US2582855A

US2582855A - Electric tunnel kiln

Info

Publication number: US2582855A
Application number: US67633A
Authority: US
Inventors: Pyl Edward Van Der
Original assignee: Norton Co
Current assignee: Saint Gobain Abrasives Inc
Priority date: 1948-12-28
Filing date: 1948-12-28
Publication date: 1952-01-15
Anticipated expiration: 1969-01-15

Description

Jan. 15, 1952 E. VAN DER PYL ELECTRIC TUNNEL KILN ll Sheets-Sheet 1 Filed Dec. 28, 1948 MK R 7W 0 V T R N v T N W T [NW5 A w wN m .kww E Y B. Q3 JR,

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6M 1; own 0 re DN 0 UN an 3 my on an n hm QM v a no a R... Q 600 000 00 000 M N" o O a ON" W G o o o o o N 0 hi my .5 ,ZMOOOMSBM M a M n o -e- P3 h 000 0900000 c \Q\ NQN N aNk\ 3 S k h 5 Q" lul Jan; 15, 1952 E. VAN DER PYL ELECTRIC TUNNEL KILN Filed Dec. 28, 1948 ll Sheets-Shqet 2 Jan. 15, 1952 E. VAN DER PYL ELECTRIC TUNNEL KILN i1 Sheets-Sheet 3 Filed Dec. 28, 1948 NVENTOR EDMRD VAN DER PyL ATTo RN E. VAN DER PYL 5 ELECTRIC TUNNEL KILN 11 Sheets-Sheet 4 lNvElvToR EDWARD VAN DER Pyl.

A 7' TO R NEy Jan. 15, 1952 Filed Dec. 28, 1948 1952 E. VAN DER PYL 2,582,855

- ELECTRIC TUNNEL KILN Filed Dec. 28, 1948 ll Sheets-Sheet 5 INVENTOR [DM/ARD W DERR L AT TO RNEy Jan. 15, 1952 E. VAN DER PYL 2,582,855

ELECTRIC TUNNEL KILN Filed Dec. 28, 1948 ll Sheets-Shah's 6 INVEN TOR EDMRDWDERPYL H 15 L-FG- ATTO R NE) 15, 1952 E. VAN DER PYL 2,582,855

ELECTRIC TUNNEL KILN Filed Dec. 28, 1948 ll Sheets-Sheet 7 11 Sheets-Sheet 8 Jan. 15, 1952 E. VAN DER PY L ELECTRIC TUNNEL KILN Filed Dec. 28, 1948 /NVENTOR n fi/ ATTo RNEy EDWARD VQNDERH L Jan. 15, 1952 E. VAN DER PYL ELECTRIC TUNNEL KILN ll Sheets-Sheet 9 Filed Dec. 28, 1948 Jan. 15, 1952 E. VAN DER PYL ELECTRIC TUNNEL KILN l1 Sheets-Sheet 10 Filed Dec. 28, 1948 INVENTOR VAN DER P 1. Y ./,f-,r+- 7 ATToR/vEy EDWARD Jan. 15, 1952 E. VAN DER PYL ELECTRIC TUNNEL KILN Filed Dec. 28, 1948 ll Sheets-Sheet 11 /NVNTOR EDW RDVANDER P q ATToRA/Ey Patented Jam. 15, 1952 assess:

ELECTRIC TUNNEL ms Edward Van der Pyl, Holden, Mam, assignor to Norton Company, Worcester, Mala, a corporation of Massachusetts Application December 28, 1948, Serial No. 67,833

Claims.

The invention relates to tunnel kilns.

One object of the invention is to provide a tunnel kiln of high production per unit mass of kiln, that is to say capable of vitriiying more pounds of ware per day per ton of kiln than previous tunnel kilns. Another object of the invention is to provide a very compact tunnel kiln capable of vitriiying a relatively large mass of ware, as represented by many unit pieces, for a given floor space occupied by the kiln. Another object of the invention is to vitrify a comparatively large mass of ware for each kilowatt hour of energy used. Another object of the invention is to provide a tunnel kiln of low capital investment compared to its productive capacity, that is to say to obtain a greater mass of total ware vitrified per year for every hundred dollars invested in the kiln than heretofore possible. Another object of the invention is to provide a tunnel kiln which will produce a greater mass of total ware vitrified per man hour of labor than hitherto practicable.

Another object of the invention is to provide means for ready access to the interior of a tunne1 kiln in order to straighten out a jam or smash. Another object of the invention is to provide a tunne1 kiln with a plurality of parallel tunnels and an efllcient charging mechanism for automatically ramming ware into the several tunnels seriatim. Another object of the invention is to provide various controls and interlocks to render the charging mechanism as foolproof as possible. Another object of the invention is to provide a tunnel kiln of the character indicated in which the only manual labor required is to place batts with green" ware on a loading conveyor and remove batts with fire-d ware from a discharging conveyor or a table located adjacent thereto.

Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which are shown two of various possible embodiments of the mechanical features of the invention,

Figure 1 is a side elevation on a smaller scale as compared with most of the remainder oi the drawings, of a tunnel kiln constructed in accordance with this invention.

Figure 2 is a side elevation on a larger scale than Figure 1 of a table to which the ware is transierred by the discharging conveyor of the Figure 3 is an end elevation of the loading or entrance end of the kiln proper on a larger scale than Figure 1.

Figure 4 is an end elevation of the exit or discharging end of the kiln proper on the same scale as Figure 3.

Figure 5 is a side elevation on a still larger scale oi the loading or charging mechanism at the entrance end of the kiln including the loading conveyor.

Figure 6 is a vertical sectional view taken on the line 6-4 of Figure 5.

Figure 7 is a central vertical longitudinal sectional view of the kiln proper showing the tunnels therein and including the preheating zone, the firing zone, and a portion of the annealing zone, this view being on a larger scale than that of Figure 1 but on a smaller scale than that of Figures 3 and 4.

Figure 8 is a vertical cross sectional view taken on the line 88 of Figure '7.

Figure 9 is a central vertical longitudinal sectional view similar to Figure 7 and on the scale thereof, illustrating the remainder of the inside of the kiln proper including the tunnels and showing the remainder of the annealing zone.

Figure 10 is a vertical cross sectional view taken on the line I0l 0 of Figure 9.

Figure 11 is a vertical sectional view taken on the line i l| I of Figure 9.

Figure 12 is a vertical sectional view taken on the line l2-i 2 of Figure 7.

Figure 13 is a vertical sectional view taken on the line 13-43 of Figure 7 but on a larger scale.

Figure 14 is a vertical sectional view taken on the line ll-Il of Figure 7 and on the same scale as Figure 13.

Figure 15 is a fluid pressure diagram.

Figure 16 is a sectional view of a solenoid and relay switch.

Figure 1'7 is the wiring diagram.

Figure 18 is a plan view of the loading conveyor and rams.

Figure 19 is a vertical sectional view on an enlarged scale showing a batt on the loading conveyor actuating a limit switch.

Figure .20 is cross sectional view on an enlarged scale of the discharging conveyors at the Figure 22 is an elevation of the front of the kiln of Figure 21 on a larger scale.

Figure 23 is an elevation of the rear or exit end oi the kiln of Figure 21 on the same scale as Figure 22.

Figure 24 is a vertical longitudinal sectional view in the axis plane of the first half of the kiln of Figure 21, on a larger scale than Figure 21.

Figure 25 is a view similar to Figure 24 showing the second half of the kiln.

Figures 26 and 2'1 are cross sectional views taken respectively on the lines 26-26 and 21--21 of Figure 24 but on a larger scale than Figure 24.

Figure 28 is an addition to the wiring diagram of Figure 17.

Figure 29 is a vertical sectional view through the elevator for the kiln of Figure 21, the section being taken on the line 29-29 of Figure 30.

Figure 30 is a plan view of the elevator for the kiln of Figure 21.

The sectional views, Figures 8, 10, 11, 12, 13 and 14, are nearly vertical sectional views but not quite since the long dimension of the kiln is slightly inclined to the horizontal, as shown being at about 2 to the horizontal, and the sections are taken parallel to the faces of the bricks which are at right angles to the bottom of the kiln.

Referring first to Figures 1, 3, 4, '1, 8 and 9 to 14, the refractory kiln structure may be supported and enclosed in a rectangular parallelepipedal box having side walls 2| and 22 a bottom 23 a top 24 and

end walls

25 and 26. All of these walls including the top and the bottom may be made out of steel plate and may be secured together by welding and may be strengthened by braces such as the angle irons 21 shown in Figure 1, including some angle iron braces 29 which are continued to form legs 29. The top 24 is preferably made of a large number of pieces of steel plate supported by angle irons 30 welded to the sides 2| and 22 at the top as well shown in Figures 13 and 14. Preferably the various sections of the top 24 are removable in order that, in the case of a bad smash, the brick work may be removed to make repairs. However, most of the time it will be suflicient to use the easy means of obtaining access to the tunnels as hereinafter described.

Referring now especially to Figures 13 and 14, resting on the bottom 23 is a course of bricks 35 which extends from end to end of the kiln. The upper surface of this course of bricks 35 is a plane surface but slightly inclined to the horizontal since the bottom 23 is slightly inclined to the horizontal as clearly shown and as already stated. Resting on the marginal bricks of the course 35 on either side of the kiln and located at a short distance from the walls 2| and 22 respectively are walls 36 of courses of bricks each wall 36 having an inside surface which is in a vertical plane and an outside surface which is in a vertical plane. Adjacent the walls 36 and resting upon the courses of bricks 35 are long courses of bricks 31 extending from end to end of the kiln.

This tunnel kiln has a preheating zone, a firing zone and an annealing zone. It has two

tunnels

40 and 4| each of which extends right through the kiln from the preheating zone through the firing zone and the annealing zone. These

tunnels

40 and 4| are connected to each other by a passage 42 in the firing zone but otherwise they are separated from each other. Figure 8, which shows a cross section through the annealing zone,

31 in the preheating and annealing zones are wide bricks 45 which are substantially rectangular parallelepipcds but have grooves in their top edges to receive long refractory pieces 41 which support rods 49 upon which slide batts 49 supporting pieces of ware such as grinding wheels 50 being vitrified. The bricks 45 completely fill the space between the courses 31 and above the courses 35 to form a bottom to the tunnel 40. It will be seen that the bricks of the courses 31 and the wide bricks 45 and the long refractory pieces 41 which flt in grooves in the .top edges of the bricks 45 together form a plane surface except for long grooves in the pieces 41 in which the rods 46 rest. Upon this plane surface rest many tunnel forming bricks which are generally of inverted U-shape but as shown are wider than they are high and have thick legs. These bricks all together form a tunnel ceiling 58 and the upper portions of the sidewalls of the tunnel 40 are inclined as shown at 59. The roof 60 of the tunnel 40 forms the floor of the tunnel 4| which is further formed by tunnel forming bricks which, like the bricks 55, extend from a wall 36 on one side to the wall 36 on the other side. As will be seen, the tops of the bricks 55 collectively form a plane except that there are grooves for the support of long refractory pieces 41. The tunnel forming bricks 65 are similar to the tunnel forming bricks 55 except that the upper bricks 65 need have no grooves in their top surfaces. Thus the upper tunnel 4| has a tunnel ceiling 69 and the upper portions of the sidewalls of the tunnel 4| are inclined as shown at 69. On the long refractory pieces 41 for the upper tunnel 4| are rods 48 supporting batts 49 supporting ware such as grinding wheels 50 being vitrified.

The structure thus far described constitutes a refractory structure forming the two

tunnels

40 and 4|, but I preferably provide additional bricks over the bricks 65 to form a thick roof for the tunnel 4| for heat insulation. For example, I may provide long courses of bricks 1| like the courses 31 resting upon the bricks 65 adjacent to the walls 36 and fill the space between these courses 1| with wide rectangular parallel epipedal bricks 12 as shown. Then on top of the plane formed by the tops of the walls 36, of the courses 1| and of the bricks 12, I may lay flatwise long bricks 15 in a plurality of courses. These long bricks 15 may be of the same dimensions and arrangement as the long courses of bricks 35, the former forming the top of the refractory structure and the latter forming the bottom of the refractory structure. A full comprehension of this entire refractory structure is readily gained from the foregoing description taken in connection with Figures 7 and 9 as well as Figure 8.

Referring now to Figures 13 and 14 which represent the firing zone, the refractory structure of the kiln is in many respects the same as that already described. The courses of bricks 35 form the bottom of the structure and the long bricks 15 form the top of the structure. The walls 26 are a continuationof the same walls in the other zones and adjacent them on the bricks 39 are the long courses of bricks 31 and under the long bricks I adjacent the walls 39 are the long courses of bricks Between these long courses of bricks II are the wide bricks I2. But in place of the wide bricks 45 are tunnel floor bricks 30 having rectangular depressions II to lower the floor of the tunnel 40 and in place of the tunnel forming bricks 55 are tunnel forming bricks 95 in pairs with a wide space between them forming the passage 42 instead of a ceiling 63. The tunnel 40, however, has inclined upper portions of the side wall 69. Similarly, instead of the tunnel forming bricks 65, the firing zone has tunnel forming bricks 06 similar to the bricks 85. The bricks 95 are cut away to support the lon refractory pieces 41 for the tunnel 4|. Between courses of bricks 96 is a long rectangular space 81 which may be of the same width as that of the passage 42 which is also rectangular but may be of slightly lesser height as shown. The ceiling of the tunnel 4| is therefore formed by the bricks 12. The bricks 80 as well as the bricks 95 are cut away to provide space for the long refractory pieces 41. These refractory pieces 41 support, in grooves therein as shown, long rods 40 upon which rest the batts 49 supporting grinding wheels 50 being vitrified. When the kiln is in operation there is, in each

tunnel

40 and 4|,

.a pair of continuous parallel sets of rods 49 and these support continuous contiguous sets of batts 49 constituting two long trains of batts and each train is moved at intervals as will later be described.

Referring now to Figures '1 and 13, extending through the side walls 2| and 22 and into the walls 36 are short refractory tubes 90 located at three levels with respect to the major axis of the kiln. 0n the lower level resistor rods 9| extend through these tubes 90 and from the tubes 90 at the side wall 2| to the tubes 90 at the side wall 22 as clearly shown. These resistor rods 9| pass through the walls 36 and through the tunnel floor bricks 80 under the long refractory pieces 41 and across the rectangular depressions 8| in the lower tunnel 40. At the middle level resistor rods 9| extend through the tubes 90 and from the tubes at the side wall 2| to the tubes 90 at the side wall 22 and through the walls 36 and through the tunnel forming bricks 95 across the passage 42. At the upper level resistor rods 9| extend through the tubes 90 and from the tubes 90 at the side wall 2| to the tubes 90 at the side wall 22 and through the walls 39 and through the tunnel forming bricks 96 and across the long rectangular space 91 of the upper tunnel 4|.

These resistor rods 9| are electrical resistors and while any refractory resistor rod capable of being heated to a high enough temperature for the purpose and having a reasonable life at such temperature may be used, the best type of resistor rod now known to me and one which is thoroughly satisfactory for use in this kiln is a recrystallized silicon carbide resistor rod having cold ends now well known to the art. During operation of the kiln all of these resistor rods 9| are connected to electrical power desirably controlled by automatic electrical controlling apparatus to maintain the current flow in them severally to the required amperage to beat them severally to temperatures sufficient to maintain the desired temperature in the firing zone of both

tunnels

40 and 4|. Such electrical controlling apparatus is available on the market. and

' clination I03.

6 need not be described herein. However it may be noted that during operation those portions of the rods 9| extending across the depressions 3| and across the passage 42 and across the space 81 respectively are customarily heated to temperatures above 1200" C. and some of them are at times as hot as 1400 C. Preferably the cold ends of the rods 9| extend on each side from their ends all the way through the various bricks right to the spaces constituting depressions 8|, the passage 42 and the space 91.

Referring now to Figure 14, on two levels the lower one of which is between the rods 9| of the lower level and the rods 9| of the middle level and the upper one of which is between the rods 9| of the middle level and the rods 9| of the upper level are short refractory tubes I90 extending through the side walls 2| and 22 and into the walls 39. On the lower of these levels extending through th tubes I00 and through the walls 38 and the bricks 35 into the tunnel 40 as shown are pyrometers IOI. These of course are refractory tubes containing wires of different metals to form a thermocouple at the end of the tube and as will be clearly seen they measure the temperature of the tunnel 40 close to the war being vitrified. that is close to the grinding wheel 30. Similarly on the upper of these two levels extending through the tubes I00 are more pyrometers Ill and this upper bank of pyrometers extends into the upper tunnel 4| adjacent the grinding wheels 50, passing through the walls 36 and through the bricks 86. The middle bank of resistor rods 9| is controlled by the electrical controlling apparatus and the pyrometers IOI, alternately an upper and lower pyrqmeter I0| for successive resistor rods 9| of the middle bank. Additionally, voltage drop across each bank of rods 9| is separately controllable manually. These measures suffice to keep both

tunnels

40 and 4| at predetermined temperatures. These tunnels per se are of course connected but the batts 49 in the upper tunnel 4| form a separating plane when the kiln is in operation and hence it is important to be able to regulate the upper bank of resistor rods 9| separately from the lower bank of resistor rods 9|. As shown in Figure 7, there are many resistor rods in the three banks on the three levels described, eighteen being shown in each bank but there need be only a few pyrometers, for example three in each bank at the firing zone but pyrometers |0I are located at intervals all through the kiln in two banks one for each tunnel as more clearly shown in Figures 1, '7 and 9.

Referring now to Figure 7, preferably the tunnel bricks of one kind change gradually into tunnel bricks of another kind. For example the wide bricks 45 gradually change into the tunnel floor bricks so as to form in the preheating zone a gradual dropping of the bottom of the tunnel 40 by a gentle decline I02 and a gradual rise of the bottom of the tunnel 40 at the start of the annealing zone in a somewhat steeper upward in- The tunnel forming bricks 65 of the upper tunnel 4| change a little bit more abruptly into the parallelepipedal bricks I2 to form tapered boundaries I04 and I05 of th roof of the upper tunnel. Likewise the passage 42 has tapered boundaries I06, I01, I08 and I09 at its ends.

The foregoing shaping of the boundaries of the tunnels is streamlining, which is desirable because there is a gentle flow of air through the

tunnels

40 and 4| when the kiln is in operation, induced by the incline of the kiln and the chimney to be described. The pressure drop involved in this flow has been found to be, as measured in the chimney, from .025 inch to .035 inch of water.

The kiln is provided with various fines and dampers such as the dampers I I3 and H4, Figure '1, to control the temperature in the various zones and also to permit gases from the burning of any temporary binder in the wheels 50 to escape. Referring now to Figure 1, a chimney pipe III! is connected to a long pipe IIS on top of the kiln. As shown in Figure 12, at, the entrance end of the kiln the bricks 45 are cut and so are the bricks 31 and the walls 38 and before the rest of the bricks are laid, a flue structure II1 made of refractory metal such as a nickel-iron-chromium alloy of 60 nickel, 24 iron and 16 chromium is insorted in place and the remainder of the bricks are cut to fit around and in the flue structure II1 as shown by Figure 12. This flue structure II1 has a bottom horizontal passage II8 opening into the bottom of the tunnel 40, a couple of horizontal passages I|9 opening from vertical passages I20 into the sides of the tunnel 40 and the vertical passages I20 are continued upwardly to the long pipe II6. The vertical passages I20 are also connected to the bottom horizontal passage I I8 so that the vertical passages I20, one on each side as clearly shown in Figure 12, take care of both sides and the bottom of the tunnel 40. The flue structure I I1 likewise has a bottom horizontal passage I28 connected to the bottom of the tunnel 4| and a pair of short horizontal passages I29 connecting vertical passage I30 to the sides of the tunnel 4| which likewise extend upwardly to the large pipe I I6 and the bottom horizontal passages I28 are connected to the vertical passages I30 and thus these vertical passages I30 take care of the bottom and sides of the tunnel 4|. To show this construction as clearly as possible, Figure 12 is a broken line section on the line I2--I2 of Figure '1 and in Figure '1 the brick work in front of the structure forming the vertical passages I20 and I30 has been removed more clearly to show the shape of this flue structure I I! Referring now to Figures 9 and 10, a flue structure I31 is connected to the overhead pipe 6 and again the brick work is cut away somewhat to accommodate this structure I31. all as shown in these two figures. This flue structure I31 however has two pipes I40 on the outside of the r kiln, these pipes I40 being connected to the long pipe IIS and extending horizontally and then vertically downward along the sides of the kiln to form an inverted U-shaped structure. Between the legs of the U extend flattened pipes I4I, I42, I43 and I44, reading from bottom to top. The pipe |4| opens into the bottom of the tunnel 40, the pipe I42 opens into the top of the tunnel 40, the pipe I43 opens into the bottom of the tunnel 4| and the pipe I44 opens into the top of the tunnel 4|. As shown in Figure 9. the bricks 45 are mitred to form depressions with inclined boundaries I45 above the pipes HI and similarly the bricks 55 are mitred to form depressions with inclined boundaries I46 above the pipes I43 to permit an even flow of the air into those pipes. As shown in Figure 1, there are dampers II, I52, I53 and I54 for the pipe I4I, I42, I43 and I44 respectively. There are such dampers I5I, I52, I53, and I54 on both sides of the kiln.

Referring now to Figure 11, I provide special removable bricks I58 and I59 and the steel side walls 2| and 22 are cut away so that these bricks I58 and I59 extend to the outside of the fu nace and they are provided with rings, not shown. whereby they can readily be withdrawn to gain access to the

tunnels

40 and 4| respectively. These bricks I58 and I59 may be shaped as shown having a slight taper for ready removal and of course the other bricks are cut away to provide the exact space in which these bricks I58 and I59 fit.

Referring now to Figure 1, at the loading and of the kiln I provide a loading conveyor I60 and at the exit end of the kiln I provide a discharging conveyor IBI. I further preferably provide as shown in Figure 2 a receiving table I62. The loading conveyor I60 has one pair of endless V-belts I63 intermittently driven by a motor I64 while the discharging conveyor I6I has two pairs of endless sprocket chains I65 and I66, and both pairs I65 and I66 are continuously driven by a motor I61. The sprocket chains I65 are at the level of the discharge end of the tunnel 40 while the sprocket chains I66 are at the level of the discharging end of the tunnel 4|. The table I62 has freely rotatable rollers I68 at the same level as the sprocket chains I65 and has freely rotatable rollers I69 at the level of the sprocket chains I66. Consequently whenever a batt emerges from either tunnel, it is promptly moved out of the way and upon the table I62 unless this is too crowded with batts whereupon it simply remains at or near the far end of the discharging conveyor I6I.

Referring now to Figures 1 and 5, I provide an elevator I10 to transfer batts 49 from the conveyor I60 to a position in front of the tunnel 40 during a given half cycle of kiln operation and to a position in front of the tunnel 4| during the next half cycle of kiln operation. This elevator I10 is connected by a piston rod |1| to a piston I12 in a cylinder I13. Batts are periodically pushed into the

tunnels

40 and 4| respectively by means of rams I14 and I15 and referring now to Figure 15, the lower ram I14 is connected by a piston rod I16 to a piston I11 and a cylinder I18 while the upper ram I15 is connected by a piston rod I19 to a piston I in a cylinder I8I.

It will be convenient to describe the cycle of operation of the kiln before describing the elevator I10, conveyor I60, conveyor I6I and table I62 in detail, and preparatory to describing the cycle of operation I shall, with special reference to Figure 17, identify the solenoids, relays, limit switches and other electrical apparatus. Three phase power can be used to operate the mechanism and is identified by the three lines I85. From two of these lines I extend wires I86 and I81 to the primary coil of a step-down transformer I88. The secondary of the transformer I88 is connected to main operating lines identified as LI and L2. The interval between the start of each cycle is determined by an adjustable timer I90 which is diagrammatically represented in Figure 17. From LI a wire I9I extends to a wire I92 which is connected to one terminal I93 of the timer I90. From L2 extends a wire I94 which is connected to a terminal I95 of the timer. The third terminal I96 of the timer I90 is connected by a wire I91 to one end of a relay I98 for the motor I64 of the loading conveyor I60 while the other end of this relay I98 is connected to the wire I92. When the relay I98 is energized, three relay switches I99 close and connect the three lines I85 to the motor I64 to operate it.

Closed by the elevator I10 whenever it is in its lowermost position is a limit switch LSI. Operated by the elevator I10 just before it comes to the level of the lower ram 114 is a limit switch LS2. Operated by the elevator 118 just before it comes to the level of the upper ram 115 is a limit switch LS2a. Operated by a batt 49 on the loading conveyor 168 when the batt has been moved as far as it will go to the right, Figure 5, is a limit switch LS3. Operated by a batt 49 as it leaves the lower tunnel 48 at the discharging end of the kiln is a limit switch LS4. Operated by a batt 49 as it leaves the tunnel 41 at the discharging end of the kiln is a limit switch LS4a.

- Operated by the lower ram 114 when it has moved all the way forward that is toward the kiln, is a limit switch LS5. Operated by the upper ram 115 when it has moved all the way forward that is toward the kiln is a limit switch LS5a. Operated by the lower ram 114 when it is fully retracted is a limit switch LS6. Operated by the upper ram 115 when it is fully retracted is a limit switch LS6a. For causing the elevator 118 to rise, a solenoid 288 is energized. For causing the elevator 118 to stop at the station of the lower tunnel 48, a solenoid 281 is energized. This operates a latch 282 which will be explained hereinafter. For causing the lower ram 114 to advance, a solenoid 283 is energized. For causing the upper ram 115 to be advanced, a solenoid 284 is energized. The electrical mechanism further includes a relay RI and a relay R2.

The timer 138 is diagrammatically illustrated in Figure 17 and any timer operating upon the general principle of the timer 198 may be employed. Timers are now made by a number of manufacturers and are readily available upon the market. The mechanism is shown as mounted upon a panel 218. The terminal 193 which is always connected to the power line L1 is connected by a wire 211 to a solenoid 212, the other terminal of which is connected by a wire 213 to a. terminal of a solenoid 214, the other terminal of which is connected to a main timer terminal 215 which can be called the reset terminal because at the close of the cycle of operation the wire 216 which leads to the terminal 215 is connected through to line L2.

Also connected to the power terminal 193 of the timer is a wire 211 which is connected to one terminal of a motor 218, the other terminal of which is connected by a wire 218 to a. switch terminal 228 opposite a switch terminal 221. The switch terminal 221 is connected by a wire 222 to the power terminal 185 of the timer.

A switch terminal 225 of the timer is connected by a wire 226 to the wire 222. A switch terminal 221 opposite the switch terminal 225 is connected by a wire 228 to the third terminal 196 of the timer which is a load terminal. While the timer is running a contactor 238 connects the

terminals

228 and 221. When the timer times out a contactor 231 connects the

terminals

225 and 221. In Figure 17 the timer parts are shown in timing position.

The motor 218 drives a pinion gear 232 and this may be driven at reduced speed for there may be a reduction gearing not shown in the casing of the motor 218. The pinion gear 232 drives a large gear 233 joumalled on a stud 234 projecting from a lever 235. Likewise projecting from the lever 235 are studs 236 and 231 and a shaft 238. Secured to the large gear 233 is a pinion gear 248 which meshes with a large gear 241 joumalled on the stud 236. Secured to the large gear 241 is a pinion gear 242 which meshes with a large gear 243 joumalled on the stud 231. Secured to the large gear 243 is a pinion gear 244 which meshes with a large gear 245 that is secured to the shaft 238. sprin 258 shown in dotted lines in Figure 17 is on the far side of the lever 235 and the inner end of this clock spring 258 is secured to the shaft 238 while the outer end is secured to a pin 251 projecting rearwardly from the lever 235.

The lever 235 is pivotally mounted on a stud 252 and has a forked left end 253 to which is connected a link 254 by means of a pin 255. A pin 256 connects the link 254 toa core member 251 of the solenoid 214. When the solenoid 214 is energized, the gear 233 is drawn into engagement with the pinion 232 and the gearing slowly rotates the final gear 245 but when the solenoid 214 is deenergized, a spring 258 connected to the pin 255 and to a pin 258 projecting from the panel 218 lifts the lever 235 thus disengaging the gear 233 from the pinion 232 and then the clock spring 258 resets the tim Projecting from the front face of the gear 245 is a cam 268. When the timer times out this cam 268 engages a detent 261 of a bell crank lever 262 mounted on a stud 263 projecting from the panel 218. On the lower end of the bell crank lever 262 is formed a latch 264 which, while the timer is timing, holds a hook 265 on the upper end of a rod 266 which extends downwardly through a guide 261 and is connected to a core member 268 of the solenoid 212. A spring 268 supported by a bracket 218 secured to the panel 218 tries to hold the bell crank lever 262 against a stop 211 also secured to the panel 218. A spring 212 extending from the guide 261 presses against a collar 213 on the rod 266 and therefore tries to hold the rod 266 in its upper position but the solenoid 212 is more powerful than the spring 212. While the latch 264 engages the hook 265, the rod 266 cannot descend even though the solenoid 212 is energized but when the cam 268 hits the detent 261 the latch 264 is withdrawn from the hook 265 and the rod 266 will go down if the solenoid 212 is energized. The reset position of the timer is determined by a stop block 215 secured to a member not shown which is rotatable on the same axis as that of the shaft 238 and which can be secured in adjusted position to fix the time interval measured by the timer. This stop block 215 is in the path of the cam 268 and when the clock spring 258 resets the timer, the cam 268 moves clockwise until it hits the block 215. By adjusting the block 215 angularly the time interval can be set from a few seconds to many minutes.

As shown in Figure 17, the timer is running and since the contactor 238 connects the

terminals

228 and 221 the motor 218 is running. The two

solenoids

212 and 214 are connected in series as shown and they are energized since the terminal 183 is always live and the wire 216 is at this time connected to line L2. Finally the cam 268 hits the detent 261 which releases the rod 266 which opens the circuit between

terminals

228 and 221 thus stopping the motor 218. At the same time the contactor 231 connects the

terminals

225 and 221 so current flows from line L1 to line L2 through the loading conveyor motor relay 188 as follows: from L1 to wire 131 to wire 182 to relay 188 to wire 191 to timer load terminal 136 to wire 228 to switch terminal 221 through contactor 231 to switch terminal 225 to wire 226 to wire 222 to timer terminal to wire 194 to line L2. Accordingly the relay switches 188 are is closed and the motor 164 starts. This causes the A clock I V-belts I63 to move and finally a batt 48 strikes limit switch LS3.

The limit switch LS3 is a double switch having a normally closed contactor 218 and a normally open contactor 219 which are mechanically connected. Engagement by a batt with the actuator of LS3 opens contactor 218 and closes contactor 219. When the batt leaves the actuator the contactors return to the position shown in Figure 17. The contactor I19 when closed connects wires 28I and 282. Line LI is connected to the relay RI as shown in Figure 17 and the other side of RI .s connected by a wire 283 to the wire 28I. The wire 282 is connected to a wire 284 which is connected by a wire 285 to a wire 286 which is connected to a normally closed contactor 281 of limit switch LS4 which is a double switch and is operated by a batt 49 leaving the tunnel 40. Contactor 281 is connected by a wire 288 to the limit switch LS4a which is operated by a batt 49 when it leaves the tunnel M. The limit switch LS4a is likewise a double switch having a normally closed contactor 289. The wire 288 is connected by this contactor 289 to a wire 290 which is connected to line L2. Accordingly when the batt 49 hits LS3 the relay RI is energized. This action causes a contactor 29I to connect a wire 292 leading from L2 to a wire 293 leading to the elevator solenoid 200, the other end of which is always connected by a wire 294 to the wire I8I which is always connected to LI. Therefore the elevator I starts upwardly.

Another function performed by the limit switch LS8 is to stop the loading conveyor I64 and also to reset the timer I90. In order to understood this I will now describe the reset circuit for the timer. Energy flows from LI through wire I9I to wire I92 to terminal I93 to wire 2 through solenoid 2I2 to wire 2I3 through solenoid 2 to terminal 2I5 to wire 2I6 through closed limit switch LS6a to wire 295 through closed limit switch LS6 to wire 296 through closed limit switch LSI to wire 291 through the contactor 218 of LS3 to wire 284 to wire 285 to the closed contactor 281 of LS4 to wire 288 through the closed contactor 289 of LS4a to wire 290 to the line L2. Opening of the contactor 218 of LS3 breaks this circuit so the solenoids 2I2 and 2I4 go dead, the spring 258 raises the arm 235 and the clock spring 250 resets the timer. Also at the same time the spring 212 raises the rod 266 and the latch 264 re-engages the hook 265. The contactor 23I is now up and the

terminals

225 and 221 are no longer connected so the relay I98 goes dead and the relay switches I99 open and the motor I 64 stops. Although as soon as the batt 49 on the elevator I 10 moves upwardly the contactor 218 again connects

wires

291 and 284, the circuit remains broken because the slightest upward movement of the elevator I10 opens the limit switch LSI this switch being held closed when the elevator I10 is down. Switch LSI is a normally open limit switch but while the timer I90 is timing, it is held closed by the elevator I10 in a manner to be hereinafter more fully described.

In Figure 17 the circuits are shown while the timer is timing and in such condition that the elevator I10 will move to its upper position so that a batt 49 will be rammed into the upper tunnel 4|. Although as soon as the elevator I10 starts to rise the contactor 219 of LS3 opens, the relay RI does not go dead because a holding circuit for it has been established as follows. From line LI to the relay RI then to wire 283 and through a contactor 300 to the wire 284 to 1! 12 wire 288 to wire 286 through the contactor 281 to wire 288 through the contactor 289 to wire 290 to line L2. As the elevator I10 rises it closes the normally open limit switch LS2 but nothing happens and the switch LS2 immediately reopens. Finally when the elevator I10 arrives at its top position it closes the limit switch LSZa and this energizes the upper ram solenoid 204 in the following manner: from line LI to wire I8I to wire 30! through solenoid 204 to wire 302 through L820 to wire 303 through a contactor 304 of the relay R2 to wire 305 to wire 388 through contactor 28I of relay RI to wire 292 to line L2. Now, with the elevator I10 still held up by fluid pressure, the upper ram I15 pushes a batt 48 into the upper tunnel 4I and consequently another batt 49 must emerge from the exit end oi the tunnel 4I onto the always moving sprocket chains I66. The emerging batt moves out onto the rollers I63 but before it gets there it actuates the limit switch LS4a and opens the contactor 288 and closes a contactor 3 I0. This momentary opening of the contactor 289 opens the holding circuit of the relay RI provided the upper ram I15 had completed its forward stroke. For there is an alternate path from the wire 288 to the wire 290 by way of a wire 3, a wire M2 and the limit switch 15511 which is a normally closed limit switch and opens when the ram I15 is fully forward. This circuit is provided so that the elevator I10 will not descend unless an incoming batt is rammed the full distance into the kiln. But with the limit switch LS5a open the moment the contactor 289 opens, the holding circuit of relay RI is definitely broken so the contactor 28I disconnects the

wires

282 and 293, the solenoid 200 is deenergized and the elevator I10 starts down. This movement soon opens the limit switch 152:: which breaks the circuit to the upper ram solenoid 204 thus causing the upper ram I15 to retract.

Momentary closing of the contactor 3I0 energized the relay R2 but before describing the circuits I shall describe this relay R2 which is a special kind of a relay.

The relay R2 is an Allen-Bradley 700 type BM-20 relay of the permanent magnet type.

Unlike mechanically held relays, this type BM employs no latches or other holding devices. The operating coil of the relay is divided into two parts, one for closing and the other for opening the relay. When the closing section of the coil is energized, the plunger is drawn upwardly. This relay has pole faces and at the end of the upward movement they meet and an auxiliary switch in the circuit of the closing coil is opened. This auxiliary switch is so designed that the tiny are which it forms interrupts the circuit at the instant of maximum magnetization of the operating magnet. Therefore a strong magnetic flux remains in the magnetic circuit and the hardened steel plunger becomes a permanent magnet, holding the relay in closed position. The flux is not dissipated until the opening section of the operating coil is energized whereupon the alternating current demagnetizes the plunger which moves to its lowermost position. The position of parts with all the contactors up and the plunger up is referred to as the closed position of the relay while the position in which the contactors and plunger are down is referred to as the open position of the relay. Figure 1'1 shows this relay in open position.

When the contactor 3I0 closes, the relay R2 is closed, The circuit is as follows: from line Ll to a wire 3I5 to the relay R2, then through the relay this being the closing circuit, then by a wire 3"; through a contactor 3I1 oi the relay R2 which is closed when the relay is open, then by way of a wire 3I8 and through the contactor 3I0 to the wire 290 to the line L2. This closes the relay R2.

When the upper ram I has been fully retracted the limit switch LS6a which is a normally open limit switch is closed. The lower ram I14 not having moved the limit switch LS6 remains closed this also being a normally open limit switch which is closed when the lower ram I14 is fully retracted. These switches LSIia and LS6 are shown as closed in Figure 17 because they are closed when the timer is timing and all switches are shown in the position which they then occupy except that the relay R2 is shown in its first position, that is to say open, it having either position when the timer is timing depending upon which tunnel the next batt is to enter. When the elevator I10 reaches the bottom the switch LSI is closed this also being a normally open limit switch. The contactor 218 of LS3 is now closed because there is no batt in contact with the switch LS3. The contactor 281 of limit switch LS4 is closed and so is the contactor 289 of limit switch LS4a. Consequently the solenoids 2 I 2 and 2I4 of the timer I90 are reenergized and the timer I90 starts timing again. Eventually it times out by the cam 260 striking the detent 26I pulling the latch 264 away from the hook 265 which stops the motor 2I8 and closes the contactor 23I to connect the power from line L2 to the loading conveyor motor relay I98, the circuit being L2, I94, I95, 222, 226, 225, 23I, 221, 228, I96, I91, I98, I92, I9I and LI. Now theloading' conveyor I60 moves a batt 49 against the limit switch LS3 again. This opens the contactor 218 which opens the circuit to the solenoids 2I2 and 2I4. The timer resets and the contactor 23I moves upwardly breaking the circuit to the motor relay I98 so the loading conveyor I60 stops. The contactor 219 closes and this energizes the relay RI which is held energized by the holding circuit through the contactor 300. Again the elevator solenoid 200 is energized which starts the elevator I10 upwardly a second time.

When the relay RI closed, the elevator latch solenoid I was energized moving the latch 202 into a position where it will hold the elevator I10 in line with the lower tunnel 40. This circuit is as follows: from line LI by way of wire 3I5 to a wire 320 through solenoid 20I to a wire 32I across a contactor 322, now closed, of relay R2 to the wire 305 to wire 309 through contactor 29I to wire 292 to line L2.

Accordingly the elevator I10 rises only to a position in front of the lower ram I" where it stops. In doing so it closes the limit switch LS2 which, like the limit switch LS2a, is a normally open switch. Closing of the switch LS2 energizes the lower ram solenoid 203 by the following circuit: from line LI to wire I9I to wire 30I to a wire 325 through the solenoid 203 to a wire 326 through LS2 to a wire 321 through a contactor 328 which is now closed, to wire 306 through contactor 29I to wire 292 to line L2. Accordingly the lower ram I14 moves forward and rams a new batt 49 into the lower tunnel 40. This causes a batt with a vitrified wheel 50 to emerge from the exit end of the tunnel 40 onto the always moving sprocket chains I65. These chains I65 carry the batt to the rollers I59 and in the course of so doing the batt actuates the limit switch LS4. This causes the contactor 281 to break the circuit between the

wires

286 and 288 which deenergizes the relay RI if the alternate circuit through the limit switch LS5 is open. The limit'switch LS5 is a normally closed limit switch the same as the limit switch LS5a and it is opened only when the lower ram I14 has moved to its extreme forward position. The alternate circuit is from wire 285 to limit switch LS5 to wire 3 to wire 3I2 through LS5a to wire 290 and then to line L2 or 285, LS5, 3, 289, 290, L2. If there is no casualty and there usually is not, LS5 and contactor 281 will be open at the same instant and this breaks the holding circuit through the contactor 300 of the relay RI which therefore goes dead and the solenoid 200 is deenergized. Therefore the elevator I10 goes down and since this opens the limit switch LS2 the lower ram solenoid 203 is deenergized and the lower ram I14 retreats closing the limit switch LS6.

Actuation of the limit switch LS4 also causes a contactor 330 thereof to close. This sends current through the relay R2 as follows: from line LI to wire 3I5 to relay R2 to a wire 33I through a now closed contactor 332 to a wire 333 through contactor 330 to a wire 334 to line L2. relay R2 and accordingly the relay opens putting the parts in the position shown in Figure 17 again. When the ram I14 has moved all the way back and when the elevator I10 has moved all the way down, the switches LS8 and LSI are closed, the switch LS6a was already closed, the contactors 281 and 299 are now closed, so the circuit is completed through the relays 2I2 ancl 2I4 and the timer I starts timing again.

This double cycle of operation continues over and over again indefinitely so long as the batts are supplied to the loading conveyor I60. At any one time a number of batts spaced a shortdistance apart may be placed upon the loading conveyor I60 and they will be fed into the kiln automatically at given intervals of time as determined by the setting of the timer I90. These batts will alternately go into the tunnel M and the tunnel 40 and since two tunnels are working all the time, this kiln can vitrify twice as much ware in a given period of time as a similar kiln of about the same size having only one tunnel.

In case the description of the relay R2 be considered too meager, it is noted that there are many relays on the market controlled by three wires which place the contactors in two positions. Mechanically held relays are an example and Figure 16 is a diagrammatic illustration of a mechanically held relay R2a which can be substituted for the relay R2 to achieve the same purpose. This relay R2a, the solenoid and operating parts of which are shown in section, is connected to the wires 3I6, 3I5 and 33I as shown. It has a solenoid coil 340 one end of which .is connected to the wire 3I6, the other end of which is connected to the wire 33I and the middle of which is connected to the wire 3I5. That part of the coil between the wires 3I6 and 3I5 is the closing part of the coil while that part of the coil between the wires 3I5 and 33I is the opening part of the coil. The relay R2a has a solenoid core I made of iron connected to a long rod 342 made of brass or other non-magnetic material. The rod 342 has welded or otherwise secured thereto a block 343 having -a pair of depressions 344 and 345. The rod 342 and the This circuit is the opening circuit of the and 386.

block 343 are slidably held in a casing 346 having an opening 341 across which extends a bar 348. A detent 349 extends through a hole in the bar 348 and is pressed toward the block 343 by a spring 350. When current flows between the wires 3I5 and 3I6 the core 34I is drawn to the left to cause the detent 349 to engage the depression 345. When current flows between the wires 3l5 and 33I the core 34! is drawn to the right to cause the detent 349 to engage the depression 344 as shown in Figure 16. The variouswires extending to the operating contacts of the relay and the contactors which open and close the circuits are the same as in the case of the relay R2 and are diagrammatically illustrated in Figure 16. Relays of this type have spring held contactors but this is a detail of electrical engineering which it is not necessary for me to illustrate since it belongs to the art of switches and is well understood. A relay of this type which can readily be used for the relay R2 is disclosed in U. 5. Letters Patent No. 2,057,380 to Lincoln M. Keefe patented October 13, 1936.

The manner in which the solenoid 200 controls the elevator I10, the manner in which the solenoid 203 controls the lower ram I14, and the manner in which the solenoid 204 controls the upper ram I15 are disclosed in Figure 15. A pipe 355 is connected to a source of fluid under presx-ure and I have found that it is quite practical and convenient to use the city water supply assuming the water is supplied at at least moderately high pressure. A pipe 356 is connected to exhaust, for example to the sewer since the amount of water used in operating this apparatus is small. The pipe 355 is connected to an inlet port 351 of a valve 358 having a valve plunger 359 with lands 360 and 36l. The pipe 356 is connected to a port 362 of the valve 358 which port 362 is connected by a passage 363 to the end of the valve 358 beyond and outside of the land 360 and-by a passage 364 to the end of the valve 358 beyond and outside of the land 36l. The port 351 is always connected to the space between the lands 360 and 36L A port 365 is sometimes connected to the space between the lands 360 and 36I and is sometimes connected to the space beyond and outside of the land 36I while a port 366 is sometimes connected to the space outside and beyond the land 360 and sometimes connected to the space between the lands 360 and 36l.

Similarly, an inlet port 361 connects the pressure pipe 355 to a valve 368 having a valve plunger 369 having a land 310 and a land 31I and the exhaust pipe 356 is connected to a port 312 leading to passages 313 and 314 and the valve 368 has

ports

315 and 316. Similarly, the pressure pipe 355 is connected to an inlet port 311 of a valve 318 having valve plunger 319 having a land 380 and a land 38I and the exhaust pipe 356 is connected to a port 382 leading to

passages

383 and 384 and the valve 318 has ports 385 The

valves

358, 368 and 318 may be identical and are so shown. The solenoid 200 controls the valve 358, the solenoid 203 controls the valve 368, and the solenoid 204 controls the valve 318. Whenever the solenoid 200 is deenergized, a spring 390 holds the valve plunger 359 in the position shown in which position pressure is connected to the port 365 and the port 366 is connected to exhaust. Whenever the solenoid 200 is energized, the plunger 359 is drawn to the left, Figure 15, and pressure is 16 connected to the port 366 and the port 365 is connected to exhaust.

A spring 39I holds the plunger 369 in the position shown in Figure 15 whenever the solenoid 203 is deenergized and in this position of the plunger 369 the port 315 is connected to pressure while the port 316 is connected to exhaust. But when the solenoid 203 is energized the valve plunger 369 is drawn upwardly, Figure 15, and then the port 316 is connected to pressure and the port 315 is connected to exhaust. Similarly, a spring 392 holds the plunger 319 in the position shown in Figure 15 whenever the solenoid 204 is deenergized and in such position the port 385 is connected to pressure and the port 386 is connected to exhaust. But when the solenoid 204 is energized, the plunger 319 is drawn upwardly, Figure 15, and then the port 386 is connected to pressure and the port 385 is connected to exhaust.

The port 365 is connected to the upper end of the cylinder I13 by means of a pipe 395 and a shunting pipe 396. The port 366 is connected to the lower end of the cylinder I13 by means of a pipe 391 and a shunting pipe 398. In the pipe 395 between the ends of the shunting pipe 396 is a throttle valve 399. In the shunting pipe 396 is a check valve 400 and the direction in which the liquid can flow is indicated by the arrow. In the pipe 391 between the ends of the shunting pipe 398 is a pressure regulating valve of the constant pressure outlet type 40I and also in the pipe 391 between the ends of the shunting pipe 398 is a check valve 402 and the direction in which the liquid can flow is indicated by the arrow. In the shunting pipe 398 is a throttle valve 403 and a check valve 404.

The port 315 is connected to the front end of the ram cylinder I18 by means of a pipe 405 and a shunting pipe 406. The port 316 is connected to the rear end of the cylinder I18 by means of a pipe 401. In the pipe 405 between the ends of the shunting pipe 406 is a throttle valve 408. In the shunting pipe 406 is a check valve 409 and the direction in which the liquid can flow is indicated by an arrow. I he pipe 401 is a throttle valve H0.

The port 385 is connected to the front end of the ram cylinder I8I by means of a pipe M5 and a shunting pipe H6. The port 386 is connected to the rear end of the cylinder I8I by means of a pipe 1. In the pipe 4I5 between the ends of the shunting pipe M6 is a throttle valve 8. In the shunting pipe M6 is a check valve H9 and the direction in which the liquid can flow is indicated by the arrow. In the pipe H1 is a throttle valve 420.

It will now be seen that when pressure is connected to the port 365, as is the case when the parts are in the position shown in Figure 15, the elevator I10 goes down or stays down. Also when the pressure is connected to the port 366 the elevator I10 goes up or stays up. It is clear that when the solenoid 200 is deenergized pressure will be connected to the port 365 and when he solenoid 200 is energized pressure will be connected to the port 366. When the elevator I10 is moving upwardly, the fluid has to flow through the check valve 402 because it cannot fiow through the check valve 404. Hence, when the elevator is rising, the valve 40I insures a constant pressure on the piston I12. However. should the load be lighter than usual, the elevator cannot rise at too fast a speed because the exhaust from the cylinder I13 has to go out through 17 the throttle valve 399 being unable to pass through the check valve 400. So these valves "I and 399 give adjustable control of the upward movement of the elevator I10 and provide for a smooth steady rise. When the elevator I10 is descending, fluid can flow through the check valve 400, but it also has to flow through the throttle valve 403 and so the speed of descent can be regulated.

In the case of the rams, the forward motion is 'under the control of both of the throttle valves 400 and M for the ram I14 and H0 and 420 for the ram I15. Rearward movement of these rams is, however, only under the control of the throttle valve 4I0 for the ram I14 and 420 for the ram I15. Accordingly the valves U0 and 420 can be set for fast movement of the ram, short of a runaway movement, while the

valves

400 and 4! can be set for a rather slow movement of the rams to avoid any accident in ramming the batts into the tunnels.

Referring now to Figures 5 and 18, the motor I64 which drives the loading conveyor I60 has a built-in speed reduction gearing so that the sprocket gear 425 driven thereby rotates only at a moderate speed. This sprocket gear 425 drives a chain 426 which drives a sprocket gear 421 keyed to a jack shaft 428 having secured thereto a pair of pulleys 429 (only one shown) over which pass the V-belts I63. These V-belts I63 rest upon rollers 430 extending between angle iron frame members 43I which are supported by legs 432 and are also supported from the front legs 29 of the kiln. This conveyor I60 is preferably a long conveyor and it is shown as broken away in Figure 5 because of lack of space on the drawing but the portion left out is the same as the portion shown. The conveyor I60 has a number of legs 432 only one of which is shown in Figure 5. A great number of batts 49 may be placed upon the belts I63 of this loading conveyor I60 and the automatic mechanism already described will feed them one by one into the tunnels of the kiln, feeding them alternately into the upper tunnel M and the lower tunnel 40 and it is not necessary for the persons loading the kiln to space the batts apart in any regular or uniform manner provided only that the edges 435 having tongues and the edges 436 having grooves are crosswise of the belts I63 and that all the edges 435 are either in front or in back so that when the batts 49 are in a tunnel, each edge 435 will come against an edge 436 for interlocking of the batts in the tunnel. This interlocking serves to hold up a batt which may break in the tunnel.

The weight of the batts 49 on the loading conveyor I60 is taken by the rollers 430 and in order that the conveyor may operate smoothly and quietly, these rollers may be provided with ball bearingsi The belts I63 are prevented from shifting laterally of the conveyor I60 by means of grooved pulleys 431 spaced at intervals along the conveyor I60. The belts I63 go out around a pair of idler pulleys 430 at the outer end of the conveyor I60, these idler pulleys 439 (only one shown) being mounted on a shaft 439 held between bearing supports 440 supported by brackets 441 secured to the outer legs 432. In their return courses, the belts I63 pass over a number of idler pulleys 442 rotatably held in position by brackets 443 depending from the frame members 43I; a tensioning pulley 444 may be provided for each belt I63 these tensioning pu s being rotatably mounted on arm 445 to which are attached weights 446, the arms 445 being pivotally mounted on brackets 441 depending from the frame members 43I. To prevent the batts 49 from moving ofi the belts I63 I preferably provide side guides 450 as shown in Figure 18. These side guides 450 are secured to the frame members 43I by means of brackets "I. These side guides 450 are not shown in Figure 5 since to do so would obscure the rest of the apparatus.

Referring now to Figures 5, 6 and 18, the elevator I10 may have the shape shown therein and it preferably has a pair of skid rods 455 upon which the batts 49 may slide the same as they slide upon the rods 40 in the tunnel. These skid rods 455 are preferably pitched at the same inclination to the horizontal as are the rods 40, all as indicated in Figure 1. The elevator I10 is secured to the piston rod "I while the cylinder I13 has a head 456 under which is a large collar 451 which is secured to a support 456 that is fastened to the underside of the angle iron frame members 43I.

Secured to the underside of the elevator I10 and extending downwardly therefrom as better shown in Figures 1 and 5 is a rod 460 having a notch 46I which is engaged by the latch 202 whenever the solenoid 20I is energized. As shown in Figure 5, the solenoid 20I has a core 462 which is connected by a link 463 to a bell crank lever 464 mounted on a stud 465 projecting from the timer panel 2I0 which is secured by a bracket 466 to one of the frame members I and also to an iron 461 extending between cross irons 468 secured to angle iron legs 469 that support the ram cylinders I16 and I6I. One end of the bell crank lever 464 is in engagement with a rod 410 projecting from a cylindrical guide member "I in a cylindrical casing 412 in which the guide member 41I slides. The latch 202 is secured to the guide member "I and projects through a hole in the end plate 413 of the casing 412. A spring 414 is located in the casing 412 and extends between the end plate 413 and the guide member "I normally to hold the latch 202 retracted and away from the rod 460; when however the solenoid 20I is energized, the core 462 is drawn downwardly, the bell crank lever 464 is rotated counter clockwise, the guide member "I is urged to the right and the latch 202 will enter the notch 46I whenever the elevator I10 has risen far enough to bring the notch 46I opposite the latch 202 and this action stops the elevator I10 in the position where the ram I14 can push a batt 49 into the lower tunnel 40. But when the solenoid MI is not energized as the elevator I10 moves upwardly, the elevator I10 moves all the way up to a position where the ram I15 can move a batt 49 into the upper tunnel 4I.

Referring now to Figures 5 and 18, the cylinder IOI has bracket-shaped heads 416 and 411 which are secured to a plate 418 which is secured to channel

irons

419 and 400. These

channel irons

419 and 400 are secured to similar channel irons 40I and 402, and all four of the

channel irons

419, 400, 48I and 432 are secured to the legs 469. The channel irons 419 and I make a pair and extend between a pair of legs 469 while the channel irons 400 and 402 make another pair and extend between the other pair of legs 469. All this is clearly indicated in Figure 5. Secured to the lower channel irons 40| and 402 is a plate 493, similar to the plate 410 and secured to this plate 463 are bracket-shaped

heads

404 and 435