Safer braking

Trams have to brake and accel­erate at every stop on their journey. Braking in partic­ular is a problem in wet weather. This is why many trams are fitted with sand spreaders to aid braking when the rails them­selves do not provide suffi­cient fric­tion. The spreaders are controlled by the driver and blow fine sand directly in front of the wheels on the rails. This increases the fric­tion and helps the brakes grip securely to even wet or icy rails.

Compact and reli­able

The sand spreaders need to be as compact as possible.

Despite being impor­tant tools for trams in everyday use, the sand spreaders need to be as compact as possible to minimise the amount of space taken up in the passenger area. For this reason, French company E.M.S. Concept turned to ebm-papst and its ECI 63 motor for the compressor, which creates the compressed air used to blow the sand onto the rails. The motor’s compact dimen­sions mean that the entire sand spreader can fit under a single block of seats.

Aside from this, the ECI 63 can be easily controlled via a 0-10 V input and requires no external control. “For safety systems like the sand spreader, reli­a­bility is also an impor­tant factor”, said Sébastien Lutz, Project Manager at E.M.S. Concept. And his colleague Richard Ostertag adds: “The motor can with­stand even long periods of use. On top of this, we can signif­i­cantly lower main­te­nance costs using a brush­less motor.” Previ­ously, sand spreaders had large brush motors installed that had a limited service life and also required much greater main­te­nance.

E.M.S. Concept’s sand spreaders are used on various tram routes in China. To opti­mise the ECI 63 for use in rail vehi­cles, ebm-papst’s engi­neers adjusted the basic firmware to easily handle the voltage fluc­tu­a­tions of up to 30 percent that are common in rail trans­port. This keeps the sand spreader ready for action when­ever it gets a bit slip­pery on the rails.