Fig. 9.
Now it has heretofore been necessary to turn on the gas before pulling the chain of a pendant burner, but as this is not always desirable the ratchet burner is made. Fig. 10 shows burner carrying a toothed wheel, which is partly rotated when the arm is pulled down. This wheel is mounted on the stem of a valve which opens or shuts according to the point of rotation, and thus shuts off or admits the gas to flow up to the burner. One pull of the arm turns the gas on; at the same time the wipe spring touches the contact on burner collar, and the gas lights. A second pull and the wheel, rotating, turns off the gas. In all burners of this class a spring is provided to carry the arm up and back into its original position ready for another pull. Some burners do not make contact when the arm flies back, thus saving battery current.
Fig. 10.
Fig. 11.
Fig. 11 is an improved form of burner wherein the movable electrode does not pass through the gas flame, neither do the electrodes come in contact with each other when the gas is being turned off. Reference to the cut will show a pin protruding from the base of the coiled spring electrodes, which pin is so arranged as to come in contact with the short end of the pull-arm. When this pull-arm is pulled down it pushes up this pin, elongating the spiral spring electrode sufficiently to make and break contact at the fixed electrode on the burner collar. This burner can be fitted with a porcelain candle slip if desired to match the imitation candle burners.
Stem Burners.
Objection is sometimes made to the ordinary chain pulls from the fact that they jar the fixtures, and also are liable to bend the fixture branches from the strain used in operating the arm. To overcome these objections the stem style of burner is manufactured (see Fig. 12). This stem, it will be seen, carries a convenient key at the end, which is turned either right or left as in an ordinary gas-cock. The moving contact only makes contact when the gas is being turned on and lighted. When turning it off, the arm is retracted so as not to touch the fixed electrode, thus saving battery current.