Products and solutions, 2005-04-26, 02:57 PM
The ThyssenKrupp Presta assembled truck camshaft
Modern truck engines are making continuously increasing demands on the valve train. Above all, engine developers are demanding high power, low friction losses, high component stiffness and low moving masses. ThyssenKrupp Presta`s assembled camshaft, where shaft and cam are produced separately and then assembled, offer a range of key advantages over conventional camshafts made from one material.
ThyssenKrupp Presta AG has been producing assembled camshafts on a large scale since 1993. The company, headquartered in Liechtenstein, has established itself as the world market leader with over twelve million camshafts per year. One of the reasons for this success lies in the cost reductions and weight savings when compared to conventional camshafts. Optimum designs allow weight savings of up to 40 percent. The reduction in moving masses leads to improved vibration performance and lower fuel consumption while increasing the payload. The materials for the individual functional elements of the camshaft can be freely selected to a great extent. An optimum combination of cam/tappet materials for the specific load application improves tribological aspects and extends the service life of the camshaft. Modern roller tip rocker arms in particular place high demands on strength which can only be met by selecting suitable materials.
In the Presta process, the tube is widened by roller knurling at the axial position where a cam or other press-on part is to be mounted. The part is then pressed onto the knurled area at the required angle.
The surface of the bore in the pressed-on part can be profiled in axial direction to provide a frictional and positive bond with the tube. Assembly is carried out on computerized lines which offer high flexibility for changing the angle and axial position of the cams.
A key advantage of the ThyssenKrupp Presta production process is the great variety of materials and tube wall thicknesses that can be used. The camshafts used in trucks need thick tube walls as they are highly stressed by e.g. pump drives. The majority of joining concepts for assembled camshafts come up against their limits here or prove to be impracticable. By contrast, even bar stock is no problem with the Presta process.
The use of assembled camshafts in trucks will increase in the next few years with the introduction of new innovative engines. Additional weight and cost reductions will be at the forefront of further developments.