A curtain semi-trailer is a type of trailer that rests with its front part on a tractor, the feature of which is sliding walls - curtains. The advantage of this type of semi-trailer is the greater strength of the tarpaulin frame compared to, for example, a flatbed semi-trailer. At the same time, it remains possible to fold it, providing convenient access to the load. Curtainsider semi-trailers are used for the transportation of bulky goods that need protection from the effects of the external environment: precipitation, dirt and excessive moisture. Curtain semi-trailers are of two types - actually curtain and curtain side. 

General Characteristics

• Semi-trailer - curtain, with a rigid sliding frame.
• The floor covering is dense, wear-resistant laminated plywood.
• Boards - aluminum or steel.
• The opening mechanism is sliding, the sides and the roof move independently of each other.
• Frame - spar with cross members.
• The awning is made of imported polyvinyl chloride (PVC).

Why Are They Needed?

Curtain and curtain-sided semi-trailers are used for the transportation of various goods that do not require special conditions for transportation and storage. It can be both raw materials and finished products of industrial enterprises, non-food products for retail chains and much more. Transportation can be carried out both for short distances (intercity transportation) and for long distances (international transportation).

Benefits of Curtain Side Semi-trailers

Curtain side semi-trailers are characterized by high load capacity and capacity with a relative simplicity of design. They are equipped with sides that provide additional rigidity, eliminating the risk of goods falling out when turning.

Advantages of Curtain Side Semi-trailers

• Reliability.
• Versatility.
• Protection of cargo from environmental influences.
• Reliable fixation of goods.

An additional advantage of the design is access from all sides to the inside of the platform. This ensures maximum convenience and speed of loading and unloading operations.

Main Structural Elements

• Sliding side curtains and folding sides. Existence of boards provides reliable fastening of any freight. The manufacture of the sides from aluminum gives them increased wear resistance. The most popular side heights are 60 and 80 cm.
• Wear resistant flooring.
• Retractable roof. Made from a movable frame that slides forward easily.
• Welded spar frame. Differs in durability and rigidity. Before priming and painting, the metal is shot-blasted.
• Durable tarpaulin. It is made from modern polymeric materials that can withstand high loads. Provides protection from adverse weather conditions. The awning is equipped with internal amplifiers, which contributes to greater tension and a decrease in its windage. The result is fuel savings. We use materials up to 900 g/m² for the sidewalls and up to 650 g/m² for the roof. On the roof, the awning has the properties of transparency for better light transmission.
• Additionally, the semi-trailer can be equipped with bunk. This makes it possible to transport long loads: pipes, rolled metal, etc.
• Rear doors - aluminum, panel type, with hidden locking mechanisms.

The main design feature of the curtain side semi-trailer is the ability to fold the roof and sides like an accordion. This is due to their sliding along the guides from the place of attachment. The folding process takes minimal time, which is an important factor when loading or unloading. Curtain and curtain-sided semi-trailers are a demanded and popular type of freight transport. Their designs incorporate the best of years of experience. The use of such semi-trailers in transportation ensures the reliability and safety of the cargo.

Structural Structure and Chassis

The basis of the design of the curtain side semi-trailer is a welded ladder frame made of high-strength alloy steel. To give additional strength and wear resistance, the frame is processed in 3 stages: it is shot-blasted, primed and painted with enamel. For the convenience of loading and unloading, the side curtains can be moved to the side.

The chassis is equipped with a three-axle axle unit SAF INTRADISC with disc brakes, which ensures the adaptation of the semi-trailer to uneven roads, absorbs potholes and potholes well to maintain the integrity of the load, and is also reliable and safe during emergency braking. This air suspension is designed specifically for the operation of heavy trailers in difficult road conditions. The connection between the arm and the axle beam in this design is one-piece, which forms a strong and reliable hitch that does not require special maintenance.

The spherical mounting brake mechanism ensures a long service life of the brake pads, all mechanisms are covered with anti-corrosion treatment. Precision-machined eccentric roller guides help to precisely control the movement of the brake pads and transfer the necessary force for safe and smooth braking. Six 22.5-inch tires from a European manufacturer and one spare wheel provide even more traction and dampening of small bumps without the need for suspension.

The chassis is equipped with JOST mechanical saddles, the total load capacity is 24 tons. The chassis is two-speed, has one-way control. When installing a curtain-sided semi-trailer separately from the tractor, two strong wheel chocks with locks are used. The chassis is also equipped with plastic fenders with mudguards that protect the body of the semi-trailer from dirt and splashes. There is aluminum side protection to prevent damage to the hull and wheelbase. Under the body of the curtain side semi-trailer there is a basket for two spare wheels, one of which has a holder. For the transportation of related necessary tools, there is a waterproof plastic box, which is located at the rear, on the driver's side. For easy access to the upper part of the semi-trailer, a retractable ladder with an upper platform is located on the rear right side of the chassis. A protective bar is placed in the rear part of the curtain side semi-trailer to increase reliability and safety.

Semi-trailer Pneumatic System

The sem-trailer is equipped with the WABCO EBS 2S/2M, RSS system in accordance with 71/320 AT (EEC). The EBS system performs an electro-pneumatic function that regulates the pneumatic control pressure and also adapts the braking forces to various conditions. This system has an integrated anti-lock function - ABS, which analyzes the speed of the wheels and determines if any of them have a tendency to block, and accordingly calculates the required amount of brake pressure. The new version of this system also implements the RSS function, which is responsible for stabilizing against rollover. Due to the relatively high center of gravity, semi-trailers are prone to tipping over when cornering quickly. The driver may notice the threat of a rollover late and not react in time, and the RSS function allows you to detect this threat much earlier and respond to it in a timely manner with automatic braking. RSS detects the presence of a rollover hazard by reducing the load on the inner wheels when turning. When the calculated lateral acceleration exceeds the critical value for roll, this function is activated and applies high pressure braking.

The Structure of the Floor and Walls of the Semi-trailer

The flooring of the low loader curtain semitrailer is made of moisture-resistant, durable bakelite plywood, the thickness of which is 27 millimeters. The floor covering is wear-resistant, dense and durable, complements the strength of the overall structure of the semi-trailer, and also withstands the load of seven-ton forklifts. If braking or turning at a sufficient speed, the load is subject to inertia, which can cause the load to damage the sides of the van or fall out of the van. 15 pairs of tension rings are used to securely fasten the load to the floor of the curtain side semi-trailer.

The front wall of the semi-trailer is stacked, aluminum, reinforced with vertical bumpers and covered with a layer of bakelite plywood, which ensures its strength and reliability in situations of emergency braking. The back wall is a door portal. The aluminum rear doors have a 270-degree opening radius and lock securely in both closed and open positions. Doors of panel type are equipped with a hidden lock system, covered with plating on the outside to protect against corrosion. 

Sliding side walls, equipped with three pairs of sliding posts, provide maximum access to the contents of the semi-trailer for handling large or fragile loads. A durable sliding curtain allows you to place any volumetric heavy loads in the semi-trailer. 

Semi-trailer Outer Cover

The curtain side semi-trailer is covered with a dense, strong tarpaulin. If necessary, the roof can also be moved for ease of loading and unloading. The roof and side walls move independently of each other using their guides. The roof usually moves towards the driver's cab, but when the latches are removed, it can also move towards the door portal. Outside, the body has reflective elements and marker lights, which complies with all existing traffic regulations. Dimensional marking on the sides is yellow, on the back is red.

Protection Elements and Electrical Equipment

Curtain side semi-trailer has an anti-shock damper, which serves to dampen the impact in a collision or other strong mechanical impact of the external environment. The rear door portal is equipped with rubber roller bumpers for cushioning during docking, the doors and fittings are protected by a rubber damper. The semi-trailer is equipped with a special socket for supplying energy to the interior lighting fixtures. Above the protective bar is a lamp holder made of steel.

Attaching a Semi-Trailer to a Tractor

Semitrailers are not independent vehicles, but one of its parts is based on the tractor. For strong and reliable docking, a fifth wheel coupling is used. A good hitch affects vehicle handling, roadholding, maneuverability, road response, fuel economy, safety and many other performance characteristics. The pivot-type fifth wheel coupling consists of a pair of pivot-grip, which forms the basis of the detachable coupling system. To prevent uncoupling of the tractor from the semi-trailer, several independent locking devices are used, one of which must be unlocked manually.

Conditions for a Long and High-Quality Service Life

Due to its design, the curtain side semi-trailer evenly distributes the weight of the load over the entire wheelbase: its own and the tractor. The correct and even distribution of the weight of the load units over the space of the semi-trailer is important not only for the efficient use of space, but also for protecting the semi-trailer from wear. The distribution of the weight of the load allows avoiding overweight on one of the sides and, as a result, tipping over of the semi-trailer, as well as excessive load on one of the chassis axles. When transporting long pipes or rolled metal, the semi-trailer platform must be equipped with conics - U-shaped welded steel structures. Strict adherence to the documentation regarding the distribution of cargo and the maximum allowable load allows you to increase the life of the semi-trailer and all its components, reduce wear on parts and eliminate the possibility of breakdowns.