Vandresen, M., Lencina, D., Fernandes, C., Silva, L. et al., "Valve Spring Compression Testing System," SAE Technical Paper 2014-36-0230, 2014, doi:10.4271/2014-36-0230.
The compression springs of the valves of automotive engines are key elements in the dynamic behavior of the engine. Its wear is slow, gradual and progressive; so the driver of the vehicle eventually get used to the decrease in the engine performance. The compressive force losses cause the valves to close slower than expected and, consequently, the engines lose their efficiency. Professionals in the area of automotive maintenance apply empirical tests with varying criteria to evaluate and to determine the life cycle end at which the springs must be replaced.This article describes the development of a workbench for compression springs based on existing models on the market and the main premise is the low cost. Correspondent loads involved were determined and the components were modeled in CAD, allowing to develop a robust device able to handle the loads generated by the compression spring. The load is applied by means of a lever and the spring deflection is measured by a digital caliper and the load by a load cell. This information is sent to an embedded system that instantly shows the information on a display. The spring load is evaluated on its mounting position (compression height) and also at the point of maximum lift of the camshaft.