy impacts and imbalances in running behavior
The wheel guide plates from CDP offer reliable track guidance through:
- Precisely adapted tread geometry
- High-strength materials, resistant to wear and weathering
- Easy to install for new builds and replacements
- Compatibility with different wheel profiles and track gauges
Particularly at high speeds or with narrow wheel guide geometries (e.g. for crossing turnouts), it is important that the running surfaces and groove dimensions are precisely maintained. CDP guarantees this precision through modern production technologies and intensive quality assurance.
Other components
In addition to the central components such as the switch blade, frog or wheel guide, there are numerous supporting elements that are less in focus but are essential for the function, stability and service life of a turnout.
These include, among others:
- Ribbed plates – connect the rails to the sleeper with a positive fit, secure the track width and reliably transfer loads to the substructure.
- Wing rails – part of the centerpiece, support the wheel track at the transition between the tracks.
- Screws, clamps, base plates – enable secure, adjustable installation and facilitate maintenance or replacement of individual elements.
- Points signals – indicate the position of the points visually or electrically and are part of the operational safety system.
These components help to ensure that differences in load progression, weather influences and mechanical stress remain manageable over the long term – a prerequisite for trouble-free operation on all routes.
Functional interaction – precision is created in the system, not in the individual part
A turnout does not function through the quality of a single component – but through the precise interaction of all components. A safe, durable and low-maintenance system is only created when the switch, frog, wheel guide, locking mechanism and bearing technology are perfectly coordinated.
Each component fulfills a specific role, but the interaction between them results in mutual dependencies. One example:
- The switch blade must lie cleanly against the stock rail.
- The actuating rod transmits the drive torque to the switch lock, which in turn ensures the movement and locking of the switch blades.
- The wheel guide takes over the guidance of the wheel when it leaves the tongue – while the centerpiece simultaneously secures the support.
- All these movements are supported by the tongue roller device – the state of which influences the positioning accuracy.
What counts:
- Tolerance chain instead of individual tolerance: Deviations add up.
- Force flow instead of individual loads: One component transfers forces to the next.
- Condition chain instead of individual condition: Maintenance of one part influences the performance of the entire system.
CDP Railsystems therefore sees turnouts not as a collection of individual parts, but as a systemic unit. The company’s own components – from the switch roller device to the frog – are precisely matched to each other and tested under real operating conditions. The result: high functional reliability with minimal maintenance – for years to come.
Repairing the switch – what to do if components fail?
Even high-quality turnouts can suffer wear or damage in the course of operation. Moving or heavily loaded components are particularly affected – for example:
- Deformed or worn tongue tips
- Run-in sliding surfaces or blocked tongue devices
- Knocked-out eccentric bushes in the area of the coupling rod connection
- Cracks in the area of the centerpiece
A targeted repair requires sound specialist knowledge and the right material. The decisive factor here is:
- Rapid condition assessment (e.g. by visual inspection, measurement technology or sensor technology)
- Modular replacement of individual components without complete disassembly
- Availability of compatible spare parts
When developing its components, CDP Railsystems focuses on repair-friendly design: many parts – such as tongue rollers or coupling rods – can be replaced or adjusted while still installed.
Quality and advantages of CDP components in the switch assembly
Turnout components are not just about dimensional accuracy or material quality – they are about system responsibility. Each component influences the operation, maintenance costs and ultimately the safety of the entire rail network. CDP Railsystems specializes in developing high-quality individual components that combine to form an optimized whole.
What characterizes CDP components:
- High dimensional accuracy – for optimum fit, minimum tolerances
- Material quality according to the latest standards – e.g. wear-resistant steels, weather-resistant coatings
- Geometrically coordinated interfaces – e.g. between tongue, rolling device and sliding chair plate
The use of these solutions offers clear advantages:
- Reduced maintenance intervals
- Less downtime due to malfunctions or blockages
- Improved operational reliability, even under load and at high actuating frequency
- Long service life even under demanding conditions (temperature, corrosion, soiling)
Conclusion: Switch design – safety starts with the details
The structure of a turnout is more than just an assembly of components – it is a system of precisely coordinated functions that together enable the safe and efficient operation of the rail network. Whether switch blade, frog, wheel guide or locking system: every component must meet the highest requirements – in terms of material, function and durability.
CDP Railsystems not only supplies individual parts, but also system quality:
- Tested, resilient and reliable
- Adaptable to existing infrastructures and tracks
- Designed for long-term, low-maintenance use
The targeted interaction of all products for turnout construction turns technical complexity into operational safety – and every component into a functional contribution to the overall railroad system.Are you planning an infrastructure project or modernization?
Our experts will be happy to advise you on suitable solutions for your turnout systems. Get in touch now →