236,635. Schucany, W. April 8, 1924. Valves, reversing.-In a gas and air reversing apparatus for regenerative furnaces, gas and air channels 1 - - 4, Figs. 2 and 3, each having a controllable supply, are connected at their mouths to an off or exhaust conduit 5 at right angles thereto, the mouths of the channels being closed and opened alternately in pairs by a reciprocating car or slide 7. The mechanism operating the car actuates the gas and air admission valves 47 and may also control a by-pass from the hearth which connects the furnace directly to the off conduit when both pairs of gas and air admission valves are open for an instant during the reversing process, the mouths of the channels then being disconnected from the off conduit by automatically operated shut-off slides 69. The car or slide 7, Fig. 4, is provided with wheels 8 and reciprocates upon rails at the sides of the channels, the rails being provided with recesses 11 into which the wheels fall when the car is in either of its extreme positions, thereby lowering sealing ledges 12 at the sides of the car into sand or water cups 13 which bound the channels. Additional sealing is provided by upturned ledges 65 on the transverse sides of the car co-operating with a partition wall 6 between the channels 1, 2, 3, 4. A hinged flap 64 forming an extension of the partition wall 6 is operated automatically to shut the hot gases from the car as they pass into the off conduit from the exhausting channels. The car 7 is operated by pinion-driven mechanism which is duplicated at each side of the system, the movement of the car being controlled by the pinion on the side towards which it is travelling. As shown diagrammatically in Fig. 15. the driving pinions 41, 42 engage rack bars 29 which are rigidly connected by a drawing-bar 30 passing through a cylindrical member 15, the latter member being connected by links 31 on its exterior to a pin 16 on the lower portion of the car 7. The pinions 41, 42 are also geared to a shaft controlling the gas and air admission valves on each side of the furnace. The ends of the cylinder 15 are enclosed to form oil chambers 38 within which pistons 40 on the bar 30 reciprocate. The chambers 38 are provided with rifling which decreases in depth towards the outer ends, and the pistons 40 are provided with valves which close when on the driving side of the system and open when on the side from which the car is travelling. The car is lifted from the recesses in the rails before it is moved transversely, the lifting mechanism comprising a sliding rack 19 engaging teeth on the lower ends of arms 14 pivoted freely at the sides of the car the movement of the rack being sufficient to turn the arms from an inclined to a vertical position. The ends of the rack 19 are respectively connected to two-armed levers 20, 21 pivoted at 32, 33 and connected by pins at their lower ends to slots in the bodies of levers 34, 35 pivoted at 36, 37 respectively. The other ends of the levers 34, 35 extend across the paths of rollers 43, 46 on the driving rack bars 29, and are engaged during the longitudinal movement of the rack bars to the right or left, thereby turning the levers 20, 21 and drawing the rack 19 in a direction opposite to that of the rack bars 29. Fig. 15 shows the relative positions of the levers when the car 7 is in the right-hand closing position and is about to be drawn to the left by the pinion 41 on the left side of the system. During the initial movement of the bars 29, 30, 29 to the left the roller 43 travels a short free-play distance before it meets the lever 34, during which travel the pistons 40 move easily within the chambers 38, so that movement of the cylinder 15 and car 7 results, the object being to enable the gas and air valves to be automatically operated before the car 7 is moved. The pull towards the right, which is exerted on the car during the turning of the levers 14 into the vertical position by the rack 19, is communicated to the cylinder 15, and resisted by the piston 40 in the left-hand counterpressure chamber 38 until the car wheels are lifted clear of the rail recesses, in which time the piston has reached the outer end of the chamber, and the further pull of the bars 29, 30 is communicated directly to the cylinder 15 and thence to the car. The gas and air valves 47, Fig. 13, are of the water shut-off type, and are operated by a screwed sleeve 48 engaging a stationary screw spindle 49, the sleeve being driven by a bevel wheel 53 keyed thereto and engaging a bevel wheel 52 on a shaft 51 driven by clutch connected bevel gear which is driven by the pinion driving the adjacent rack bar 29. The clutch is controlled by a cam device which is mounted on the rack bar and operates during the free-play travel of the latter. The cam devices may be arranged in two different ways : (a) A cam projection at the inner end of a rail mounted on each rack bar 29 bears upon a roller on the clutch controlling arm. Thus, with the system in the position shown in Fig. 15, the cam on the right-hand rack bar is operative during the free-play travel and closes the gas and air valves on that side before the car 7 is moved, the valves on both sides thus being closed while the car is moved across to the left. The cam on the left-hand bar becomes operative at the end of the movement to the left and opens the valves on that side to attain a working condition again. (b) To obviate the closing of the valves during the movement of the car a constant supply of gas is maintained to the hearth, the valves on both sides being open simultaneously for a short period during the reversal, and the chambers being disconnected from the off conduit by shut-off slides 69 moving in synchronism with the valves but with opposite actions. During this period the middle of the hearth is connected to the off conduit by an auxiliary by-pass controlling by a flap. In this arrangement each rack bar 29 is provided with two cam rails, each forming a separate closed loop within which a roller on the arm of a reversing clutch is guided, the cammed portions of the rails being disposed so that those on the driving rack bar alone are effective, one at the beginning of a movement to close the valves on that side to attain a working condition, and the other at the end of the movement to re-open the valves, the valves on the other side being open throughout.