The G-Lader is a scroll-type supercharger used in various Volkswagen Passenger Cars models. Its purpose is to increase the motive power output from the internal combustion engine attainable with a given engine displacement. Since it is not enough to simply inject more fuel, as this produces too rich an air-fuel mixture, more intake air has to be added at the same time. This can be achieved with an
exhaust-driven turbocharger, or a crankshaft-driven positive displacement compressor. The G-Lader is in the compressor category, since it is crankshaft-driven and does not have the "lag" usually associated with turbocharged engines. This type of air pump, notable for low noise and high efficiency, was patented on 3 October 1905 by Léon Creux of France (US Patent 801,182).[1] Due to the very imprecise production methods of the period, however, it was not manufacturable for a long time, since the displacer (described below) inside the compressor comes within tenths of a millimetre of the housing wall without making contact. Only with the more advanced engineering methods of the 1980s, did it become possible to produce the G-Lader. Contrary to expectations, Volkswagen's designs turned out to need relatively frequent repair in normal operation, which was one of the reasons why that manufacturer eventually abandoned this technology at the time. The main cause of its relatively high failure rate was that Volkswagen misrepresented the G-Lader as maintenance-free. Depending on RPMs, load, and design details, various parts wear out, with results ranging from impaired performance, to destruction of the G-Lader. Yet it is frequently possible to extend the life of the G-Lader, sometimes to several hundred thousand kilometres, by periodically overhauling it with suitable replacement parts. The supercharger housing holds what is called the displacer plate (or just displacer), on both sides of which are spirals, with seals between the latter and the housing. The housing itself also has spirals on both sides that mesh with those on the displacer. Driven by the crankshaft, which is connected to the displacer shaft by a small belt, the displacer moves eccentrically with respect to the supercharger housing (like the rotor in a Wankel engine) and, through this motion, forces the intake air into a smaller and smaller space, ultimately producing a maximum gauge pressure of 0.8 bars (11.6 psi) with standard delivered pulleys
