Established in 1895 and based in Hungary, in the heart of Europe, legendary bus manufacturer Ikarus was a key player in the global bus market between 1950 and 1989.
The company’s predecessor, the Uhri Imre Blacksmith Workshop and Coach Factory, was established in Budapest in 1895. The factory received its first major order in 1924, when the Hungarian state railway MÁV commissioned a consignment of truck trailers. First developed in the 1950s, Ikarus buses can still be found in service all over the world.

Ikarus 280: world’s most-produced bus

The Ikarus 280 is the world’s most-produced articulated bus, a total of 60,993 vehicles having left the assembly line. The ongoing economic crisis has, of course, an adverse impact on the Hungarian economy as well. A number of investments failed to materialize, including new buses for the Budapest Transport Company (BKV).

It was raining into the buses

Pictures posted on various social media sites showing people sitting on a bus holding up umbrellas highlighted the fact that several of the older vehicles had already started to let in rain water. Although the old Ikarus buses with their metal roofs are extremely durable, when they have been in operation for 20 to 25 years, the company has to decide whether to replace them or to repair them and extend their service life. The pictures of clients in Social Media had such a negative impact that the company gave urgent priority to repairing the old vehicles.

What is the solution for bus repair about?

Gábor Farkas, Director of Target Market Industry at Sika Hungary comments on the job specification to repair the busses: “The remit was to do a complete renovation of the vehicle roof subject to the following conditions: The vehicle may not leak. A solution to the leaking roof problem has to be found that will hold until the vehicle is taken out of service (another 3-5 years), The solution has to be relatively easy and quick to implement as well as cold applicable.

MTC technology: no need to paint the roof

The BKV provided a number of companies with a sample vehicle to work on, including Sika Hungary. The usual seam sealing was not feasible because large parts of the roof were in a very bad condition. We considered applying a weather-resistant coating with good adhesion on painted surfaces. After consulting with the Key Account Manager Roofing, we decided to use SikaRoof® MTC (moisture-triggered chemistry) technology.

An added advantage of MTC technology is UV resistance, avoiding the need to paint the roof. It proved to be a more economical solution than those proposed by our competitors, all requiring that the roof be subsequently painted. A further condition of winning the contract was for the sample vehicle to be ready.”

The real challenge was to waterproof the steel roof

Roofing of the sample vehicle was carried out by roofing technician Zoltán Dávid, who explains the technical aspects of this work: “SikaRoof® MTC 8 system was applied to the undamaged parts of the bus roof, while damaged and corroded parts were treated with the SikaRoof® MTC 15 system complete with reinforcing. To prime the MTC 8 system, we used Sika® Zinc Phosphate Primer on metal surfaces, and Sika® Bonding Primer on painted surfaces.

Sikalastic®-621 TC topcoat was used for waterproofing. When working with the MTC 15 system, we applied Sikalastic®-621 TC in two stages, embedding Sika® Reemat Premium in the first coat, and then re-applying a second top coat. The real challenge was to securely waterproof the steel roof, which revealed different degrees of corrosion. It was important to combine the two systems. Sika® Reemat Premium was used on all bodywork parts that were more exposed to water damage, such as the bends and the drainage groove on either side of the bus.

1000 vehicles waiting to be repaired

Gábor Farkas adds: “The complete roof repair took 12 to 14 hours, but this time can be reduced as the work becomes routine. The vehicle was back in service immediately after repair at the end of March. The BKV valuation of the sample buses was scheduled for the end of June. The Sika solution has in the meantime successfully weathered numerous storms. Although the valuation has not yet been carried out, the BKV has already ordered material for further bus roof renovations, because they like this solution. There are 1000 vehicles waiting to be repaired.

References in automotive industries and railways

Sika can draw on experience in bus roof refurbishment as a reference for other automotive industries or, for example, railway rolling stock roof repairs. The cold-applied technology used is an advantage since it eliminates the need to take down the internal covering of the vehicle and also cuts down working time by 2 to 3 days.

So customers will be able to continue sitting in the retro bus remembering good old times. And those from the next generations, who were born after the Ikarus boom, can have an idea of what it was like. Sitting in the world`s most produced bus, over the last decades – and the best of all: it is still running.

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