US3221861A - Coin freed vending machines - Google Patents

Description

Dec. 7, 1965 s. A. MAXWELL 3,221,861

COIN FREED VENDING MACHINES Filed Aug. 14, 1963 4 Sheets-Sheet 1 La glfi /I4 45 10 i I f 576414127 Fhne v HflxwaL Dec. 7, 1965 s. A. MAXWELL 3,221,861

COIN FREED VENDING MACHINES Filed Aug. 14, 1965 4 Sheets-Sheet 2 //v l/z/v T Dec. 7, 1965 S. A. MAXWELL COIN FREED VENDING MACHINES Filed Aug. 14, 1963 4 Sheets-Sheet 5 M, g 1424 654 T SWH ' Dec. 7, 1965 s. A. MAXWELL- 3,221,861

' com FREED VENDING MACHINES Filed Aug. 14, 1963 4 Sheets-Sheet 4 :Z' SWE Q 4 JPOSNUZ.

A 45 C D E 6 G 64 United States Patent 3,221,861 CGIN FREED VENDING MAQHINES Stewart Alfred ltdaxwell, Walsail, England, assignor to Fisher & Ludlow Limited, Birmingham, England, a British company Filed Aug. 14, 1963, Ser. No. 302,137 Claims priority, application Great Britain, Aug. 17, 1962, 31,588/62 6 Claims. (Cl. 194-13) This invention relates to coin-freed vending machines of the kind in which the delivery of the commodity to be vended is electrically controlled and, more particularly, to machines of this kind which include a setting-up relay operable in response to the insertion of the correct coinage in to the machine to deliver, or permit delivery of, the commodity.

Such setting-up relays are often used in machines in which the operator has a choice of two or more commodities, the choice being made by pressing an appropriate selector button after the setting-up relay has been operated by inserting the requisite coinage. Pressing the selector button wall automatically deliver the chosen commodity. A choice of commodities is provided, for example, in many beverage dispensing machines. The beverages may be completely different (e.g. coffee and chocolate) or the difference may lie in the subsidiary ingredients of the beverage (e.g. coffee with or without milk and/or sugar).

The object of the invention is to provide an improved construction of electrically controlled coin-freed vending machine.

The invention will now be described by way of example with reference to the accompanying drawings in which:

FIGURE 1 is a front partly fragmentary View of a beverage dispensing machine adapted to vend tea or coffee.

FIGURES 2, 3, 4, and 5 show the electrical circuitry of the machine.

FIGURE 6 shows the way in which FIGURES 2, 3, 4, and 5 are fixed together.

FIGURES 7, 8 and 9 show the sequence diagram of one of the switches, and

FIGURE 10 is a view of the switch box for alternating the purchase price of the beverages.

The machine includes a rectangular cabinet It arranged with its major axis vertical and having a front door (not shown) hinged along a vertical side. In the upper half of the interior of the machine is a removable shelf 11 which carries a rotatable cup containing turret 12 from which cups are removed singly by a cup dispensing mechanism 13 also carried by the shelf 11 whenever the machine is operated. Mounted for rotation at the rear of the machine are four canisters (not shown) containing the dry beverage ingredients, tea, coffee, dried milk and sugar. When a canister is rotated as a result of operation of the machine a predetermined quantity of the dry ingredients is delivered to a mixing chamber 14 below the shelf 11.

In the lower half of the machine is a thermostatically controlled water boiler 15 to which water is fed by a pump 16 from a mains suppl ed pressure break tank. Hot water is delivered to the mixing chamber 14 by the operation of the solenoid valve and hot water mixes with the dry ingredients or ingredient and is then delivered into a cup which has previously been fed to a dispensing station 17 accessible from the front of the machine.

3,221,851 Patented Dec. 7, 1965 A refrigerated milk tank 18 is mounted in the top half of the machine. This milk is used when tea is dispensed whereas dried milk is used for coffee. This arrangement is adopted because it is generally preferred that coffee should have higher milk content than tea and to accomplish this it is more convenient to deliver this higher milk content in solid form rather than to arrange for a greater quantity of liquid milk to be dispensed with coffee than with tea. The latter course would also entail a corresponding restriction in the volume of water. The base of the milk tank is provided with a valve which, like the hot water valve, is opened by the energisation of a solenoid for a predetermined time when the machine is operated.

The milk flowing through the open valve is delivered by a pipe 19 to a cup in the dispensing station17.

The hot water delivery system also includes a further solenoid operated valve which, when fresh milk has been used and, near the end of a vending cycle, is energised to supply hot water for flushing purposes to the base of the tank and to the milk delivery supply pipe 19 to main tain these in a clean hygienic state.

Referring now to the circuit diagrams, i.e.. FIGURES 2, 3, 4 and 5 the power for the machine is supplied from a transformer T and a service light X1 is operated by switch 81.5. In order to calculate the total number of vending operations a total counter TC is provided which is operated by a drop-out cam DCZ at the end of each cycle. A means water supply valve is operated by a solenoid WV, a fluorescent lamp FL with a starter S is provided for illumination of the interior of the machine, a cup station light CSL2 is provided and a fan F is mounted on the underside of the removable shelf 11 which projects an air flow above the mixing station to extract steam which would otherwise rise and might have a detrimental eifect on the delivery of the dry ingredients.

A coin insertion slot on the front of the machine registers with a chute down which an inserted coin falls to a coin selector mechanism which applies the usual tests to accept or reject the coin. The selector mechanism is of the known type which will test two different coins, for example, a penny and a threepenny piece, a threepenny piece and a Sixpence, or a penny and a Sixpence. The operation of the machine will first be described assurrn ing that a ld.3d. selector is provided. Just below the points at which the different coins assume different paths of travel through the selector mechanism are two coin blocking relays, one for the higher denomination coin and the other for the lower denomination coin. These are represented by relays BH and BL respectively in FIG- URE 2. The relays are normally energized to allow a coin to pass through the selector mechanism but if deenergized the armatures are caused to project into the coin paths to prevent their passage. The arrested coins may be retrieved by pressing a rejector button on the front of the machine. At the lower ends of the two coin paths are spring-urged change-over switches indicated in FIGURE 1 by CSH and CSL for high and low denomination coins respectively.

Inside the machine, near the top right-hand corner, is a box (shown in FIGURE 10) containing five switches arranged side by side, the switches being of the toggle type with the toggles projecting through the front of the box. These five switches are shown as SW.A, SW.E, SW.C, SW1) and SW.E in FIGURE 2. Switches A, B, C and E each have three positions and switch D has two. The

following table shows the settings of the switches necessary for obtaining the different purchase prices indicated:

Prices Switch positions Tea Coffee A B G D E 1d. 2 3 1 1 1 2d. 1 1 1 1 1 3d. 2 1 3 1 1 4d. 2 1 3 1 3 2d. 1 2 1 1 1 3d. 3 2 3 1 1 4d. 3 2 3 1 3 3d. 2 3 2, 1 or 2 1 4d. 1 1 2 I 1 6d. 1 1 1, 2 or 3 2 1 (uses two 3d. pieces to give 6d. vond, Disconnect link L) (k) 4d. 4d. 1 2 1 2 2 (l) 6d. 6d. 1 2 1,2or32 1 (uses two 3d. pieces to give 6d. vend, Disconnect link L) These will now be described separately:

(a) The insertion of a penny, if accepted by the selector mechanism will operate CSL and energise relay 1L1. Contacts IL1/1 will close to maintain the energisation of the relay when CSL returns to its original position after passage of the penny. Contacts IL1/2 will energise relay IL2 when CSL returns to its original position and the energisation of this relay is maintained through IL2/1. IL2/2 will close and since SW.B is in position 3 relay E will be energised, whereupon E/l will maintain this energisation and de-energise 1L1, E/ 2 will close and E/3 will de-energise the blocking relays and energise relay SU. E and SU are the two setting-up relays referred to above and are both energised and, as explained hereinafter, this will enable either tea or coffee to be obtained by the operator of the machine.

Since both blocking relays are now de-enerigsed no further coins will be accepted.

If instead of a penny a threepenny piece is inserted it will be readily seen that relay E, and consequently relay SU, will be energised directly. This applies also to settings (b) and (f) discussed below in which at least one beverage can be obtained for 1d. or 2d. Thus if a person is not in possession of the necessary number of pennies he will be able to obtain the desired beverage upon inserting a threepenny piece.

After the vending operation has been completed dropout cam DC2 will operate to de-energise relays SU, E, 1L1 and IL2, and re-energise the blocking relays.

(b) Since SW.B is in position 1 the insertion of a penny will energise SU through the intermediary action of relays 1L1 and IL2. E is not energised and, as explained below, only tea can now be dispensed by the machine. Since E is not energised and SW.C is in position 1, neither of the blocking relays is de-energised and therefore another penny may be inserted. Since change-over switch 112/ 3 has previously operated the second penny will energise relay E through SW.A, SU remaining energised. The blocking relays will now be de-energised.

(c) The insertion of a penny will energise SU through SW.B and, as SW.C is in position 3 the operation SU/l will de-energise BL thus preventing acceptance of another penny. Alternatively a three-penny piece may be inserted to energise both E and SU.

(d) The insertion of a penny will energise SU through SW.B, as SW.C is in position 3 the operation of SU/ 1 will de-energise BL thus preventing acceptance of another penny and as SW.B is in position 3 the operation of IL1/3 will energise BH and the insertion of a threepenny piece will energise relay E, SU remaining energised.

(e) SW.B is in position 2, i.e. off, and the insertion of a penny will therefore not energise either SU or E but ILI and IL2 will be energised as before. SW.A is in position 1 and therefore the insertion of a second coin will energise E (and also SU) through SW.A.

(f) SW.B in its off position will prevent energisation of SU or E upon inserting a first penny, and SW.A in position 3 will energise SU upon inserting a second penny, whereupon BL will de-energise. Alternatively the insertion of a threepenny piece will energise both E and SU.

(g) SW.B in its off position will prevent energisation of SU or E upon inserting a first penny, if now a second penny is inserted with SW.A in position 3 SU will be energised and BL will de-energise. SW.B in position 3 causes BH to be energised on inserting the first penny so that if a threepenny piece is now inserted both SU and E Will be energised.

(h) SW.B is in position 2 and this reverses the eifects obtained in position 1 upon inserting high and low denomination coins. Thus the insertion of a threepenny piece will energise IL1, IL2 and E (and SU) through SW.B. SW.C is in position 2 and a penny cannot therefore be accepted.

(i) A penny cannot yet be accepted since SW.C is in position 2. The insertion of a threepenny piece will energise SU through SW.B, and SU/l will operate to now allow acceptance of a penny (which may have been inserted before the 3d. and arrested by BL) to energise E directly. Thus in this arrangement the higher price is obtained by the addition of 1d. and 3d.

(j) The link between SW.C and B1 is disconnected and therefore BL is permanently de-energised irrespective of the SW.C setting and a penny will not be accepted at any stage of the operation. The insertion of one threepenny piece will energise SU through SW.B and a second threepenny piece will energise E through SW.A.

(k) With SW.B in position 1 and SW.D in position 2 and the threepenny piece is inserted first, no setting up relay is operated but IL1/3 energises BL so that on the insertion of a penny SU and E will both be energised.

(l) The link between SW.C and BL is disconnected and therefore B1 is permanently disconnected irrespective of the SW.C setting and a penny will not be accepted at any stage of the operation. SW.B in its off position will prevent energisation of SU or E upon inserting a first threepenny piece, but 1L1 and IL2 will be energised. SW.A is in position 1 and therefore the insertion of a second threepenny piece will energise E and SU through SW.A.

If a selector mechanism is provided which accepts threepenny pieces and sixpences, then the machine will vend at the following prices by setting the switches as indicated:

Prices Switch positions Tea Coffee 3d. 3d. as (a). 3d. 6d. as (b) or (c). 3d. 9d. as d 6d. (id. as (c), (f) or (l1). 6d. 9d. as (g) or (1). 6d. 1/ as (.1). 9d. 9d. as (k). 1/ 1/ as (1).

Similarly, if the machine is provided with a 1d.6d. selector it will vend at the following price combinations by setting the switches appropriately: 1d. and 1d., and 1d. and 2d., and 1d. and 6d., 1d and 7d., 2d. and 2d., 2d. and 6d., 2d. and 7d., 6d. and 6d., 6d. and 7d., 6d. and 1/, 7d. and 7d., 1/- and 1/, with switch positions (a) to (1) respectively, or at 6d. and 1/ by disconnecting the link and using the setting described in the previous paragraphs.

Referring now to FIGURES 3, 4, and 5 of the circuit drawings the various switches control the operation of the following motors and solenoid valves, the cup turret motor TMl, the cup drop motor CMl, the water pump motor PM, the hot water delivery solenoid valve SVl the water flush valve SVZ, the dry milk canister motor MM, the coffee canister motor CM2, the tea canister motor TM2, the sugar canister motor SM, the counter TCZ for counting the number of cups of tea dispensed and the fresh milk valve M.V.

Switches SW1, SW2, SW3, SW4 and SW5 in FIGURE 3 are closed by pressing corresponding selector buttons on the front of the machine, and these switches control relays A, B, C, D1 and D2. If neither of the relays SU and E has been energised as a result of the insertion of coinage into the machine, then the closure of these switche will not energise any of the relays.

The effects of closing the switches will now be considered assuming that sufiicient coinage has been inserted to energise both relays SU and E and, therefore, close contacts SU/Z and 13/2.

Closure of SW1 will energise relay B whereupon contacts B/l will energise the sugar canister motor SM when switch C516 permits, for a time controlled by cam switch CS4, contacts B/2 to maintain energisation of the relay. When SW1 is released and B/3 energises relay A, A/l operates the turret motor TMl through switch TS, the cup drop motor CMI, the pump motor PM through switch SW10, and the solenoid valve SVl through switch SW10, and contact A/2 maintains relay A in an energised condition. Contact Dl/l remains in the position shown and the coffee canister motor CM2 .is, therefore, operated through switch C514. Black coffee with sugar is thus dispensed.

If switch SW2 is closed relay C is energized and kept energized by contact C/2. Contact C/l is closed and the dry milk canister motor MM is operated through switch CS13 and contact C/ 3 energises relay A the effect of which is as above. White coffee without sugar is thus dispensed.

If switch SW3 is closed relay C and relay B are energised with consequent energisation of relay A. Sweetened white coffee is thus dispensed.

Closure of switch SW4 energises relay D1 and D2 and relay B through open switch SW5. Contact B/3 energises relay A and D2/2 energises relay C. DIl/S maintains the energisation of relays D1 and D2. D2/ 1 opens and prevents the insertion of any further coins once the vending operation has started and D1/ 1 operates to open the coifee and dried milk circuit and closes the tea and fresh milk circuit. Switches SW1, SW2, SW3, SW4, are three pole switches so that even it switches SW1, SW2, or SW3 are pressed after switch SW4- Dl/l will not return to its original position and it is thus impossible to obtain a mixture of tea and coffee. Motors TM CMl, PM, TM2, and SM and valves SVi and MV are thus operated. The fresh milk valve MV is opened for the time allowed by cam switch CS6 and a contact D2/3, which operates the tea counter TC2, after the milk valve MV has closed, operates the flushing valve SV2 for the time allowed by cam switch CS5. Closure of switch SW4 thus delivers tea with fresh milk and sugar.

Closure of switch SW5 energises relays D1 and D2 which in turn energise relay C to energise relay A and de-energises the blocking relays BH and BL. Closure of switch SW5 provides tea with fresh milk and without sugar.

If only sufficient coins have been inserted to energise relay SU then closure of switches SW1, SW2, or SW3 will energise no relays since these switches are in series with contact E/2 which is open and coffee can not thus be obtained. Switches SW4, and SW5 are in parallel with E/2 and since SU/2 is closed operation of either of these switches will deliver tea in the same way as before.

If SW1, SW2 or SW3 have been closed to select coffee as the beverage to be dispensed then the opening of contacts A/ 3 will prevent subsequent energisation of relays D1 and D2 upon closing switches SW4 or SW5 so that contact Dl/l will remain in the position shown in the drawings and contact D2/ 3 will remain open.

When the vending operation has been completed the drop-out cam C2 will operate change-over switches CS1, CS3 and C812, to interrupt the electrical supply to the selection, setting-up and delivery circuitry simultaneously and will also operate a total counter TC and if tea has been dispensed a tea counter TC2. The total number 'of cups of tea and coffee dispensed can thus be obtained.

The empty switch ESW is operated upon depletion of the cups in the machine and will de-energise the blocking relays BH and BL to prevent the insertion of further coinage and light a warning sold out lamp X2.

What I claim then is:

1. A coin-freed vending machine adapted to deliver a commodity, selected from a plurality of available commodities, in response to the insertion of the appropriate coinage into the machine and the subsequent closure of an electrical circuit associated with the selected commodity, the commodities being comprised of two groups and the machine including electrical switch means operable to alter the vending price of at least one group independently of the other by altering the value of the coinage which must be inserted into the machine to enable the electrical circuit associated with a commodity of the said one group to be closed, a pair of setting-up relays, the first of which has normally open contacts in series with the electrical circuit associated with one group of commodities and the second of which has normally open contacts in series with the electrical circuit associated with the other group of commodities, a blocking nelay which, when energized, permits the acceptance of a selected denomination of coinage by the machine and which, when de-energized, prevents the acceptance of said selected denomination of coinage by the machine, a change-over switch controlled by said first setting-up relay, and a control switch connected between the blocking relay and the change-over switch which can be moved into a first position for by-passing the change-over switch, which can be moved into a second position to establish an electrical connection through the changeover switch and the control switch to the blocking relay when the first setting-up relay is energized and which can be moved into a third position to establish an electrical connection through the change-over switch and the control switch to the blocking relay when the first setting-up relay is tie-energized.

2. A vending machine according to claim 1 in which the switch means includes a second control switch which can be set in a first position to establish an electrical connection through said second switch to the first setting-up relay and which can be set in a second position to establish an electrical connection through said second switch to the second setting-up relay whereby the setting-up relay to which a connection is thus established can be energized in response to the insertion into the machine of a single coin of a particular denomination, the second setting-up relay having at least one normally open contact in parallel with a contact of the first setting-up relay whereby the first setting-up relay is energized upon energization of the second setting-up relay to enable a cheaper commodity of one group to be obtained even if sufficient coinage has been inserted to obtain a more expensive commodity of the other group.

3. A vending machine according to claim 1 which includes a second blocking relay which is normally energized to permit the acceptance of a higher denomination coin by the machine, the second blocking relay when de-energized blocking the path of a higher denomination coin to prevent its acceptance, the second blocking relay being in parallel with the first blocking relay, the first control switch and the change-over switch, the two blocking relays being in series with normally closed contacts of the second setting-up relay, which contacts are operated upon energization of the second setting-up {clay to break the connections to the two blocking reays.

4. A vending machine according to claim 3 which includes a further control switch having three positions, the arrangement being such that with said further control switch in its first position and said first control switch in its second position then upon insertion of a higher denomination coin neither setting-up relay is energized but the first blocking relay is energized so that the subsequent insertion of a lower denomination coin effects energization of both setting-up relays.

5. A coin freed beverage dispensing machine adapted to deliver a beverage, selected from a plurality of available beverages, in response to the insertion of the appropriate coinage into the machine and the subsequent closure of an electrical circuit associated with the selected beverage, the beverages being comprised of two groups and the machine including electrical switch means operable to alter the vending price of at least one group of beverages independently of the other by altering the value of coinage which must be inserted into the machine to enable the electrical circuit associated with a beverage of the said one group to be closed, means whereby higher and lower denominations of coinage may be accepted by the machine, a first setting-up relay having a pair of normally open contacts in series with the electrical circuit associated with one group of beverages, a second setting-up relay having a pair of normally open contacts in series with the electrical circuit associated with the other group of beverages and having at least one normally open contact in series with the first setting up relay whereby the first setting-up relay is energized upon energization of said second setting-up relay, first and second control switches each of which can be set in a first position to establish an electrical connection through said control switch to the first setting-up relay and each of which can be set in a second position to establish an electrical connection through said control switch to the second setting-up relay, a change-over switch operation of which is controlled by said first setting-up relay, a blocking relay which is normally energized to permit acceptance of lower denomination coins by the machine but which, when de-energized, prevents acceptance of a lower denomination coin, a third control switch connected between, and in series with, the blocking relay and the change-over switch, said third control switch having a first position for by-passing the change-over switch, a second position in which an electrical connection is established through said change-over switch and the third control switch to the blocking relay when the first setting-up relay is energized and a third position in which an electrical connection is established through the change-over switch and said third control switch when the first setting-up relay is de-energized.

6. A coin freed beverage disepnsing machine adapted to deliver a beverage, selected from a plurality of available beverages, in response to the insertion of the appropriate coinage into the machine and the subsequent closure of an electrical circuit associated with the selected beverage, the beverages being comprised of two groups and the machine including electrical switch means operable to alter the vending price of at least one group of beverages independently of the other by altering the value of coinage which must be inserted in to the machine to enable the electrical circuit associated with a beverage of the said one group to be closed, means whereby higher and lower denominations of coinage may be accepted by the machine, a first settingup relay having a pair of normally open contacts in series with the electrical circuit associated with one group of beverages, a second setting-up relay having a pair of normally open contacts in series with the electrical circuit associated with the other group of beverages and having at least one normally open contact in series with the first settingup relay whereby the first setting-up relay is energised upon energization of said second setting-up relay, first and second control switches each of which can be set in a first position to establish an electrical connection through said control switch to the first setting-up relay and each of which can be set in a second position to establish an electrical connection through said control switch to the second setting-up relay, a third control switch movable between two positions in which one of which the effect of inserting higher and lower denominations of coinage is reversed, a change-over switch operation of which is controlled by said first setting-up relay, a first blocking relay which is normally energized to permit acceptance of lower denomination coins by the machine but which, when tie-energized, prevents acceptance of a lower denomination coin, a second blocking relay which is normally energized to permit acceptance of higher denomination coins by the machine but which, when de-energized, prevents acceptance of a higher denomination coin, a fourth control switch connected between, and in series with, the first blocking relay and the changeover switch, said fourth control switch having a first position for by-passing the change-over switch, a second position in which an electrical connection is established through said change-over switch and the fourth control switch to the first blocking relay when the first settingup relay is energized and a third position in which an electrical connection is established through the changeover switch and said fourth control switch when the first setting-up relay is de-energized, said second blocking relay being in parallel with said first blocking relay, the fourth control switch and the change-over switch, and the two blocking relays being in series with normally closed contacts of the second setting-up relay, which contacts are operated upon energization of the second settingup relay to break the electrical connections to the first and second blocking relays.

References Cited by the Examiner UNITED STATES PATENTS 2,967,644 1/1961 Barber et a1 2222 X 3,023,874 3/1962 Zindel 194-10 3,068,984 12/1962 Timms 194l0 SAMUEL F. COLEMAN, Primary Examiner.

ERNEST A. FALLER, Examiner,

Claims (1)

1. A COIN-FREED VENDING MACHINE ADAPTED TO DELIVER A COMMODITY, SELECTED FROM A PLURALITY OF AVAILABLE COMMODITIES, IN RESPONSE TO THE INSERTION OF THE APOROPRIATE COINAGE INTO THE MACHINE AND THE SUBSEQUENT CLOSURE OF AN ELECTRICAL CIRCUIT ASSOCIATED WITH THE SELECTED COMMODITY, THE COMMODITIES BEING COMPRISED OF TWO GROUPS AND THE MACHINE INCLUDING ELECTRICAL SWITCH MEANS OPERABLE TO ALTER THE VENDING PRICE OF AT LEAST ONE GROUP INDEPENDENTLY OF THE OTHER BY ALTERING THE VALUE OF THE COINAGE WHICH MUST BE INSERTED INTO THE MACHINE TO ENABLE THE ELECTRICAL CIRCUIT ASSOCIATED WITH A COMMODITY OF THE SAID ONE GROUP TO BE CLOSED, A PAIR OF SETTING-UP RELAYS, THE FIRST OF WHICH HAS NORMALLY OPEN CONTACTS IN SERIES WITH THE ELECTRICAL CIRCUIT ASSOCIATED WITH ONE GROUP OF COMMODITIES AND THE SECOND OF WHICH HAS NORMALLY OPEN CONTACTS IN SERIES WITH THE ELECTRICAL CIRCUIT ASSOCIATED WITH THE OTHER GROUP OF COMMODITIES, A BLOCKING RELAY WHICH, WHEN ENERGIZED, PERMITS THE ACCEPTANCE OF A SELECTED DENOMINATION OF COINAGE BY THE MACHINE AND WHICH, WHEN DE-ENERGIZED, PREVENTS THE ACCEPTANCE OF SAID SELECTED DENOMINATION OF COINAGE BY THE MACHINE, A CHANGE-OVER SWITCH CONTROLLED BY SAID FIRST SETTING-UP RELAY, AND A CONTROL SWITCH CONNECTED BETWEEN THE BLOCKING RELAY AND THE CHANGE-OVER SWITCH WHICH CAN BE MOVED INTO A FIRST POSITION FOR BY-PASSING THE CHANGE-OVER SWITCH, WHICH CAN BE MOVED INTO A SECOND POSITION TO ESTABLISH AN ELECTRICAL CONNECTION THROUGH THE CHANGEOVER SWITCH THE CONTROL SWITCH TO THE BLOCKING RELAY

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