26 Dutch trams to be upgraded with Atlas Copco oil-free compressors

BRU’s original SIG railcars featured compact compressed-air systems, but they were oil-lubricated and non-cooled piston compressors with separate service-intensive desiccant dryers. When BRU requested proposals to overhaul these compressed air systems, Atlas Copco suggested the replacement of each old unit with a 100 percent oil-free unit with minimal noise and vibration levels, forced cooling and a fully integrated air treatment system.

The new system is fully compatible to the vehicle structure. The new compressor is designed as an integrated solution. The vehicle interface (mounting points) can be used without any modifications. The new compressor is adapted by an auxiliary frame. This allows a quick and easy installation on the vehicle.

The SFR 5 compressor: a completely customized solution

Atlas Copco’s Railway Competence Center presented a completely customized compressed air solution with fully integrated maintenance-free membrane dryers and proven railway core components. The basic air supply unit is a 100 percent oil-free 5.5 kW SFR 5 scroll. The SFR 5 features a minimum of moving parts, a shaft-driven cooling fan, corrosion-resistant stainless steel and aluminum, and a sturdy construction to withstand external vibrations, shock loads and projectiles. The air treatment is carried out by a fully integrated water separator, fine pre-filter and a maintenance-free membrane dryer that supplies clean, dry, oil-free compressed air with a quality class of at least 2.2.0 according to ISO 8573-1.

The new SFR 5 units take up less space and weigh far less than the previous units. The oil-free compressor operates between 8.5 bar cut-in and 10 bar cut-off pressure supplies the compressed air into a 150 l railway-approved aluminum air tank, which is installed under the tram floor next to the compressor.

The compressor performs in ambient temperatures from -25° C to +50° C, and is designed to withstand the most extreme weather conditions. The compressed air is cooled down to a maximum of 15°C above ambient temperature. The rated FAD air flow is 400 l/min at 10 bar end pressure at outlet after the dryer.

Maintenance is simplified and cost effective, with easy access to the unit’s two air filters, hour counter and electric connectors. The membrane dryer is placed in a horizontal position along the inside of the unit since no further access space is required to maintain it. The SFR 5 features long service intervals, which further reduce its overall lifecycle costs.

Written by Michael Gaar