57.2. Indicate the most common types of coupling devices for cargo vehicles – tractors.
UAВкажіть найбільш поширені види тягово-зчіпних пристроїв вантажних транспортних засобів – тягачів.
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This exam question from the Traffic Rules of Ukraine concerns the safe formation of a road train and the reliability of connecting a cargo tractor to a trailer unit. Understanding the types of coupling devices is important not only for the theoretical exam but also for practical driving: proper coupling affects the transmission of tractive effort, stability during movement, braking, and maneuvering, especially when carrying cargo.
The question tests terminology and basic definitions from the “General Provisions” section of the traffic rules, specifically clause 1.10 (the concepts of “Trailer”, “Semi-trailer”, “Road train”). The logic is simple: for trailers with a drawbar in everyday use, hook coupling is most commonly used (tractor hook and drawbar eye), while for semi-trailers, the standard is a fifth-wheel coupling without a gap, where fixation occurs through the kingpin of the semi-trailer. These two solutions are the most widespread for cargo vehicles-tractors.
When comparing the options, the correct description should cover both real “mass” schemes: hook coupling for working with a trailer and gapless kingpin coupling for a semi-trailer. Formulations with “ball” couplings are more typical for passenger cars and light trailers, so for cargo tractors, this does not fit the context. The option with “hookless and with a gap in the kingpin” does not reflect the most common design of the fifth-wheel coupling, which in training materials and on the theoretical exam is presented as gapless with kingpin fixation.
Clause 1.10 (term “Trailer”)
Trailer — a vehicle designed to move in conjunction with a motor vehicle. Trailers include semi-trailers and dolly trailers.
This term in the Traffic Rules sets the general framework for coupling a tractor with a trailer combination (including via hook-type coupling devices).
Clause 1.10 (term “Semi-trailer”)
Semi-trailer — a trailer that rests its front part on the fifth-wheel coupling device of the tractor.
The mention of the “fifth-wheel coupling device” in the Traffic Rules directly refers to the gapless coupling of the tractor with the semi-trailer (structurally, this connection is implemented via the kingpin of the semi-trailer).
Clause 1.10 (term “Road train”)
Road train — a motor vehicle connected to one or more trailers.
The question essentially tests the understanding of which types of coupling devices are used in practice to form a “road train” (hook-type — for trailers with a drawbar, and gapless fifth-wheel couplings — for semi-trailers).
That is, the correct answer is “Hook-type and gapless with kingpin,” given that, according to the Traffic Rules, coupling with a trailer/road train covers both the connection of a tractor with a trailer (typically with hook-type devices) and with a semi-trailer via a fifth-wheel coupling device (typically gapless coupling with a kingpin).
When a cargo vehicle operates as a tractor, its main task is to reliably connect with a trailer or semi-trailer so that during movement it can safely transmit tractive force and withstand the load. In practice, two structural solutions for coupling devices are most commonly used in Ukraine, and these are the ones expected in the exam answer.
The first common option is the hook-type coupling device. It is mainly used when the tractor tows a trailer with a drawbar: the drawbar has a coupling loop that is secured on the tractor’s hook. This type is valued for its simplicity, quick connection and disconnection, and that is why it is widely used on cargo vehicles working with conventional trailers.
The second common option is the fifth-wheel coupling device with a kingpin, that is, a saddle-type coupling mechanism. It is typical for tractor units with semi-trailers: the semi-trailer is equipped with a kingpin that enters the tractor’s fifth wheel and is secured by a lock. This solution provides a reliable connection and proper load distribution between the tractor and the semi-trailer, which is the standard for long-haul transport.
These two types are the most typical for cargo tractor vehicles: the hook for trailers with a drawbar and the fifth-wheel coupling with a kingpin for semi-trailers. Other designs are much less common and are not considered “the most widespread” in the context of the exam question.
Therefore, the correct answer is "Hook-type and fifth-wheel with kingpin," since most often tractors are connected either by a hook with a drawbar coupling loop or by a fifth-wheel device where the semi-trailer is secured by a kingpin.