Newton, MA--When ZEF-TEK(reg) engineers (Montgomery, AL) set out to create a better rail-car hatch cover, they concentrated on finding a material that would best fill the bill for the new design's major components. They found that material in a specialty compound formulated by RTP Co. (Winona, MN) material specialists.
"Other hatch covers were poorly designed and made from blow-molded polyethylene," explains John Anderson, manager of engineering for ZEFTEK. "Our new covers use a center hatch ring that exerts tremendous force to create an even seal. The material we selected had to withstand this pressure."
RTP developed the special ZEFTEK compound for the cover's hood, base, and pellet screen frame that provides enough stiffness to keep the cover from buckling. The material also exhibits strong impact resistance, having a notched impact strength of 16 ft lbs/inch (854J/m) and a Rockwell R hardness of 115.
"We tried to balance economics with performance," Anderson adds. "RTP came through with the versatile compound that met our demands for stability, strength, color, and price. It's difficult to find a single material that can do all of this well."
The cover must last many years. As a result, the compound has a UV-stabilized formulation that will maintain long-term cosmetic appearance. With a heat-deflection temperature of 240F/264 psi (116C/1,820 kPa), covers can operate reliably in a wide range of temperatures--from 200F down to -50F.
Not only does the new cover design maintain the integrity of the rail-car compartment, it protects the car's contents from damage. Its umbrella style seals out water contaminants. Baffles in the base also prohibit water from drifting to the cover's center.
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