func_train
Used for moving platforms or machinery. This example makes a simple moving platform circle a room.
1.Firstly, create a good sized room (300x300x300) and place your info_player_start and a light in there.
2.Make a 64x64x16 square platform in one corner, about 1/2 way up the wall. Apply the func_train entity to this brush. Give it a "target" of "path1".
3.Place 4 path_corner entities in each of the 4 corners of the room. This part can be a bit frustrating to place them exactly where you want the train to go. TIP: The path_corner will be where, from the top-down view of your editor, the bottom left-hand corner of the train will move to.
4.The path_corners should each have a target and targetname, each pointing at the next, and back to the first. In this example, we use:path_corner #1
"target" "path2"
"targetname" "path1"
path_corner #2
"target" "path3"
"targetname" "path2"
path_corner #3
"target" "path4"
"targetname" "path3"
path_corner #4
"target" "path1"
"targetname" "path4"