IMPROVEMENT OF THE DESIGN OF THE WHEEL OF THE TRANSFER BOGIE FOR MOVING METRO CARS FOR PLACEMENT FOR REPAIR WORK OF THE STATE UNITARY ENTERPRISE "TASHKENT METRO", ROLLING STOCK REPAIR DEPOT (TC-3)

ABSTRACT

To enhance the reliability, operational efficiency, and longevity of the maintenance system, this research focuses on improving the transfer bogie wheel design used at the Tashkent Metro rolling stock depot. The primary objective is achieved by developing a new wheel unit that replaces the bronze bushing with two No. 314 rolling bearings (ball bearings). This design optimization aims to reduce maintenance costs and downtime associated with frequent bushing replacement, simplify lubrication, decrease rolling resistance, and ultimately accelerate the overall repair cycle for metro cars.

АННОТАЦИЯ

Для повышения надежности, эффективности эксплуатации и долговечности системы технического обслуживания данное исследование направлено на совершенствование конструкции колеса переводной тележки, используемой в депо подвижного состава Ташкентского метрополитена. Основная цель достигается путем разработки нового колесного узла, в котором бронзовая втулка заменена двумя подшипниками качения № 314 (шариковыми подшипниками). Оптимизация конструкции направлена ​​на снижение затрат на техническое обслуживание и простоев, связанных с частой заменой втулок, упрощение процесса смазки, снижение сопротивления качению и, в конечном итоге, ускорение общего цикла ремонта вагонов метро.

Keywords: machine, mechanism, kinematic pair, kinematic chain, classification of kinematic pairs.

Ключевые слова: трансбордерная тележка, колесный узел, рельсовая путь, опора скольжения, опора качения, опорные втулки.

Introduction. A tram is a railway system designed to transport passengers and it weighs less than other railway vehicles. The tram also provides easy access to towns and cities as the tracks are placed on vehicular roads. In addition, the infrastructure of the tram enables easy construction. The efficiency and speed of metro car maintenance are critically dependent on the support equipment used to manage these massive vehicles. When metro cars require inspection or heavy repair, they must be moved from the main line to specialized repair bays, often necessitating the use of transfer bogies (or translation trolleys). This process, however, is a common bottleneck in the maintenance lifecycle.

The current design of the transfer bogie wheels often presents limitations—such as issues with excessive wear and tear, high rolling resistance, noise levels, or inadequate load distribution—which can lead to frequent equipment downtime, increased energy consumption, and slower overall car movement within the depot.

This research focuses on the Improvement of the design of the wheel of the transfer bogie for moving metro cars for placement for repair work. The primary objective is to develop an optimized wheel design that enhances the reliability, operational efficiency, and longevity of the transfer bogie system. By focusing on material selection, profile geometry, and load-bearing mechanisms, this study aims to reduce maintenance costs, accelerate the repair cycle, and contribute to the overall resilience of urban rail transit operations.

The Tashkent Metro rolling stock repair depot operates a transfer trolley, which is designed to move metro cars onto the tracks of the rolling stock repair depot and back onto the operational tracks of the Tashkent Metro. The transfer trolley moves along the transverse track on its own special wheels. The transfer trolley wheel is a solid (cast) wheel with a pressed bronze bushing 260 mm in diameter and 125 mm in height, with an internal shaft seat diameter of 215 mm. With prolonged use, the bushing becomes unusable due to wear, requiring replacement. Replacement is a labor-intensive and expensive process. Manufacturing the bronze bushing requires a blank of BROTC tin bronze or BRAJM aluminum bronze; the specific weight of each bushing is approximately 20 kg. Another operational inconvenience is lubrication, which requires intensive application. The wheel assembly design is inconvenient for this process, creating difficulties for maintenance personnel during lubrication. For this purpose, a new version of the wheel unit of the transborder trolley was developed; in place of the bronze bushings, two No. 314 rolling bearings (ball bearings) were installed.

Figure 1 shows the design of wheel assemblies with a bronze bushing and using ball bearing № 315.

a)

b)

Figure 1. Design of a wheel assembly with a bronze bushing (a), design of a wheel assembly with ball bearing No. 315 (b).

Figure 2. Transfer trolleys

The characteristic features of the two types of wheel assemblies are evident in the figure; for durability, the bearings are installed in a sealed design.

This paper addresses a critical maintenance bottleneck in urban rail transit: the movement of metro cars within repair depots using transfer bogies (translation trolleys). While trams and metro systems offer high-capacity transport, their maintenance efficiency relies heavily on the supporting equipment. The current design of the transfer bogie wheels—specifically the solid (cast) wheel utilizing a pressed bronze bushing—presents significant operational drawbacks, including high friction, excessive wear, and a labor-intensive, costly maintenance process for the $20 \text{ kg}$ bronze bushing replacement and intensive lubrication.

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