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About parallelism of bridges of the car and trailer

Each is engaged in operation of lorries is not a secret that the exact centering of the steering axle increases tire life, improves the stability of the vehicle and facilitates its management. It is also well known for two important reasons because of which is necessary to support parallelism of leading bridges of the car and trailer axes: service life of tires and fuel. But there is a third factor that is sometimes overlooked, but it can be the most important. This factor is safety.

Whenever disturbed alignment in a component, regardless of whether it is in the engine, transmission or suspension, there can be unsafe traffic conditions. In addition, there is an increasing possibility of "folding" the lorry convoy at movement on dangerous roads, if dual axes of the trailer are not parallel. If all axes are parallel to the train, it will make rectilinear movement on the road. But if the trailer axle is not perpendicular to the longitudinal axis of the train, the trailer will have a tendency to move in the direction which is perpendicular to its axis. This complicates driving and causes lateral slippage of tires in addition to advance. There is a premature wear of the rear tires and additional deterioration of the front. Of course, this tire slippage caused by the parallelism of bridges will cause an increase in fuel consumption.

Car with not parallel bridges undoubtedly much harder to control on dangerous roads. If parallelism is high enough, the car can become dangerous even on good road as the driver should struggle constantly with the tendency of the vehicle to turn.

Parallelism of dual bridges should be checked every time the car comes into the workshop for maintenance of the suspension. This check should be carried out not more than 50 thousand. Kilometers of the tractor and the trailer - from 160 thousand. 200 thousand. Km on the corresponding equipment.

You need the following centering of axes can come before the expiration of 160 thousand. Km. It can be caused by small strokes (when driving over curbs or hitting the corner post), or injury in a collision. Even normal wear sleeves reactive suspension rods on one side of the vehicle may cause misalignment of the bridges.

With left-hand drive wheel starboard perceive greater shock than the wheels of the left side, as they no longer move on irregularities at the edges of the road, and as a result of redistribution of weight of the car on the sides due to the fact that the majority of roads has slightly convex profile. Normal wear sleeves or replacement jet bar can cause misalignment of the twin bridges. There is no doubt that the check of parallelism of bridges at any repair work should become the rule.

Radials are more sensitive to the parallelism of bridges, than the tire with a diagonal cord for all types of axles and suspensions. Symptoms of deterioration of tires with a radial cord often appear after 16-32 thousand. Kilometers, and at tires with a diagonal cord - after 80-92 thousand. Km.

For radial tires mounted on controlled axes, characterized by deterioration of humeral zones from the internal and external parties. By turning the edge of the tread tends to rise, as unlike the tires established on leading bridges, in this case there is no force that preserves the plane of contact of the tire with the roadbed. This wear typically does not affect the durability of the tire, since it occurs only on the first tread width of 0.79 mm.

Nonparallel bridges usually leads to cross-waved wear of the tire. If bridges are not parallel and the trailer tends to move away from the longitudinal axis of the road train, will be uneven wear of internal and external bus at the double busbar or the inner and outer parts of the tread at a single busbar. This causes a slippage of the tire and its wavy deterioration very similar to deterioration of the tire, mounted on the steering axle. The result of this uneven tread wear can be "scalping" of the tire.

Forms a radial tire wear and diagonal ply different. For example, the first of them as too large and too little air pressure leads to the same tread wear about the inner and outer shoulder zones. The second pressurized air increases the wear of the central portion of the tread and under a reduced air pressure - the inner and outer edges of the tread. This wear is generally faster than is found in tires with diagonal, than radials. Single wide-tire has the same contact patch with the road surface as both dual tires of a usual profile.

Wear caused by parallelism of bridges probably will not appear on unary wide tires as quickly because they have less wear on turns, than dual tires of a usual profile. Nevertheless, they are more expensive, so check of parallelism of bridges at installation of unary wide tires is mandatory.

At new trailers it is necessary to check parallelism of installation of their axes. However, it must be remembered that this regulation will not be the last. There is a period of grinding parts, especially when using chetyrehressornoy suspension.

After a short run chassis must be checked, because there may be some shift to the right because of backlashes in earrings. Typically the offset longitudinal axis of the chassis (relative to the bridge axis) increases over the lifetime of the trailer. The more mileage of the trailer, the more wear occurs in guide devices suspension or earrings.

While tire wear and fuel consumption depending on maintaining parallelism of bridges can be determined, traffic safety are even more important factor is not easily measured. Regular inspection and adjustment of parallelism of bridges only for safety significantly reduce the additional costs associated with injuries, accidents and downtime cars.