Balancing spring (chassis)

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The compensating spring is a spring element in the chassis of an automobile which is only effective when the vehicle body is compressed and rebounded on the same side and which does not hinder its rolling movement . So that the spring rate remains unchanged when the compression and rebound are equal, the main springs are made softer.

In vehicles with a rear swing axle and rear-wheel drive , a compensating spring reduces the tendency to oversteer in the limit range by increasingly supporting the suspension torque on the front axle and reducing the excessive wheel load difference on the rear axle. The latter is a consequence of the high roll center of the pendulum axis, in which that part of the moment from centrifugal force and height of the center of gravity that is not supported by the springs is already too large. The compensating spring also reduces the “ support effect”, which is also a consequence of the high roll center and its dependence on the spring deflection.

The function of the balancing spring is the opposite of that of a stabilizer .

A compensating spring had u. a. the following models:

  • as torsion bar spring (Z-shaped angled: Z-bar ) in the VW Beetle from August 1966: two-joint swing axle,
  • as a transverse leaf spring (working like a balance beam) in the Porsche 356 from 1959, two-joint pendulum axle,
  • as a coil spring on the central rear axle joint in the Mercedes-Benz W110 : single- joint swing axle,
  • as a gas-hydraulic unit in the Mercedes-Benz W108 with level compensation: single-joint swing axle,
  • in the Chevrolet Corvair : two-joint swing axle.

Example: Pendulum axle with leaf compensating spring

The leaf spring is installed parallel to the pendulum axis and rotatable about a vehicle longitudinal axis. The pivot point is in the middle and in the middle of the vehicle width. There it is supported on the vehicle body , e.g. B. from below on the housing of the differential gear . Their ends are linked to the pendulum half-axles above. When the semi-axles deflect, the compensating spring is elastically deformed upwards. It reduces the deflection of the two semi-axes to the same extent. When the vehicle body sways, nothing changes because the leaf spring rotates in its support bearing and follows the rotations of the semi-axes. These rotations are the same on both sides, so that the deformation state of the compensating spring does not change.

Individual evidence

  1. ↑ Wolfgang Matschinsky: Determination of mechanical parameters of wheel suspensions . Dissertation approved by the Faculty of Mechanical Engineering at the Technical University of Hanover to obtain the academic degree of Doctoral Engineer, 1992, p. 68.
  2. ↑ Wolfgang Matschinsky: Wheel guides of road vehicles: statics, kinematics, elasto-kinematics and construction . 3. Edition. Springer, 2007, ISBN 978-3-540-71196-4 , pp. 174 .
  3. ↑ Manfred Mitschke, Henning Wallentowitz: Dynamics of motor vehicles . 4th edition. Springer, 2004, ISBN 978-3-662-06803-8 , pp. 724-726 . ( limited preview in Google Book search)
  4. ↑ Michael Trzesniowski: Racing car technology: basics, construction, components, systems . 4th edition. Springer Vieweg, 2014, ISBN 978-3-658-04918-8 , pp. 267–270 fig. H. 13 . ( limited preview in Google Book search)
  5. ↑ Wolfgang Matschinsky: Wheel guides of road vehicles: statics, kinematics, elasto-kinematics and construction . 2nd Edition. Springer, 1998, ISBN 978-3-662-09653-6 , pp. 188–191 ( limited preview in Google Book Search).