Category O Trailers: What Are the Vehicle Categories and Type Criteria? #Basics

Our new blog post on the definitions and criteria for Category O trailers is now live in the academy.

Welcome to the third article in our series, discussing the definitions and type criteria for vehicle categories related to O category trailers. This article summarises the third intermediate category approved under the EU 2018/858 regulation.

In the previous articles of our series, we examined in detail the classification of M category vehicles, including cars and buses, as well as N category vehicles, such as trucks and vans.

General Definition of O1, O2, O3, and O4 Category Vehicles

Category O trailers are divided into four subcategories. These vehicles, commonly known as trailers, are primarily used for transporting goods. In short, O category vehicles refer to non-motorized vehicles utilized for freight transportation.

According to EU Regulation 2018/858, a trailer is defined as:
“‘trailer’ means any non-self-propelled vehicle on wheels designed and constructed to be towed by a motor vehicle, that can articulate at least around a horizontal axis perpendicular to the longitudinal median plane and around a vertical axis parallel to the longitudinal median plane of the towing motor vehicle.”

The four subcategories under the O category are:

  • Category O1: Trailers with a maximum mass not exceeding 0.75 tonnes.
  • Category O2: Trailers with a maximum mass exceeding 0.75 tonnes but not exceeding 3.5 tonnes.
  • Category O3: Trailers with a maximum mass exceeding 3.5 tonnes but not exceeding 10 tonnes.
  • Category O4: Trailers with a maximum mass exceeding 10 tonnes.

Here are some real-life examples of each category:

  • O1 category trailers are lightweight trailers typically towed by passenger cars and used for transporting small loads.
  • O2 category trailers: Examples include caravans, boat trailers, and generator carriers. They are generally towed by light commercial vehicles.
  • O3 category trailers: These trailers are often used for household moves and are towed by trucks or tractors.
  • O4 category trailers: These are heavy-duty trailers used in construction and long-haul transport, towed by large commercial vehicles.

These examples aim to provide a basic understanding, although trailers in each category can be used across different applications.


Category O Trailers: Criteria for Vehicle Types, Variants, and Versions (Acc. to EU 2018/858)

The criteria for type, variant, and version are applied across all category O trailers. Below is a detailed breakdown of type criteria based on the regulation:

5. Categories O1 and O2

  • 5.1. Type of vehicle
    A ‘type of vehicle’ consists of vehicles sharing the following features:
    • (a) The manufacturer’s name. A change in ownership does not require new approval.
    • (b) The vehicle category.
    • (c) The concept as defined in Part C, Point 5.
    • (d) Key design elements, including the chassis and body structure (for self-supporting bodies).
    • (e) The number of axles.

For example, if a manufacturer produces a two-axle, center-axle trailer under one type approval, a separate type approval is required for a single-axle trailer.

  • 5.2. Variant
    A ‘variant’ groups vehicles with the following common characteristics:
    • (a) The type of bodywork (for complete and completed vehicles).
    • (b) Stage of completion (complete, incomplete, or completed).
    • (c) Braking system (unbraked, inertia, or power-assisted).

A type approval may include multiple variants, such as flat-bed and generator trailers, as long as they share the same type approval.

  • 5.3. Version
    A ‘version’ within a variant shares the following features:
    • (a) Technically permissible maximum laden mass.
    • (b) Suspension type (air, steel, rubber, or torsion bar).
    • (c) Drawbar concept (triangular, tubular, or other).

6. Categories O3 and O4

Similar criteria apply to O3 and O4 category vehicles. Typically, semi-trailers and full trailers are certified under these categories.

  • 6.1. Type of vehicle
    A ‘type of vehicle’ consists of vehicles sharing the following features:
    • (a) Manufacturer’s name. Ownership changes do not require new approval.
    • (b) Category.
    • (c) Trailer concept as defined in Part C, Point 5.
    • (d) Design aspects, including the chassis, body structure, and (for e-trailers) energy storage systems.
    • (e) Number of axles.
  • 6.2. Variants
    Variants share the following characteristics:
    • (a) Bodywork type (as per Appendix 2).
    • (b) Stage of completion (complete/incomplete/completed).
    • (c) Suspension type (steel, air, or hydraulic).
    • (d) Additional features, such as extendable chassis or deck height (low-loader, semi-low loader, etc.).
  • 6.3. Versions
    Versions share the following features:
    • (a) Technically permissible maximum laden mass.
    • (b) Axle spacing in accordance with Directive 96/53/EC.
    • (c) Axle definitions, including liftable, loadable, and steered axles.

List of Superstructures and Bodywork Codes for Category O Trailers

Category O Trailers Definitons and Type Criteria

Below is a list of bodywork codes used for O category trailers:

Ref.CodeNameDefinition
5.1DASemi-trailerDesigned to impose a significant vertical load on the towing vehicle or converter dolly.
5.2DBDrawbar trailerHas at least two axles, one of which is steerable.
5.3DCCentre-axle trailerAxles positioned near the center of gravity, transmitting minimal vertical load.
5.4DERigid drawbar trailerEquipped with a drawbar transmitting less than 4,000 daN static load.
5.5DFLink semi-trailerSemi-trailer with a fifth wheel at the rear for towing additional trailers.
5.6DGLink drawbar trailerDrawbar trailer with a rear-mounted fifth wheel for towing other semi-trailers.

If the bodywork type is not listed, it can be coded as 99. For example, a caravan trailer would use code 99, while a boat carrier would be assigned code 21.


Summary

O category vehicles are non-motorized transport vehicles used for freight, offering a wide range of configurations. If you have questions, feel free to leave a comment or contact us directly.

Homologation Professional
Homologation Professional

I have been acquainted with homologation in the automotive sector for over 10 years now. We have accomplished great things in many projects within various teams. Adapting to the recently updated homologation processes has been particularly exciting. Integrating past experiences with new procedures fosters a fertile ground for innovation and productivity. Having a special interest and expertise in both automotive and technology,

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