US2321124A - Apparatus for drying - Google Patents

Description

Juhe 8, 1943. G, E, BOWDOIN ETAL 2,321,124

APPARATUS FOR DRYING Original Filed dot. 12, 1935 8 Sheets-Sheet 1 START STOF INVENTOR GEORGE. E. BOWDON 'WlLLlAM STROBRIDGE ATTORN vs June 8 1943. ca. E. BOWDOIN ETAL 2,321,124

APPARATUS FOR DRYING Original Filed Oct. 12, 1935 8 Shets-Sheet 2 INVENTORS GEORGE E. sowoom AND WILLIAM STRODRIDGE ATTORNE June 8, 1943. G. EQBOWDOIN (ET AL APPARATUS FOR DRYING Original Filed Oct. 12, 1935 8 Sheets-Sheet 3 MF- G Mm N 0 N E 4 R m m T m L I ml. l GW B June 8, .1943. a. E. aowoom ET AL 2,321,124

APPARATUS FOR DRYING Original Filed 0st. 12, 1935 8 Sheets-Sheet 4 INVENTORS GEORGE E. BOWDCNN AND B WILLIAM STROBRDGE ATTORN 5 l Juns,-1943.

G. aaowoom EI'AL APPARATUS- FOR DRYING Original Filed Oct. 12, 1935 8 Sheets-Sheet 5 INVENTORS GEORGE E. BOWDOIN AND WILLIAM STRQBRIDGE EaMLGMhLI ATTQRN Y8 Jim 8, 1943- G; E. sowoom ET AL APPARATUS FOR DRYING Original Filed Oct. 12, 1935 8 Sheets-Sheet 6 .INVENTOR GEORGE E. sownom AND B WILLIAMSTROBRIDGE I IIbAN ATTORNE June 8, 1943. e. E. BOWDOIN ET AL 2,321,124

I APPARATUS FOR DRYING Original Filed 001;. 12, 1935 .8 Sheets-Sheet '7 INVENTORS GEORGE E. sownom AND WILLIAM STROBR\DGE ATTOR N EYS June 8, 1943. e. E. BOWDOIN El'AL 2,321,124 APPARATUS FOR DRYING Original Filed Oct. 12, 1935 8 sheets-sheet 8 INVENTORS GEORGE E. BOWDONAND WILLIAM STROBRHDGE ATTORNE s Patented June 8, 1943 'UNirEn STATES PATENT OFFICE APPARAT IfZ DRYING George E. Bowdoin, New York, and William Strobridge, Syracuse, N. Y., assignors to United States Hoffman Machiner Corporation, New York, N. Y., a corporation of Delaware Application October 12, 1935, SerialNo. 44,724, now Patent No. 2,142,042, dated December 2'7. 1938, which is a division of application Serial No. 133,344, March 27, 1937, now Patent No. 2,217,153, dated October 8, 1940. Divided and this application September 7, 1940; Serial No.

2 Claims.

This invention relates to apparatus employed in dry cleaning, and more particularly to apparatus for drying materials which have previously been treated with an inflammable cleaning solvent.

This application is a division of application Serial No. 133,344, patented October 8, 1940, No. 2,217,153, filed in the United States Patent O-ffi'ce March 27, 1937, the latter being a division of application Serial No. 44,724, filed October 12, 1935, now Patent No. 2,142,042 issued December 27, 1938.

An object of the invention is to provide simple and trustworthy means, interlocked with certain of the manually operated parts of the apparatus, for preventing operation of such part unless predetermined safe operating conditions obtain.

Further objects of the invention are in part obvious and in part will be pointed out hereinafter.

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

In the accompanying drawings, in which is shown a preferred embodiment of the invention capable of use in carrying out the purposes above mentioned:

Fig. 1 is a front elevation of a drying tumbler embodying features of the present invention;

Fig. 2 is a left side elevation thereof;

Fig. 3 is a back elevation of the tumbler;

Fig. 4 is a cross-section taken on line t& of Fig. 3;

Fig. 5 shows on a larger scale the upper-portion of the tumbler, and the control mechanism in the same position it occupies in Fig. 2, the shell door being in open position;

Fig; 6 is 'a view similar to Fig. 5 showing the control mechanism in a difierent position and the shell door closed;

Fig. 7' is a view of certain elements of the control mechanism in positions different from those'oc-cupied by the same elementsin Figs.' 2, 5 and 6;

Fig. 8 is a view showing the'control elements of Fig. 7 in still different positions;

Figs. 9 and were respectively back and side elevations, on an enlarged scale, of the belt pul leyand beltshifting header assembly; and

Fig. 11 is a wiring diagram pertaining to the apparatus and devices shown in' the preceding ur Similar reference characters refer to'similar a tumbler comprising an outer shellor casing Ill having rotatably mounted therein a foraminous drum ll. The" drum jll is' surrounded-by an internal cylindrical shell l2 which encloses the drum for approximately three-quarters of the periphery thereof, the hinged outer shell door l3 at the front of the tumbler" housing completing the enclosure. To the rear of the drum chamber is formed a rectangular coilboX f4, connected with the atmosphere" through the rear plate of the housing bymeans of two-air in'lets' l5 and it, the inlet l5 giving access of[air to the upper portion of the coil'box and the inlet I6 at a point near the bottom of the coil box. These two inlets are equipped respectively with rectangular air intake nozzles l1 and I8 adapted to be opened or closed to the atmosphere by means of dampers l9 and 20. The damper l9 is rotatably mounted upon a shait 2| and similarly the damper 29 is'rotatably mounted upon a shaft 22. These dampers areconnecte'din' predetermined relationship by means of'an' adjustable rod '23; the'length of the rod and its mode of attachment to the two dampers beingsu'ch that whenever one of said dampers is open the other willbe closed.

Thehcuter Air for solvent removal is admitted through one or the other of the air inlets l5 l6 to the coil box It and after being heated by passing over steam coils; is'led to the toner the tumbler and admitted to thetumblerdrum through an opening'29' in theinner shell l2-. Admission oi steam for heating the steam coils is controlled automatically to insure that" at the beginning of a drying operation the heated-air entering the tumbler drum does; not exceed" a predeter; mined temperature. Theoutlet'from thecylin the fan housing 33 is at 34 projecting through the rear wall of the tumbler housing near the bottom thereof.

The fan 3| is driven by a direct connected motor 35 and serves to draw air through the air inlet l5 or I6 over the steam coils, thence by way of the air inlet 29, down through the drum chamher, and by way of outlet 30 into the lower part of the tumbler housing, whence the air is exhausted to the atmosphere, preferably outside of the building in which the tumbler is installed.

Cylinder drive The tumbler drum H is journaled in bearings 46 mounted on brackets 41 secured to the side plates of the tumbler housing.

Upon the drum shaft H is mounted a spur gear 48 driven by a pinion 49 mounted upon a jack shaft 50 forming part of a pulley and belt shifting header assembly, for a better understanding of which reference is made to Figs. 9 and in which the jack shaft 50 is shown to be rotatably mounted in a pair of bearings 5|, 52 carried by a header bracket or arm 53. This bracket is bolted to the side of the tumbler housing. The jack shaft 50 carries a tight pulley 54 and a pair of loose pulleys 55, 55. Also loosely mounted upon the shaft 50 is the header worm 51 which has a pin-and-slot connection with the coaxial relation to the shaft is a header arm assembly comprising the support 58, to which is pivotally connected the belt shifter fork 59.

The header arm assembly includes a worm gear 69 on support 58 meshing with the worm 51, and a reciprocating slide shaft 6| slidably and rotatably mounted at the upper end of the support 58 in a block 62. Projecting from the block 62 parallel to the shaft 6| is a guide rod 63. A weighted pin or header fall 64 secured to. and extending at right angles to the slide shaft 6| shifts with the slide shaft about its axis so that the pin 64 may engage the upper end of the shifter fork '59 when the pin 64 is swung in one direction to a horizontal position, eventually settling in the notch 65 formed in said upper end, and when swung. in the opposite direction to a horizontal position will be free of the shifter fork 59, but will enga e one or the other of the beveled surfaces 66 formed on the block 62 and ride down to a neutral position. Near the end of the slide shaft 6| which is nearest the tumbler housing is a shifter sleeve 61 loosely mounted upon the said slide shaft, but held against endwise movement by means of cotter pins 68.- This shifter sleeve carries a forked arm 69 cooperating with the guide rod 63 to prevent the shifter sleeve 6'! from rocking about the axis of the shaft 6|. This shifter sleeve carries a shifter arm l9 extending in opposite directions above the belt pulleys and provided with belt guide blocks 1|, l2, each equipped with a belt guide 13. The belt guides are so disposed'that when the shifter pin 64 occupies its center. or neutral position the two drive belts l4, 15 (see Fig. 3) will be positioned upon the loose pulleys, so that under these conditions no power will be transmitted to the tumbler drum. It will be noted that the belt 15 is direct and the belt 14 crossed whereby the shifting of one belt off and the other belt on to the tight pulley will effect a reversal of the rotation of the tumbler drum. It will be understood that belts I4 and I5 connect with a suitable line shaft (not shown) and are of a width to enable them to drive the tight pulley without disengaging their respective loose pulleys. The operation of the header assembly will now be briefly described. It will be noted that since the worm 51 is driven by the loose pulley 56 it will always rotate in the same direction irrespective of the location of the belts with respect to the tight pulley. Thus, also, the Worm wheel 60 will rotate constantly in one direction. This wheel drives a crank pin slidable up and down in a slot 71 provided for that purpose in the shifter fork 59. Thus rotation of the loose pulley produces constant oscillation of the shifter fork at a slow rate of speed. When the pin 64 does not engage the notch 65 in the upper end of the shifter fork no motion will be transmitted to the belt guides, but when the pin 64 engages the notch 65, it will cause the slide shaft 6| to reciprocate slowly. This action will periodically shift the driving belts and reverse operation -of the tumbler drum. No claim is made to this header construction per se, but, as will be seen hereinafter, it is associated with other control mechanism to insure safe operation of the apparatus.

Safety air inlet At the top of the tumbler housing there is provided an auxiliary air inlet I8 communicating directly with the air outside the tumbler housing and serving as a vent when the fan is not running. This air inlet 18 may be closed by means of a vent damper l9 pivotally mounted upon arms which themselves are rotatably mounted upon brackets 8| secured to the housing. The rock shaft 82 which supports the arm 80 carries a crank arm 83 connected by means of a link 34 to one end of a counterbalanced lever 85 pivotally supported at 66 upon the tumbler housing. The weight lever 85 has mounted at its free end a counterweight 88, the tendency of which is to maintain the vent damper l9 always in an open position. The operation of this damper, as will be hereinafter disclosed, is associated with other automatic control mechanism;

Mechanical control mechanism Referring again to the drawings, mechanical means for setting the tumbler in operation to begin the drying cycle will now be described. It will be noted that in Fig. 5 the vent damper I9 is open, the tumbler shell door [3 is also open, and that the belt-shifting header-fall 64 occupies its disengaged position as in Fig. 2, so that the drum is at rest. The means for shifting the headerfall into or out of engagement to cause belt drive of the tight pulley on the jack shaft comprises an operating lever 89 which, with other operating parts, is mounted upon a cast bed-plate 96 bolted to the side sheet of the tumbler housing. The operating lever 83 is pinned to a shaft 91 rotatable in a bearing-forming part of the said bedplate casting. Attached to one end of the operating lever is a roller 92 adapted, when the lever 89 is thrown to engage the belt-shifting header-fall in operating position, to come in contact with an arm 93, moving said arm to shift an electric switch A to initiate the operation of certainautomatic controls, not included in the present specification.

Pinned to the shaft 9| in proper angular relation to the lever 89 is an arm 94, connected by a link 95 to a crank arm '96 which is free to turn about a shaft 91 mounted in bed-plate casting 90..

A branch arm 96 of crank arm 96 is connected by an adjustablelink 98 to a gear segment 99 rotatably mounted on a pin I fixed to a casting IllI which is adjustably mounted on the side of the tumbler housing toward the rear. of said housing relative to the position of the bed-plate 90. The gear segment 99 meshes with teeth out on a rotating sleeve I02 rotatably mounted on a pin I93 carried by the bed-plate I9I (see Fig. 3). The rotatable sleeve I92 surrounds an extension of the reciprocating slide shaft 6| of the header assembly hereinbefore described. This extended shaft BI is provided at the end nearest the tumbler with a pin I94 which projects through a longitudinal slot I05 in the sleeve I02. It is obvious, therefore, that when the operating lever 89 is thrown toward the centerof the tumbler to the position shown in Fig. 6, the toggle composed of the members 94, 95 straightens out and causes rotation of the crank arm 96 about its axis of rotation, causing the branch arm 96 to assume the position shown in Fig. 6, thus rocking the gear segment 99 toward the front of the tumbler.

This motion of the gear segment causes rotation of the sleeve I 92 and because of the engagement of the pin I94 with a side of the slot I05 produces rotation of the shaft 6| in a counterclockwise direction, as looked at. in Figs. 5 and 6, throwing the weighted header pin or fall 64 from the position shown in Fig. 5 to that shown in Fig. 6, where it will engage the slot 65in the header fork 59, thus, by reason of the slow reciprocation of the shaft 6 I, shifting one or the other of the driving belts on to the tight pulley 54 and causing rotation of the tumbler drum through pinion 49 and gear 48. It should be noted at this point that straightening the toggle 94, 95 looks the operating lever in the engaged position of the belt-shifting header, thus insuring that the tumbler drum drive will continue until the starting lever 89 is returned to its forward or disengaged position.

Sajety devices associated with mechanical control mechanism There will now be described means connected with this operating mechanism for preventing the opening of theshell door I3 when the belt-shifting header isengaged and also for preventing any actuation of the operating mechanism to start rotation of the drum when the shell door is open. There will also be described means associated with this operating mechanism. for controlling the operation of the vent damper I9 in association with magnetic means adapted to open the vent damper I9 in case of failure of current to the fan motor 35.

Referring to thedrawings, it will be seen that the crank arm 96is provided withanotherbranch arm 96 which serves to form an interlock between the operating lever 89' and the shell door I3. The latter isequipped with an abutment casting Hit-so shaped and disposed that the shell doorcan -be opened only when the operating lever 89-is inits forward or header-disengaging position, as willbe clearly understood-by comparingthe-positions of the parts in- Figs. 5 and 6. It will-be seen that the abutment HIE-prevents rearwa rdmovement of the brancharm 96 and thus rearward movement of operating lever 89, when the tumbler door stands in open position and, re-

versely, the said arm 96 opposes movement of the abutment member I96 should an attempt be made to open the door I3 while the operating lever 89 stands in its rearward position, as shown in Fig. 6. Now since, as will be shown hereinafter, it is impossible that the starting lever 89 be put in engagement position unless current is being supplied to the fan motor, it follows-that the dryer cylinder can not be set in operation until after the fan is started. The crank arm 99 is also provided with a third branch arm 96 which carries pivotally mounted thereon a latch member I91, the movement of which is restrained in one direction by means of a spring I98 attached at one end to the latch member I91 and at the other end to a fixed pin I99. This latch member I91 normally stands in interlocking engagement (see Figs. 5 and 6) with a coacting projection H9 formed upon a slide block IIl, which is constrained to a straightline motion by three rollers II2 mounted upon the bed-plate 96. Attached tothe slide block I I I is a spring housing H3 which by means of a spring H4, a bolt H5, and a link I I6 connects'the slide block I I I with a crank arm III, pinned to the vent damper shaft 82.

Obviously, then, when the operating lever 89 is thrown to the header-engaged position, as in Fig. 6, it causes a rotation of branch arm 96 0f crank arm 96, thus moving the latch member I91 from the position shown in Fig. 5 to that shown in Fig. 6. Thus, the slide block Ill is drawn down and through its spring connection with the crank III, the vent damper I9 is drawn down to cover the vent opening I9, the extra travel of the parts needed to insure proper seating of this damper being taken up through .the spring I I4.

Safety device operable upon failure of electric energy Also supported upon thesbed-plate 99 is a solenoid I I8 to the core of which is attached a weight I I9 of sufficient mass to cause the immediate descent of thesolenoid core whenever excitation ceases. As will be more fully explained in connection with the wiring diagram shown in Fig. 11., this solenoid is energized under normalworking conditions immediately after the closing: of a magnetic starter, indicated in the drawings bythe letters MS, whose position on. the tumbler housing is substantially. as disclosed in'Figs. 1 and 2. It should be explained at this timethat operation of the magnetic starter, among other things, startsthe tumbler fan rotating; and that the solenoid I i8 remains energized as long as the main switch in the magnetic starter remains closed or so long as failure of current in th fan circuit does not occur. Below the weight H9 is a lever I29 pivoted on the pin 19 herein-before mentioned. One end of this lever is connected by means of a link I2I to a bell crank lever I22 turning, freely about a pin I23. The throw of the-bell crank lever I22 is limited by the adjustment screws I24 and I25. In Figs. 5 and 6, the solenoid core and parts coacting therewith are shown in the normalposition they would occupy during the operating cycle while the solenoid is energized. Should current fail-at any time dur ing the operating cycle the solenoid H8 will become de-energized, dropping its core and per-' mitting the weight I I9 to fall upon thofrce end of the lever I29; turning'the lever- 2913091197190- sltion shown in Fig. '7, in moving to which'p'osi tion movement of the bell crank I22 is effected to the position also shown in Fig. '1. Referring to Figs. 5, 6, '1 and 8, it will be noticed that also pivoted on pin I23 there is provided a trigger I15 lying in back of the bell crank I22. At one end this trigger is provided with a detent hook I16 adapted to engage the projection I I on slide II I when the slide is drawn down to the position shown in Fig. 6 by the latch member I01, as above described. The slide will thus be held in its lower position by the trigger even though the operating lever 89 be thrown to its header disengaged position, as is clearly shown in Fig. 8, which shows the latch member I01 in its raised position and the trigger I interlocked with the slide projection III]. Trigger I15 tends always to follow up any movement of the bell crank I22 in a counterclockwise direction by reason of its weighted end I11. However, when the bell crank I22 is moved in a clockwise direction by the dropping of the solenoid core, the trigger is also swung in the same direction under the compulsion of an adjustable abutment bolt I18 carried by the bell crank.

If failure of current occurs when the operating lever 89 occupies its header-engaged position, as in Fig. 6, the upper arm of the bell crank lever I22 will strike the latch member I01, driving it and consequently trigger I15 out of engagement with the slide block projection I I0, thus permitting the slide block to move upward under the re-. action of the spring H4 and the effect of the counterweight 88. Therefore, if the tumbler has been in operating condition when failure of current occurs the vent damper on top of the tumbler will be automatically opened. Should the failure of current occur when the operating lever 89 is in th header-disengaged position and slide III in its upper position, as in Fig. 7, the movement of the bell crank I22 in response to the dropping of the solenoid weight is to the position shown in Fig. 7 where the upper arm of the bell crank moves under the projecting surface I26 of the latch member I01 and 30 serves as a strut to prevent the operating lever 89 from being moved to its header-engaged position until current has been restored and the solenoid re-energized. Again, should current failure occur when the operating lever 89 is in header-disengaged position and slide III in its lower position (damper 19 closed and held in place by trigger I15 as in Fig. 6), the movement of the bell crank I22 in response to the dropping of the solenoid weight will swing the bell crank in a clockwise direction and cause the trigger I15 to release the slide projection. The slide will now assume its upper position, as in Fig. '1, opening the damper, and the upper arm of the bell crank will pass under the latch I26 to serve as a strut to prevent downward movement of latch member I01 and hence the manipulation of lever 89 to header-engaged position until current to the fan has again been restored. Thus, irrespective of the period in the drying cycle that such current failure may occur, the drying tumbler will be put out of operation and/or held out of operation until after current is once more made to flow in the fan circuit. The bell crank lever I22 is held in its normal rearward position by means of a spring I21. It will be seen as we proceed with the description of the wiring diagram in what manner the fan is energized concurrently with excitation of the solenoid and so becomes operative before operating lever 89 can be moved away from its header-disengaged position. 1 v I Wiring diagram operatethe magnetic contaotor JM. F is a thermostatic control-switch, the bulb for operating which is indicated at I39 in Figs. 2 and 4 where it is shown disposed in the air passage leading to the top of the tumbler cylinder in a position to measure the temperature of the air entering the tumbler drum. Bulb I39 is connected to switch F by means of flexible tubing I40. The thermostatic control of the switch F should be such that the switch will close when the temperature in the air passage falls to or below the predetermined temperature desired for the preliminary low heat stage of dryer operation.

' Referring to the wiring diagram, LI and L2 indicate respectively the two sides of a power line entering the magnetic starter MS. When the starting lever 89 is in its disengaged position, line LI connects with the start switch of the magnetic starter MS by means of the switch A, mentioned above. This connection only obtains when the machine starting lever 89 stands in its forward or disengaged position. The momentary closing of the starting switch, indicated on the drawings by word Start, completes a circuit through the normally closed stop switch, indicated by the word Stop, through the magnet coil I4I of the ma netic starter. The energizing of this coil closes the main circuit contactors I42, I43 and I44, and as soon as these main circuit contactors come to closed-circuit position the circuit through V the magnet coil MI is maintained by means of a bridge member I45 which completes a circuit shunting the contacts A2, A3 of-which A and the Start switch, the maintaining circuit then being made from LI through the bridge member I45, the Stop switch and the magnet coil I4I back to line L2.

The closing of contacts I42 and I44 completes a circuit through the fan motor which immediately starts the tumbler fan in operation, and since at this time the tumbler vent damper 19 is open, atmospheric air is drawn in at the top of the tumbler through the tumbler cylinder and discharged out-Of-doors. Should, for any reason, the fan motor not start, thermal elements in the magnetic starter, indicated at I46 and I41, will heat up and, after a few seconds of this abnormal condition, throw themain switch to open position. It will be noted that the line L2 has a branch'LZA which is closed by the switch contact I43, and also that a branch line LIA takes off from line LI at a point beyond switch contact I44. Thus, we have a circuit LI, L2 through the fan motor and a circuit LIA, L2Ain shunt therewith, adapted to supply current to various control devices (not shown). It will be understood that as soon as the main switch of the magnetic starter closes, the line LIA becomes alive as far as the thermostatic switch F.

The switch F is normally held in open position at temperaturesabove the selected temperature at which the apparatus is to operate during the low heat period, as, for instance, F. If. at the beginning of a cycle, the temperature stands below or at 140 F., the switch F will be closed and a circuit will be completed from LIA through switch contact K, through the coil of the magnetic contactor J and back to the line L2A. Thus, the magnetic contactor will be energized and drawing up its core will complete circuits respectively by means of switch contacts MI and M2 from line LIA through magnetic contactor J and solenoid H8. Thus, the solenoid will become energized and by the raising of its core open the circuit through the switch K, the magnetic switch J, M thereafter being maintained by current flowing through the switch contact M and its connections. Switch K (see Fig. 3) is mounted upon the tumbler housing adjacent the solenoid H8. Its interior contact member, not shown, is operably associated with an exterior arm KI, normally biased, by any suitable means, to hold the switch K in open position whenever permitted to act through the energization of the solenoid I 18. Upon de-energization of the solenoid, the dropping of the weight H9 produces movement of the arm KI to close the switch K.

It will be remembered that with the solenoid II8 de-energized the vent damper I8 stands in open position and an interlock is maintained between the bell crank I22 and latch member I01, preventing operation of the belt-shifter operating lever 89. However, upon energization of solenoid coil I 18, the weight I I9 is removed from engagement with the lever I26 releasing the beltshifter mechanism for hand actuation.

Now, upon the operator throwing the hand lever 89 to its rearward or header-engaging position, as shown in Fig. 6, one of the driving belts is shifted to the tight pulley on the jack shaft and the tumbler drum rotates. At the same time the vent damper at the top of the tumbler is closed. Also, the throw of operating lever 89 breaks the connection between line LI, and the Start switch of the magnetic starter.

It will be understood from the foregoing that when the machine is prepared for operation by closing the Start switch, the fan is immediately set in operation and, at the same time, the solenoid I I8 is energized and opens the switch K. Now when the starting lever 89 is thrown to the position shown in Fig. 6, the damper I9 is closed by the movement of the hook IIiI which engages the corresponding hook element III] on the damper slide I I I. It will be understood also that when there is no interlocking of these hooks, the damper will close automatically by spring action, but, after the parts have been moved to the position shown in Fig. 6, the damper may not be released simply by moving the starting lever from the position of Fig. 6 to the position of Fig. 5, because the energized solenoid I 18 has brought the bell crank lever I22 to the position shown in either Figs. or 6, in which position the gravity actuated hook I16 engages the hook III] and holds the damper closed. Thus it is impossible to open the damper without failure of current in the fan and solenoid circuits, due either to opening the stop switch or to accident or other cause of general power failure. If the parts are in the position shown in Fig. 6 and momentary current failure occurs, the vertical arm of bell crank-lever I22 moves to the right and shoves both of the hooks III! and IIfiout of engagement with H8. The damper I9 immediately opens and the machine may not again be put in operation until the starting lever has been moved to its idle position, as shown in Fig. 5, and the temperature within the tumbler has fallen to its required setting so as to permit closing of the switch F. During the movement of the starting lever 89 to its idle position, the hook I61, which has been pushed backwards by the upstanding portion of the bell crank lever I22, merely slides up along the back of that upstanding portion until it reaches the position shown in Fig. 7 when its hook engages with the hook III) of the slide, at which time the hook I25 at the upper end of I01 overlies the upper end of the said upstanding arm of the bell crank lever so that thereafter the starting lever 89 may not be moved back to operating position until the solenoid has again been energized by starting the fan, by which means the bell crank lever I22 is permitted to return to the position shown in Figs. 6 and 8.

As many possible embodiments may be made in the above invention and as many changes might be made in the embodiments above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

We claim:

1. In apparatus of the character described, in combination, a drying chamber, a rotatably mounted cylinder in said chamber, a heater chamber, a fan for drawing heated air through said drying chamber from said heater chamber, driving means for said cylinder, driving means for said fan, control means for engaging or disengaging said driving means with said cylinder, means for supplying energy to said fan driving means, a damper biased to stand in open position for admitting cold air directly to said cylinder chamber, means operated by said control means for closing said damper when said control means is moved to engaging position, means including an electrical circuit for driving said fan, means for releasing said damper from said closing means, and means in said electrical circuit for operating said damper releasing means upon failure of said fan energy supply.

2. In apparatus of the character described, in combination, a drying chamber, a rotatably mounted cylinder in said chamber, a heater chamber, a fan for drawing heated air through said drying chamber from said heater chamber, driving means for said cylinder, driving means for said fan, control means for engaging or disengaging said driving means with said cylinder, means for supplying energy to said fan driving means, a damper biased to stand in open position for admitting cold air directly to said cylinder chamber, means operated by said control means for closing said damper when said control means is moved to engaging position, means including an electrical circuit for driving said fan, means for releasing said damper from said closing means, means in said electrical circuit for operating said damper releasing means upon failure of said fan energy supply, and means cooperatively associated with said releasing means and said damper closing means and operated by said releasing means to prevent movement of said cylinder control means to engaging position should failure of said energy supply occur while said control means stands in its disengaging position.

GEORGE E. BOWDOIN. WILLIAM STROBRIDGE.

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