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Chassis
Published in Tom Denton, Automotive Technician Training, 2015
Use an open-end wrench, or Allen key, to prevent the upper end from turning. Then remove the upper retaining nut. On some vehicles, it may be necessary to remove a wheel panel for better access. Remove the bolts retaining the lower shock absorber pivot to the control arm. Prior to installation, place the grommet and washer in position on the upper stem. Insert the stem through the upper mount, push the grommet and washer into place and install the retaining nut. Tighten the nut to the specified torque.Place the lower end of the shock absorber in position and install the bolts. Tighten the bolts to the specified torque.
Suspension System
Published in Georg Rill, Abel Arrieta Castro, Road Vehicle Dynamics, 2020
Georg Rill, Abel Arrieta Castro
The kinematics of a wheel/axle suspension can be described by two generalized coordinates. In a more general approach the position of the wheel center W and the orientation of the knuckle with respect to the vehicle fixed reference frame V are then defined by rVW,V=rVW,VD+[x(u,h)y(u,h)z(u,h)]andAVW=Aγ(u,h)Aα(u,h)Aβ(u,h) where rVW,VD defines the design position of the wheel center. The displacements x, y, z as well as the angles α, β, γ, which describe elementary rotations about the x-, y-, and z-axis, depend on the generalized coordinates u and h. In the case of the double wishbone suspension, u represents the rack displacement and h is substituted by the rotation angle φ of the lower control arm. The rotation sequence γ, α, β corresponds with the steer, the camber, and the pitch motion of the knuckle.
Numerical stability of co-simulation approaches to evaluate wheel profile evolution due to wear
Published in International Journal of Rail Transportation, 2020
The wheel-rail contact forces are evaluated by specific contact modules, called ‘wheel-rail pair’ in Simpack, using the FASTSIM contact algorithm. The S1002 profile is used for the wheelsets, while the UIC60 profile, canted 1:20, is adopted for the rails. The wheel-rail friction coefficient assumed for the numerical model is equal to 0.4. Each axle-box is constrained to the respective wheelset by a revolute joint, which allows only the relative rotation between the two bodies. The axle-box is connected to the bogie frame by means of two force elements: a first force element, modelled as an elastic flexicoil element, simulates the vertical and transverse stiffness of the helical spring of the primary suspension, while a second elastic element (bushing) reproduces the rubber joint connecting the axle-box control arm and bogie frame. The function of this element is to allow a yaw angle between a wheelset and a bogie frame during curve negotiation. The elastic characteristic of this element has an important influence on the wheel profile wear. The secondary suspension is simulated with flexicoil elements that simulate the vertical and transverse stiffness of the helical springs. These force elements are defined between the bolster and bogie frame. Both bolster and bogie frame are constrained with respect to the global reference system through ‘general rail-track joints’, which allow 6 degrees of freedom for each body. The coach, jointed to the main reference system with the same type of constraint, is connected to two bogie bolsters by means of two bushing elements with no rotational stiffness around the vertical z axis. The two bushings simulate the centre pivots that allow the bogie rotation with respect to the coach. The secondary suspension is completed by two lateral bumpstops that act between the bolster and the bogie frame when the lateral displacement of the bogie exceeds a certain value. The function of these elements is to limit the coach roll angle during cornering. The vehicle trailing system is simulated, on each bogie, by means of two elastic force elements acting in the longitudinal direction between the bolster and the bogie frame. The numerical model includes on each bogie two vertical dampers and two lateral dampers on the secondary suspension level. Table 2 shows the stiffness of the force elements used to build the model.