headchair

1. (railways) Part of a block switch on a railway line that the ends of the moveable rails rest on, and to which the stationary rails are attached.Examples: "I desire to be understood'as disclaimin g the broad features, first, of making a railway headchair with bearing-cheeks of different heights, one for the flange and the other for the tread of a car-wheel, whereby, in passing over theswitch on either the main or the side track rail, the wheel will have bearing upon respective cheek of the chair; and, second, of providing such side bearings with detachable wearing surfaces, either inclined, plane, or grooved."; "The defendant's roadmaster testified that the flanges of the car wheels would constantly wear the blocking until it got beyond their reach; that frequently the blocking was split the same day that it was put in; and that in the course of two or three days the blocking would be worn down, through its entire length, so that its surface would be practically level with the headchair, which was two inches below the surface of the rail, and an inch and a quarter below the bottom of the head of the rail."