Single-action doors fitted with a spring, whether in the hinge or separate from it, are sure to slam violently (if there is sufficient tension in the spring to close the door), and to avoid this very objectionable feature, several devices for checking the door while closing have been invented, and double-action spring hinges are nearly as often used to prevent the slamming of the door as to permit it being opened either way. Double-action doors, however, cannot be made very tight, and are objectionable in this respect for outside entrances.

It has been found that the most practical forms of door checks are those which are attached to the top of the door and frame, and which are known as "overhead checks."

There are two distinct kinds of door checks; A, those which simply check the door when closed by a spring or by hand, and B, those which both close the door and prevent its slamming. The former class are commonly used with single-action spring hinges, while the latter class are used with ordinary butts. Although several styles of door checks of class A have been patented, the "Eclipse Door Check," manufactured by Sargent & Co., appears to be the most popular and is quite extensively used. It consists of a piston secured to the head of the door frame and working in a cylinder attached to the top of the door. The piston rod is attached in such a way that lateral motion is prevented, while it can be accurately adjusted to meet the cylinder. When the door is opened, the cylinder is drawn entirely away from the piston, while the compression of the air in the cylinder when the door closes, prevents any slamming. The air escapes through openings in the end of the cylinder, so arranged as to be easily regulated. A special spring for closing the door is also made for doors hung with ordinary butts.

Door Check With Spring. - It is usually considered more desirable to combine the self-closing and checking features in one piece of mechanism, and two or three of such door checks have been placed on the market which work very satisfactorily The first of these to be patented, the author believes, was the "Norton Door Check," in which the checking apparatus consists of a cylinder with a piston working against an air cushion and a strong spiral spring which closes the door. When the door is opened the piston is drawn out, the spring is compressed and air enters the cylinder filling the space between its head and the piston. When the door is released, the spring tends to close it, but the air behind the piston prevents the door from closing too quickly or from slamming. The spring is made sufficiently strong to both close the door and to latch it after the air has escaped from the cylinder. The main part of the check is attached to the head casing of the door, while the arm connecting with the piston rod is attached to the inside of the top rail of the door. A check and spring (the Columbia) working on practically the same principles as the Norton, but with the spring and cylinder differently arranged, is made by the Russell & Erwin Manufacturing Co.

Fig. 418.   Blount Door Check.

Fig. 418. - Blount Door Check.

It has been claimed that in all door checks depending upon an air cushion, the bearings will wear loose after having been used for a certain time, so that the air will escape too freely to make a reliable check, and several attempts have been made to produce a practical door check in which some liquid could be used for the cushion, and the author believes the liquid door check and spring to be the latest improvement in the way of a self-closing apparatus for heavy single-acting doors.

Of these liquid door checks, "The Blount,*" Fig. 418, is believed to be the most satisfactory as well as the most compact and pleasing in appearance. The cylinder portion is attached to the inside of the upper rail of the door from 4 to 6 inches from the hanging edge, and the end of the arm to the head casing.

*Yale A Towne Manufacturing Co., sole selling agents.

The check opposes no appreciable resistance to opening the door, but when the door is released the tendency of the spring to close it is regulated by an automatic valve, so that as the door nears the jamb it almost comes to a standstill, and then quietly but positively closes by the operation of the spring.

Overhead door checks with spring, are being more extensively used every year for the entrance doors of public buildings, banks, stores, outside storm doors, etc., and also on the pantry or closet doors of private residences.