Self-service of a car requires not only knowledge and tools, but also convenient access to its lower part. For garage owners who are not equipped with a full-fledged inspection hole, an excellent solution is auto overpass. This design allows you to raise the car to a comfortable height, providing unobstructed access to the underbody, suspension and exhaust system.
The most reliable and durable option is metal overpass, assembled from a profile pipe. Unlike its wooden counterparts, a steel structure does not rot, can withstand enormous loads and, with proper anti-corrosion treatment, lasts for decades. Making such a ramp yourself is a real cost savings, since ready-made factory models are quite expensive.
In this article we will take a detailed look at the design process, selection of materials and assembly. steel overpass. You will learn how to calculate the dimensions for your car, what pipes to use for the frame and how to ensure maximum safety of the structure. Following the welding technology and the accuracy of the drawings is the key to ensuring that your car will stand on the ramp stably and safely.
Design and selection of structure dimensions
Before purchasing metal, it is necessary to clearly determine the geometry of the future structure. A standard overpass consists of two parallel platforms (rails) on which a car drives, and a support frame. The lifting height usually varies from 40 to 60 cm, which is the optimal value for working while lying down or sitting on a stool. The drive-in length should be at least 1 meter to ensure a smooth approach angle, especially for low-clearance vehicles.
Track width is a critical parameter that depends on the model of your car. The distance between the inner edges of the rails should be such that the wheels move freely, but the driver does not risk sliding inside. For passenger cars, the standard track width is about 80-90 cm, but it is better to measure the distance between the centers of the wheels of your car and add a margin of 10-15 cm on each side.
When creating drawings, it is important to consider lifting capacity. The structure must support the weight of the car with a margin. If you plan to service only passenger sedans, the load rating may be less than for SUVs or light trucks. Also at the design stage it is worth considering the presence travel limiters at the end of the overpass to prevent the car from accidentally leaving the platform.
⚠️ Attention: Never make the length of the approach part less than 80 cm. Too steep an approach angle can lead to the bumper or “belly” of the car hitting the end of the overpass, which will damage the body.
Required materials and tools
The basis of any high-quality overpass is the correct choice of rolled metal. For load-bearing frame elements, a profile pipe of square or rectangular cross-section is best suited. The optimal choice for racks and lintels would be a pipe measuring 50x50 mm or 60x40 mm with a wall thickness of at least 3-4 mm. The use of thin-walled metal is unacceptable, as it can deform under the weight of the car.
For the rails themselves, on which the wheels will roll, a channel (No. 10 or No. 12) or the same profile pipe, reinforced with additional stiffening ribs, is often used. If you are making rails from a pipe, you need to weld strips of metal or reinforcement on top in increments of 10-15 cm so that the wheels do not fall through or slip. You will also need corners to strengthen the nodes and sheet steel 4-5 mm thick for manufacturing stops and sites.
The list of tools for work is quite standard for welding work, but requires preparation:
- 🛠️ Welding machine (inverter or semi-automatic) and consumables (electrodes, wire, gas).
- 📐 Angle grinder (grinder) with discs for cutting and cleaning metal.
- 📏 Tape measure, square, construction level and metal marker for marking.
- 🎨 Equipment for painting: metal primer, hammer paint and brushes or spray gun.
Don't forget about personal protective equipment. Welding involves the presence of sparks and ultraviolet radiation, so welding mask, leggings and thick clothing are required. When cutting metal with a grinder, be sure to wear safety glasses, as scale may get into your eyes.
To cut a thick-walled profile pipe, use cutting discs 2.5 mm thick - they heat the metal less and do not jam in the seam, unlike thin metal discs.
Step-by-step instructions for assembling the frame
Assembling the overpass begins with cutting the blanks according to your drawing. First, two side frames are made, which are then connected by cross members. Lay the pipes on a flat surface (for example, on the concrete floor of a garage or on a specially prepared slipway) and tack them by welding. After checking the diagonals and angles, you can cook it clean. It is important to observe the geometry so that the overpass does not turn out skewed.
Next, we proceed to install the vertical racks. They are welded to the lower frame in increments of 50-70 cm. The racks must be strictly vertical, which is controlled by the level. An upper frame is welded to the upper ends of the racks, which will bear the main load from the wheels of the car. It is best to reinforce pipe connection nodes with sheet metal gussets - this will give the structure additional rigidity and torsion resistance.
Pay special attention to the arrival area. Here the frame often experiences maximum fracture loads. It is recommended to strengthen this area with additional diagonal braces from an angle or pipe of a smaller cross-section. If the structure is collapsible, the connections are made with bolts through flanges, but the all-welded version is always more reliable and safer for permanent use in the garage.
☑️ Stages of frame assembly
Manufacturing of rails and driving surfaces
After the main frame is ready, we move on to creating the working surface. If you use a channel as a rail, it is laid with the flange up and welded to the upper contour of the frame. The channel is convenient because its sides serve as a natural stop for the wheel, preventing it from sliding to the side. However, to create an anti-slip effect, it is necessary to weld inside the channel or on top of a flat pipe. cross members.
Reinforcement with a diameter of 12-14 mm or a steel strip 40x4 mm are excellent as crossbars. They are welded perpendicular to the direction of movement in increments of 10-15 cm. This “comb” provides excellent adhesion between rubber and metal even in winter, when snow or moisture may remain on the wheels. The surface should be rough, but not so sharp that it damages the tire tread.
At the ends of the overpass, where the rise ends, restrictive bars or metal stops must be installed. Their height should be sufficient (minimum 10-15 cm) to stop the inertia of the car upon arrival. Often, for these purposes, large-diameter pipe sections or powerful angles welded at an angle of 90 degrees to the ramp plane are used.
| Design element | Recommended Material | Purpose |
|---|---|---|
| Support racks | Pipe 60x60x4 mm | Vertical support, holds weight |
| Rails (runners) | Channel No. 10 or pipe 80x80 | Wheel path |
| Cross members (ribs) | Reinforcement d12 mm or strip 40x4 | Anti-slip effect |
| Node Amplifiers | Sheet steel 4-5 mm | Gussets for rigidity of welds |
⚠️ Attention: When welding reinforcement onto rails, make sure that the ends of the rods do not protrude beyond the vehicle track dimensions. Protruding reinforcement can damage the sidewalls of the tires during careless driving.
How to make a collapsible overpass?
If space in the garage is limited, you can make the overpass modular. To do this, the frames are connected not by welding, but by powerful bolted connections through flanges. A flange is a plate with 4 holes welded to the end of the pipe. During disassembly, the bolts are unscrewed and the overpass is disassembled into separate sections for storage. However, remember that bolted connections require regular checks for tightness.
Welding work and structural strengthening
The quality of welds is a matter of your safety. All joints must be welded in a circle (if it is a butt joint of pipes) or along the perimeter (if it is an overlap joint). Pay special attention to the places where the vertical posts connect to the horizontal frames. This is where maximum stress occurs when a car drives in. The seam should be smooth, without pores or undercuts.
To strengthen the structure, the method is often used headscarf. These are triangular metal plates that are welded into the corner of the junction of two pipes. The gusset significantly increases the joint area and distributes the load, preventing pipe breakage at the seam itself. Use metal of the same thickness as the main elements to avoid stress imbalance.
After completing all welding work, it is necessary to clean the seams with a grinder. Scale and slag must be completely removed, since corrosion can begin underneath them, which will imperceptibly destroy the connection from the inside. Cleaned seams are also better visible during subsequent visual inspection for defects. If you notice fistulas or cracks, they must be resealed immediately.
The main principle of welding a trestle is: it is better to overcook than to undercook. The thickness of the seam must be no less than the thickness of the pipe wall, and in loaded units - exceed it by 1.5 times.
Anti-corrosion treatment and painting
Metal, especially in a garage where it may be damp, is susceptible to corrosion. Therefore, the painting stage cannot be ignored. Before applying paint, the entire structure must be degreased (for example, with white spirit or Galosh gasoline) and treated with a rust converter if there are already oxides on the metal. This will ensure adhesion of the coating.
As a primer, it is best to use epoxy or zinc-containing primers, which create barrier protection. Hammer paint is ideal for finishing coats. It not only looks aesthetically pleasing, hiding small irregularities in the metal, but also forms a durable, chemically resistant film. The paint should be applied in 2-3 layers, allowing each layer to dry according to the manufacturer's instructions.
It is better to choose a bright color for the overpass (orange, yellow, blue) so that it is clearly visible in the twilight of the garage. This will reduce the risk of tripping over the structure or parking incorrectly. After the paint has dried, let the overpass stand for several days for the coating to completely cure before driving a car onto it.
How often does the overpass surface need to be resurfaced?
When using high-quality hammer paint and proper surface preparation, the coating lasts 5-7 years. However, once a year it is recommended to carry out an inspection: inspect the structure for paint chips and scratches. If the metal begins to rust at the points of contact with the wheels or at the welds, these places need to be cleaned and tinted locally, without waiting for the corrosion to spread.
Is it possible to use the overpass outdoors in winter?
The metal overpass is intended primarily for garage use. If you plan to use it outside, keep in mind that in winter the metal becomes covered with ice, which makes driving extremely dangerous. In addition, temperature changes and humidity accelerate corrosion. For outdoor use, special frost-resistant paint and constant monitoring of the condition of the metal are required.
What is the minimum gap required between the rails?
The minimum gap between the inner edges of the rails depends on the width of the wheelbase of your car, but is usually at least 70-80 cm for passenger cars. It is important to leave room for possible wheel play when driving. If you make the track too narrow, you risk damaging the sills or rims. If it is too wide, the stability of the platform will decrease. The golden mean is to measure your car and add 10-15 cm of extra space on each side.
Is it necessary to concrete the base under the overpass?
Concreting the base is not strictly necessary if the floor in the garage is made of durable concrete screed with a thickness of at least 10 cm. In this case, the overpass is simply placed on the floor. However, if the soil under the garage is weak or the floor is wooden/clay, then it is necessary to make separate concrete “nickels” under the overpass posts or use wide metal pads so that the structure does not sink into the ground under the weight of the car.