{"product_id":"intermountain-48915-04-procor-pressure-flow-hopper-norfolk-southern-292372-ho-scale","title":"InterMountain (48915-04) | Procor Pressure Flow Hopper | Norfolk Southern #292372 | HO Scale","description":"\u003cp data-start=\"0\" data-end=\"282\" class=\"\"\u003ePressure 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.\u003c\/p\u003e\n\u003cp data-start=\"284\" data-end=\"797\" class=\"\"\u003eIn 1964, the American Car \u0026amp; 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.\u003c\/p\u003e\n\u003cp data-start=\"799\" data-end=\"1085\" class=\"\"\u003eThe 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.\u003c\/p\u003e\n\u003cp data-start=\"1087\" data-end=\"1489\" class=\"\"\u003eThe 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.\u003c\/p\u003e\n\u003cp data-start=\"1491\" data-end=\"1828\" class=\"\"\u003eThe 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.\u003c\/p\u003e\n\u003cp data-start=\"1491\" data-end=\"1828\" class=\"\"\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003eFeatures:\u003c\/strong\u003e\u003c\/span\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli data-start=\"1491\" data-end=\"1828\" style=\"font-weight: bold; color: rgb(43, 0, 255);\"\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003eLaser Sharp Painting and Printing\u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003cli data-start=\"1491\" data-end=\"1828\" style=\"font-weight: bold; color: rgb(43, 0, 255);\"\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003eEtched Metal Roofwalks and End Ladders\u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003cli data-start=\"1491\" data-end=\"1828\" style=\"font-weight: bold; color: rgb(43, 0, 255);\"\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003eIndividual Separately Applied Valve Handles\u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003cli data-start=\"1491\" data-end=\"1828\" style=\"font-weight: bold; color: rgb(43, 0, 255);\"\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003e36\" InterMountain Metal Wheelsets\u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003cli data-start=\"1491\" data-end=\"1828\" style=\"font-weight: bold; color: rgb(43, 0, 255);\"\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003eMetal Knuckle Couplers\u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003cli data-start=\"1491\" data-end=\"1828\" style=\"font-weight: bold; color: rgb(43, 0, 255);\"\u003e\u003cspan style=\"color: rgb(43, 0, 255);\"\u003e\u003cstrong\u003eMinimum Radius - 22\" \u003c\/strong\u003e\u003c\/span\u003e\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"InterMountain","offers":[{"title":"Default Title","offer_id":47713123270794,"sku":"48915-04","price":49.99,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0685\/3954\/7786\/files\/48915wl.jpg?v=1746926078","url":"https:\/\/denvertrains.com\/products\/intermountain-48915-04-procor-pressure-flow-hopper-norfolk-southern-292372-ho-scale","provider":"Denver Model Trains      ","version":"1.0","type":"link"}