Windscreen Wiper - Geometry

Geometry

Most wipers are of the pivot (or radial) type: they are attached to a single arm, which in turn is attached to the motor. These are commonly found on many cars, trucks, trains, boats, airplanes, etc.

Another type of wiper design is pantograph-based (see Fig. 6, below), which are used on many commercial vehicles, especially buses with large windscreens. Pantograph wipers feature two arms for each blade, with the blade assembly itself supported on a horizontal bar connecting the two arms. One of the arms is attached to the motor, while the other is on an idle pivot. The pantograph mechanism, while being more complex, allows the blade to cover more of the windscreen on each wipe. However, it also usually requires the wiper to be "parked" in the middle of the windscreen, where it may partially obstruct the driver's view when not in use. Some larger cars in the late '70s and early '80s, especially LH driver American cars, had a pantograph wiper on the driver's side, with a conventional pivot on the passenger side.

Mercedes-Benz pioneered a system called the Monoblade, based on cantilevers (see Fig. 5, below), in which a single arm extends outward to reach the top corners of the windscreen, and pulls in at the ends and middle of the stroke, sweeping out a somewhat 'M'-shaped path. This way, a single blade is able to cover more of the windscreen, and displace the residual streaks away from the center of the windscreen.

Asymmetric wiper arrangements are usually configured to clear more windscreen area on the driver's side, and so are mostly mirrored for left and right-hand-drive vehicles. One exception is found on Renault Clios, where the wipers always sweep towards the left. On right-hand-drive models, a linkage allows the right-hand wiper to move outwards towards the corner of the windscreen and clear more area.

• Fig. 1: most common geometry, found on vast majority of vehicles, mainly LHD car

• Fig. 2: Mercedes-Benz W114, W168, W169; VW Sharan, Mitsubishi Delica, Honda Civic, Oldsmobile Cutlass Supreme (Fifth Generation), some minivans, some school buses, Peugeot 307, Ford Focus (third generation), Peugeot 308, Citroën C4, Citroën Xsara Picasso, Mitsubishi Grandis, Opel Zafira

• Fig. 3: SEAT Altea, SEAT León Mk2, SEAT Toledo Mk3

• Fig. 4: VAZ-1111 Oka, Fiat Panda Mk1/SEAT Marbella, Fiat Uno (1983–1995), Citroën AX, Citroën BX, Citroën ZX, SEAT Ibiza Mk1

• Fig. 5: Subaru XT, Mercedes-Benz W124, W201, W202, W210

• Fig. 6: Buses, some school buses, Mercedes-Benz O305

• Fig. 7: MAN, Toyota FJ Cruiser, Jaguar E-type, MGB, MG Midget, Austin Healey Sprite (a 1968 US-only ruling required a certain percentage of the windscreen to be wiped).

• Fig. 8: obsolete, found on some older firetrucks

• Fig. 9: U.S. military wheeled vehicles, jeepneys, some school buses

• Fig. 10: Like Fig. 1 but mirrored, Mercedes-Benz W140, mainly RHD car