Selecting the right
drive technology
drive technology
The drive system in the shunting process
When selecting the right shunting solution, it is important to first clarify the general conditions, such as the country of operation, climate, and other local characteristics. The answers to the following questions are crucial here: What will be loaded, unloaded, or shunted? What tonnages are expected? What are the operational procedures, where, and, of course, when?
Shunting technology for every application
Based on these key factors, the performance requirements for the shunting technology to be planned can be determined. It is clear that no two customers have the same requirements. These must be specifically identified and addressed on a case-by-case basis. For example, in refineries, ATEX zones—that is, areas where explosion-proof components are used—must not be overlooked.
Drive Technologies - A Comparison
Before we examine the individual propulsion technologies, let’s take a look at an interesting trend that has gained significant momentum over the past decade: the demand for low-emission and environmentally friendly propulsion systems. The reasons for this include increasingly stringent legal requirements and standards—particularly regarding exhaust technology in diesel engines—as well as a general rise in environmental awareness. Another factor is the use of low-maintenance technologies to reduce costs and meet sustainability requirements.
However, particularly in powertrain design, it is essential that all components be considered holistically. For example, when does a powertrain battery—from manufacturing through to recycling—pay for itself compared to a diesel engine? At the same time, this trend poses a major challenge for intelligent hybrid systems, as the proportional balance of various powertrain technologies must be tailored to specific customer needs.
Classic: The diesel engine
In a diesel engine, the chemical energy stored in the fuel is converted in several stages: First, the combustion process generates thermal energy, which is transferred to the crankshaft as mechanical energy and then converted into electrical energy by a generator. Modern shunting vehicles can be equipped with generators operating at different voltage levels, allowing them to be flexibly adapted to various requirements.
A key advantage of the diesel drive system is its high availability. Vehicles can be operated independently of external energy infrastructure and deliver high traction power directly on site. Downtime is essentially limited to refueling or scheduled maintenance—a crucial factor for reliable shunting operations.
Despite significant advances in exhaust aftertreatment, however, completely emission-free operation remains impossible. Additionally, relatively low efficiency, higher operating and maintenance costs, and the expense of providing refueling infrastructure are among the disadvantages of this propulsion concept.
Zero emissions: The electric drive
The battery-electric drive system offers a compelling alternative to the traditional diesel engine and compensates for many of its drawbacks. It enables locally emission-free operation and is characterized by relatively low maintenance requirements. Battery-powered vehicles can also operate autonomously on sidings and are therefore independent of an external power supply during operation.
However, operating time is limited by the available battery capacity. In practice, two-shift operation is generally possible before a charging break is required. The charging time is approximately eight hours. Furthermore, the battery’s service life depends significantly on the number of charging cycles—batteries undergo a natural aging process but can be recycled at the end of their life cycle.
A suitable charging infrastructure is always required for operation. The corresponding charging station must be planned so that it does not interfere with other shunting operations.
Lithium-iron batteries are becoming increasingly popular in the industrial sector today, as safety, cycle stability, and reliability are often more important than maximum energy density. The voltage remains stable over long periods of time. As a result, devices or vehicles deliver consistent performance, even at low states of charge. They are significantly more thermally stable and less prone to fire, and are also robust against deep discharge and frequent charging cycles, requiring less maintenance.
Durable: The cable reel drive
In the cable drum drive system, power is supplied via a cable that is carried along and can be wound up and down. The operating principle can be clearly illustrated by comparing it to a corded household appliance: The cable is constantly under tension and is automatically fed through a drum—regardless of whether the vehicle is moving away from or toward the power supply point.
As with battery-powered systems, this concept also enables locally emission-free operation with minimal maintenance requirements. In addition to pure power transmission, the cable offers additional benefits: for example, signal and video data can be transmitted via integrated optical fibers. This allows alternative transmission methods, such as radio, to be reduced or eliminated entirely.
However, these advantages are offset by limitations. The shunting distance is limited by the available cable, and the cable routing—particularly over switches—can affect operational procedures. In certain situations, the laid cable can obstruct other rail vehicles. Furthermore, the system faces physical limitations: for higher drive power, the cable cross-section and the maximum cable length play a decisive role.
2-in-1: The Hybrid Drive
The hybrid powertrain combines two different propulsion technologies to make optimal use of their respective strengths. This can involve either different systems—such as diesel and electric drives—or two smaller units of the same type. This intelligent combination allows energy to be used more efficiently and, for example, significantly reduces reactive power.
When high power is required, both systems can operate in parallel and supply the powertrain simultaneously. At the same time, hybrid operation allows for more flexible use of the individual components, which reduces their operating hours and potentially extends their service life.
However, this also comes with higher demands: The additional technology generally leads to higher investment costs as well as increased maintenance requirements. Furthermore, powerful and individually tailored energy management systems are necessary to optimally control energy flows and fully leverage the advantages of the hybrid drive.
