Freight car trucks are an essential component of freight cars, providing support, stability, and smooth movement along the tracks. Over the years, hundreds of truck designs have been developed, each tailored to meet the needs of different car types and load requirements. Each truck supports half the weight of a carbody and its cargo, thanks to a pair of bolsters integrated into the car’s underframe.
The major parts of a truck frame are made from cast steel, machined to precise specifications for proper fit and performance. Central to the truck’s functionality is a cast-steel bolster, which connects the sideframes and houses a kingpin. This kingpin aligns the truck under the carbody while allowing it to swivel, ensuring smooth operation even on curves.
Heavy-duty springs, typically packaged in sets of five or more, play a critical role in shock absorption and weight distribution. These springs, combined with robust construction, determine the truck’s load capacity.
Older freight cars used solid bearings—sometimes incorrectly referred to as “friction bearings”—that rest atop the axle journals in a housing partially filled with lubricating oil. Modern trucks, however, feature roller bearings pressed directly onto the axles, reducing friction and improving efficiency.
Freight trucks typically have two axles, each with machined wheels pressed onto collars near their ends. These wheels ensure smooth and reliable operation, supported by journals at the axle extremities that fit securely into the sideframe bearings.
The capacity of a freight truck is defined by the total weight it can carry, encompassing both the empty car and its load. Early wooden freight cars were limited to 30-40 tons, while late steam-era steel cars could handle 50-55 tons. By the late 1950s, truck capacities had increased to 70 tons, and by the 1960s, they reached 100 tons. Today, many freight cars remain in the 70-ton range, but specialized cars, such as articulated double-stack intermodal units, can handle loads of 100 to 125 tons.
The Archbar Truck
The Archbar truck was one of the most common designs in the early days of railroading. It was constructed from shaped steel bars and journal box castings that were bolted together. While these trucks were reliable for their time, they required frequent maintenance, including the regular tightening of bolts, which was labour-intensive.
By the 1920s, cast-steel trucks began to replace Archbar trucks due to their greater durability and reduced maintenance needs. Archbar trucks were officially banned from interchange service after 31 December 1939, although a few remained in use on maintenance-of-way cars for some years thereafter.
The Andrews Truck
The Andrews truck featured partially cast sideframes, which addressed many of the maintenance challenges associated with the Archbar truck. Like its predecessor, it utilised individual journal boxes, but its design included bolted reinforcements between the lower sideframes and the journal boxes, making it easy to identify.
Introduced in 1910, Andrews trucks were manufactured through the 1930s. One of their major advantages was the ability to reuse the older Archbar journals, a cost-effective feature that significantly contributed to their popularity during their time in service.
The Vulcan Truck
The Vulcan truck, introduced in the 1920s, was another cast-steel replacement for the Archbar truck. Its sideframe design featured reinforced journal box supports at both ends, improving strength and durability. The journal boxes were secured with a pin, enabling quick and straightforward replacement, which made the design particularly practical.
The Vulcan truck remained in use until the end of the mainline steam era. However, it continued to serve for much longer on logging railroads and short line maintenance equipment, particularly where cars were confined to the owner’s property and did not enter interchange service
The Bettendorf T-Section Truck
The Bettendorf T-section truck marked the beginning of a new generation of truck designs. In this configuration, the journal boxes were cast as integral parts of the diamond-shaped sideframes, providing greater strength and reliability. The Bettendorf Company introduced this design, featuring a T-shaped cross-section, as early as 1903. It became a popular choice for general service and remained in widespread use through the 1920s.
Like other solid bearing trucks of the time, the Bettendorf design used cast brass bearings. These bearings were fitted into a notch in the upper part of the journal box, with their curved bottoms resting on the axle ends, ensuring smooth operation and durability.
The Bettendorf Truck
The Bettendorf design truck represented a significant improvement over the earlier T-section version, featuring a stronger cast construction with a larger cross-section. This rugged and durable design gained widespread popularity, and although many manufacturers produced similar trucks, the name “Bettendorf truck” became commonly associated with it due to the Bettendorf Company’s extensive licensing of its design.
The truck’s U-shaped cast-steel cross-section was adopted as an early industry standard. A later evolution of this design became the AAR (Association of American Railroads) Type Y standard truck, solidifying its place as a benchmark in freight car truck design.
The American Steel Foundries (ASF) 50-ton
The American Steel Foundries (ASF) 50-ton A-3 Ride Control truck was introduced during World War II and quickly became one of the most popular truck designs of its era. Marketed as offering a smoother ride, the A-3 design reduced wheel and spring wear and was less damaging to track and roadbed, making it a practical choice for railroads.
The A-3 Ride Control trucks were widely adopted due to their durability and performance. Each truck’s specifications, including its manufacturer, AAR truck type, spring package details, and railroad owner, were cast into the sideframes, providing a clear identification of its features and origin. This attention to detail contributed to the truck’s rapid success and enduring legacy in freight car design.
The ASF 70-ton Roller-Bearing Truck
The ASF 70-ton roller-bearing truck is a later development of the ASF Ride Control design, featuring heavier sideframes and a pair of visible springs on the exterior. These trucks incorporate roller bearings, which include rotating axle end caps, replacing the traditional journal boxes with their hinged lids.
Roller-bearing trucks offer significant advantages over older designs, including reduced friction and improved efficiency. Due to their superior performance and durability, regulations introduced in 1966 mandated that all new freight cars be equipped with roller-bearing trucks, making them the standard for modern railroading.
The ASF 100-ton Roller-Bearing Truck
The ASF 100-ton roller-bearing truck is a heavy-duty evolution of American Steel Foundries’ Ride Control design, engineered to handle the demands of modern high-capacity freight cars. Featuring three visible exterior springs, it provides increased strength and stability for heavier loads. The roller-bearing system replaces traditional journal boxes, offering reduced friction, improved efficiency, and lower maintenance requirements.
Introduced to meet the growing needs of the rail industry, the 100-ton truck became indispensable for freight cars requiring greater weight capacities. Its robust construction and reliable performance have made it a standard choice for industries relying on heavy-duty transportation, cementing ASF’s reputation as a leader in railcar truck innovation.
Micro-Trains 1051 – 1 pair = 003 02 010, 10 pairs = 003 10 010
http://www.spookshow.net/trucks/andrews.html
N Scale Bettendorf Truck Measurements
| Manufacturer | Type | Wheelbase (mm) | Frame Width (mm) | Wheel Size (inches) | Axle Length (mm) |
|---|---|---|---|---|---|
| Micro-Trains | 50-ton | 10.1 | 16 | 33 | 13.7 |
| Atlas | 40-ton | 10.25 | 15.9 | 33 | 14.25 |
| Atlas (Original) | 50-ton | 10.5 | 16 | 33 | 13.6 |
| Atlas (Revised) | 50-ton | 10 | 16.7 | 33 | 14.25 |
| Intermountain | 50-ton | 10.07 | 15.93 | 33 | 14 |
| Broadway Limited | 70-ton | 10.25 | 17.23 | 33 | 13.7 |
http://www.spookshow.net/trucks/bettendorf.html
More Information
- Fugate, Joe. Make It Run Like A Dream – Rolling Stock. MRH Media, 2018, pp.28-36.
- Wilson, Jeff. The Model Railroader’s Guide To Freight Cars. Kalmbach Books, 2005, pp. 80-84.