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This study deals with the design of variable displacement oil pumps, with particular focus on wear of the inner components. A multibody model has been developed in order to achieve detailed knowledge on the dynamic loads which the main components are subjected to and to carry out a comparative analysis between different pump designs. A qualitative correlation, between the resulting wear following endurance tests and simulation results, has also been found. Design guidelines leading up to a good pump reliability have been obtained as a result of this activity.

The paper analyses an undesired dynamic behaviour which occurs at the front suspension of a tilting motorcycle having two front wheels and a rear one. In particular, experimental data obtained on a first prototype of the vehicle have shown that the amplitude of the hop oscillation of the two front wheels becomes very high when the velocity of the three wheeler is about 85 km/h. In order to analyze the oscillations and to understand how to reduce them, a linear model of the front axle has been developed to estimate the eigenvectors and eigenvalues of the front suspension. Afterwards, two different ways to reduce the undesired oscillation are presented and evaluated. The obtained results show that, by the use of properly designed mass dampers, it is possible to greatly reduce the vibrations without affecting the handling behaviour of the vehicle. Finally, a multibody model allowed to analyze the effects of different sources of nonlinearities such as those due to the tire contact forces.

In this work a lumped-parameter model, able to simulate the dynamic behavior of different types of valve train systems, was developed. Among the various aspects, the rocker arm flexibility, the valve lash, the possibility that the mechanical elements lose contact with each other and the possible impact of the valve in its seat were taken into account. The model includes two different descriptions of the valve spring, which can be schematized either by an ideal elastic reaction or by a multi-mass scheme, including the possibility of contact among adjacent masses.

In this work the modal analysis of a three-wheeled tilting motorcycle is presented. This new kind of vehicle has two front wheels and a single rear wheel, but is driven like a common motorcycle. In order to study the stability of the system in straight running, two models have been developed: a simplified motorcycle model, with locked suspensions and rigid and thin tires and a more accurate model having 14 degrees of freedom, in which the stiffness and damping of suspensions and the radial stiffness of tires have been taken into account. In both models the frame has been considered as rigid and the driver was assumed to be fixed to the frame. A linear model with transient behaviour has been employed for describing the tire behaviour. A reference model of a two wheeler with similar inertial properties has been also developed for comparison.

This paper deals with the analysis of the handling behaviour of a novel three-wheeled motorcycle. This vehicle has two front steering wheels and a single rear wheel and can be driven much like a common two wheeler. In order to analyse the handling behaviour of such vehicle and to compare it to an ordinary two wheeler, an experimental campaign was conducted with the vehicle endowed with several transducers. Experimental tests included some classical handling manoeuvres. Concurrently, a simulation model was developed using a multi-body code. A simple logic was employed to drive the model; it consists in a roll follower and a longitudinal velocity follower. The main dynamic parameters obtained from simulations, such as the steering angle and steering torque are compared to the experimental data and discussed. The effect of the driving style on the manoeuvre is also analysed with reference to steering pad manoeuvres.

In the present paper a theoretical model for the analysis of compound crank axle is presented. It is based on the set of equilibrium, constitutive and congruence equations of the axle; to this aim, the cross-member is described by its stiffness matrix, the longitudinal arms are assumed as rigid and the bearing which connects the axle to the body as ideal. For this configuration, a closed form solution for the elastokinematic analysis is obtained in the small displacements field, for the pure roll condition. This can be summarized by the knowledge of the position, in a 3D space, of the instantaneous axis of rotation of each wheel; it is shown how the instantaneous axis of rotation is determined by both the axle geometry and the stiffness properties of the cross member. An iterative procedure has been also developed for the large displacement analysis. Results, in terms of camber and toe angle alteration, are discussed in comparison with those obtained by finite element analyses.