The Dover Harbor is silent now. No friendly Pullman porters walk its halls, no well-heeled passengers call for drinks or nap in its paneled sleeping compartments. An era of luxury rail travel has ended on a lonely siding in Silver Spring, yards from where sleek Metrorail cars hiss their way to and from the District.

But every Saturday for a few hours, the Dover Harbor--a 93-ton marvel of engineering and one of only two such railroad cars left in the country--comes alive again. Under the care of a small band of railroad buffs from Maryland and Virginia, the car is being restored to a condition that recalls the golden years of American railroads, when trains were virtually the only mode of long-distance travel.

Members of the Washington chapter of the National Railway Historical Society have spent three years replacing expensive mechancial parts and mahogany fittings, stripping layers of paint, polishing brass fixtures and rewiring an elaborate buzzer system once used to summon porters.

"Even when the going is slow, it's still pretty enjoyable," said Bernie Gallagher of Beltsville, one of the mechanics on the restoration job. The work already has cost $50,000, and it will continue for at least two more years.

The job has brought together an unusual assortment of government workers, military officers and technical people--all of them in love with trains and each quietly fanatical about restoring the car down to the last screw and carpet tack.

"What's neat about it is that it's not everyday work," said Rhonda Ward, who was curious about the train a year ago and stayed on to help with the restoration.

Ward, a nurse at the Bethesda Naval Hospital, spent several hours last Saturday polishing the trains compact, stainless steel stove while her husband, Larry, an electric systems designer, ran wires through bulkheads in the car's roof and walls.

The 400-member railroad chapter paid $15,000 for the car in 1979--a bargain price compared with the $52,500 it brought in an earlier sale. Built in 1923 by the Pullman Co. of Chicago, the 83-foot-long Dover Harbor was first called the "Maple Shade" and included a lounge area, barber shop and baggage section.

After 11 years on Pennsylvania tracks, the car was rebuilt and fitted with six double bedrooms, a buffet area and a lounge, complete with thick carpeting, massive armchairs and dark mahogany sidetables. Renamed the Dover Harbor in 1934, it joined eight other restaurant-sleeper cars in Pullman's Dover fleet.

"What's special about the Dover Harbor is that it's only one of two that we know of in the country that have been restored to what it was like in the '30s," said Stan Gimbert, a Voice of America employe and a member of the restoration team.

The painstaking restoration has been slow: Repairing the car's leaky roof took the better part of two years, as workers broke one grinding wheel after another stripping the roof down to bare metal. The car's self-contained power system, a complex system that includes a 39-kilowatt diesel generator, pumps and compressors, had to be specially made. New wheels and couplers were added to make the car "Amtrak-compatible"--able to be pulled by modern locomotives over modern track.

But the Dover Harbor's beauty is inside its steel-sheathed walls, say those who work on the car. "The subtleties of engineering are simply incredible," Larry Ward said. "Sure, the way Pullman did things may have been crude compared to what we'd do now, but they worked."

The car was designed with the passenger's comfort in mind. Each thickly padded sleeping berth had its own buzzer to call porters, as did each armchair in the lounge. Sleeping compartments had four-speed fans--"the first in the country," Ward said--and compartment doors were fitted with thin metal flanges to prevent an occupant from being pinched as the door swung shut.

Some of the creature comforts were hidden. The Dover Harbor's floor, made of horsehair stuffing sandwiched between two steel sheets that were topped by two inches of concrete, is still impervious to the cold. Electrical conduits in the walls and ceiling were fitted so exactly that to this day they don't rattle, Ward said. The air conditioning system, vintage 1934, keeps the car a cool 70 degrees in 100-degree weather.

The railroad society has run the Dover Harbor on several charter trips between Alexandria and Charlottesville, Va., to raise money for the renovation. The car was featured in a recent public television documentary on Pullman porters and served as the backdrop for a fashion layout in a glossy Washington magazine.

"For most people who who ride the Dover, or the people who just want to see the inside of the car, it represents luxury, I guess," said Gallagher, who works as a machinist in the District. "Me, I just love trains. All of us here do. And the Dover Harbor is a special kind of train."