GB/T 12540-2009 in English

《GB/T 12540-2009汽车最小转弯直径、最小转弯通道圆直径和外摆值测量方法》由TC114（全国汽车标准化技术委员会）归口，TC114SC19（全国汽车标准化技术委员会整车分会）执行，主管部门为工业和信息化部。
本标准规定了汽车最小转弯直径、最小转弯通道圆直径和外摆值的测量方法。
本标准适用于汽车及汽车列车。

1 Scope

This standard specifies the measuring method of minimum turning circle diameter, minimum turning clearance circle diameter and out value for automobile.
This standard is applicable to the automobile and the truck combination.

2 Terms and Definitions

The following terms and definitions are applicable to this standard.
2.1 Turning circle diameters d1
The diameter of trajectory circle, with the center (for a double-tire, it's the center of the double-tire) of each wheel's tire surface (inside and outside) on flat ground where the handwheel goes to the limit position (see Figure 1).
2.2 Minimum turning circle diameter d
Where the handwheel goes to the limit position, the center of the outside vehicle guide wheel tire surface go round on the flat ground, and the bigger diameter of the trajectory circle is the minimum turning circle diameter.
2.3 Turning clearance circle
Where the vehicle is turning a corner, the following two circles are the vehicle turning clearance circles (see Figure 2).
a) The projection of all the parts of the vehicle(except the rearview mirror, lower vision mirror and antenna, the same below ) on the flat ground is located in the minimum encircle inside the circles - encircle of the turning clearance circle (diameter D1) .
b) The projection of all the parts of the vehicle on the flat ground is located in the max inner circle outside the circles - inner circle of the turning clearance circle (diameter D2).
2.4 Turning clearance circle width b
The turning clearance circle width B is one half of the difference between excircle of the turning clearance circle (diameter D 1) and inner circle of the turning clearance circle ( diameter D2), namely B = ( D 1 - D 2)/2.
2.5 Minimum turning clearance circle
The minimum turning clearance circle is the turning clearance circle where the handwheel goes to the limit position.
2.6 Maximum turning clearance circle width
The maximum turning clearance circle width is the turning passage width where the handwheel go to the limit position.
2.7 Out value T
Where automobile or truck combination is parked in straight line traveling state on the flat ground, draw a projection line paralleling with the vertical center line of the vehicle on the ground along the outermost lateral point of the vehicle; then they start and transfer from straight line traveling to circle traveling on the 25m diameter of the turning clearance circle excircle(except the rearview mirror ,lower vision mirror and antenna ,count from the outermost lateral part without taking into account the projecting part of the operation - functional isolated plant until the tail enter into this circle entirely ;in this process, the projection of any outer lateral part of the vehicle form a group of outer pendulum trajectory, and the distance between these group trajectory and the projection line of the outermost lateral part of the vehicle on the ground where the vehicle are at a standstill is the out value test (see Figure 3) .

1 Scope
2 Terms and Definitions
3 Test Conditions
4 Testing Methods
5 Results and Testing Records