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Small Engine Crank Shaft Cover

A manufacturer of small engines required a cost effective method to align a crankshaft cover to an aluminum engine block.



The manufacturer used a press-fit Ground Dowel to align the crankshaft cover to an aluminum engine block. The solution was required to hold the cover in position until permanent fasteners were installed in a subsequent operation.

Ground Dowels must be retained via a press-fit. This requires holes to be reamed, a costly process that is not efficient. Solid Dowels displace host material to achieve retention. Not only does this require high insertion force, it also introduces the potential for error in alignment to occur as the result of hole deformation. This also introduces high levels of internal stress within the hole.



SPIROL Engineering recommended a light duty Coiled Spring Pin for use in this application. This pin provided the flexibility required to install without galling or damaging the soft aluminum host material.

The customer’s total hole tolerance increased which reduced the difficulty and cost of hole preparation. The recommended product was from SPIROL’s standard offering thereby providing a low cost solution that could be provided quickly for evaluation and testing.

Coiled Spring Pins are superior to press-fit Solid Dowels in alignment applications not requiring the shear strength of a Solid Dowel. The Coiled Spring Pin allows significantly greater hole tolerance which decreases the cost of hole preparation. Unlike press-fit dowels which much displace host material to achieve retention, the Coiled Spring Pin is compressed within the hole. This protects hole integrity and maintains the desired degree of interference after repeated cycles of assembly and disassembly. The Coiled Spring Pins ability to conform to the hole in which it is installed ensures that alignment reflects hole quality and placement.

Complimentary Applications Engineering Support: SPIROL Engineers will review your application needs and work with your design team to recommend the best solution.