Perhaps the most lasting legacy of Model Products Corporation on the history of Lionel trains was its use of a material called Delrin. And their competitors, including Marx and K-Line, quickly started using it too. But what is Delrin, and why was it better than the tried and true stuff Lionel Corporation used?
Delrin is a trademark of DuPont, a type of plastic called Polyoxymethylene POM. You can cast parts from it like other plastics such as styrene or ABS, but it is slippery and self-lubricating.
Advantages of Delrin over styrene or ABS
During the postwar era, Lionel made its trucks from diecast zamac or styrene, depending on the price point it wanted to hit. The diecast trucks looked realistic and had reasonably good rolling properties. The plastic trucks became notorous for developing an unrealistic white film on the surface as they aged. As the postwar era wore on, Lionel worked out that issue and used plastic trucks more frequently as a way to control costs, especially during the troubled Cohn era.
In the late 1960s, Lionel Corporation went bankrupt. Meanwhile, the cereal company General Mills was turning itself into a conglomerate, buying up toy companies. General Mills bought Lionel in 1970, hoping its managers from other toy companies could turn it around.
One of the things Lionel’s new managers at General Mills’ Model Products Corporation subsidiary looked at was the humble truck. This is the assembly that holds the wheels and couplers underneath model railroad boxcars, gondolas, and other rolling stock. They knew about a DuPont product called Delrin, that was a slippery, self-lubricating plastic. By making two subtle changes to the design, they could lower the cars’ rolling resistance, allowing for longer trains. The first change was molding new trucks out of DuPont’s Delrin plastic. The second change was sharpening the ends of the axles to a point to reduce the surface area.
You can lower the rolling resistance further by adding a drop of oil to each bearing point, but it’s unnecessary.
The power behind Pullmor
One way MPC sought to differentiate itself from Marx, its last remaining competitor in the United States, was to say it could pull longer trains. So they dusted off Pullmor, an old American Flyer trademark, and applied it to… the motor. MPC’s trains really could pull more, but it was because of the new plastic trucks and the needle-sharp axles. The motor was the same as it ever was. But people get more excited about motors than plastics. Remember the movie The Graduate? Dustin Hoffman’s character wanted to experience life, and the adults in his life–other than Mrs. Robinson–wanted him to get into plastics. Even by the late 60s, plastics were easy to cast as dull and boring.
Bragging about the new motor was better marketing, even if it was the same as the old motor.
MPC had some good ideas but fell short of recapturing the golden era of the postwar years so it’s trendy to dish on it. But General Mills’ foray into toys wasn’t the unmitigated disaster people make it out to be. Another company General Mills bought in the late 60s was Kenner, and it was under their ownership that Kenner licensed the rights to produce Star Wars toys, which became a gold mine for everyone involved.
The use of DuPont’s slippery plastic continued even after General Mills sold off Lionel to new ownership and most of their competitors, notably K-Line, copied it. Though it wouldn’t surprise me if the competitors, and perhaps Lionel itself, use a knockoff today.
Marx and Delrin
Speaking of Marx, and motors, Marx made use of Delrin too. They didn’t cast trucks out of Delrin, but they did start making their motor brush plates out of the slippery plastic in the 1970s. This allowed them to remove a brass bearing, which reduced costs and the part count.
Disadvantages of Delrin
Of course, most advantages come with a tradeoff. Delrin is flexible so it’s hard to break, but like any plastic, if you stress it enough, it will snap. And while many plastics are hard to glue, Delrin’s slippery properties make it even harder to glue than others. I won’t say impossible, but it’s extremely impractical. So if a Delrin truck breaks, it’s really difficult to fix it, unlike other Lionel parts.
That said, these parts have been in continuous production more than 50 years, so if you have a broken truck, replacements are available and reasonably inexpensive.
In most cases, friction isn’t very sensitive to surface area – it doesn’t even show up in the classic physics equations for friction. Tapering the axle ends is more about reducing the torque on the axle caused by friction, because the friction occurs closer to the center of rotation.