10:31. Angles of installation of forward wheels
Angles of installation of wheels of the car
The angles of installation of forward wheels define geometry of situation of the last concerning a suspension bracket of the car and a paving. Violation of adjustment of this geometry leads to decrease in controllability of the car and increase in speed of wear of tires. Disorder, выбег (a corner of a longitudinal inclination of an axis of turn of a wheel), the corner of a cross inclination of an axis of turn of a wheel and convergence are among the angles of installation of forward wheels of the car which are subject to control (see an illustration the Angles of installation of wheels of the car). Only one of parameters — convergence is subject to adjustment. You designate parameters have to be checked on a regular basis for assessment of degree of wear of components of a suspension bracket and the steering drive.
Adjustment of angles of installation of wheels is among the procedures demanding the special accuracy of measurement which high-quality implementation requires existence of special, rather bulky and expensive equipment. Performance of this work will be most correct to be charged to professional mechanics of car service. Below, for the general understanding, definitions of each of the under control angles of installation of wheels of the car which knowledge will facilitate communication of the owner of the car with personnel of car service are given.
Corner of a longitudinal inclination of an axis of turn of a wheel (vybegy) is called the deviation corner from a vertical of an axis of turn of a wheel in the plane of the last. If the axis of turn is inclined back (the lower part of an axis is pushed forward), выбег is called positive and vice versa. Adjustment of a vybeg of forward wheels is carried out by selection of the remote washers enclosed under the pushing suspension bracket bars.
Disorder is called the tilt angle of the plane of wheels concerning a vertical. If wheels are inclined by the upper edges outside, disorder is called positive and vice versa. The size of disorder is measured in degrees. Correctness of adjustment of disorder determines the size and the provision of a spot of contact of protectors with the road and allows to compensate changes in suspension bracket geometry during commission of turns and at the movement of the car on an uneven paving. On the considered models of cars the possibility of adjustment of disorder is not provided.
Corner of a cross inclination of an axis of turn of a wheel is called the corner between an axis of an inclination of a rotary fist and parallel DP of the car the vertical plane which is carried out through a point of fastening of a wheel.
Thanks to disorder and a corner of a cross inclination of an axis of turn of a wheel, a point of a contact of wheels with the road settle down closer to an axis of a rotary fist, than the so-called "shoulder of a running in" the facilitating driving and reducing effect of transfer of blows of wheels about roughness of a covering on steering is supported.
Convergence is called data size to each other of forward edges of wheels of the car. Such violation of parallelism of installation of wheels allows to minimize wear of a protector at the expense of a skid at commission of turns. At zero convergence the distance between forward edges of wheels is equal to distance between their rear edges. Normal convergence is given in Specifications. Adjustment of convergence of forward wheels is carried out by adjustment of length of steering drafts due to change of provision of their tips. For correction of convergence of back wheels the special adjusting cam bolt screwed in the internal end of a control lever of a back suspension bracket is provided. Violation of adjustment of convergence leads to acceleration of wear of protectors of tires due to slipping them on a paving.
Conditions of check of angles of installation of wheels
Check of angles of installation of the car demands existence of a viewing hole or the special measuring elevator. When carrying out measurement it is necessary to satisfy the following conditions:
Air pressure in tires conforms to requirements of Specifications;
Forward wheels are established in rectilinear situation;
The car is not loaded, the fuel tank is completely filled;
Car suspension brackets strongly prozhata;
The steering drive correctly is adjusted;
Side plays of a joint of components of a suspension bracket and the steering drive do not exceed the limit of admissible ranges;
Depth of a pattern of a protector of tires of one axis is identical.
All parameters, except convergence, are established by production of the car and are not subject to adjustment. If the car did not visit serious accident, the angles of installation of wheels have to remain during all service life of the car. In the absence of confidence in correctness of determination of the parameters which are not subject to adjustment ask for the help experts.
Convergence can be measured in house conditions in two ways. In the first the measurement of distances between forward inner edges of rims of wheels the suitable measuring instrument is made. When using the second method the special plate will be required. Having established a plate perpendicular to a wheel and rotating it, it is possible to reveal a deviation of wheels. The measuring instrument or a plate can be bought in specialized shops.
If as a result of check it became clear that convergence needs adjustment, weaken lock-nuts of tips. Turn out a wheel against the stop to the left and precisely count visible number of strings of a carving on the right steering draft. After that turn a wheel against the stop to the right and count visible number of threads on the left draft.
If two numbers coincide, at the subsequent adjustment it will be necessary to turn off or wrap both tips on identical quantity of turns.
If the received results differ from each other, at the subsequent adjustment it is necessary to compensate a difference. After adjustment on both drafts the identical quantity of free strings of a carving has to take place.
Having finished adjustment, tighten lock-nuts — as drafts rotated, protective covers of the steering mechanism most likely will be deformed and it is necessary to weaken collars of their fastening and to make the corresponding corrections.