US2757771A - Time limit mechanism - Google Patents

Description

Aug 7, 1956 M. H. BORCHERDING 2,757,771

TIME LIMIT MECHANISM Filed April 7, 195o 2 sheets-sneer 1 ELvm H. BofzcHzRmNG INVENTOR.

A'TT'ORNEY M. H. BORCHERDING TIME LIMIT MECHANISM Aug. 7, 1956 2 Sheelts-Sheet 2 Filed April '7, 195o4 u' ovm )NDER MELWN H. BORGHERDI NQ INVENToR.

ATTORNEY United States Patent Oflice y 2,757,771 Patented Aug, 7, 195,6

TIME LIMIT MECHANISM Melvin H. Borcherding, Fort Wayne, Ind.

Application vApril 7, 1950Serial No. 154,679.

19 Claims; (Cl. 19,4-9)

This invention relates to` a., time limit mechanism. More specically, it relates to a mechanism which is actuated by the deposit of coins toclosea power supply circuit. andactuated in proportion to the passage of time to open said circuit.

v While the mechanism is suitablefor a. number of uses, it is particularly useful for collecting the time payments on electric appliances, suchas electricy stoves, refrigerators, hot water heaters, etc.,

It is an object` of` the inventionI to produce, a mechanism which is inexpensive, yet reliable.

Another object is to provide a mechanism, which is easily reset and which is simple.

A further. object of the invention is.to1provide a mech'- anism which is positive in operation.

Yet another object of the inventiony is to provide a mechanism which will indicate thecredit ordeiicitwhich obtains` at any time.

These and other objects will become apparentfrom a study of this specification and the` drawings which are attached hereto and made a part hereof and inwhich:

Figure 1 is a front elevationzof thel preferred form of the devicewith thecase broken away.

Figure 2 is a sectional view taken on:the;line 2-2 of Figure 1.

Figure 3 is a sectional', view taken substantially on line 3-3 of Figure 1 showing the electrical connections.

Figure 4 is a sectional view taken substantially on line 4 4 of Figure 1 showing the coin accepting mechanism.

Figure 5 is a section taken substantially on line 5--5 of Figure 4 showing the coin guide.

Figure 6 is a diagrammatic view of the direct control circuit.

Figure 7 is a diagrammatic view of a relay controly circuit.

Figure 8 is a front elevation of a modified form of the mechanism.

Figure 9 is a diagrammatic view of a modied form of relay control circuit.

Figure 10 is a front elevation of a third form of mechanism.

Figure 11 is a side elevation of the mechanism of Figure 10 taken on line 11 of Figure 10.

Figure 12 is a sectional view takenv substantially on line 12-12 of Figure 10 showing'the splitnut.

Referring tirst to Figures 1 to 6, the numeral 1 designates a case having coin slots 2. Fixedv tothe case is a fulcrum bar 3 on which rests theknife edges 5 and 6 of a beam 7. At one end of the beam is suspended the bucket 9 While the pointer 11 depends from the beam below the opening 13 which forms clearance for bar 3. A scale 14 is mounted behind the pointer and a window in cover 22 exposes them.

The beam is preferably U-shaped in cross-section and one leg is formed with a rack 15,' a notch 16` and a stop 17.

A carriage 19 has one end Zl riding in the groove of the beam from which it loops downwardly and under the beam as shown in Figure Zand supports a weight 23.

A shaft 25 is rotatably mounted on the carriage and has a gear 27 in mesh with the rack. A second gear 29 meshes with a gear 31 which is driven by clutch 33 from the clock motor 34'also mounted on the carriage. Gear 31 has a knurled knob 35 so that it may be ,rotated by hand. Gear 27 may rotate freely in notch 16 if the carriage is driven to the end of the beam.

As shown in Figure 3,' the fulcrum bar 3 comprisesl a pair of sleeves 39 and 40'which are insulated from each other andl from the post` by spacers 41 and are held in position by screw 43. The knife edges 5 land 6 rest on flats on the sleeves 39 and 40 and are formed with terminal pieces 45and 46. The knife edges are insulated from each other andfrom the beam by spacers 47 and are held together by rivets 49. Flexible metal strips 51, 52 connect the terminals 45, 46 respectively to the terminals of motor 34. Wires 36, 38 connect the sleeves to the power line. p

The coin chute mechanism comprises coin guide 53 mounted by ears 55 on cover 22 adjacent slots 2 and hascoin ways 5.7, 59 and` 61 for dimes, quarters and halves, although provision may be made forother coins.

A shutter 63 slides over the guide and has an end 65 projecting through the covery and a stop 66.

The shutter has a` front leg 69 adjacent'the cover and has, slots 67 ywhich are alignedwith slots 2' and the ways whenV the shutter is lifted to thelimit of stop 66. The rear leg 73 has slots 711which registenwith the ways when the shutter is down. In=the down position of the shutter, thev front leg closes slot 2; whenthe shutter isilifted, the rear legcloses the ways.v

A switch 75is mounted onthe case 1 and a lever 77 is'mounted on*` the-beamin positionto operate the switch through a lost motion mechanism consisting of a button 78 which yields after the switch is closed. The switch may be of the enclosed type, such as a Micro switch. It is preferably normally openl andrarranged to the right of the fulcrum, as shown in Figure l, so that it will be,

closed when the Weight of coins tiltsthe beam counter clockwise. The lines 81` and S3V connect the switch to main 38 and the control socketSS, while line 87 connects they main 36 4with this socket.

To deposit coins-for credit, they are entered in the ways 57, 59, 61 according to their denominations, through slots Zand 67, which are, in alignment when the shutterl israised tothe limit-of stop 66. The shutter is then dropped and the coins slide through slots 71 into bucket 9.

The beam 7 is tilted proportional to the weight of the coins and pointer 11 indicates thel amount of credit on the scale 14, arm 77- closes switch 75. Since the carriage 19 is not, pivotally supported on the beam 7, the

. deposit of coins in receptacle 9,,which tilts the beam counterclockwise (Fig. 1), vthrows the lower end of the carriage 19 and weight 23 outwardly (to the right) and thus makes their weight more effective so that they coun-l terbalance the weight of the coins andthe receptacle.

The pointer 11 thus stops at a point between the zero and end portion of scale 14 whichy is substantially proportionaltolthe weight of the coins. Thus the appliance socketSS is energized. The motor 34 is constantly operatingand it gradually moves the carriage 19 toward the` stop 17 and eventually overbalances the Weight of the coins so-that theV beam will tilt .clockwise and relieve the pressure of arm 77 on'switch 75 which opens to deenergize the ysocket 85. If `no coins are inserted, the motor will continue to run out on the beam and the pointer-will indicate more and more of a deficit which must7 be made upV by additional coinsy before the switch will again close. f

The cover is periodically removed by an authorized person, the coins are removed from the bucket and the knob 35 is operated to return the carriage toward the fulcrum to the point where the switch 7S is just open. The pointer then should read zero.

Should the carriage not be reset before it reaches the outer end of the beam, the gear 27 will merely ride off the rack into notch 16 where it will rotate idly until attended to. Stop 17 prevents the carriage from being removed from the beam. The motor operates continuously at a constant speed.

The metal strips 51, 52 are very flexible so that they impose little load on the carriage.

The weight 23 is suited to the weight of the coins to be collected. The heaviest weight is used when 50 a week is to be collected. `The carriage travels the same distance per month, but is reset nearer the fulcrum when heavier weights are used.

First modification In the form shown in Figure 8,.the structure is similar to that of Figures 1 to 6 with the exception that 101 is shown as an exposed contact type and is mounted at the left of the fulcrum. The arm 103 projects to the left from the beam to engage the switch.

A relay 105 is mounted in the case and comprises the magnet 107 and a pair of normally closed contacts 109.

In operation the switch opens as the beam is rotated counter-clockwise by the weight of coins and closes when the weight of coins is overbalanced by the carriage.

This mechanism may be used with the circuit shown in Figure 7 in which the mains 113 and 115 are connected to the motor 34, as described above. Main 113 is connected by wire 117 to the switch 101 and by wires 117 and 119 to the appliance socket 121. The other side of switch 101 is connected by wire 123 to the magnet 107 and by line 125 to main 115. Line 125 is also connected to the normally open switch 109 from which line 127 extends to socket 121.

Thus when switch 101 `is closed, the relay will be energized to open switch 109 and deenergize socket 121. If enough coins are inserted to open the switch 101, the relay is deenergized and the switch 109 will again energize the socket. The switch arms are long and form a lost motion device which permits the beam to rotate even after the switch is closed.

This operation can be reversed by utilizing the mechanism shown in Figures l to 6 with a relay having normally open contacts as shown in Figure 9.

In this case switch 75 is closed when the machine shows a credit. This energizes relay 129 to close the normally open contacts 131 to energize the socket 134 through wires 133, 135, 137.

Second modification (Figs. to I2) A screw 207 is rotatably mounted in the case parallel to the vertical axis of the spring and bucket and is connected by gearing 209 and clutch 210 to the motor 211.

A C-shaped carriage 213 is mounted at its upper end on a bushing 215 which is slidably mounted on the screw and has a second bushing 217, also slidable on the screw, at its lower end.

A split nut 219 (Figure 12) is mounted on a pair of pivotally connected arms 221 which are urged toward nut closing position by a spring 223. The halves of the nut are mounted on the arms by a spring and pin construction 225, 227. The `one arm has a pointer 229 on it which cooperates with a scale 230 on the carriage. The ends of the arms extend through a slot 231 in the carriage and a spring 235 surrounds the screwand bears on the bushing 215 and nut so as to support the carriage upon the nut. This lost motion support of the carriage on the screw and nut enables the carriage to move relative to the nut as coins accumulate in the bucket.

Also carried on the carriage is a normally open switch 237. A button 238 of insulating material is supported in a hole 239 in arm 241 of the carriage and is disposed thereby under the bucket.

A pointer 243 is carried by the bucket and cooperates with a scale 245 on the carriage. The bucket also carries two pairs of bifurcated members 247 which ride on guides 249 fixed in the case to guide the bucket in a vertical path and to prevent rotation thereof.

Screw 207 is provided with a knurled wheel 251 and with a reduced diameter at 253. The upper end of the screw is provided with a cross-pin 255 which is disposed beneath the reset crank 259. The hole is closed by a slide 261 which is held in closed position by the cover 263.

The coin guide 265 detlects coins from the coin slots 267 in the case into the bucket 201.

Operation The coins are inserted by way of slots 267 and guides 265 into bucket 201. The additional weight stretches spring 205 and the bucket eventually depresses button 238 and closes switch 237. The latter will close the circuit to the receptacle in the manner shown by either Figures 6 or 9. The pointer229 and scale 230 show the amount of credit since the carriage and switch move downwardly relative to the nut compressing spring 235 as coins are added.

The motor. 211, which is continuously operating, rotates screw to move the nut downwardly where it eventually picks up the carriage and moves it relative to the bucket so that the switch 237 is opened and the appliance socket is deenergized.

Further rotation of the screw moves the carriage and scale 245 relative to the pointer 243 on the bucket to indicate the deficit.

The cover is periodically removed by an authorized person and the coins are removed from the bucket. Slide 261, which can be opened only when the cover is removed, is withdrawn and a crank 259 is inserted in hole 257 so that the screw may be revolved to raise the nut. The final adjustment can be made by wheel 251. The clutch 210 permits relative rotation of the screw and motor.

Should the mechanism not be attended properly, the nut 219 will run off the screw` onto the reduced portion 253. It will drop with `the carriage into the gearing 210 and the screw will idlein the nut. The nut may be reengaged with the screw by pressing the levers 221 to open the nut and by moving the nut and carriage upwardly until they engage the screw.

Different strengths 0f the spring 205 are used for the dierent weights of coins to be collected. Thus where a week is to be collected, the spring must extend a lesser distance in response to a given weight of coins then if 25 a week are to be collected. The carriage 213 travels continuously, the same distance in equal lengths of time.

It is obvious that various changes may be made in the form, structure and arrangement of parts without departing from the spirit of the invention. Accordingly, applicant does not desire to be limited to the specific embodiment disclosed herein primarily for purposes of illustration; but instead, he desires protection falling fairly within the scope of the appended claims.

What I claim to be new and desire to protect by Letters Patent of the United States is:

l. A mechanism for controlling the supply of energy to an apparatus, the combination of supply means having effective. and inetective conditions, a coin accumulating receptacle, means mounting said receptacle for movement in one direction a distance proportional to the weight of coins therein, indicating means operable by the receptacle, first means operable by the movement of said receptacle for rendering the supply means effective,

second means operable in proportion to the elapse of time for relatively moving said receptacle and first means for rendering the supply means ineffective, one of said `operable means including a lost motion device to permit overtravel of said receptacle relative to said rst operable means.

2. A mechanism for controlling the supply ofI energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a fulcrum, 'a beam mounted thereon, a receptaclev for accumulating coins supported on the beam on one side of the fulcrurn, a weight movably mounted'on the beam on the opposite side of the fulcrum, continuously operating time responsive means for moving the weight away from. the fulcrum, control means operable by the beam in response to the weight of the receptacle 'and coins for rendering the supply means eifective, said beam being thereafter responsive to the movement of the weight for operating said control means to render saidsupply meansineffective. f

3. A mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a fulcrum a beam mounted thereon, a receptacle for accumulating coins supported on the beam-on one sideof the fulcrum, a weight movably mounted onthe beam on the opposite side of the fulcrum, said4 weightbeing constructed and arranged to apply an increasingtorque to the beam as the beam is tilted from a balanced condition by and in proportion to the weight of coins added after the beam is balanced, time responsive means for movingAv the weight away from the fulcrum, control, means operable by the beam in response to an overbalance of the weight by the weight of the receptacle and coins for rendering the supply means effective, said beam being: thereafter responsive to the movement. of the weight for operating said control means to rendersaid. supply means ineffective, and a lost motion device between. saidbeam and control means for permitting said proportional tilting of of the beam.

4. A mechanism for controlling the supply. of energy to an apparatus, the combinationof a supply means having effective and ineffective4 conditions, a fulcrum, a beam mounted thereon, a receptacle for laccumulating coins supported on the beam on, one side of the fulcrum, a weight movably mountedv on the beam on the opposite side of the fulcrum, said weight being constructed and arranged to apply an increasing torque to the beamas the beam is tilted from a` balanced condition by and in proportion to the weight of coins added after the beam is balanced, time responsive means for moving the weight away from the fulcrum', control means operable by the beam in response to an overbalance of the weight by the y weight of the receptacle 4and coins for rendering the supply means effective, said beam being thereafter responsive to the movement of the weight' for operating said control means to render said supply means ineffective, a lost motion device between said beam and control means for permitting said proportional tilting of the beam.

5. A mechanism for controlling the supplyof energy to an apparatus, the combination of a supply means having effective and ineffective conditions, `a fulcrum, a double aimed beam mounted thereon, a coin receptacle mounted on one arm, a carriage movably mounted on the other arm, a motor on the carriage, means driven by the motor and engaging said beam for moving the carriage along the beam away from the fulcrum, a weight on the carriage, said weight and carriage being constructed and arranged to apply an increasing torque to the beam as the beam is tilted from a balanced condition by deposited coins, a switch connected to said supply means, an arm on the beam disposed to actuate said switch, said switch comprising yieldable means to prevent limitation of further motion of the. beam after the switch is actuated, whereby the deposit of additional coins will increase the tilt of the beam to establish a credit.v

6. A mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a fulcrum, a double armed beam mounted thereon, a coin receptacle mounted on one arm, a carriage movably mounted on the other arm, a motor on the carriage, a gear driven by the motor and engaging a rack carried by said beam for moving the carriage along the beam away from the fulcrum, a weight on the carriage, said weight and carriage being constructed and arranged to apply an increasing torque to the beam'as the beam is tilted from a balanced condition by deposited coins, a switch connected to said supply means, an arm on the beam disposed to actuate said switch, said switch comprising yieldable means to prevent limitation of further motion of the beam after the switch is actuated, whereby the deposit of additional coins will increase the tilt of the beam to establish a credit.

7. A mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having eifective and ineffective conditions, a fulcrum, a double armed beam mounted thereon, a coin receptacle mounted on one arm, a carriage movably mounted on the other arm, a motor on the carriage, a gear driven by the motor and engaging a rack carried by said beam for moving the carriage along the beam away from the fulcrum, said driven means including a clutch, a weight on the carriage, said weight and carriage being constructed and arranged to apply an increasing torque to the beam as the beam is tilted from a balanced condition by deposited coins, manual means for operating the driven means to move the weight toward the fulcrum, a switch connected to said supply means, an arm on the beam disposed to actuate said switch, said switch comprising yieldable means to prevent limitation of further motion of the beam after the switch is actuated, whereby the deposit of additional coins will increase the tilt of the beam to establish a credit.

8. A mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a fulcrum, a double armed beam mounted thereon, a coin receptacle mounted on one arm,- a carriage movably mounted on the other arm, a motor on the carriage, a gear driven by the motor and engaging a rack carried by said beam yfor moving the carriage along the beam away from the fulcrum, a weight on the carriage, said weight and carriage being constructed and arranged to apply an increasing torque to the beam as the beam is tilted from a balanced condition by deposited coins, a recess in the beam at the outer end of the racktto clear the gear and limit the movement of the weight, a switchtconnected to said supply means, an arm on the beam disposed to actuate said switch, said switch comprising yieldable means to preventlimitationof further motion of the beam after the switch is actuated, whereby the deposit of additional coins will increase the tilt of the beam to establish a credit.

9. In a mechanism for controlling the supply of energy to an apparatus, a fulcrum comprising a pair of electrically conductive fulcrum members, a knife blade resting upon each member, means for connecting said blades to a beam, means insulating the blades therefrom, a carriage movably mounted on the beam, a motor on the carriage, means connecting the motor and beam to drive the carriage and flexible conductors connecting said` blades to the motor,

l0. In a mechanism for controlling the supply of eni drive the carriage and flexible conductors connecting said blades to the motor, said conductors each comprising a loop of thin, resilient metal.

ll. In a mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a coin receptacle, means mounting said receptacle for movement in proportion to the weight of the coins deposited therein, a member movable in a predetermined path, means driving said member along said path a distance proportional to the lapse of time, a carriage mounted on said member for movement therewith and for movement relative thereto by said receptacle, a switch mounted on the carriage and disposed for operation by said member, said receptacle serving thereafter to overtake said carriage and to move said switch away from said receptacle, means connecting said switch to render the supply means effective when it is operated by the receptacle.

l2. In a mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a coin receptacle, means mounting said receptacle for movement in proportion to the weight of the coins deposited therein, a member movable in a predetermined path, means driving said member along said path with a distance proportional to the lapse of time, a carriage mounted on said member for movement therewith and for movement relative thereto by said receptacle, a switch mounted on the ,i

carriage and disposed for operation by said member, said receptacle serving thereafter to overtake said car riage and to move said switch away from said receptacle, means connecting said switch to render the supply means effective when it is operated by the receptacle, said connecting means comprising a relay in series with the switch and means connecting the relay to said supply means.

13. In a mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a coin receptacle, means mounting said receptacle for movement in proportion to the weight of the coins deposited therein, a member movable in a predetermined path, means driving said member along said path a distance proportional to the lapse of time, means for yieldably connecting the member and driving means, manual means for actuating the member in a direction opposite to that in which it is moved by said driving means, a carriage mounted on said member for movement therewith and for movement relative thereto by said receptacle, a switch mounted on the carriage and disposed for operation by said member, said receptacle serving thereafter to overtake said carriage and to move said switch away from said receptacle, means connecting said switch to render the supply means effective when it is operated by the receptacle,

I4. In a mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a coin receptacle, means mounting said receptacle for movement in proportion to the weight of the coins deposited therein, a screw mounted for rotation, a nut mounted on the screw, a motor connected to drive the screw, a carriage slidably mounted on the screw, for movement relative to `the nut, yieldable means for holding one end of the carriage against the nut, a switch mounted on the carriage, means on the receptacle for actuating the switch, actuating means including said receptacle serving to close the switch as it is moved by the deposit of coins and thereafter move said carriage and switch relative to the nut and screw, said motor and screw serving to move said nut to overtake said carriage and move the switch away from the actuating means and means connecting said switch to condition said supply means.

l5. In a mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineffective conditions, a coin receptacle, means mounting said receptacle for movement in proportion to the weight of the coins deposited therein, a screw mounted for rotation, a nut mounted on the screw, said nut being longitudinally split, means for yieldably holding said nut together, manual means for releasing said nut from said screw for resetting it relative thereto, a motor connected to drive the screw, a carriage slidably mounted on the screw, for movement relative to the nut, yieldable means for holding one end of the carriage against the nut, a switch mounted on the carriage, means on the receptacle for actuating the switch, actuating means including said receptacle serving to close the switch as it is moved by the .deposit of coins and thereafter move said carriage and switch relative to the nut and screw, said motor and screw serving to move said nut to overtake said carriage and move the switch away from the actuating means, and means connecting said switch to condition said supply means.

16. In a mechanism for controlling the supply of energy to an apparatus, the combination of a supply means `having effective and ineective conditions, a coin receptacle, means mounting said receptacle for movement in proportion to the weight of the coins deposited therein, a screw mounted for rotation, a nut mounted on the screw, a motor connected to drive the screw, a carriage slidably mounted `on the screw, for movement relative to the nut, yieldable means for holding one end of thc carriage against the nut, a switch mounted on the carriage, means on the receptacle for actuating the switch, actuating means including said receptacle serving to close the switch as it is moved by the deposit of coins and thereafter move said carriage and switch relative to the nut and screw, said motor and screw serving to move said nut to overtake said carriage and move the switch away from the actuating means, means connecting said switch to condition said supply means and means on said carriage and nut for indicating the amount of credit established by the deposit of coins.

17. In a mechanism for controlling the supply of energy to an apparatus, the combination of a supply means having effective and ineEective conditions, a coin receptacle, means mounting said receptacle for movement in proportion to the weight of the coins deposited therein, a screw mounted for rotation, a nut mounted on the screw, a motor connected to drive the screw, a carriage slidably mounted on the screw, for movement relative to the nut, yieldable means for holding one end of the carriage against the nut, a switch mounted on the carriage, means on the receptacle for actuating the switch, actuating means including said receptacle serving to close the switch as it is moved by the deposit of coins and thereafter move said carriage and switch relative to the nut and screw, said motor and screw serving to move said nut to overtake said carriage and move the switch away from the actuating means, means connecting said switch to condition said supply means, means on said carriage and nut for indicating the amount of credit established by the deposit of coins and additional indicating means on said carriage and receptacle for indicating the amount of deficit incurred.

18. A mechanism for controlling the supply of energy to an apparatus, the combination of supply means having effective and ineffective conditions, a coin accumulating receptacle, means mounting said receptacle for movement in one direction in response to the weight of coins deposited therein, a switch having open and closed con ditions, means operable in response to movement of the receptacle past a predetermined position relative to said switch for establishing the switch in one condition, continuously operable time responsive means and means operable thereby for relatively moving the switch and receptacle to establish the switch in the other condition when the amount of credit represented by the accumulated coins is exhausted and thereafter to further relatively move said switch and receptacle to accumulate a l a debit and means responsive to said switch in its two conditions for rendering said supply means effective o1' ineiective.

19. A mechanism for controlling the supply of energy to an apparatus, the combination of supply means having efective and ineffective conditions, a coin accumulating receptacle, means mounting said receptacle for movement in one direction in response to the weight of coins deposited therein, indicating means operable by the receptacle, a switch having open and closed conditions, means operable in response to movement of the receptacle to a predetermined position relative to the switch for establishing the switch in one condition, continuously operable time responsive means and means operable thereby for relatively moving the receptacle and operable means to establish the switch in its other condition when the amount of credit represented by the accumulated coins is exhausted and thereafter to further relatively move said switch and receptacle to ac- 10 cumulate a debit, means responsive to said switch in its two conditions for rendering said supply means eiective or ineiective and lost motion means between said switch and one of said operable means to permit overtravel of said receptacle after said switch is established in said one condition thereby.

References Cited in the tile of this patent UNITED STATES PATENTS 669,429 Paine Mar. 5, 1901 1,049,535 Rosenfeld Jan. 7, 1913 1,577,395 Walch Mar. 16, 1926 2,193,531 Esval Mar. 12, 1940 2,414,467 Hunt lan. 21, 1947 FOREIGN PATENTS 217,639 Great Britain June 16, 1924

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