All springs and spring hinges should, in good work, have a check action - that is to say, when the door is within a few inches of the closing point the spring should be checked and the door allowed to close gently, to avoid banging backwards and forwards in the case of swing doors, and slamming in the case of doors opening one way only.

The check action is generally obtained by means of a piston coming in contact with a cushion of air in a piston box, from which the air can only escape slowly. Thus the violent swing of the door is checked and slowed when near the closing point.

Hinges 208

Fig. 179.

One of the simplest and most effective springs for unimportant positions is the ordinary adjustable coil spring, fixed at one end to the frame and at the other to the hanging stile. The spring is often wrongly fixed with the ends parallel to the edge of door, causing the spring to follow the form of a letter S. It should be very slightly extended, and fixed as shown at Fig. 180, A, and care should be taken that it is fixed so that opening the door winds the spring up.

A helical spring is shown at B. The spring is enclosed in the barrel attached to the jamb, and can be readily adjusted as to strength. There is a small wheel in the end of the arm, which runs on a plate screwed to one of the rails of the door.

Weston's steel-rod door spring is illustrated at C. The spring is obtained by means of a twist in the rod itself, and its strength can be regulated by means of the capstan head.

Figs. 181 and 182 illustrate respectively the "Improved Norton " and the " Blount" door springs and pueumatic checks, while Fig. 183 illustrates the "Bardsley" of which Messrs. Nettlefold & Sons are the sole agents. This spring has an oil check, which it is claimed is superior to the pueumatic check, and it has a releasing device by means of which the checking power is removed when the door is nearly closed, thus allowing the spring to exert its full power in order to latch the door. There are several other makes of check springs differing in details.

Hinges 209

Fig. 180.

Hinges 210

Fig. 181.

Among the several varieties of spring hinges the neatest and most effectual are those contained in boxes let in flush with the floor or paving, and having top centres secured to top of frame. They can be had either with or without check action. There are several makes of these hinges, all very similar in outward appearance, but differing in construction. They are made with either single or double action, the former for doors opening one way only, the latter for swing doors. Fig. 184 is a plan, with top plate removed, showing the construction of "Smith's" double action hinge, by which it will be seen that on opening the door in either direction a set of spring rings are forced open. In the "Climax," illustrated by Fig. 185, the power is obtained by means of two spiral springs. Both "Smiths" and the "Climax" are made in varying strengths to suit doors of different weight. "Hill's Improved Swing Door Centres," illustrated by Fig. 186, are actuated by a single spiral spring, the strength of which can be adjusted to suit varying weights of doors by means of the capstan head B; while the capstan headed screw marked A enables the door to be set perfectly true, and so saves much time in fixing. The "Slave" single-action and the "Slave" double-action floor springs with pneumatic checks are respectively illustrated at A and B in Fig. 187.

Hinges 211

Fig. 182.

Hinges 212

Fig. 183.

The floor springs patented and manufactured by Robert Adams comprise several patterns suitable for various positions. They are made either with or without checks, and the checks are either pneumatic or hydraulic. The latter pattern is generally to be preferred, as, the liquid being oil, the internal parts are always kept lubricated. Fig. 188, A and B, illustrate respectively the "Crown Victor" (double action) and the "London Victor" (single action). Both can be had either with or without oil checks, and it will be noticed that these hinges take up much less space than most other patterns. The special features of the hinge comprise a wide angle of opening, (in the case of the "Crown" the door can be opened to an angle of 135o and in the case of the "London" to an angle of 180o); a large size internal spring A, which ensures great elasticity and durability; a capstan screw C, by means of which the closing power can be regulated; an automatic compensating action, which prevents any slackness from wear; a safety valve to prevent injury by unduly violent use; and a screw S, by means of which the speed of closing may be regulated.

Hinges 213

Fig. 184.

Hinges 214

Fig. 185.

Fig. 188, D, illustrates the "King Victor" double-action floor spring for exposed situations. This hinge is designed specially to resist strong currents of wind blowing in one direction, but to open easily the reverse way. This is effected by means of separate and independent closing springs, only one of which comes into action at a time, according as the door is opened in or out, and each of which can be regulated for strength independently. The spring is provided with a silent oil check, and possesses most of the advantages claimed for the "Crown." It will not, however, open to quite such a wide angle, and a stop should be provided to prevent breakage by undue violence. The " Hurricane Victor," specially designed to stand exceptional wear and to open 135o, is shown at C, but a stop should be provided to prevent its opening beyond this. Each spring can be independently adjusted, so that the door may be set to resist a hurricane on one side and be easily opened in the opposite direction. This hinge is without the check action. Special patterns are catalogued for situations where the ordinary floor springs cannot be employed, as, for example, immediately over a girder. The several shoes and top centres for use with the "Victor" hinges include adjustable patterns, by means of which the door can be adjusted both laterally and vertically after the hinge is fixed.