A long-distance trip or active rest often puts the car owner in front of the question of a lack of space in the trunk. It is at this point that the driver thinks about expanding the useful volume of the vehicle. The first question is: The roof of the car is called the What are the options for a particular model? In professional environments and auto accessories stores, this system is most often called luggage-system or roof-car.
However, if you go into the technical details, it becomes clear that there is no single name for all the elements, since the design consists of several key components. The basis of the entire design is a bunch of longitudinal arcs (or crossbars) and special stops that are attached directly to the body. Cross-sectionsThese are often confused with the whole system, but are only horizontal elements on which boxes, bicycle fixtures or baskets are already installed.
The wrong choice of the type of fixation can lead to damage to the body or, even worse, to the loss of cargo at high speed. The variety of names and designs is great: from classical pole to aerodynamic profiles. Understanding the difference between them will help you choose the best solution that will not create unnecessary noise and fuel consumption.
Basic design elements: crossbars and supports
Understanding how to properly call the trunk on the roof, it is important to clearly separate the concepts of components. Horizontal elements that run across the motion are called cross-sectional Or traverses. It is on them that the main burden of retaining the cargo falls. Modern models often have an oval or aerodynamic cross section, which reduces air resistance and noise levels when driving on the track.
The second critical element is support (or paws) They serve as a link between the crossbars and the body of the car. Depending on the type of roof, the supports can be universal or specific, designed for a specific brand and model. The reliability of the entire system depends on the quality of the materials from which these units are made, usually it is powder-painted steel or lightweight, but durable aluminum.
When buying a system, pay attention to the maximum static and dynamic load. Dynamic (when moving) is always much lower than static (in the parking lot).
There is a misconception that all the crosses are the same. In fact, the profile can be rectangular, square or winged. Wing-shaped profile It is considered the most modern, as it not only looks aesthetically pleasing, but also minimizes the whistling of the wind. Square profiles are more common in budget segments or in systems for the transportation of heavy construction equipment.
Types of attachment to the car body
The answer to the question of what the roof mount is called often depends on the way it is installed. The design of the roof dictates the choice of the type of supports. The most common option for modern sedans and hatchbacks are systems with fixation for the doorway. In this case, the legs of the trunk capture the upper edge of the door frame through special rubber seals, without damaging the metal of the body.
For cars with integrated longitudinal arcs (rails) running along the roof, completely different mechanisms are used. They're used here. T-shaped adapterswhich are inserted into the groove of the arc and tightened by a screw or a special key. This method is considered one of the most reliable, since the mounting point is originally provided by the manufacturer of the car for high loads.
Owners of commercial vehicles or vehicles without any elements on the roof often use systems with a high-performance vehicle. magnetic-fixer Or vacuum suction cups. However, they are less suitable for permanent operation due to the risk of displacement during sharp maneuvers. A more reliable option for smooth roofs are systems with mounting points hidden under decorative hatches in gutters or directly in the roof.
⚠️ Attention: Never use door-grab systems on cars with framed glassless windows or on a sloping roof coupe without a special adapter. This can cause the door to deform or break the glass when tightened.
Railings and their difference from the luggage system
Often, motorists confuse concepts, calling the trunk what is actually only part of it. Railings These are longitudinal arcs installed by the car manufacturer along the roof parallel to the movement. They can be functional (have inside a channel for cross-sections) or decorative. If your car already has such arcs, you do not need to buy a complete system with supports, just buy a car. cross-section.
The main difference between rails from a full-fledged luggage set is that rails are a regular body element. They are not removed without a special tool and serve as a basis. Crossbars are a removable accessory that can be dismantled when they are not necessary, so as not to spoil the aerodynamics.
There are universal crossbars that are attached to round or square rails using clamps. There are also models that require drilling or the use of special T-bolts, if the arc profile suggests this. It is important to measure the distance between rails, as the length of the traverse you buy should correspond to the width of the roof.
Can I drive without crosses on the rails?
Technically possible, but prohibited by traffic rules in many countries, if the cargo is out of size. In addition, it is dangerous to tie the cargo directly to round rails - it can slip off when braking.
Specialized types of anchorages
In addition to universal solutions, the market offers highly specialized systems, which also fall into the category of "roof mounts". They're included cycling-mount, which can be fixed both on the crossbars and directly on the body through magnets or suction cups (although the latter are less reliable). Special attention should be paid to systems for the transportation of skis and snowboards, often equipped with locks to protect against theft.
For the transportation of bulky cargoes, such as boats or construction materials, are used. basket Or platforms. They are mounted on standard crossbars using bolt joints. This turns a passenger car into a mini truck, allowing you to transport dirty or heavy items that can’t be put in the cabin.
There are also soft attachments, for example, boot-staff from a durable fabric with belts, thrown through the interior of the car. Although this solution is cheap and compact, it is not suitable for high-speed driving and heavy loads, being rather a temporary solution for summer residents.
| Type of attachment | What roof? | Reliability | Noise |
|---|---|---|---|
| Behind the doorway | Smooth roof, 4 doors | Tall. | Medium |
| Holder in groove (T-slot) | Staff railings | Very high. | Low. |
| Magnetic | Metallic smooth | Low. | Low. |
| At anchorage points | Hidden hatches | Maximum | Minimum |
Manufacturing materials and aerodynamics
When choosing what your future trunk will be called and look like, it is worth considering the material of the profile. Classical steel It is characterized by high strength and low price, but is susceptible to corrosion when the coating is damaged and creates significant noise. Aluminum alloys are lighter and do not rust, making them the preferred choice for most modern systems.
Aerodynamics plays a key role in fuel economy. The box mounted on the roof or even just cross-sections increase drag. Aerodynamic arcs They are shaped like an aircraft wing, directing airflows in a way that minimizes vortices and whistles. The difference in fuel consumption between square and streamlined profiles at a speed of 110 km / h can reach 1-2 liters per 100 km.
☑️ Pre-purchase check
Covering the elements is also important. Plastic linings protect the metal from scratches and ultraviolet light. Rubber seals in the areas of contact with the body should be made of EPDM rubber, which does not crack in the cold and does not leave traces on the paint coating of the car.
Installation rules and safety of operation
Installation of the luggage system requires strict compliance with the manufacturer's instructions. The first step is always to clean the contact areas of dust and dirt. If you are installing a door grip system, you need to make sure the door seal doesn’t clamped too hard, but doesn’t hang around either. Excessive force during tightening can lead to dents on the metal.
After installation, be sure to conduct a strength test. Try to move the crossbars with your hands - they should stand dead. When traveling at the first time, it is recommended to move at a low speed, listening to extraneous sounds. Wind can reveal poorly tightened screws or improperly installed adapters.
⚠️ Attention: The distribution of the goods should be uniform. Shifting the center of gravity sideways or backwards can critically impair the handling of the car, especially when cornering or braking. Always place heavy objects closer to the center of the roof.
Check the tightening of fasteners regularly, especially after the first 50-100 km run. Vibration and temperature changes can weaken the compounds. If you use the system in winter, make sure that the lock mechanisms do not freeze using silicone lubricant.
Properly selected and installed luggage system expands the capabilities of the car, but requires regular check of the fastener and taking into account aerodynamic constraints.
Legal aspects and limitations
The use of additional roof mounts is governed by traffic rules. In most countries, the height of the vehicle with the load should not exceed 4 meters (or 2.5-2.8 meters from the ground, depending on the region). Also, the load must not extend beyond the dimensions of the vehicle more than a certain distance in front and behind without special signs.
It is important to remember the maximum load on the roof specified in the manual for the operation of your car (section). Technical Data or Specifications). Usually, the dynamic load is from 50 to 100 kg, including the weight of the crosses themselves. Exceeding this limit is dangerous not only by a fine, but also by the risk of a deflection of the roof or a detachment of the structure.
If you plan to use the trunk frequently, it makes sense to purchase a certified kit that has a safety label (for example, a safety label). TÜV or City Crash). Cheap analogues without certification may not withstand the declared loads in an extreme situation.
Can I wash my car in an automatic wash with crossbars installed?
In most cases, luggage manufacturers recommend removing the crossbars before visiting automatic washers with brushes. Brushes can catch the mounts, damage them or tear them off the roof. Contactless washers are generally safe if the system is installed correctly and has no backlashes.
Will there be any footprints on the roof after the trunk is removed?
When using systems with a grip behind the doorway or standard railings, traces, as a rule, do not remain. However, if dust or sand has accumulated under their feet, they can act as an abrasive, leaving scuffs. Regular cleaning of contact sites prevents this effect. On older cars, there may be a slight difference in the color of the paint under the supports due to the burnout of the rest of the surface.
How to reduce the noise of the trunk whistle at high speed?
Whistling occurs due to the swirling air. To eliminate, try to change the distance between the crossbars (optimally 60-70 cm). Also helps the installation of deflectors or the use of aerodynamic profiles. Sometimes it is enough to just turn the crossbar, if it is symmetrical, or tighten the free ends of the belts.
Will the universal trunk fit any car?
No, the term "universal" refers to the ability to adjust the length or type of grip, but compatibility is always limited. For example, the system for the sedan is not suitable for a coupe with a sloping roof, and mounts for round-section rails will not stand on oval arcs. Always check the suitment list for your particular model.
Do I need to remove the crossbars if they are not used?
From a technical point of view, it is not necessary to remove them, if they do not interfere with the arrival in the garage. However, their dismantling will reduce fuel consumption, reduce cabin noise and prolong the service life of the elements themselves, protecting them from ultraviolet light and reagents. In addition, it will reduce the risk of theft of the crossbars themselves, if they are not equipped with locks.