Eco-retrofits: the future of tamping

Electrically powered tamping units increase cost-efficiency and benefit the environment significantly. When used on European construction sites for the first time, their advantages were shown to be particularly promising. Recent measurements on two machines that were retrofitted with electric tamping units strongly confirm this.

Rising fuel prices, stricter environmental protection requirements, tenders which favour green working methods: railway construction needs solutions that offer both economic and environmental added value. By developing electrically powered tamping units, Plasser & Theurer succeeded in finding a ground-breaking solution to that end. We recently began offering the eco-retrofit upgrade service so that existing machines can also make use of the major advantages of the new technology. It is particularly interesting in cases in which entire machines are to be modernised or old tamping units are to be replaced with new ones.

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Advantages of the electrically powered tamping unit

  • Less fuel consumption thanks to reduced rotational speed of the drive engine during working mode and reduced power consumption while increasing total efficiency
  • Higher efficiency thanks to improved response time of the electric motors
  • Lower noise emissions thanks to lower idling speed
  • Reduced wear thanks to higher rotational speed during penetration
  • Heat development reduction of the entire system thanks to reduced hydraulics
  • New opportunity for powering other components electrically (e.g. AC unit, heating system, ventilation unit, and measuring systems such as the Levelling and Alignment Laser/Curve Alignment Laser)

Significantly lower fuel consumption and noise emissions

An eco-retrofit essentially means mounting a hydraulically operated generator which drives the vibration shaft of the tamping unit electrically. It is a single change; however, it creates a multitude of advantages. Thanks to the electric drive, the speed of the diesel engine can be reduced by approx. 500 rpm. In other words, the engine runs in the ideal speed range, there is maximum utilisation of torque, and diesel engine speed drops disappear completely during work.

All things considered, this results in fuel savings of up to 40%. Noise emissions decrease by an average of 7 dB, with peak values of 12 dB being measured. The efficiency of the entire system increases by an impressive 30%. A reduction in wear losses is also to be expected. In turn, this translates into a decrease in maintenance requirements.

Streamlined hydraulics and much potential for further electrification

A drastic reduction in hydraulics is typical of electrically powered tamping units. The directly mounted hydraulic motor for the electric generator enables shorter hydraulic paths, which decreases losses accordingly. Additional reductions in the hydraulics result from the change to the vibration shaft’s drive.

Safe tamping process

Upgrading to electric tamping only changes the vibration shaft’s drive type. Plasser & Theurer’s reliable asynchronous tamping principle at 35 Hz has been tried and tested thousands of times and remains unchanged.

An eco-retrofit for the Unimat 08-4x4/4S owned by Swietelsky

A typical application scenario for our eco-retrofits: The Unimat 08-4x4/4S, owned by Swietelsky and part of a contract with the English company Network Rail, should already be taken out of service. The machine, manufactured in 2004, could no longer meet the requirements. After Swietelsky was told about the option of an eco-retrofit and its advantages, the machine’s tamping unit was electrified in Maidenhead (UK). It was possible to execute the project within 13 weeks in the summer of 2022. This included commissioning and testing in Maidenhead. The Unimat was then transferred to the test track in Stoke-on-Trent for further testing and trial operations.

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Successfully in operation again as of 2023

After the 2022/23 winter break, Swietelsky began using the Unimat 08-4x4/4S again for work for Network Rail. After around 20 years of service and now featuring electric tamping units, the customer confirmed these improvements:

  1. On average, 30 l decrease in fuel consumption per hour (equals savings of approximately 40%)
  2. On average, 7 dB decrease in noise emissions (with peaks of 12 dB)
  3. No more diesel engine speed drops, the engine runs extremely quietly in the ideal speed range
  4. Fewer vibrations while tamping

An eco-retrofit for the Unimat 08-475/4S owned by Strukton

Strukton’s Unimat 08-475/4S was repaired by Plasser Robel Services at the Opladen maintenance workshop after an accident. It was an ideal opportunity to perform an eco-retrofit directly afterwards. When told about this option, Struktion quickly opted to take advantage of the benefits of electric tamping for its machine, which was also manufactured in 2004. The upgrade took place in Opladen from March to mid-May. The machine then went to iaf 2022 in Münster, where it was among the highlights on display outdoors. Finally, it went to Strukton’s test track in Zutphen (NL), where trial operations took place. This was immediately followed by its first regular use on-site.

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Also approved for international operations

While the Unimat 08-475/4S was being retrofitted, applications were made for operating approvals for Germany, Belgium, and Sweden. They were granted in September 2022. Thanks to the positive experiences with the eco-retrofit, this 20-year-old machine will undergo additional retrofits and upgrades in 2023.

Get your upgrade now

The first two retrofits clearly demonstrate the advantages of upgrading to electrically powered tamping units. Don’t hesitate to contact us: We are happy to inform you as to whether your machine is suited for an eco-retrofit.