Windshield wipers

Windscreen wipers are safety-critical wear parts within the wiper system of trucks, buses and vans. A wiper blade must remove water, road salt, insect residue and road film evenly from the windscreen without streaking, skipping or causing distracting reflections. For MAN TGL, TGM, TGS, TGX and TG3, Mercedes Atego, Axor, Actros, Arocs, Sprinter and Vito, as well as Citaro, Tourismo, Lion’s City and Neoplan buses, a clear field of vision is essential due to the large windscreen surfaces and long daily operating hours. Windscreen wipers must always be identified using the vehicle chassis number. Visual comparison or selection based solely on the model name is never sufficient.

Windscreen wipers differ not only in length, but also in blade profile, attachment, curvature and pressure distribution. Depending on the vehicle version, conventional wiper blades with a metal frame, flat blades with an integrated spoiler or vehicle-specific wiper blades with a pre-fitted adapter are used. The wiper arm may be fitted with a hook, bayonet, side-lock or specific vehicle connection. An incorrect adapter type can cause play, come loose during operation or damage the wiper arm.

For wide and highly curved windscreens on coaches, city buses and modern truck cabs, blade curvature is particularly important. The wiper rubber must maintain sufficient and even contact pressure against the glass throughout the entire sweep. Blades that are too short leave an insufficient cleaning area; versions that are too long may strike each other, the A-pillar or the edge of the windscreen. Therefore, in addition to the chassis number, also check the position: the driver's side, passenger side and, where applicable, centre wiper regularly differ in length and connection.

The wiping lip profile generally consists of synthetic rubber or a rubber compound with a graphite coating. This coating reduces the coefficient of friction, limits juddering movements and reduces squeaking noises on a dry or lightly soiled windscreen. The supporting spine of the blade must be torsionally rigid enough to distribute the wiper pressure, while remaining flexible at low temperatures. On vehicles frequently operated in road salt, dirty water or intense sunlight, rubber deteriorates more quickly due to UV radiation, ozone and chemical contamination.

Streaks in the field of vision often indicate a torn, hardened or contaminated wiping lip. Skipping can result from a contaminated windscreen surface, incorrect blade curvature, insufficient spring tension in the wiper arm or a twisted arm position. When the wiper chatters with every sweep, the mechanic should check whether the lip flips over correctly in both directions. An excessive arm angle in relation to the windscreen causes a scraping motion instead of a controlled wiping action.

Begin diagnosis by cleaning and degreasing the windscreen; silicone residues from cleaning agents or car wash products often create a misleading symptom that resembles worn windscreen wipers. Then inspect the rubber lip along its full length for cracks, fraying, flat wear edges and local deformation. Check the mounting adapter for play and measure the spring force of the wiper arm with a pull force gauge if the wiper only makes contact locally. Compare the measured contact pressure with the vehicle-specific workshop specification. Also inspect the windscreen for stone chips, scratches and baked-on dirt, as these can quickly damage the new wiping lip.

Replace windscreen wipers in case of visible lip damage, persistent streaking after cleaning, increased noise or insufficient wiping performance in rain. Preferably replace both front wiper blades at the same time, so that the wiping pattern and degree of wear remain consistent. Lift the arms carefully, protect the windscreen against the spring-loaded arm snapping back and ensure that the new blades audibly lock into the correct adapter. Then test all wiper speeds, intermittent operation and the park position. Also check the windscreen washers: an incorrectly aimed spray pattern causes dry wiping zones and accelerated wear of the wiper rubber.

A correctly selected set of windscreen wipers reduces downtime caused by poor visibility and prevents unnecessary stress on wiper arms and wiper systems. Braem can assist with fast parts identification based on the chassis number for a technically suitable replacement.