Many students enrolled at Fairfax County, Va. schools for the disabled cannot talk. But they greet their teachers every day, pressing a finger or a toe to a switch that prompts a recorded voice to say 'Hello!' or 'Good morning.' The switches are part of a breathtaking array of technology that helps students communicate or turn on music or choose what they want for lunch. Other devices help them move around the building and play sports. With so many gadgets, it helps to have someone handy around to fix them when they break. That's where Lee Jost and Bill Porter come in. Both retired engineers in their 70s, they spent their careers working on satellites or elaborate circuits for the railroads. Now they are tightening loose wires and adjusting wheelchairs. Kilmer Center in Vienna and Key Center in Springfield serve students with severe disabilities, often birth defects or disorders that affect their brains and bodies. The specialized schools have small classes, each with a teacher and two health aides, and students get extra help from physical therapists, occupational therapists, a speech therapist, a psychologist, a social worker, a registered nurse, a vocational coordinator and, not least, a handyman. 'We created a job description, which is Mr. Fix-it,' Kilmer Principal Michael Marsallo said. 'If things break down, we can take care of it on site and make sure students are using the right equipment ... that will lead them to be more independent.' Jost and Porter have never met, but they have traveled similar life paths. Both were born during the Depression to parents who knew how to stretch a dollar by repairing things, not replacing them. They both served in the Army Signal Corps developing communications systems for the military. They worked for rival phone companies before finding their way to special education and the world of assistive technology. Porter, 76, came to Kilmer in the early 1990s with the Telephone Pioneers, volunteers who were asked to design and build an indoor playground that would be safe for students with disabilities. He was nervous at first. 'I didn't want to be around handicapped kids,' he recalled. But his admiration grew for students who were 'doing the best they could,' he said. 'Pretty soon, you realize that you are in love with these kids.' Nearly two decades later, the slides and tunnels have long since been stowed away. But Porter is still there, now a full-time employee, fixing electronics and repairing equipment. Jost, 74, had a personal connection to Key Center: His grandson went to school there. Carson, now 17, was born with Wolf-Hirschhorn syndrome, a rare condition caused by missing genetic material on the fourth chromosome. What's missing, Jost explained, is 'all the instructions for living.' He recalled how a nurse taught his infant grandson to suck by stimulating different nerves in his face, because he did not have that instinct. In 1997, soon after retirement, Jost thought he'd like to volunteer at Key Center but was uneasy working with such fragile students. Then a flier was sent home advertising back-to-school night. 'If you have a wrench or a hammer or a screwdriver, please bring it along,' the flier stated. 'We have lots of things that need to be fixed.' Jost was there the next morning, his trunk filled with tools. A physical therapist had amassed a list of 27 things that needed to be fixed. By noon, 11 of them were. Students who can talk call him 'Mr. Pound Pound,' for the hammer he wields, or 'Papa,' the name his grandchildren gave him. On any given day, Jost or Porter might be asked to build a bookshelf, alter a piece of equipment for a student whose legs are different lengths or arrange switches so that a paralyzed student can operate a computer by moving her head. Many students have problems that affect muscle control, and part of what they learn in school is how to control their movements. Jost and Porter modify chairs and desks to limit their range of motion so they can practice control safely. Recently, a teacher asked Jost to adapt a chair for a student who was repeatedly twisting around. He attached two 15-inch boards on either side of a wooden chair so she could move, but not as widely. The chair also has a seat belt and a platform at its base so she won't tip over. At Kilmer Center, Porter built an L-shaped frame out of PVC pipe for a teacher who wanted her students to practice stretching their tightly curled arms or clenched fingers. The teacher added a row of chimes to the pipe. Now, when the students reach out their hands, they are rewarded with the tinkling of bells. Both men have a knack for improvisation. Porter, for instance, rigged a feeding tube pole with PVC pipe and a Christmas tree stand. Past and current creations and all their raw materials fill every cranny of Porter's workshop at Kilmer Center. There, a Masonite board, a pasta machine, some antique telephone equipment, his mother's old Singer sewing machine and vast collections of clamps, power drills, saws and wrenches, are all jumbled together and covered by a thin layer of sawdust. The creations have saved the schools a lot of money. Jost noticed that teachers were often changing their students' diapers on the floor because the changing tables were too small. The low, heavy-duty tables fitted with mats he built for each classroom would have cost $1,000 retail, he found. Jost also began teaching the students at Key how to use tools. They built birdhouses, race cars and toothbrush holders with a hammer supported by Jost. The thwack-thwack sensation of the hammer often elicited a surprising response. 'It brought out things in those kids that had not been seen by a lot of people,' he said. Porter -- 'Uncle Bill,' as he came to be known -- has sometimes spent the lunch hour helping spoon-feed students in the cafeteria. But in recent years he has struggled with his own problems. He has gained weight, uses an oxygen tank and travels the school in a motorized wheelchair or a yellow cart with a basket of tools. 'My time here is getting close to the end,' Porter said. 'I'd like to think I made a difference.' Jost said he wants to stay as long as possible at Key Center. 'It's really satisfying,' he said. 'It's really, really satisfying.' 