Fig. 115
88. Door Springs and Checks.—During recent years considerable improvement has been noticeable in the construction of the devices known as door springs and checks. Formerly, the common torsion rod and coil springs, which are illustrated in [Fig. 116], at (a) and (b), respectively, were the only articles of this kind available. These devices have been in extensive use for many years, and have performed the work of closing the door, but not without the unnecessary bang and slam made by the door when striking the jambs. This was overcome to some extent, however, by the introduction of the air-check, which depends on the use of an air cushion to resist the force of the spring. In effect, each check is a small air pump.
Prominent among the older type of air-checks is the Eclipse made by Sargent & Co. This check is clearly illustrated in [Fig. 117]. At (a) and (b) are shown two methods of applying the Eclipse air-checks. In (a), the spring-check that closes the door is shown at a attached to the door, while its lever-arm is fastened to the door casing. The cylinder b is also secured to the door, and the piston c, operating in the cylinder, is applied to the door casing. At (b), the parts are differently arranged. The spring-check occupies the same relative position as shown in (a), its lever-arm being shown at a, while the piston c is fastened to the door and the cylinder b affixed to the head-jamb of the door frame. Either method is adapted for inside doors, but that shown at (b) is preferable for doors opening outwards, on account of fewer parts being exposed; the spring-check and its lever-arms, in this case, being the only parts exposed to the weather. In construction these checks consist of a cylinder b with a polished interior, in which works the piston c. On the end of the piston there is provided a cup made of leather that has previously been soaked in oil. By the insertion of the piston into the cylinder as the door closes, there is a tendency to compress the air in the cylinder, thus forming an air cushion with air outlet at the caps. These outlets can be regulated by turning, or screwing, the cap to the right or the left, as the case may require.
Fig. 116
Fig. 117
Devices of this kind, however, did not prove satisfactory until the introduction of the Yale-Blount, or hydraulic, combined spring and check, which is shown in [Fig. 118]. In this device, the coil spring a, shown in (b), is enclosed in the vertical portion of the check, the regulating of the tension being accomplished by turning the ratchet sleeve b with a wrench made for that purpose. The check enclosed in the horizontal part consists of a metallic piston c, without packing, that moves in a tightly sealed metallic cylinder containing a lubricating and non-freezing liquid. The movement of the door in closing depends on the escape of the liquid through a by-pass from one end of the cylinder to the center, this by-pass being controlled by a small valve that may be readily adjusted to produce any desired action of the door and thus permit the door to be closed silently, with a smooth, steady motion, and without rebound. Since the introduction of the Yale-Blount type of check and spring combined, other manufacturers are making similar styles, the most prominent being the Bardsley, the Corbin, the Sargent, and the Ogden.
