Method and apparatus for detecting a restricted or bypassed transmission oil filter

摘要

A method and apparatus for detecting a restricted or bypassed transmission oil filter by providing pressure transducers on both sides of the oil filter whereby the pressure differential will indicate the extent of filter restriction. A first alarm is activated at a first pressure differential to indicate a restricted filter and the need for filter replacement. A second, higher level, alarm is activated to indicate the filter is bypassed and the engine is reduced in speed to allow the pressure and the pressure differential to drop to the point that the filter is no longer bypassed. This enables the vehicle to be operated with limited capabilities to allow the vehicle to be driven to the shop for filter replacement. If the lowered engine speed is insufficient to reduce the pressure differential to stop the bypass, then the engine speed is further reduced to a low idle and the transmission shifted to neutral. The filter must be replaced before the vehicle is can be operated again to prevent damage to the hydrostatic unit in the transmission.