[1572]. Boiler saddle tank.
[1573]. Circulating tank for hot water.
The level of water may be maintained in tanks by either an overflow pipe or notch, or by a ball cock on the supply pipe. Glass water gauges can be fixed outside to show the level of the water inside; and floats are used, attached to a cord and pulleys, for the same purpose. See also [No. 1730].
Section 87.—THROWING IN AND OUT OF GEAR.
[1574]. The driving wheel is loose on shaft, and is locked to its shaft by the hand wheel nut (see [No. 945]), or by a ratchet wheel and locking pawl.
[1575]. Two half-nuts are lifted in or out of gear with the screw by cam or lever motion. See [No. 942].
[1576]. One shaft runs in eccentric bearings, which can be revolved so as to throw it out of gear with the other shaft.
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