Some people never stop playing with trains.

Take 84-year-old Bill Ewing of Anderson Township, whose ''toy'' is a real, bright yellow B&O Railroad caboose, for which he paid $2,500 15 years ago.

He keeps it in the rail yard of the Railway Museum of Greater Cincinnati, in Covington's Latonia neighborhood, where he and other volunteers work on the museum's 80-piece collection every Wednesday and Saturday.

''It's just something that gets under your skin and never lets it go,'' he said.

The caboose serves as Ewing's home away from home and as a storeroom for his personal railroad memorabilia collection.

A 20-year-old photo of him in uniform as a conductor on the Indiana and Ohio Railroad hangs on the wall. Nearby hangs a photo of a passenger car with a glass dome, which the museum sold for $350,000 to pay for a fence around its exhibits.

Hand-held switch lamps, used to give the green light to trains switching tracks, hang from the ceiling.

The collection began in 1975 when a club of local railroad enthusiasts decided to run passenger cars on Amtrak trains, said Tim Hyde, the museum's vice president of operation. At that time, the only cars available to them were 1940s and 1950s models.

In the late 1980s, Amtrak tightened its restrictions on passenger cars, making it too expensive for most private citizens to keep them up. So the Amtrak excursions ended, but the collection remained, Hyde said.

The museum is supported through admissions fees, a gift shop and contributions.

In the rail yard, each car has a unique story, and Ewing is eager to tell them.

A tiny green engine with a No. 1 on its face used to push coal into a power house, he said.

He helped paint a dark green passenger car, which he said was at least 75 years old. ''It's priceless,'' he said.

A red passenger car, which had two master bedrooms and a shower, was one of four end cars for the Broadway Limited in New York, volunteer Bill Williams said.

An E-9 General Motors locomotive nearby, or one like it, might have pulled that train. The railroaders are in their fourth year of restoring the locomotive.

Williams walked through the old iron horse, a well-worn and blackened pair of cloth gloves in his back pocket, a Huntington railroad cap on his head. He stopped to unlatch an observation port and exposed a huge piston, covered in black grease.

It's a tight fit through the narrow corridor, and it must have been hellishly hot with the pistons pumping. Williams pointed out the tiny air vents in the wall overhead.

A theatrical baggage car on the track beside the locomotive will serve as a mobile staging area for the renovation. The car is a Juliet model, one of 47 built by the Pennsylvania Railway between 1917 and 1922.

There was a Romeo model, Williams said, but it has long since been cut up into razor blades.

The Juliet showed her age last week, when the heavy steel threshold for its sliding side door fell off, prompting Hyde to make repairs.

He squirted WD-40 onto a row of bolts to loosen them. When working on an old train, you learn how to deal with rust and how to hit things, he said, gesturing with a really big hammer in his hand.

The Walnut Hills resident designs multi-media presentations for a living. Volunteering at the museum gives him a chance to do things he can't at work.

''It's dirty. It's big. I can hit it with a hammer,'' he said.