US2298795A

US2298795A - Switching mechanism

Info

Publication number: US2298795A
Application number: US141299A
Authority: US
Inventors: Albert L Judson
Original assignee: Honeywell Inc
Current assignee: Honeywell Inc
Priority date: 1937-05-07
Filing date: 1937-05-07
Publication date: 1942-10-13
Anticipated expiration: 1959-10-13

Description

Oct. 13, 1942. A. L. JuDsoN 2,298,795

swITcHING MECHANISM Filed May 7, 1937 3 Sheets-Sheet l if-719.1 2 65 )9219.4 ,77119.5

Oct. 13, 1942. A L. JUDSON SWITCHING MECHANISM Filed May 7, 1937 I5 Sheets-Sheet 2 Il; H5 ne nol Oct. 13, 1942. A, L. JUDSON swITcHING MECHANISM Filed May 7, 1937 3 Sheets-Shut 3 jlz'g. j]

latentes oci. 13, 1942 SWITCHIN G MECHANISM Albert L. Judson, Minneapolis, Minn., assigner to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware Application May 7, 1937, Serial No. 141,299

29 Claims.

This invention relates to switching mechanism, more particularly to that type of switching mechanism wherein a circuit making and breaking mechanism or analogous device is utilized to control apparatus in turn controlling a condition in response to variations in the value of the condition such as illustratively, temperature or pressure.

In devices of this character it is customary that the condition value at which the circuit controlled mechanism opens differ from the value at which the same closes and vice versa. A primary object of this invention is to provide an improved means whereby the operating differential of the instrument may be readily varied in both directions, each differential adjusting means being adapted to operate independently of the other.

An additional object of the invention is the provision of improved differential adjustment in combination with a leverage arrangement whereby a lost motion connection may be provided between the operating mechanism and the contact structure, and whereby the extent of such lost motion connection may be readily varied in such manner that the operating differential of the instrument may be increased or decreased and the operating range varied upwardly or downwardly simultaneously.

An additional object is to provide in combination with the mechanism to be hereinafter described as mentioned in the foregoing, means to impart a relatively rapid action to the switching mechanism, such action being known in the art as a snap action.

An additional and more specific object is the provision of visual indicating means in association with the differential adjustment above mentioned whereby the setting of the instrument may be readily determined at a glance.

A still further specific object is the provision of improved differential adjusting means of a novel type.

A further specific object is the provision of yieldable means in association with the differential adjusting means in combination with the features set forth above whereby undue strain is precluded from affecting the contact structure or circuit controlling mechanism should such strain be imparted to other portions of the operating mechanism by undue condition value variation.

Further objects reside in the provision of a mechanism embodying the other objects of this invention as set forth in the foregoing which lpart be pointed out hereinafter.

The invention accordingly consists in the combinations of elements, arrangements of parts and features of construction all as will be more fully pointed out hereinafter and disclosed in the accompanying drawings.

In the drawings wherein are shown several of the various possible embodiments of this invention:

Figure 1 is a side fragmentary view partly in section of one form of device incorporating features of the instant invention,

Figure 2 is a view similar to Figure 1, certain parts thereof being omitted showing the mechanism in a different position of adjustment,

Figure 3 is a perspective view as taken from the upper left hand corner of Figure 1,

Figure 4 is a sectional view taken along the line 4 4 of Figure 1 as viewed from the left,

Figure 5 is a fragmentary side view of certain portions of the mechanism shown in Figures 1 and 2 as viewed from the right,

Figure 6 is a side elevational view of a different embodiment of the invention, certain parts thereof being shown in section,

Figure 7 is a sectional view taken along the line 'l-l of Figure 6 as viewed from the top,

Figure 8 is a perspective view showing one of the component parts of the device of Figure 6,

Figure 9 is a fragmentary sectional view taken along the line 9-9 of Figure 6 as viewed from the top,

Figure 10 is a fragmentary view of mechanism similar to that shown in Figure 6 showing various modified constructional details,

Figure 11 is a side elevational view partly in section of a still further modified form of structure embodying this invention,

Figure l2 is a side sectional view taken along the line I2-l2 of Figure 11, and

Figure 13 is a perspective view ci certain of the component parts of the structure shown in Figures ll and 12.

Similar reference characters designate similar parts throughout the several views of the drawings.

Having reference now to the drawings, and more particularly to Figures 1 to 5 inclusive, there is disclosed at 20 a fragment of a casing containing the operating mechanism of this embodiment of the invention. Secured to the base of casing 20 as by suitable screws 2l is a housing 22 to the base of which is secured a nipple 23 having a suitable aperture therein into which extends a threaded end of a pressure tube 24 which extends from any suitable source of pressure which is adapted to be positioned in any desired location, the temperature, pressure or other condition of which it is desired to control. Housing 22 contains a bellows 25 to the lower end of which is secured an operating rod 26 which extends upwardly out of housing 22 and terminates in a point 21. A suitable spring 28 serves to bias bellows 25 downwardly against the pressure exerted thereon by the volatilized fluid in housing 22. The end 21 of operating rod 26 engages a recess 30 in a boss 3| carried by a lever 32. Lever 32 is pivotally mounted as on a pivot 33 the ends of which are carried by a U- shaped bracket 34 supported on the base of casing 20. A spring 40 is secured in any desired manner in position between one end of lever 32 and the base of casing and serves to bias lever 32 about its pivot 33 against the pressure exerted by operating rod 26, spring however is not sufficiently strong to effect the operation of operating rod 26 and serves only to maintain recess 30 in close juxtaposition with point 21 upon a drop in pressure in housing 22. The end of lever 32 opposite spring 40 carries a pair of upwardly projecting lugs 4| through suitable apertures in which is passed a pivot pin 42. pin 42 is a second lever 43 provided with an extending portion 44, the purpose of which will be more fully described hereinafter, and a second extending portion 45. Portion 45 is provided at its end with a slot 46 adapted to engage a pin 41 carried by a U-shaped member 48 which latter is pivotally mounted as by pivot pins 49 on bracket 34. Secured to bracket member 48 in any desired manner is a mercury switch clip 50 in which is positioned a mercury switch 5|. As better shown in Figure 3 that side of bracket 48 opposite mercury switch clip 50 carries a pin 52. That leg of bracket 34 disposed adjacent pin 52 is provided with a pair of upstanding lugs 53 positioned on either side of pin 52 and serving as a stop therefor for a purpose to be hereinafter described.

Referring back to portion 44 of lever 43 it will be seen that portion 44 extends between two cam shaped members 60, having bevelled edges a in order to provide a knife edge contact surface. Cam shaped members 60 are carried by a pair of rods 6| disposed on opposite sides of portion 44 and provided with flattened portions 62 which serve to preclude rotation of cams 60 thereupon. Nuts 63 engaging the ends of rods 6| serve to hold the component parts assembled thereon in related assembly.

Spacers 64 are provided adjacent cams 60 and positioned adjacent spacers 04 are a second pair of cams 65. Spring collars 10 are interposed between cams 65 and the side wall of casing 20. Extending exteriorly of casing 20 and mounted upon the exterior extremity of screws 0| are knobs 1| provided with pointers 12 and knurled heads 13. As better shown in Figure 5 the wall of casing 20 adjacent knob 13 is provided with indicia with which pointers 12 cooperate.

From the foregoing the operation of the mechanism should now be obvious. As the pressure in housing 22 is increased by the increase in temperature or other condition in the space adjacent the volatile fluid filled bulb operating rod 26 is forced upwardly and through the engagement of point 21 with recess 30 moves lever 32 up- Secured to pivot Cil wardly correspondingly. This movement of lever 32 will have no effect on mercury switch 5| until such time as extension 44 of lever 43 engages the beveled surface of the upper of cams 60. At this time continued upward pressure on lever 32 will cause pivotal movement of lever 43 about its pivot 42 with respect to lever 32 and through aperture 46 and pin 41 will cause bracket 48 to be rotated about its pivots 49 and hence tilt mercury switch 5| to open or closed circuit position depending upon the position of the electrodes (not shown) of the mercury switch 5|. correspondingly as the pressure decreases in housing 2|, spring 40 will force that end of lever 32 adjacent lever 43 downwardly until extension 44 engages the adjacent surface of the lower of cams 60 at which time further reduction in pressure in housing 22 will permit extension 45 of lever 43 to move downwardly and through the pin and aperture connection previously described move bracket 48 to the opposite position. Projections 53 serve to limit the tilting movement of the bracket 48 and hence of mercury switch 5|, in order that the switch may be limited to movement Within its desired normal angle of lnclination.

From a consideration of Figures 4 and 5 it will be seen that the cams 60 may be rotated by means of knurled portions 13 of knobs 1| in order to vary the distance therebetween and that such variation of the distance therebetween will cause a divergence in the operating differential of the mechanism. It will be seen additionally that by rotation of the cams a constant differential may be maintained and yet the high and low points thereof be varied within the operating limits of the mechanism as defined by the cams. For example, when a low dwell of the upper of cams 60 is adjacent extension 44 and a high dwell of the lower of cam 60 adjacent thereto the differential of operation will be at a minimum and within the higher range of the device. When the converse is true the differential will be correspondingly narrow but within the lower range of the device. Similarly when a low dwell of each of cams 60 is adjacent extension 44 the differential will be exceedingly wide and range from the high operating limits to the low operating limits of the device.

As shown in Figures 1, 4 and 5 knobs 1| are so set that an intermediate portion of each of the cams are adjacent extension 44, thus the differential is as narrow as possible and the operating range is at the mid point of the possible scale setting. By rotating the lower of knobs 1| to the left as viewed in Figure 5 a low dwell of the lower of cams 60 is brought adjacent extension 44 and by rotating the upper of knobs 1| to the right a low dwell of the upper of cam 60 is brought adjacent extension 44. Thus by such rotation it will be seen that the upper and lower operating limits of the device are diverged and by such divergence the operating differential of the instrument increased. From the above it will readily be seen that the converse of this operation is also true.

Referring now to the Figures 6 to 10 inclusive there is disclosed a different modification of the inventive concept but one wherein the principles of operation disclosed in the foregoing modification are also embodied.

In the form shown in Figure .6 the base |04 of housing is provided with a downwardly extending nipple |05 having a threaded portion to which is adapted to be secured a pressure tube leading from any suitable source of pressure (not shown). A bellows |06 is contained within housing |0| and secured to the base |04 thereof. A spring |01 abuts a shoulder |08 of base |04 and biases bellows |06 upwardly for a purpose to be described hereinafter. A stop |09 is interposed between spring 01 and bellows |06 to prevent complete collapse of bellows |06. An operating rod ||0 extends upwardly from the top of bellows |06 through a suitable aperture in threaded portion |03 into casing |00. The upper end of operating rod ||0 seats in a recess in a lever ||2. Lever ||2 is pivoted as by a pivot pin 3 to a second lever |4 which is in turn pivoted as by a pivot I5 to a bracket |6 secured to the side wall of casing |00. Lever |4 is provided with two extending portions and |2| positioned for abutment respectively with a pair of screws |22 and |23 provided with knurled and enlarged heads which extend through suitable threaded apertures exteriorly of casing |00. A screw |25 extends through an opening in the top wall of casing |00 and is rotatably secured thereto as by a collar |26. Screw |25 threadedly engages a boss |21 to which in turn is secured a spring |28. The lower end of spring |28 is secured to a plate |29 which carries a point |30 adapted to engage lever ||2 at a point substantially opposite the point of engagement of operating rod ||0 therewith.

As better shown in Figure 9 an extending member is secured to boss |21 and passes into a slot |36 in the side wall of casing |00. Thus it will be seen that rotation of screw |25 is not imparted to spring |28 since rotation thereof is precluded by member |35 but that such rotation increases or decreases the compression in spring |28 for a purpose to be hereinafter described.

Lever ||2 is provided with an extending portion |40 which is provided with a pair of slots |4| and |42. In one of the slots, slot |4| as shown, is positioned a pin held in place as by a lock nut |46. A bracket |41 extends upwardly from the base of casing |00 and is secured thereto as by screws |48. Pivotally mounted on bracket |41 as by a pivot |1| is a member generally indicated at comprised of, as best shown in Figure 8, an extending portion |5| having two slots |52 and |53 therein and an insulating block |54 rigidly secured to extending member |5|. With the parts in related assembly pin |45 extends into one of slots |5| or |53 dependent upon which of slots |4| or |42 the same is initially positioned in. The illustrative embodiment discloses pin |45 as extending into slot |52. Secured to insulating block |54 as by a screw |55 is an extending member |56 which carries a contact |51. Positioned adjacent contact |51 and carried by an insulating panel |61 is a second contact |58 and surrounding contact |58 is a horse- `,renee-magnet4.59 secured to panel |61 as by a bar and screw |6|. A pair of terminals |62 and |63 may be electrically associated in any desired manner with contact |58 and contact |51 respectively, as for example a wire |65 may extend from terminal |63 to screw |55. A coil spring |10 is positioned about pivot |1| and serves normaly to bias contact |51 in a direction away from engagement with contact |58.

From the foregoing the operation of the mechanismwill be readily understood by those skilled in the art.

An increase in pressure in the space the pressure of which it is desired to control will cause the expansion of bellows |06 and move operating rod ||0 upwardly. Such movement will be transmitted to lever ||2 which in turn will move upwardly carrying with it lever |-4 and consequently rotating about pivot ||5 until such time as arm |20 of lever ||4 abuts screw |22 to preclude further movement of lever |4. At this time upon a further increase in pressure lever I2 will rotate about pivot ||3 and through pin |45 cause member |50 to move contact |51 into engagement with contact |56. Upon a drop in pressure in bellows |06 it will be readily understood that the opposite action will take place when contacts |56 and |51 separate. In this case no movement will be imparted to contact |51 until arm |2| abuts screw |23. It will thus be seen that by varying the position of the ends of screws |22 and |23 the operating differential of the instrument may be varied over a wide range since no movement of contact |51 can take place in either direction until arm |20 or arm |2| has engaged its associated screw abutment.

It should here be pointed out that spring |01 biasing bellows |06 upwardly permits the instrument to be operated at sub-atmospheric pressures since upon the creation of a partial vacuum in bellows |06 the atmospheric pressure in housing |0| will compress the same to move operating rod |0 downwardly whereupon lever ||2 will be forced downwardly by compression spring |28 to separate contacts |56 and |51. Should reverse action of the instrument be desired it will be readily understood that by positioning pin |45 and its associated lock nut |46 in slot |42 whereby pin |45 will engage slot |53, contacts |56 and |51 may be opened upon an increase in pressure in bellows |06 and closed upon a decrease in such pressure. The pressure or other analogous condition value at which the instrument operates may readily be varied by varying the compression in spring |28 as it will readily be understood that an increased cornpression in spring |28 will require higher pressure to open or close contacts |56 and |51 whereas a lower compression will require a decreased ressure, the converse being true when the instrument is operated at subatmospheric pressures if desired.

It will be understood however, that the adjustment hereinbefore described of screw |25 by which the compression of spring |28 is varied may be omitted if desired without affecting operation of the instrument inasmuch as substantially the same results may be achieved by suitable adjustments of screws |22 and |23. This particular structure is of particular utility in those cases where it is desired that the instrument respond to temperature rather than pressure and wherein one of the screws |22 or 23 is omitted for a reason to be hereinafter described.

An instrument of analogous character but designed to respond to variations in temperature rather than pressure is disclosed in Figure 10. In this case screw |22 is supplanted by an abutment |15 and bellows assembly contained within housingr |0| is varied to the extent that base plate |04 is provided with a boss |16 to which is suitably secured a capillary tube |11 leading from a suitable volatile fluid iilled bulb (not shown). In such a case pivot I3 is supplanted by a pivot pin ||3' positioned relatively closer to pivot ||5 in order to provide a greater mechanical advantage over lever ||2. This is desirable for the reason that temperature controlled instruments are unable to exert the force of corresponding pressure controlled instruments and further because the differential adjustment utilized in connection with pressure controlled instruments need not be as wide as that used in connection with instruments of the pressure type. Therefore, it will be readily understood that the instrument as shown in Figure may be suitably calibrated by means of screw |25 and screw |23 in a manner similar to that discussed in connection with the device operated. by pressure as shown in Figure 6.

With the above noted exceptions, the parts disclosed in Figure 10 are identical to those disclosed in Figure 6, and accordingly, reference characters denoting identical parts in Figure 6 are utilized in Figure 10.

A still further modified form of the inventive concept is disclosed in Figures 1l to 13 inclusive. Having reference now to these figures a casing 200 has secured thereto as by screws 20|, a housing 202 provided at its lower extremity with a boss 203 to which is attached a capillary tube 204 leading to a suitable source of pressure (not shown). Housing 202 contains a bellows 205 having a base plate 206 to which is secured an operating rod 201 which extends upwardly into casing 200 and terminates in a point 208. A stop 209 is positioned within bellows 205 and terminates in a flange 2|0 which supports one end of a compression spring 2||, the other end of which abuts a collar 2|2 positioned about 0perating rod 201. Spring 2|| serves normally to compress bellows 205 whereby the structure shown in Figures 11 to 13 may be advantageously utilized to operate at subatmospheric pressures since operating rod 201 will be forced upwardly by spring 2|| as long as the pressure in housing 202 is equal to or above atmospheric pressure. It will of course be understood that the device may be so constructed as to operate on pressures greater than atmospheric merely by the omission of spring 2| Point 208 abuts a lever 2|5 which is pivoted as by a pivot 2|6 to a second lever 2|1 which is in turn pivoted as by pivot pin 2|8 to a bracket 2|9 secured to the side wall of casing 200. As better shown in Figure 12 lever 2|1 is comprised of a bracket like member having two extending

portions

225 and 226, the purpose of which will be hereinafter described. A screw 229 is non-rotatably secured to the top wall of casing 200 and threadedly engages a boss 230 to which is secured a spring 23|. The other end cf spring 23| is secured to a second boss 232 which has aixed thereto a point 233 positioned for abutment with lever 2|5 at a point diametrically opposed to the point of abutment of point 208. A pair of

levers

240 and 24| are pivotally mounted on pivot pin 2|8. Lever 240 is provided with an extending abutment portion 242 and so positioned that it may engage extending portion 226 and its depending flange 221 of lever 2|1. Lever 24| is provided with an abutment 245 as better shown in Figure 13 positioned to engage portion 225 of lever 2|1. Each of

members

240 and 24| is provided with an

extension

250 and 25| respectively, each of which has a threaded aperture passed therethrough to accommodate respectively screws 252 and 253. Screw 253 extends outwardly through a suitable aperture in the side wall of casing 200 and has positioned thereabout and secured thereto a spring collar 254 which serves to bias the same inwardly for a purpose to be described hereinafter. Screw 252 extends similarly out through an aperture in casing side wall 200 and is provided with an outwardly disposed collar 255 which serves to bias the same outwardly with respect to casing 200, also for a purpose to be more fully described hereinafter.

Levers

240 and 24| terminate respectively in

pointers

260 and 26| disposed adjacent a scale plate 262 secured in any desired manner to the top wall of casing 200.

Referring back to lever 2| 5 as best shown in Figure 11 it will be seen that the same is provided with a disaligned portion 210 and likewise with a resilient member 21| secured thereto in any desired manner as by a rivet 212 to provide a slot at the extremity thereof. The slot comprised of bent portion 210 and resilient member 21| is positioned to engage a pin 213 carried by an insulating block 214 which is pivoted as by a pin 215 in a bracket 216 carried by the base of casing 200. insulating block 214 has projecting upwardly therefrom a contact carrying arm 218 which extends through a suitable aperture into a housing 219 of insulating material. Housing 219 carries therein oppositely disposed

contacts

280, 28|, 282 and 283 positioned for engagement with

contact buttons

284 and 285 carried by a member 286 in turn carried by a member 218. Magnets 290 and 29| having incut edges 292 and 293 respectively aie held in position in housing 219 as by

screws

294 and 295 and

bars

296 and 291. Suitable electrical connections extend from each of

contacts

280, 28|, 282 and 283 to any desired source of condition control. These electrical connections may advantageously take the form disclosed in the copending application of Carl G. Kronmiller and Albert L. Judson, Serial No. 141,300, led of even date herewith.

The operation of the device should be readily understood from the foregoing. Assuming the parts to be in the position shown in Figure 1l, it will be seen that an increase in pressure in housing 202 will occasion an upward movement of operating rod 201 causing lever 2|5 to pivot about pin 213 and similarly lever 2|1 about pivot 2| 8 until such time as portion 226 of lever 2|1 engages abutment 242 of member 240 at which time further movement of lever 2|1 is precluded. Lever 2| 5 will then move about pivot 2|6 and through the pin 213 and the aperture formed by bent portion 210 and yieldable portion 21| be transmitted to contact carrying member 218 and hence to

contacts

285 and 286. The device is shown in Figure 11 in a position indicating a low pressure in housing 202 and upon an increase in

pressure contacts

284 and 280 will engage as

will contacts

285 and 282. As the contact carrying arm 218 is moved past center position it will enter the magnetic eld of magnet 290 and be pulled in a direction towards

contacts

280 and 282 with a relatively snap action. Correspondingly upon a decrease in pressure the converse action will take place t0 bridge a circuit between electrical contacts 28| and 283, magnet 29| serving to complete a snap action to the reverse motion of the device in a manner similar to that just described. Upon such a reverse movement of the device it will be understood that lever 2|5 will move with lever 2|1 until such time as portion 225 of lever 2|1 engages-abutment 245 of member 24| whereupon lever 2|5 will move about its pivot 2|6 to impart reverse movement to contact carrying member 218. It

should here be pointed out that magnets 290 and 29| may, due to the inclined or bevelled edges 292 and 293 be positioned in a relatively limited space in housing 219 and at the same time exert a relatively great magnetic force on contact carrying member 286.

It will additionally be seen that rotation of boss 230, by increasing the compression on spring 23|, will vary the condition value to which the device responds in a manner similar to that disclosed in connection with the modification of Figures 6 to 10. Correspondingly by rotating screw 253 the position of abutment 245 may be changed while rotation of screw 2512 will change the position of extending portion 242 to provide a variable operating differential for the instrument.

Pointers

260 and 26| will moreover indicate the relative operating differential on scale plate 262 in such manner that the adjustment of the instrument may be readily determined by examination. From the foregoing it will be seen also that the tendency of arm 24| is to pull screw 253 inwardly with respect to casing 200 and that consequently it is necessary that resilient collar 254 be positioned interior-ly of the casing to hold the head of screw 253 together against the casing to preclude any lost motion and overcome such tendency. Conversely, lever 240 tends to force screw 252 outwardly with respect to casing 200 and thus spring collar 255 is positioned exteriorly of the casing.

In the foregoing there have been described three illustrative embodiments of this inventive concept which, as will be seen, accomplish the objects of this invention and many others including numerous advantages of great practical importance.

As many additional embodiments may be made of this invention and as many modifications may be made in the embodiments above described and illustrated in the drawings it is to be understood that all such matter hereinbefore described or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In a device of the character described, in combination, a movable member, a lever movable thereby, a second lever associated with said rst lever and movable thereby, contact means movable by said first lever, abutment means disposed adjacent an end of said second lever, the arrangement being such that said movable contact is not moved until said first lever has moved said second lever into engagement with one of said abutments and yieldable means associated with said second lever and said contact mechanism whereby excessive motion of said second lever is not transmitted to said contact means.

2. In a device of the character described, in combination, a movable member, a lever movable thereby. a second lever associated with said first lever and movable thereby, contact means movable by said first lever, abutment means disposed adjacent an end of said second lever, the arrangement being such that said movable contact is not moved until said first lever has moved said second lever into engagement with one of said abutments, yieldable means associated with said second lever and said contact mechanism whereby excessive motion of said second lever is not transmitted to said contact means, and means for varying the position of said abutments with respect to said end of said second lever.

3. In a. device of the character described, in

combination, a movable member, a lever movable thereby, a second lever associated with said first lever and movable thereby, contact means movable by said first lever, abutment means disposed adjacent an end 0 fsaid second lever, the arrangement being such that said movable contact is not moved until said first lever has moved said second lever into engagement with one of said abutments, yieldable means associated with said second lever andv said contact mechanism whereby excessive motion of said second lever is not transmitted to said contact means, and means for independently varying the position of each of said abutments with respect to said end of said second lever.

4. In a device of the character described, in combination, a movable member, a lever movable thereby, a second lever associated with said first lever and movable thereby, contact means movable by said first lever, abutment means disposed adjacent an end of said second lever, the arrangement being such that said movable contact is not moved until said first lever has moved said second lever into engagement with one of said abutments, yieldable means associated with said second lever and said contact mechanism whereby excessive motion of said second lever is not transmitted to said contact means, means for independently varying the position of each of said abutments with respect to said end of said second lever and visual means for indicating the relative position of each of said abutments.

5. In a device of the character described, in combination, a movable member, a lever movable thereby, a second lever associated with said first lever and movable thereby, contact means movable by said first lever, abutment means disposed adjacent an end of said second lever, the arrangement being such that said movable Contact is not moved until said first lever has moved said second lever into engagement with one of said abutments, yieldable means associated with said second lever and said contact mechanism whereby excessive motion of said second lever is not transmitted to said contact means and means to impart a relatively snap action to the movement of said contact mechanism.

6. In a device of the character described, in combination, a movable member, a lever movable thereby, a second lever associated with said first lever and movable thereby, a fixed contact, a movable contact adapted to engage said fixed contact upon movement of said first mentioned lever in one direction, a pair of oppositely disposed abutments positioned adjacent an end of said second lever, means for independently varying the position of each of said abutments and means associated with said movable contact and said second lever whereby said movable contact may be made to disengage said first mentioned contact upon movement of said lever in said same direction.

7. In a device of the character described, in combination, a movable member, a lever movable thereby, a second lever associated with said first lever and movable thereby, a fixed contact, a movable contact adapted to engage said fixed contact upon movement of said iirst mentioned lever in one direction, a pair of oppositely disposed abutments positioned adjacent an end of said second lever, means for independently varying the position of each of said abutments, means associated with said movable contact and said second lever whereby said movable contact may be made to disengage said first mentioned contact upon movement of said lever in said same direction and means for imparting a relatively rapid snap action to the movement of said movable contact, said means comprising a magnet associated with one of said contacts.

8. In a device of the character described, in combination, a movable member, a lever movable thereby, a second lever associated with said rst lever and movable thereby, mechanism controlled by said levers, two oppositely positioned abutment means adjacent an end of one of said levers, the arrangement being such that said mechanism is not operated until one of said levers has engaged said abutment means, means for independently varying the position of each of said abutment means with respect to said end of said lever and means for imparting a relatively rapid snap action to the movement of said controlled mechanism.

9. In a device of the character described, in combination, a condition responsive member, a lever adjacent said member and movable thereby, a second lever pivoted on said rst lever, said second lever being provided with a pair of extending portions, a pair of abutment members disposed each adjacent one of said extending portions, contact means associated with an end of said first mentioned lever, the arrangement being such that said lever is incapable of moving said contact means until it has moved said second lever to such position that one of said extending portions is engaged by its associated abutment member, and means for varying the relative position of each of said abutment members with respect to its associated extending portion independently of the other.

l0. In a device of the character described, in combination, a condition responsive member, a lever adjacent said member and movable thereby, a second lever pivoted on said first lever, said second lever being provided with a pair of extending portions, a pair of abutment members disposed each adjacent one of said extending portions, contact means associated with an end of said first mentioned lever, the arrangement being such that said first lever is incapable of moving said contact means until it has moved said second lever to such position that one of said extending portions is engaged by its associated abutment, means for varying the relative position of each of said abutment members with respect to its associated extending portion independently of the other and visual means indicating the relative position of each of the said abutment members With respect to its associated extending member.

11. In a device of the character described, in combination, a movable member, a lever movable thereby, a second lever movable by said rst lever, abutment means adjacent an end of said second lever, mechanism operable by said second lever adjacent the opposite end thereof, said second lever being inoperative to operate said mechanism until said first lever has moved said rst mentioned end into operative association with said abutment, whereby said second lever is moved only by the conjoint action of said rst lever and said abutment.

12. In a device of the character described comprising in combination, a lever, a control member, one end of said lever being free to move, means to limit positively the amount of such movement in each direction, the other end of said lever being operatively associated with said control member, and condition responsive means for first moving the free end of said lever to one of its limits and then moving said other end to actuate said control member.

13. In a device of the character described comprising in combination, a lever, a control member, one end of said lever being free to move, means to limit positively the amount of such movement, the other end of said lever being operatively associated with said control member, condition responsive means for first moving the free end of said lever to one of its limits and then moving said other end to actuate said control member, and means for individually adjusting each of said limits.

14. In a device of the character described comprising in combination, a lever, a pivotally mounted arm, a switch mounted for actuation thereby, one end of said lever being free to move, means to limit positively the amount of such movement in each direction, the other end of said lever being pivotally connected to said arm, and condition responsive means engaging said lever between said ends to cause it to pivot about its connection to said arm until its free end reaches one of its limits after which the other end of said lever rotates said arm to cause switch actuation.

15. In a device of the character described comprising in combination, a lever, a pivotally mounted arm, a switch mounted for actuation thereby, one end of said lever being free to move, means to limit positively the amount of such movement, the other end of said lever being pivotally connected to said arm, condition responsive means engaging said lever between said ends to cause it to pivot about its connection to said arm until its free end reaches one of its limits after which the other end of said lever rotates said arm to cause switch actuation, and means for varying the distance between said limits.

16. In a device of the character described comprising in combination, a lever, a pivotally mounted arm, a switch mounted for actuation thereby, one end of said lever being free to move, means to limit positively the amount of such movement, the other end of said lever being pivotally connected to said arm, condition responsive means engaging said lever between said ends to cause it to pivot about its connection to said arm until its free end reaches one of its limits after which the other end of said lever rotates said arm to cause switch actuation, means for individually adjusting each of said limits, and means for indicating each of said adjustments.

17. In a device of the character described comprising in combination, a lever, a pivotally mounted arm, a switch mounted for actuation thereby, one end of said lever being free to move, means to limit the amount of such movement, the other end of said lever being pivotally connected to said arm, condition responsive means engaging said lever between said ends to cause it to pivot about its connection to said arm until its free end reaches one of its limits after which the other end of said lever rotates said arm to cause switch actuation, means for varying the distance between said limits, resilient means for opposing movement of said lever by said condition responsive means, and adjustable means for varying the force exerted by said resilient means.

18. In a device of the character described comprising in combination, a lever, a condition responsive device for moving said lever, a pivotally mounted contact arm, a spring tending to rotate said arm in one direction, a magnet tending to rotate said arm in the opposite direction, one end of said lever `being connected to said contact arm for rotating it about its pivot, the other end of said lever being free to swing, and adjustable means for limiting the amount of said swing.

19. In a device of the character described cornprising in combination, a level', a condition responsive device for moving said lever, a pivotally mounted contact arm, magnets on either side of said arm, one trying to rotate it one direction and the other trying to rotate it in the other, one end of said lever' being connected to said contact arm for rotating it about its pivot, the other end of said lever being free to swing, adjustable means for limiting the amount of said swing, and a resilient member on said lever permitting overrun of said condition responsive device.

20. In a device of the character described comprising in combination, a lever, a condition responsive device for moving said lever, a switch arm, a switch adapted to be actuated by said arm, one end of said lever being operatively connected to said switch arm whereby the latter is operated by the former, the other end of said lever being free to swing, and means for limiting said swing in each direction, said means comprising a pair of individually adjustable cams.

21. In a device of the character described comprising in combination, a lever', a condition responsive device for moving said lever, a pivoted switch arm having two extensions, one on each side of said pivot, means for connecting one end of said lever to either one of said extensions whereby movement of said lever in one direction may be made to rotate said switch arm in either direction, the other end of said lever being free to swing, and adjustable means lor limiting the amount of said swing in each direction.

22. In a device of the character described, in combination, a movable member, a lever movable by said member, a second lever substantially parallel to said first mentioned lever and adjacent thereto, said rst lever so positioned as to abut an intermediate portion of said second lever whereby movement of said movable member is transmitted to said second lever only through said rst lever, means to vary the position of an end of said second lever with respect to said first lever, and mechanism operated by said second lever.

23. In a device of the kind described, a base, a lever having a free end and a fulcrum portion, both being displaceable by translation, fulcrum means on said base comprising two fulcrum elements for said lever, power means connected to the lever to move it in two directions to bring its fulcrum portion against said fulcrums, the ful crum portion abutting one of said fulcrum elements in one direction of its travel, and the other fulcrum element in the other direction, and said power means thereafter moving the lever against the respective fulcrum to shift the free end, and one of said fulcrum elements being adjustable relative to the other so that the free end of the lever will be displaced at one point of movement of said power means in one direction, and at another point in the other direction, and means actuated by the free end of the lever.

24. In a device of the character described, power means, a lever, spaced abutment means adapted to be engaged by one portion of said lever for limiting its motion in each direction, a control member associated with a second portion of said lever for actuation thereby, means operatively connecting said power means with a third portion of said lever, and means yieldably resisting movement of the second portion of said lever whereby said rst portion is always moved firstl by said power means into engagement with one of said abutment means after which said second portion is moved to actuate said control member.

25. In a device of the kind described, power means, including a member expansible and contractible, a lever, means transmitting movements of the member to the lever including an adjustent mechanism for presetting the position of the lever relative to the expansible member, means normally releasably urging one end of the lever into either of two opposite positions, and a pair of opposed, relatively adjustable l'ulcrums for the opposite end of the lever, said power means being adapted to displace the fulcrum end of the lever to a fulcrum, and thereafter to pivot the same about the fulcrum to displace its other end against the moving of the yieldable means.

26. In a device of the character described, power means, a lever, means connecting said power means to one portion of said lever whereby rotative movements of said lever may be controlled by said power means, a pair of abutment means limiting the movement of another portion of said lever in both directions, a control device actuated by a third portion of said lever, and magnetic means cooperating with said control device to produce a snap action.

27. In a device of the character described comprising in combination, a first lever, a condition responsive member for moving said lever, a freely movable second lever, said first lever being connected at one end to said second lever for moving the same, stop means for limiting the movement of said second lever in each direction, a control device actuated between first and second positions by the other end of said first lever, and magnetic means cooperating with said control device for resisting its movement from each of its said positions whereby upon movement of said condition responsive device said first lever first moves said second lever until its movement is limited by said stop means, and thereafter upon continued movement of said condition responsive member said first lever' actuates said control device with a snap action.

28. In a device of the character described comprising in combination, a first lever, a condition responsive member for moving said lever, a freely movable second lever, said first lever being connected at one end to said second lever for moving the same, stop means for limiting the movement of said second lever in each direction, a control device actuated between first and second positions by the other end of said rst lever, magnetic means cooperating with said control device for resisting its movement from each of its said positions whereby upon movement of said condition responsive device said first lever first moves said second lever until its movement is limited by said stop means, and thereafter upon continued movement of said condition responsive member said rst lever actuates said control device with a snap action, means for varying the condition values at which said second lever reaches each limit of its movement, and means for indicating said condition values.

29. In a device of the character described comprising in combination, a first lever, a condition responsive member for moving said lever, a freely movable second lever, said first lever being connected at one end to said second lever for moving the same, stop means for limiting the movement of said second lever in each direction, a control device actuated between first and second positions by the other end of said rst lever, magnetic means cooperating with said control device for resisting its movement from each of its said positions whereby upon movement of said condition responsive device said first lever rst moves said second lever until its movement is limited by said stop means, and thereafter upon continued movement of said condition responsive member said first lever actuates said control device with a snap action, and means for varying the condition values at which said second lever reaches each limit of its movement, said last named means including means for varying at least one of said values independently of the other.

ALBERT L. JUDSON.