Railway freight car bogies

Since the founding of the People’s Republic of China, my country’s railway freight car bogies have undergone three major development phases. The first phase, from 1949 to 1963, saw the coexistence of various types of bogies, primarily copied from other models. The second phase, from 1964 to 1997, saw the production and operation of independently designed and manufactured bogies, with the Zhuan-8A bogie as the primary model. The third phase, from 1998 to the present, has witnessed the innovative development of high-speed, heavy-load bogies. During these three phases, four major technological upgrades have been achieved.

The first technological upgrade, from the founding of the People’s Republic of China to the 1970s, gradually eliminated various miscellaneous bogies with poor performance and low axle loads. The simpler, higher-performing Zhuan-8A bogie became the primary bogie for freight cars, increasing freight car operating speeds from 50-60 km/h to 70-80 km/h.

The third technical upgrade was from 2003 to 2011. New freight cars gradually stopped being equipped with 21t axle-load bogies, and 70t-class general-purpose freight cars and 80t-class special-purpose freight cars fully adopted the Zhuan K6 and Zhuan K5 speed-raising heavy-duty bogies, increasing the axle weight of my country’s railway freight cars from 21t to 23-25t and the speed to 100-120km/h.

1. Zhuan K2 Bogie

The Zhuan K2 bogie features a lower cross-bracing device to enhance bogie anti-slip rigidity, suppress vehicle snaking and instability, and improve derailment safety for empty wagons. This improves the dynamic performance of traditional three-piece bogies and meets my country’s railway freight car speed requirements of 120 km/h. The Zhuan K2 bogie is primarily designed for use in my country’s 21-ton axle-load open wagons, covered wagons, flat wagons, tank wagons, hopper wagons, and container wagons.

3. Zhuan K4 Bogie

The Zhuan K4 bogie incorporates new technologies such as two-stage springs, nylon core wear plates, constant-contact elastic side bearings, combined cams, and combined brake beams. It employs a rocker-sway mechanism similar to that used on passenger car bogies, resulting in a two-stage lateral stiffness characteristic. This increases the vehicle’s lateral flexibility, improves lateral dynamics, reduces wheel-rail wear, and enhances vehicle ride quality.

The Zhuan K4 bogie structure builds on the traditional three-piece bogie by adding a spring support plate, improving the bogie’s anti-slip stiffness and vehicle lateral ride quality. It is installed on new models such as the C64H, NX17BH, and C70E(H). It primarily consists of a bolster, side frame, spring support plate, rocker seat, rocker seat support, load spring, vibration damping device, wheelset and bearings, foundation brake system, and constant-contact elastic side bearings.

2. Zhuan K6 Bogie

The Zhuan K6 bogie is an independently designed and developed model based on the Zhuan K2 bogie, featuring an additional primary axlebox elastic suspension. It utilizes new technologies such as primary axlebox elastic suspension, lower cross bracing, two-stage springs, nylon center plate wear plates, constant contact rubber elastic side bearings, combined cams, and a combined brake beam.

The Zhuan K6 bogie is a three-piece cast steel, lower cross-braced bogie, primarily consisting of wheelsets, sideframes, rubber pads, bolsters, foundation brakes, cross bracing, rolling bearings, double-acting elastic side bearings, and cams.

1. DZ1 Bogie

The DZ1 bogie is a high-axle-load, low-power cross-bracing bogie independently developed in my country. It utilizes new technologies, including a lower cross brace, two-stage springs, nylon core wear plates, constant-contact rubber elastic side bearings, combined cams, combined brake beams, a weld-free structure, and integral core casting of the bolster and side frames.

The DZ1 bogie is a three-piece cast steel cross-bracing bogie, primarily consisting of wheelsets, rolling bearings, side frames, bolsters, brakes, spring dampers, elastic side bearings, axlebox rubber pads, and cross bracing. The DZ1 bogie is primarily used on 27t axle-load general-purpose freight cars, such as the C80E, P80, and GQ80.

3. DZ3 Bogie

The DZ3 bogie is a high-axle-load, sub-frame radial bogie developed and designed through independent innovation based on the operational experience of the K7 bogie and related technical research results, with the goal of adapting it to heavy-load transportation on existing lines.

The DZ3 sub-frame bogie is a three-piece cast steel freight car bogie, primarily consisting of a wheelset, rolling bearings, bolster, sideframe, elastic side bearings, brake assembly, spring damper, wheelset radial assembly, and rubber pads. The DZ3 bogie is primarily used on C80EF open wagons.

2. DZ5 Bogie

The DZ5 bogie is a self-developed, high-axle-load, low-power swing bogie. It incorporates new technologies, including a sideframe swing mechanism, primary axlebox rubber suspension, two-stage springs, nylon core wear plates, constant-contact rubber side bearings, combined cams, unitized brake cylinders, embedded splayed wear plates, a weld-free construction, bolsters, and integrally cast sideframe cores.

The DZ5 bogie structure is essentially the same as the DZ2 bogie. The crossbeam support is integrally cast with the sideframes. The DZ5 bogie is primarily used for 30t axle-load special-purpose freight cars, such as the C96H and KM98AH.