In an electromagnetic actuator including a bearing member which slidably supports a variable core, a yoke for retaining a coil assembly by cooperation with a bottom wall of a housing is connected to the housing, and the bearing member is fitted into the yoke. The sponge core barrel includes an outer barrel assembly, a core bit secured to a lower end thereof, and an inner barrel assembly disposed therein. The frame may include an A-post, a B-post, and a C-post arranged along a side of the cab and extending along a height direction of the cab. The exposed portion includes a photosensitive material configured to at least attempt to change a dimension when exposed to the leakage light.