Patent GB-191121195-A (GB)
Title: Improvements in Furnaces for Steam Boilers.
Inventor: RAMSBOTTOM EDWIN
IPC: F23M7/00
Filed: 1911-09-26
Granted: 1912-10-28
Abstract: 21,195. Ramsbottom, E. Sept. 26. [Cognate Application, 5623/12.] Air supply, regulating; fire - bridges. - The supply of air above a furnace grate and beyond the fire-bridge is controlled by the movement of the furnace door, which operates through special mechanism air - supply valves in the furnace door and fire-bridge. In the first form of mechanism shown in Figs. 1, 3, and 5, a hinged door Y under the fire-bridge is opened during the opening of the furnace door D, and a circular grid 0 in the furnace door is opened during the closing of the furnace door, the hinged door and circular grid being arranged to close simultaneously after a period of time. Upon opening the door D, a cam L fixed to the door comes into contact with a flange S<5> of a clutch S mounted on a rotating shaft U driven by worm and bevel gearing. The teeth on the side of the clutch S are normally disengaged from teeth on a pinion T mounted loosely on the shaft U. Further movement of the door causes a snug K thereon to engage with a projection v on a lever M mounted on the door spindle. The lever M is turned and, through a rod Q connected thereto and to a sliding rack bar R, mounted in a bracket P, and a rod or chain f, causes the opening of the counterweighted door Y in the fire-bridge. The teeth R<1> of the rack bar R engage with the pinion T. Upon closing the furnace door, the grid 0 which is provided with a counterweight at O<4> is pulled open by a chain C<5> attached to the grid and the projection v on the lever M. The cam L also releases the flange S<5> of the clutch S and allows the clutch to engage with the pinion T, which is then rotated with the shaft U and causes the rack bar R to move inward and close the hinged door Y. The clutch is disengaged from the pinion during the inward movement of the rack bar by means of a V- shaped lever R', Fig. 5, pivoted at R<4> to the rack bar and adapted to engage with a fixed inclined surface R<9> on the bracket P and an inclined surface R<6>, pivoted at R<8> to the bracket P, and comprising a forked lever R<7> which engages with the clutch S and disengages it from the pinion T. The inward movement of the rack bar rotates the lever M and allows the grid 0 to close under the action of the weight O<4>. In the second form of mechanism. the modified parts of which are shown in Figs. 12 and 13, the bridge door Y and grid 0 are opened simultaneously during the closing of the furnace door, and are allowed to close simultaneously after a period of time. Upon opening the furnace door, the snug K engages with the lug v on the lever M and operates the link w and lever x pivoted at y to the bracket P. The end of the lever x moves inward, and the rod z hinged thereto slides on the side of the projection R<2> of the rack R and is finally pressed inwards past the end of the projection R<2> by a spring a<1>. When the furnace door is closed, a pin N on the door engages with the face w<1> of the link w and rotates the lever x in the opposite direction. The hinged rod z, being engaged with the projection R<2> on the rack-bar R, causes the rack-bar to move outward until the hinged rod z comes in contact with the inclined piece a<3> on the bracket P and is disengaged from the rack-bar, thus leaving the rack-bar free to move inwards again. The chain C<5> is so fixed to the grid 0 that, when the rack-bar R is out, the grid 0 is open to admit air and, when the rack-bar moves inwards, the chain C<5> pulls the grid through the necessary angle to close the air-openings. A modification is shown in Fig. 15 in which the grid 0 and door Y are closed by a hand-lever H<2>, which is pivoted at H<3> to the bracket P and is provided with a pin H<4> engaging with a slot in the end of the rack-bar R. Two forms of firebridges are shown in Figs. 3 and 4, one in which the air passes through inverted U-shaped passages formed by castings W, W<1>, and is carried downwards into a chamber e closed at the rear by a wall g, and the other in which the air passages are formed by inverted L-shaped castings W provided with extension-pieces W<2>.