Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering Transport Technology
T.J. Boeschoten Asophangingen voor mobiele havenkranen.
Masters thesis, Report 95.3.TT.4508, Transport Engineering and Logistics.
The hydraulic suspension that Nelcon applied until now for the six-axled mobile harbour crane suffered from oil-leakage. A better suspension has to be developed for the cranes to be built in the future, especially for the six-axled M1600. The new suspension has to be an improved hydraulic or a mechanical suspension.
Important requirements are a good support for each corner of the undercarriage, while the total strain for each corner has to be distributed over the three wheels. Moving over an uneven terrain must be possible. Implicit in these requirements is appropriate mobility. Too much mobility causes instability while too little makes it impossible to drive over an uneven terrain.
By considering the suspension as a mechanism of elements which are not rigid, degrees of freedom and possibilities of movement can be determined. The consequences of which must be correctly determined.
For reasons of complexity of the design the concept suspension was not directly developed from the requirements and limiting conditions. Using a design-methodology, first the function of the suspension, 'to support the crane', was divided into components. For each component a separate construction was developed. These are constructions made of rods to 'resist horizontal axle-forces' and constructions made of beams or hydraulic cylinders to 'distribute the load over the three axles'. The constructions are evaluated on mobility and strain resistance.
Two of the most convenient separate constructions were' combined and developed to form a mechanical suspension. An important feature of this suspension is that its mobility does not cause stresses in the construction. This simplifies the further design of the suspension.
Based on the developed 3+3-axle-suspension it is relatively easy to develop other concepts, also hydraulic ones. A choice can then be made. Doing so, a mechanical suspension was also developed for the eight-axled M2000. A change, consisting of a bended balance was carried out on the Nelcon-designed suspension of the M700-crane. The change consists of a bended beam/balance. This is also a feature of the developed suspensions for the M1600 and M2000.
One conclusion is that the developed mechanical suspension is an alternative for the current A hydraulic suspension. Further, that using a
design-methodology is helpful in designing. Finally, that a theoretical -kinematic- analysis of degrees of freedom is insufficient to evaluate mobility of a suspension. The consequences of degrees of freedom on the actual movement has to be investigated well.
Reports on Transport Engineering and Logistics (in Dutch)
