Coiled spring pins solve oil pump quandary

The sole purpose of the dowels is to provide finished assembly alignment to the engine block. In an effort to reduce cost, total assembly weight and installation forces, a manufacturer approached Spirol Industries' Applications Engineering Department to determine the best alignment pin for a new design of engine oil pump. Following a comprehensive design review, Spirol recommended the use of a standard duty coiled spring pin as the alignment pin in the new oil pump application. Coiled pins are designed such that their pre-installed diameter is larger than the recommended hole. The diameter of the coiled pin is compressed during insertion which prevents deformation of the hole in the pump resulting in a good "press fit" between the pin and the hole. Once installed, the coiled pin retains itself by exerting constant radial force against the hole wall as it attempts to recover back to its pre-installed diameter. By replacing the rigid solid dowel with a coiled spring pin, the customer was able to achieve the primary goal of reducing cost - the customer has realised an annual component cost savings of £25,000. Savings were also achieved through the reduction in hole preparation time, reduction in weight of the final assembly, lowering of installation forces and the decrease in total assembly time.