Door closers are mechanical devices used to control the closing of a door. Two common configurations are identifiable by their arm placement relative to the door and frame. One type features an arm that projects roughly perpendicular to the door surface when viewed from above, connecting to the frame at a point distant from the hinge. The other type has an arm that runs more or less parallel to the door surface, typically connecting to the frame much closer to the hinge point.
The selection between these configurations often depends on aesthetics, space constraints, and required closing force. The parallel configuration is frequently chosen for its neater appearance and reduced projection into the doorway. This can be particularly beneficial in high-traffic areas, mitigating the risk of accidental contact. The regular arm configuration, due to its geometry, may offer a greater mechanical advantage in certain installations, potentially providing more closing power for heavy or difficult-to-close doors. Historically, the regular arm design was more prevalent, with the parallel design emerging as building design and accessibility requirements evolved.