49.23. Which of the listed elements is not characteristic of a hook-type towing coupling device?
UAЯкий з перелічених елементів не характерний для гакового тягово-зчіпного пристрою?
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This exam question from the Traffic Rules of Ukraine concerns the safety of road trains and the technical serviceability of equipment, on which the reliability of the connection between the tractor and the trailer directly depends. In real conditions, a faulty or structurally inappropriate coupling can cause decoupling while driving, loss of control, and an emergency situation. That is why basic knowledge about the types of towing and coupling devices and their characteristic elements is often included in the theoretical exam.
In essence, this question tests understanding of the requirements of Section 31 of the Traffic Rules regarding the technical condition of vehicles and their equipment, in particular the prohibition of operation in case of a faulty towing and coupling device. It is also related to the definitions from paragraph 1.10 of the traffic rules (the concepts of road train and trailer), since in the composition of a road train, the serviceability and correctness of coupling are critical.
To briefly analyze the options: for a hook-type coupling device of the "hook–loop" type, typical parts are those that ensure the capture and retention of the loop: a latch with a locking pawl as an element of the locking mechanism is quite logical, as is the lifting device of the kingpin, which is used for coupling-uncoupling operations and fixation. In contrast, a guide flange is more characteristic of other types of couplings where more precise centering is required during docking; in the "hook–loop" design, it is usually intended to work with permissible play and without additional guiding elements, so such a flange is not a typical feature of a hook-type device.
Clause 1.10 (term “Road train (vehicle combination)”)
Road train (vehicle combination) — a motor vehicle connected to one or more trailers (semi-trailers).
Clause 1.10 (term “Trailer”)
Trailer — a vehicle designed to move in conjunction with a motor vehicle.
Clause 31.4 (section 31 “Technical condition of vehicles and their equipment”)
The operation of vehicles is prohibited according to legislation in the presence of technical malfunctions and non-compliance with standards related to road safety and environmental protection.
Clause 31.4 (section 31 “Technical condition of vehicles and their equipment”, requirement regarding the towing-coupling device)
The operation of a vehicle (including as part of a road train) is prohibited in case of malfunction of the towing-coupling (coupling) device and/or devices ensuring the reliability of the connection between the tractor and the trailer.
Explanation of the application of the clause: the Traffic Rules check the understanding that the coupling in a road train must be technically sound and comply with safety requirements; the structural elements of a specific type of coupling (in particular, the “hook-eye” type) belong to knowledge of vehicle construction, not to separate definitions of the Traffic Rules.
That is, the correct answer is “Guide flange.”, given that according to the definition in the Traffic Rules, the emphasis is on the serviceability and safety of the towing-coupling device as part of the road train, and the “guide flange” is not a characteristic element of the hook-type coupling device of the “hook-eye” type.
The hook-type towing-coupling device is used in a “hook–loop” type connection, where one element (the hook) on the towing vehicle enters the coupling element of the trailer (the drawbar loop) and is secured by a locking mechanism. This scheme is designed to operate in more challenging road conditions and allows for certain clearances, making it easier for the driver to couple and uncouple the vehicles.
The hook device is characterized specifically by elements that ensure the capture and retention of the loop: the hook, the lock (latch), and components that prevent the loop from slipping off during movement. Since coupling is often performed manually and with possible misalignments on uneven surfaces, the design provides sufficient clearance in the “hook–loop” pair, rather than precise centering through additional guiding components.
A guiding flange as a structural element is typical for other types of coupling devices, where more rigid guidance and centering are required during docking. In the hook-type variant, such a part is not essential and is not considered “characteristic” structurally, since the main function is performed by the entry of the loop onto the hook and its fixation by the lock.
Therefore, the correct answer is “Guiding flange,” since for a hook-type “hook–loop” device, the hook and locking elements are characteristic, while the guiding flange is not a typical component of this design.