# Case Study of an Integrated Design and Technical Concept for a Scalable Hyperloop System
## 4 Functional Definition
### Suspension  
The suspension of a vehicle traveling at 600 \(\frac{\mathrm{km}}{\mathrm{h}}\) is a challenging aspect of the hyperloop system. Technically, it is possible to suspend the pod with wheels similar to a train. However, at such high speeds, this approach is expected to be uneconomic due to the high maintenance costs and the difficulty of lubrication in a vacuum environment. Electodynamic suspension (EDS), which utilizes repelling forces between a conductor in the track and a permanent magnetic field in the vehicle, resulting in eddy currents, poses one viable concept. Nevertheless, the hyperloop community has converged on electromagnetic suspension (EMS), which uses attracting forces between ferromagnetic steel and a controlled electromagnet. This design is structurally more complex on the infrastructure side compared to the EDS design, but it reduces drag considerably and enables active damping. Unlike EDS, EMS enables levitation while the vehicle is stationary, which is an advantage for handling the pods and makes the incorporation of wheels unnecessary. More in-depth considerations on this topic can be found in a previous paper [14]. Table 3 summarizes the important parameters of the levitation and guidance (lev&guid) system. To further reduce the drag induced by the levitation system, the arrangement plays a crucial role. In the Transrapid system, the levitation system is arranged in a heteropolar configuration due to its combination with propulsion, meaning that magnetic poles alternate in the driving direction. In contrast, the Transport System Bogl (TSB) arranges the levitation system in a homopolar configuration, maintaining a constant magnetic field over the entire length of the vehicle. This configuration reduces drag from the levitation system considerably and enables higher speeds, making it the preferred choice for a hyperloop system. In the long term, increasing the air gap of the EMS would reduce the accuracy requirements for the track and simplify the mechanical suspension in the pod. One potential solution is the use of superconducting coils in combination with conventional copper coils, as researched in a test stand by [PERSON] [17]. Additionally, the question of lateral suspension arises. Alongside similar considerations between EDS and EMS, there is the option to combine the EMS geometrically with a U-shaped counter plate in the track to achieve a passive guidance effect. However, due to the high speeds and resulting vibrations, this is not seen as sensible, and a separate active guidance system is therefore preferred. Navigating dense urban environments and compact stations necessitates hyperloop pods that can handle tight curves, limited not by acceleration but by geometry -- a common challenge for track-bound vehicles. Conventional trains use separate bogies with rotational freedom (Figure 4A) to navigate curves, but the hyperloop requires a \"snake\" system; a multi-bogie chain allowing for distribution of forces along the pod's length. A vertical spring dampening system compensates for curved elevation changes, limited by the maximum displacement differential along the snake. For horizontal curves, two design approaches exist. The first is a Transrapid-style layout, where each bogie retainsits stiff rectangular shape, joined to the carriage to enable translation in the y-direction and rotation around the z-axis (Figure 4B). This allows the snake to bend around curves, with increasing distance between outer levitation modules and decreasing distance between inner modules. The alternative approach, as utilized by several low-speed maglev systems [13; 18; 19], maintains a constant x-distance between individual modules on each side, particularly relevant for the motor concept described in Section 4.4. Here, each bogie can shift into a parallelogram shape to conform to the track (Figure 4C). This geometric transformation, however, increases the guidance airgap, which must be considered in the design.