The key to the profitability of services related to repairs to the structure of commercial vehicles is the skillful selection of technology, devices and the appropriate implementation of the entire system in the service. Although workshop owners and management staff increasingly understand the need for the company to be properly equipped with equipment, insufficient training of the staff is still a common mistake. Sometimes it even doesn’t exist at all. Reports from car shops show that the technology provider is often to blame.

Service design

When working with investors, it is usually the stage after the construction of the site, permits and the execution of the construction design that they are now wondering what the equipment in this site will be like. When asked whether there is a project for the application technology, investors may come up if a problem occurs. Unfortunately, it is too common for an investor to deal with the basic stage of designing a car service. This problem applies to both services used to repair vehicles and vehicles above 3.5 t GVM. The basic step of creating a car app, made available by its purpose, is made available technologically. It would be incredible, but it is a stage that is very often ignored by investors. Of course, all assumptions are necessary, but it is necessary to ensure the complete completion of the technical design of the service. Construction projects that do not address the needs related to the organization of repair and diagnostic services are a real nightmare. The design company has no experience in designing car services, or commercial vehicle services. It is not a sin, but it is a sin not to be supported by professionals with experience in the organization and technology.

Planning a repair station

When planning technology, it is crucial to optimally locate the supporting grate in the hall floor, which will constitute the direct basis for repairs. An appropriate, well-thought-out choice of the location of the stand is very important, because in this case it is “very stationary” and it will not be possible to easily change its location in the future. As always, much depends on the specificity of the service and the planned capacity of the post-accident repair department. If you intend to carry out ad hoc repairs, there is no need to create unnecessary infrastructure, extensive stations equipped with overhead cranes, etc. However, if you plan to create a post-accident repair center serving a large area of ​​land or a group of transport companies, or carrying out orders from insurance companies, the problem should be approached more seriously. more comprehensively. One of the key factors in the selection of equipment should be their design and the resulting durability, reliability and ergonomics. It is best if employee-operated replaceable components are made of materials with the lowest possible weight and are easy to assemble and disassemble. The use of elements made of light alloys with high mechanical parameters, which in this respect correspond to steel alloys, has become a standard.

 

Photo: working elements made of high-grade light alloys

Supporting grate

As standard, it is recommended to make one load-bearing grate, 16 m long and 4.5 m wide. It will be intended for both the assembly of vehicles during frame repairs and the driver’s cabin mounting accessories, which will be repaired after their disassembly from the vehicle. To increase the capacity of the stand, you can make an additional grate of the same dimensions, but an equally good, proven solution is to make a 16 m x 4.5 m grate and an additional 5 m x 5 m cabin repair grate. 

Fig. Grate

 

Photo: Method of attaching work equipment to the support truss

Frame repair equipment

The main elements of a standard frame repair kit are: two horizontal presses, a counterstay, two vertical presses, two jack-stands, a “C” press and chain holders securing the frame. It is worth paying attention to the power supply system for the hydraulic cylinders, which is powered by compressed air from the service installation. There are two systems: with a multi-way pump enabling simultaneous connection and control of several devices, and the option of powering individual repair devices with separate pumps. Although both solutions have their supporters and opponents, based on contacts with many repair services around the world, we can confidently say that using separate power supplies for all system devices has more advantages.

 

Photo: press and horizontal dam system during frame repair

 

Photo: press type “C”

It is also necessary to use auxiliary equipment in the form of roller holders for securing the vehicle frame during straightening, pads protecting against undesirable deformation of the vehicle frame edges during the impact of the press system and spreading systems.

Photo Attachments that are necessary during repairs

 

Photo: Vertical press with pneumatic lifting assistance

Induction heater

Is it possible to heat the vehicle frame without losing its strength parameters? Yes, and you should, but it requires vigilance and precise dosing of the supplied heat. When straightening the structure “cold”, microcracks in the structure of the material from which the frame is made most often occur. Heating allows the metal crystals to move more easily when subjected to straightening forces. When asked whether it is safe for the frame, one must answer honestly that any damage or repair by straightening must have negative consequences for the vehicle’s structure. It is important not to exceed the safety limit. Cars designed with a certain safety margin and minor interventions do not make the vehicle dangerous. For example, the temperature to which the repair zone is heated is crucial. It should not exceed 650 degrees C, because above this limit, steel alloys irreversibly lose the mechanical properties given to them in the production process. When heating with a gas torch, it is not possible to have full control over the temperature because the element does not heat up “throughout” but is heated “from the outside” of the frame and before the interior heats up to the expected temperature, its outer layers will be seriously overheated.

Fig. Comparison of performance of induction and gas burner

Additionally, this process takes so long that adjacent zones are undesirably heated, making straightening difficult. The safety aspect is also important. The solution is to use highly efficient induction heaters. The heating process is performed pointwise in the desired zone and takes place almost simultaneously over the entire volume of the frame surface, while the adjacent zones do not heat up excessively.

Overhead cranes and cranes

Repairs of commercial vehicles often require the use of auxiliary devices during disassembly and assembly of vehicle components. This applies to both the disassembly of cabins and the engine and other vehicle components. The most convenient solution is to use an overhead crane, but it is a relatively expensive solution and is only justified in the case of a large number of repairs. Very convenient from the organizational and cost point of view is the use of a manual chain winch mounted on a support beam specially made for this purpose. This may not be a solution that provides full mobility, but for ad hoc work it is completely sufficient.

Auxiliary equipment and sheet metal tools

In the case of post-accident repairs of cabins, buses and vehicles with sheet metal paneling, it is necessary to use basic technologies in the same way as in the case of passenger cars. The basic devices are an inverter welding machine designed for welding high-quality sheet metal, a welding machine with the possibility of brazing and other tools of a modern sheet metal worker.

Diagnostic equipment

It is difficult to imagine a doctor performing surgery without performing diagnostic tests on the patient. How to treat when it is not known exactly what is the cause of the ailments ailments with which the patient reported? Unfortunately, in the post-accident repair industry, it happens too often that body workers repair the vehicle using the “successive approximations” method. It is true that experience is a serious argument in favor of the so-called old professionals. No one intends to diminish this distinguished group of professionals’ knowledge and reliability. However, it is worth getting them interested in the possibility of speeding up work and improving quality not only by using tools for direct repair. If the repair system is skillfully implemented, you can successfully interest service employees in diagnostic and measurement methods, showing that it is an integral part of the technological process.

Post-accident repair service for commercial vehicles should use two diagnostic systems:

  • for measuring the shape of frames,
  • wheel alignment and axles alignment.

Optimal post-accident repairs are those that, carried out in the appropriate technological cycle, allow not only the restoration of the correct shape of the vehicle frame but also its repair, taking into account the wheel alignment. It is not too complicated provided that appropriate measurement technologies are used.

The diagnostic system should enable the control of the shape of the frame and the possibility of checking and at the same time adjusting the basic parameters of the alignment wheels and axles.

Diagnostics

After initial straightening of the supporting frame, it is necessary to check the geometry of the non-adjustable axes, and in case of deviations, it is necessary to correct their position in relation to the central axis of the supporting frame at this stage. This allows you to avoid serious problems in the last phase of the repair, which involves the final adjustment of wheel alignment. This is one of the examples of the advisability of continuous control of the shape of the frame and the alignment of wheels and axles. In practice, very different cases often arise in which support with a diagnostic system turns out to be indispensable. It should be noted that for proper rolling of the vehicle’s wheels, it is not enough to ensure wheel alignment. Equally important are the Camber, Caster and King-Pin, whose role in the entire diagnostic and adjustment process is still underestimated.

Photo Diagnosing the chassis system

Photo Diagnosing the shape of the frame

Post-accident repair and operational straightening

In the case of vehicles weighing up to 3.5 t GVM, there is no need for operational use of the vehicles. The overwhelming majority of cars from this group are self-supporting or frame-self-supporting structures. These types of bodies are not subject to operational straightening, only post-collision and post-accident repairs and possible reconstruction. The situation is different with vehicles over 3.5 t GVW, where the supporting frame structure often becomes distorted during use. It happens as a result of overload, uneven road surfaces or during the assembly of semi-trailers to tractor units. Operational straightening can be very helpful, and in some cases even necessary, to prepare the vehicle for adjusting the wheel alignment. It is true that the arrangement of the wheel and axle system relative to each other determines the quality of the vehicle’s rolling, but too large deviations in the shape of the frame may make the effective adjustment of some parameters much more difficult or even impossible. For example, it is crucial to initially set the perpendicularity of the fixed axis(s) in relation to the center of the supporting frame. An additional complication is diagonal curvature and frame twist. Especially in the case of built-up vehicles, there are defects that are difficult to diagnose without the use of appropriate diagnostic devices.

The article discusses basic problems regarding the organization and planning of the construction of services for commercial vehicles, mainly related to technical conditions and technology. The commercial vehicle market is very interesting due to the number of vehicles traveling around the world, but also to the potentially high profits of services repairing such vehicles. Investing in a post-accident and operational repair service for commercial vehicles is a very serious decision that requires careful planning and implementation, step by step with the participation of specialists.

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