During the post-war era, Lionel supplied its dealers with adapters that allowed pre-war box couplers to work with the post-war knuckle couplers.
Lionel themselves hasn’t made these adapters for decades, but reproduction parts dealers make reasonable copies of them that we can still purchase and use today.
The two parts were called the TT-100 and the TS-162. The TT-100 was for 600- and 2600-series 027 cars, while the TS-162 was for the larger 800- and 2800-series O gauge cars. The difference between the two parts was an l-shaped bend to adjust the coupler height. The height on the 2600 series cars was about right for the postwar knuckle coupler, but the 2800 series cars loom large over the old gauge cars, so that adapter has a step down to reach the knuckle coupler.
The adapter is deceptively simple. It fits over the hook on the earlier coupler and changes the end to match up with a knuckle coupler. It renders the coupler inoperable except in conjunction with a knuckle coupler. You cannot couple two cars with the adapter together. There are also some problems when you install the adapter. Lionel explained in their service manual how to install the adapter so that it won’t fall off while a train is running, but parts dealers don’t always supply that page. And I think the instructions could have been a bit more clear.
So if you came here looking for instructions, you found them.
Installing the Lionel TT-100 or TS-162 coupler adapter
The adapter has two grooves in it. One of those groups matches a lip inside the box coupler. The other groove matches with the hook. Line the adapter up so that one of the grooves is inside the box coupler, and the second lines up with the hook.
Stopping here is where most people make the mistake. The fit may be fairly tight, but under the stress of running a train, especially around a curve, the adapter can work its way loose. It also may need some slight adjustment to stay coupled with a knuckle.
Refer to the diagram below.
Position A tightens the hold on the adapter. Squeeze the adapter at position A to tighten it. You don’t have to cinch it down crazy tight, just enough to eliminate any play in the adapter.
Next, try the fit out against a post war or modern car with a knuckle coupler. The adapter should line up with the middle of the knuckle. If it seems excessively high or low, uncouple the car, and bend the adapter at point B to adjust the height until it meets the middle of the knuckle. This makes it much less likely that a bump in the track will cause the two cars to uncouple.
Disadvantages of the coupler adapter and alternatives
There are two complaints about this adapter. The first is that it can come off while running, although the adjustments I described in the section above will eliminate that.
The second problem is harder to do much about. The adapter increases the gap between the cars by a noticeable amount. Some people don’t mind it, but now that I’ve pointed it out to you, it might bother you.
There are three alternative ways to adapt pre-war cars to work with post-war cars.
You can install a post-war knuckle coupler on one side of the car to replace a box coupler, the same way I convert Marx cars to work with Lionel. This adapter, part# 480-25, works better on Marx and Lionel Scout cars because it doesn’t exactly match the wheel spacing on the prewar cars, but it will work, and I’ve seen prewar cars with this adapter installed.
You can also replace one of the box couplers with a 1938 American Flyer curly q coupler. This coupler is not exactly common because AC Gilbert produced it for exactly one year before switching to link couplers, but parts dealers sometimes carry reproductions. Coincidentally, this 1938 sheet metal coupler will connect up with a post-war Lionel knuckle coupler.
It didn’t allow automatic coupling and uncoupling, which is why Gilbert switched to the link coupler design, but if you just want to run trains around in circles, the 1938 design works really well and was ahead of its time.
The third option is swapping the trucks with postwar or modern trucks with knuckle couplers.