Turning radius
The turning circle is the smallest circle (based on the most prominent parts in the curve outside of the vehicle), in which a vehicle can perform a circular drive with full steering lock. The indicator for vehicles of turning circle denotes ( abbreviated also called Tropic ) the diameter of this smallest turning circle. The turning radius is the radius of this circle, that is half as large as the diameter.
A related term is the track circuit. This describes the circular path (track) during the circular movement of the outermost running wheel. Analogous to the turning circle of the term turning circle is also used as a characteristic of vehicles and then refers to the diameter of this circle. This is measured from the tire center.
Clearly is the turning circle to the diameter of a cylindrical wall, enclosing a vehicle at full lock just can go in a circle. The turning circle on the other hand indicates the diameter of the smallest circular disk on which a vehicle can just go round in circles. In this case, parts of the vehicle, then protrude through the circular disk also.
The turning circle diameter is always smaller than the turning circle, because the tire is not the most projecting part of the vehicle when cornering.
Depending on the vehicle type, the turning circle diameter vary greatly. A tight turning circle means better handling, for example, in the urban area. The typical turning circle of cars is about 10 m to 12 m ( body turning circle ). Buses - depending on the type and length between 18 m (for example Citaro K or Lion's City M) and about 25 m (15 -meter buses, articulated buses with 18.75 m or more in length) - and trucks on the other hand need a multiple of this value.
The calculation of the turning circle of a single moving vehicle using front axle can be simplified by D = 2 * express L / sin α (D: track circle diameter, L: Wheelbase; α: turning angle of the wheels). The influence of the steering rolling radius is neglected, the influence of the body overhang can be derived through the trigonometric functions. For the indication of α, the influence of steering trapezoid should (see steering trapezium ) are observed, the wheels of one axle does not usually hit ( at Einzelradlenkung ) equidistant one.
Situation in Germany
In Germany § 32d traffic regulations prescribes " cornering characteristics " for cars and carriages. These include an implicit restriction of the Tropic. Thus, rolling stock must be a circle with radius 12.5 m, based on the front ( rear with rear wheel steering) outermost point of the vehicle drive. To meet this requirement the radius, a vehicle must obviously a (minimal) turning circle exhibit, which has more than twice, ie 25 m in diameter.
However, this does not ensure that all vehicles can use all the curves and roundabouts, this geometry of the drag curve is crucial. Road Trains and Euro Combis (so-called " GigaLiner " ) may possibly then fulfill the conditions of BOKraft circle, provided that in addition to the usual steering axis other axes are forced steering.
Comments
From the intuitive interpretation of the Tropic using an imaginary cylindrical wall is clear that the turning circle diameter of rigid vehicles without joint even with four-wheel steering and a maximum steering angle of 90 ° is always at least as large as the length of the vehicle diagonal. In particular, a turning circle of 0 m there can not be so.