InterMountain Procor Pressure Flow Hopper - Canadian National CN #374541 - HO Scale

Pressure flow hopper cars, commonly known as "Flexi-Flo" hoppers, revolutionized the transportation of dry bulk commodities by rail. Developed in the 1960s, these cars utilized pressure differential technology to efficiently unload materials such as cement and other dry bulk goods.

In 1964, the American Car & Foundry (ACF) introduced the PD3500, a 3,500-cubic-foot pressure differential covered hopper, branded as "Flexi-Flo." This design featured a cylindrical shape and eliminated the traditional center sill, allowing for a single outlet centered between the rails. By applying air pressure inside the car, the contents could be rapidly discharged into pressure-equipped trucks or storage facilities, significantly improving unloading efficiency compared to conventional gravity-fed methods.

The New York Central Railroad (NYC) was among the first to adopt this technology, purchasing 220 Flexi-Flo hoppers in the mid-1960s. These cars were primarily used to transport cement, aiming to recapture business lost to trucking by offering faster and more reliable unloading options.

The development of pressure flow hopper cars can also be credited to advancements in bulk material handling research. Engineer Andrew W. Jenike, in the 1950s, laid the groundwork for hopper design principles that facilitated mass flow of bulk solids. His research led to the development of the Jenike Shear Tester and provided guidelines that influenced the design of pressure differential hopper cars.

The introduction of Flexi-Flo hoppers marked a significant shift in rail freight, offering efficient unloading and helping railroads compete with the growing dominance of trucking. Today, pressure differential technology remains a standard feature in hopper car designs, underscoring their lasting impact on bulk material transportation.

Features:

• Laser Sharp Painting and Printing
• Etched Metal Roofwalks and End Ladders
• Individual Separately Applied Valve Handles
• 36" InterMountain Metal Wheelsets
• Metal Knuckle Couplers
• Minimum Radius - 22"