Car-trailer coupling devices - description of requirements and overview of flexible and static load measuring solutions

The article presents an overview of the current normative, national, and international documents, containing in their content the requirements for devices coupling a car with a trailer in terms of technical conditions that these devices must meet to confirm proper performance and ensure the possibility of safe use during exploitation before will go on sale. Attention was paid to the division of coupling devices of motor vehicles and trailers into classes according to Regulation 55 of the UN/ECE and the resulting requirements. The principles according to which it should be accepted that couplings meet the approval requirements are discussed, and the meaning and way equipment manufacturers determine the characteristic values of the indicated coupling parameters are explained. Requirements for the minimum and maximum loads exerted by the trailer on the coupling device are presented. Particular attention was paid to the existing technical solutions (including patent claims in the Patent Office of the Republic of Poland or in the European Patent Office) regarding coupling devices characterized by the possibility of measuring the static vertical force on the coupling and couplings with vertical flexibility (compliance), which can potentially reduce dynamic loads on the coupling device. Calculations focused on two practical applications are planned using the article's content and simulation. The first is the ability to assess the impact of introducing vertical compliance to the coupling device on its durability. The second is the ability to assess the impact of the value of the static vertical load of the coupling device (resulting from the trailer load and the longitudinal position of its center of mass) on the length of the braking distance of the combination: towing vehicle - trailer.