US3066809A

US3066809A - Car loading apparatus

Info

Publication number: US3066809A
Application number: US839245A
Authority: US
Inventors: Burridge Frederick James; Waddington Basil Riley
Original assignee: Woodall Duckham Construction Co Ltd
Current assignee: Woodall Duckham Construction Co Ltd
Priority date: 1959-09-10
Filing date: 1959-09-10
Publication date: 1962-12-04
Anticipated expiration: 1979-12-04

Description

Dec. 4, 1962 Filed Sept. 10. 1959 F. J. BURRIDGE ETAL CAR LOADING APPARATUS 3 Sheets-Sheet l ORS ansa mfr waan/1670M- A 7- rash/sf De- 4, 1962 F, J. BURRIDGE ETAL 3,066,809

cAR LOADING APPARATUS Filed sept. 1o, 1959 3 Sheets-Sheet 2 INVENTO fff'klf JAMES 502k ME, ana-IL 2126)/ wAaoI/VGTOW.

Dec. 4, 1962 Filed Sept. l0 1959 F. J. BURRIDGE ETAI.

CAR LOADING APPARATUS 3)' 7 im E4-m0 l *j mi' I 3 Sheets-Sheet 3 HJIL RIZ EY WADDIAG 7'0 3,066,809 CAR LUADHNG APPARATUS Frederick James Burridge and Basii Ridley Waddington,

London, England, assignors to Woodaii-duciriiani Construction Company Limited, London, Engiand, a cernpany of Great Britain Filed Sept. 10, 1959, Ser. No. 839,245' 13 Claims. (Ci. 214-41) This invention concerns apparatus for conveying coal to horizontal coke oven batteries, vertical retort batteries and other installations wherein charging or transfer cars are employed for conveying material, e.g. coal to be carlbonized, from containers such as bunkers to points at which such material is required for delivery to the ovens. Thus, for example, in coal carbonizing installations the ovens or retorts are arranged in batteries, each oven or retort usually having a plurality of top charging holes which receive coal from a charging car running on rails on the top of the battery, the charging car being moved under the control of an operator on the car and the latter having a transfer hopper for each charging hole of an oven or retort. The charging car is usually loaded with coal periodically from a bunker arranged above the level of the charging car, and usually at one end of the battery, and the arrangement is such that the charging car can be moved under such bunker and each of the transfer hoppers of the car filled with coal through discharge chutes leading from the bunker.

Usually each said discharge chute of the bunker is furnished with a pair of doors to permit coal to pass to the corresponding transfer hopper of the charging car. It sometimes happens that the charging car operator moves the filled charging car away from below the bunker chutes before the chute doors have all been closed with the consequence that large quantities of coal (possibly 500 tons or more) are erroneously discharged and have to be removed from the area of the base for the car, a procedure which entails much labor and often a serious interruption in the charging sequence of the ovens or retorts.

A variety of mechanical interlocking systems using mechanical links operating limit switches have previously been proposed for preventing the filled charging car from being moved away from below the bunker before the discharge chute doors have all been closed but these systems are not always efficient in action and have not proved satisfactory in the past. Moreover they are expensive and relatively complicated and prone to failure. It is an object of the present invention to provide an improved and more reliable form of interlocking system which, while particularly applicable to the charging arrangements of coal carbonizing installations is also, as will hereinafter become apparent, applicable to analogous material transfer installations wherein a material-receiving car must be prevented from movement until such time as the ow of material thereto from a container has been cut off.

In its broadest aspect the present invention therefore provides in conjunction with the chutes of such an installation, equipment comprising a transmitter for projecting a beam of electromagnetic radiation to a detector sensitive to such radiation and adapted to prevent movement of said car, at least when the same is positioned to receive material from said discharge chute and the intensity of the radiation incident upon such detector is below a predetermined value, said transmitter and detector being so located, at least when the car is positioned as aforesaid, that said beam will be intercepted when a door controlling the flow of material through said discharge chute is open, the radiation projected by the transmitter having an energy such that when the beam is intercepted es tt Patented Dec. 4, 1932 as aforesaid the radiation incident upon said detector will be `below said predetermined value, but such that the beam will penetrate smoke, dust and other atmospheric obstructions between the transmitter and detector without reducing the intensity of radiation incident upon the latter below said predetermined value.

Radiation energies having the above characteristics lie substantially within the range 0.005 to mev. (million electron volts) and have a wavelength in the range 2.47 A.U. to 8.25 10-5 A.U., that is to say, corresponding with the wavelength of the gamma-rays as emitted by radioactive substances and X-rays. This wavelength range may be compared with that of visible light, namely 3900 A.U. to 8100 A.U. and with that of infra-red radiation, namely 8100 A.U. to 3.14 106 A.U.

While energies within the range quoted above may be employed, in practice energies within the range 0.05 to l5 mev. may be preferable for the purposes of the present invention whilst energies within the range 0.5 to 1.5 mev. are at present believed to be the optimum.

rEhe minimum beam energy which can be employed in practice is determined by the need for the beam to be capable of penetrating atmospheric obstructions such as smoke, dust and the like betveen the transmitter and the detector. As will be explained hereinafter, however, when the radiation is obtained from a radio-active substance the amount of radio-active substance measured in miilicuries or equivalent units must be greater for lower beam energies so that it is preferred, when the transmitter incorporates a radio-active substance, to ernploy a beam energy somewhat higher than the minimum, for the sake of economy.

The maximum beam energy is governed by the degree of diiferentiation and/ or sensitivity required for the detector to indicate whether or not the beam is intercepted as aforesaid, and with a sulhciently robust detector for practical purposes the maximum beam energy that may be successfully employed will probably be of the order of 150 mev.

Where, as is preferred, the source of electromagnetic radiation in the transmitter is a radio-active substance, the approximate optimal quantity thereof required may be calculated as follows:

It is known that TCE.

where R is the radiation in milliroentgen required per hour at the detector when this is at a distance of D feet from the radio-active substance, C is the source strength in millicuries and E is the effective energy of the radiation in rnev.

Since cosmic radiation amounts to about 0.02 milli- `roentgen per hour the radiation at distance D should be considerably greater than this in order that the detector may easily dierentiate between the beam and cosmic radiation. Thus, for example, if a radiation of 1 milliroentgen per hour at a distance of, say, 25 feet be desired, by substitution in Equation 1 one obtains:

znpfzixas@ (2) 7E' 7 E 7 E Hence if the source of radiation is the cobalt (60) isotope which simultaneously emits two `beams in cascade having energies of about 1.3 mev. and 1.2 mev., the approximate value for the source strength is:

A distance of about 25 feet between the transmitter and the detector may, for example, obtain when the equipment is employed in a coal carbonizing installation R: milliroentgen per hour 36 (approx.) miliicuries epesses Such as a coke oven battery and the transmitter and detector are located to project and receive, respectively, a beam of radiation extending in a direction transverse to the direction of movement of the coal charging car along the top of the battery, such beam being caused to be intercepted by any open door of a row of discharge chutes of the coal bunker as will hereinafter be more fully explained.

However, in a preferred arrangement ot the equipment for a coke oven battery, the transmitter and detector are located, preferably on the coal charging car, to project and receive, respectively, a beam of radiation which extends along the direction of movement of the car vand which is caused to be intercepted by an open door of one or two laterally adjacent discharge chutes; in such arrangement the distance betwen the transmitter and receiver may be only of the order of 2 feet 6 inches so that a radiation level of 1 milliroentgen per hour at the detector could be achieved with a cobalt (60) source having a strength of only 0.36 (approx.) millicuries.

With such a short distance between the transmitter and the receiver a lower energy beam could be employed without the need for an excessive source strength. Thus in the preferred arrangement discussed above, the isotope caesiurn (137), usually available in the form oi' the compound caesium (137) sulphate, may conveniently be employed, which emits a beam having an energy of about 0.6 meV. so that a radiation level of l milliroentgen per hour can be obtained at a distance of 2 feet 6 inches with a source strength of 1.5 (approx.) millicuries. In practice a source strength of 5 millicuries may conveniently be employed to allow for attenuation of the beam by encapsulation of the isotope compound in the transmitter and by the presence of a metallic window through which the beam passes out of the transmitter, and also to allow for the gradual decay of radioactivity of the source with time.

Such values for the source strength under the operating conditions mentioned gives a radiation level at the detector which is fty times greater than any cosmic radiation likely to be incident upon the detector but is also well within the limit of permissible radiation in industry. Thus not only can cosmic radiation not arect the proper functioning of equipment in accordance with the present invention, but such equipment is quite safe from the point of view of exposure of operating personnel to the radiation.

As indicated above, the preferred source of electromagnetic radiation in the transmitter is a radioactive substance since this enables the transmitter to be of a robust and reliable form; also suitable sources may be obtained relatively inexpensively compared with the cost of X- ray equipment while the latter has other disadvantages noted below.

The source may thus conveniently comprise the radioactive isotope cobalt (60) when a long beam is required or when high ambient temperatures may be encountered since this isotope is stable at relatively high temperatures, or the radioactive isotope compound caesium (137) sulphate for shorter beams or when high temperatures are unlikely to be encountered as the compound is somewhat volatile. Cobalt (60) has a reasonable half-life of 5.3 years and it has the added advantage of being relatively inexpensive under present economic conditions. Caesium 137) sulphate has the advantage of a longer half-life, namely about 33 years. v

Other radio-active substances which could be used are the radio-active isotopes tantalum (182) and iridium (192). One of the disadvantages of tantaluni 182) and iridium (192) is that these isotopes have relatively short half-lives, namely 120 days and 73 days respective ly. Still other radio-active substances which have various advantages and disadvantages in relation to halflives, volatilization, cost and penetrating ability are the radio-active isotopes caesium v(134), europium (154),

thulium (17), selenium (75), antimony (125) and radium.

As an alternative to the use of a radio-active substances as a source of the electromagnetic radiation in the transmitter, X-ray generating equipment may be used. Such equipment has however the disadvantage that it requires electric power cables and other electrical equipment (usually operating `at high voltages) which have to be elaborately protected against the conditions liable to be encountered by the equipment in practical operation. Moreover, present day X-ray equipment is also much more expensive than suitable radio-active substances and the life of X-ray equipment is usually cornparatively short, especially in the Working conditions like ly to be encountered by the equipment.

X-ray equipment has, of course, the advantage that it can be switch-controlled so that projection of the beam of radiation can be readily cut ori when it is not required, While with a transmitter incorporating a radio active substance means must usually be provided for cuttingo the emission of the beam of radiation, especially when the source has a high strength, when such beam is not required and particularly when the equipment is being serviced or personnel are for other reasons in the Vicinity of the transmitter.

rhe detector may take several forms and may for example consist of a sensing unit such as a Geiger-Muller tube or scintillation counter tube or crystal detector, whose rate of counting determines whether a relay should be operated or not. With a detector having such a sensing unit, the latter may be operated from a stabilized power supply and connected to an amplier adapted to amplify the pulses emitted by the uni-t, the ampliiied pulses being rectied or Acounted electrically. If the pulses are rectied, the rectified current wiil be proportional to the 'number' of pulses per unit time and hence to the amount of radiation incident on the unit; thus the rectified current may be led to the operating coil of a relay so that the latter will operate when the current reaches a predetermined value. Gn the other hand, if the pulses are counted electrically, then the counting unit may be arranged to trip a relay when a predetermined number or" pulses occur in a specified time interval. The use of a pulse amplier may not be necessary if the pulses from the sensing unit are suiciently strong or if a very sensitive relay is used.

ln equipment in accordance with the present invention the transmitter and the detector may both be located in iixed relationship to the said container, eg. the coal bunk er ot a coal carbonizing installation, or, preferably, they may both be carried by the car. It would also be possible to arrange one or the other in iixed relationship to the container and the other on the car, but in any event it will be arranged that the beam between the transmitter and the detector will f e intercepted whenever a door of a discharge chute is in its open position. This interception may `be caused by the door itself moving into the path of the beam upon opening of the door or it may be caused `by a shutter or the like carried by or associated with the door for movement therewith.

ln coal carbonizing installation there are usually a plud rality of discharge chutes arranged in rows extending across the path of movement of the coal charging car,- the transfer hoppers on the car receiving coal through, usually, the chutes ot one such row at any one time, and unless the doors of all such chutes that lead to the transfer hoppers of the car at any one time happen to be mechanicaliy interlinlied so that all such doors open and close together it will be necessary for the arrangement to be such that any one of such doors, when open, causes inten ception of a beam between a transmitter and a detector.

Thus, for example, a `transmitter and a detector may be mounted in lined positions with respect to the bunker and be associated with each row of discharge chutes so thatthe beam from the transmitter will be intercepted when accesos any chute door of its associated row is open, all the detectors being so associated that all must have an unintercepted beam incident thereon for movement of the car away from the bunker to be possible. If, however, as is often the case in coal carbonizing installations, the rows of discharge chutes are relatively closely spaced a single bearn may be projected from a transmitter between two rows of discharge chutes the doors of which, themselves or by means of associated shutters, intercept such beam when open. Thus for example, with four rows of discharge chutes two transmitters and two detectors mounted in iixed positions with respect to the bunker could be employed to detect the presence of any one open discharge chute door.

If the transmitter and detector are mounted on the car and the beam extends transverse to the direction of movement of the car, a single beam Iwill usually be suilicient to prevent movement of the car away from the container or bunker should any one of several discharge chute doors on the latter be open, since in most cases the discharge chutes lwhich convey material to the car at any one time will be relatively close to one another so that interception of a single beam may be brought about by any one of such doors when open. Thus in a coal carbonizing installation usually only a single substantially straight row of discharge chutes will at any one time convey coal to the transfer hoppers of the charging car and in practice it is only necessary to guard against movement of the car away from the bunker when any chute door of the particular row ot chutes which have been conveying coal to the car is open. However, this will involve the use of a beam of the order of 25 feet in length.

A preferred arrangement, therefore, for a coal carbonizing installation, which avoids the use of a lengthy beam, comprises mounting on the car a transmitter and a detector for projecting and receiving, respectively, a beam which extends in the direction of movement of the car, such beam being located to be intercepted when a particular chute door is open in the row oi chutes which at any one time may be used for conveying coal to the car; if the chutes are closely spaced in the row, a single beam may be adapted to be intercepted by an open door of either or" two adjacent chutes in the row so that if there are three or four chutes in the row two beams will be required whilst if there are tive or six chutes three beams will be required, the beams extending, when the car is in position to receive coal from the bunker, between pairs of adjacent chutes so that any open door in the row of chutes will result in the interception of at least one beam. In this way, beam lengths of the order of two to three feet will be needed with the consequence that low beam energies and low source strengths can be used.

Where, as is usually the case in coal carbonizing installations, the coal charging car is driven by an electric motor on the car the detector or detectors of the equipment may be arranged to control the power supply to such electric motor. lt the transmitter(s) and detector(s) are mounted in fixed positions relatively to the container then the detector(s) may conveniently be arranged to control the supply of electrical power to the conductor wires or rails from which the car draws its electrical power. On the other hand, if the transmitter(s) and detector(s) are mounted on the car `the electrical circuits for the car motor may be directly controlled by the detector(s).

ln installations in which the cars are driven otherwise than by an electric motor on the car, for example where they are hauled by cables or the like, the driving means for the cars may be controlled by the detector(s) of the equipment in any convenient manner. For example where the cars are hauled by cables or the like drawn by means other than electric motors, eg. internal combustion engines, the haulage means may include an electromagnetic or an electromechanical clutch or like device Controlled by the detector(s).

Although it will usually be preferred to employ a cond tinuous beam from the or each transmitter during the operative period of the equipment nevertheless the or each transmitter may emit an intermittent or modulated beam of radiation and the detector(s) be adapted to respond to such form of beam.

Tre detector(s) of the equipment may if desired be adapted to operate signalling means such as indicator lights or audible warning devices for indicating to the operator of the car and/ or the operator of the door or doors of the discharge chute or chutes the condition of the door or doors.

In order that the invention may be thoroughly understood some alternative arrangements of equipment in accordance with this invention, as applied to controlling movement of the charging car in a coal carbonizing installation, will now be described by way of example and with reference to the accompanying drawings in which:

FiGURE l is a horizontal top plan View through a bunker at different levels which diagrammatically illustrates a pair of transmitters and receivers located on the underside of the coal bunker of a coal carbonizing installation and associated with the doors of two rows of discharge chutes on such bunker;

FiGURE 2 is a somewhat schematic side elevation of the doors of a discharge chute of each such row;

FIGURE 3 is a diagrammatic view similar to FIG- URE l but showing an alternative arrangement;

FlGURE 4 is a somewhat schematic illustration of the door arrangement of FIGURE 3; and

FIGURE 5 is a schematic view showing the relationship or" the coal bunkers and coke oven battery.

As shown in FG. 5, coal from bunkers la at one end of a coke oven battery ti is conveyed thereto by hoppers 7a on a coal charging car 7.

Referring to FIGURES l and 2 of the drawings, FIG- URE. l shows diagrammatically bunkers la with two rows of four discharge chutes i underneath the bunkers la, the quadrant-like doors 2 of these chutes being shown in schematic bottom plan view in FIG. l, the doors 2 being shown in their open positions for the left-hand row and in their closed position for the right-hand row. FIG- URE 2 is an enlarged more detailed schematic end elevational view of the discharge chute doors showing the manner in which the doors swing to control the flow of coal through the discharge chutes with which they are associated. Y

ln the arrangement shown in these figures, a transmitter 3 is located on the underside of the bunker in end alignment association with each row of discharge chutes 1, the transmitters 3 being so located that they each project a beam of electromagnetic radiation parallel with their associated row of discharge chutes 1 and laterally spaced from the center line of such row by a distance such that the beam will be intercepted by one of the two doors 2 of each chute when such doors are in their open position. lt will be seen that for the left-hand row of chutes in FIGURE l, the beam which is indicated by the dotted line d is intercepted by the right-hand door of the discharge chute l nearest to the transmitter 3, but it will be understood that if the doors of such chute were closed the beam would be intercepted by right-hand door of the next discharge chute nearest to the transmitter if such door were open and so on. On the: other hand, as indicated by the right-hand side of FIGURE 1, when the doors 2 of a row of discharge chutes 1 are all closed, the beam i may pass all the chutes of the row to be received by a detector 5.

It will be noted that in FIGURE l the beam 4 from each transmitter 3 is parallel with the swinging axes of the doors 2 ofthe chutes l in the row of chutes associated with the transmitter and the doors themselves intercept the beam when the doors are open. However, it Will be understood that the doors could carry shutters to intercept a beam at a distance spaced further from the center line of the row of chutes than the periphery of the doors when open, and with a pair of closely-spaced rows of chutes, a single transmitter could be located, as shown in FIG. 3, to transmit a beam of radiation along a line midway between the centre lines of such two rows, the adiacent doors of the chutes of which rows could carry shutters so that all such adjacent doors of the two rows would be eifective when open to intercept the beam.

FIGURES 3 and 4 illustrate this alternative arrangement in which a transmitter 3 is arranged to project a beam of radiation 4 along a line midway between the center lines of two rows of each of two pairs of rows of discharge chutes l', the doors 2 under bunker 3a of which swing about axes perpendicular to the beam d so that the doors themselves cannot intercept the beam. However, one door of each chute carries a shutter d which extends towards the adjacent row and is so disposed that when the door carrying such shutter is in its open position as shown for one pair of rows on the left-1 hand side of FIG. 3, the shutter intercepts the beam fr', whereas when the doors are all closed as shown for the other pair of rows on the right-hand side of FlG. 3, the shutter does not intercept the beam 4. The upper part of FIGURE 4 shows diagrammatically a shutter 6 in its beam-intercepting position with the door Z carrying such shutter open, the lower part of FIGURE 4 shows how the beam is unatiected by the shutter o with all doors 2' closed.

The arrangements illustrated in FlG. 4 of the drawings have the transmitters and the detectors fixed relativelyv to the bunker but it will be understood that one of these components 3 of the equipment could be carried by the coal charging car 7, as shown in FIG. 1, to be positionedA as indicated in the drawings, relatively to the

doors

2, 2" of the discharge chutes il, 1,', when the charging car 7, as shown in FIG. 1, is in position to receive coal from the chutes 1. When, as shown in FIG. 4 of the drawings,4 the transmitter(s) and detector( s) are located on the underside of the bunker la, 3a, then the beam(s) of radiation may be projected in directions which are either parallel with (FIGS. l, 2) or transverse to (FlGS. 3, 4) the direction of movement of the coal chargirny car; likewise, when the transmittcr(s) and detector(s) are located on the charging car 7, as in FlG. 3, the beams may be projected transverse to the direction of movement of the charging car, or the beams may be projected generally parallel with the direction of movement of the car although with the latter arrangement, which is preferred, the positions of the transmitter(s) and detector(s) must be so chosen as to avoid these components fouling the chutes or doors, or shutters carried by the latter, upon movement of the car.

Thus in this preferred arrangement, the transmitterts) and the detector(s) are preferably arranged on the car as in FIG. 3 so as to pass between discharge chutes in any row thereof transverse to the movement of the car, the chute doors or shutters, thereon, being adapted to intercept the beam(s) when the doors are open but which swing out of the path of the bearn(s), when the doors close, to positions which are clear of the paths of the transmitter(s) and detector(s) during movement of the car.

Thus, for example, if the bunker 7 is provided with several rows of discharge chutes, each row consisting of four chutes, two transmitters and two detectors may be located on the car, one transmitter of a transmitter/ detector pair being located to pass midway between the adjacent two chutes at one end of each of two rows and the other detector of a transmitter/detector pair being located to pass midway between the two adiacent chutes at the other end of each of two rows as the car moves under the bunker. If the swinging axes of the chute doors are aligned with the direction of movement of the car, the doors themselves nearer to the paths of the transmitters and detectors, or shutters extending from the peripheries of such doors, may intercept the beams of radiation when such doors are open, while if the swinging axes of the doors are transverse to the direction of movement of the car, shutters such as shown in FIG- URES 3 and 4 may be carried by the doors to edect interception of the beams when such doors are open. Preferably the distance between the transmitters and their associated detectors will be such that only the doors of the row or rows of chutes which at any one time may convey coal to the charging car transfer hoppers will be monitored by the equipment so that doors of other rows may be opened and closed without affecting the movement of the charging car. This feature is desirable when, for example, two charging cars may be required to operate on opposite sides of the bunker, since it enables each car to maneuver under the bunker and to receive coal therefrom independently of the other car, while each individual car is prevented from movement away from the bunker unless the doors controlling the discharge chutes from which it has been receiving coal have .been re-closed.

ln the drawings, the transmitters 3, .3', and

detectors

5, 5 ot the equipment have been symbolically indicated; it will be understood that the detectors may take any of the forms described hereinabove while the form of the transmitter will, of course, depend on the nature of the source of electro-magnetic radiation employed. However, usually the source will be a radio-active substance such as the radio-active isotope cobalt (60) or the radioactive isotope compound caesiurn (137) sulphate and with such a source the transmitter may conveniently comprise a container for such source, such container being opaque to the radiation emitted by the source therewithin except for a window through which such radiation may pass to form the beam. The container may thus, for example, comprise a box-like enclosure of lead or steel of suitable thickness (eg. 2" of lead) adapted to house the desired radio-active substance (which may be encapsulated in a material such as aluminium which is relatively transparent to the radiation), such enclosure having an aperture through which a 4beam of radiation may pass. Such aperture may be closed by a material such as aluminium or brass which is relatively transparent to the radiation but which seals the interior of the enclosure from the ambient atmosphere. The enclosure may be double-walled and/ or clad with insulating material if the transmitter is to be located in a situation where it may be subject to high ambient temperatures, to minimise the transmission of heat to the radio-active substance especially if the latter tends to volatilize at high temperatures.

lf the transmitter has to project a beam of radiation for a considerable distance to the detector and in consequence contains a relatively strong source or one producing a high energy beam, it should desirably include a shutter by means of which the beam from the window can be cut off or attenuated to a safe level when the equipment is not in use, or has to be serviced, or at other times when personnel may have to be in the vicinity of the transmitter window. Under such circumstances, a convenient form of transmitter which may be adopted is described and illustrated in the specifications of British Patents Nos. 861,116 and 801,117.

As mentioned, the detector may take any of the forms described hereinabove and includes conventional means such as a relay 9 with a switch lil in a motor circuit 11, for controlling a motor 1 3 which drives the car 7, so that when the detectors show a predetermined radiation value, the circuit is closed, whereas when the value drops below this amount, the circuit is opened to prevent the motor from driving the car. If, having regard to the situation in which the detector is to be located, it is desirable to protect the components of the detector from ambient atmospheric conditions, such components may be housed in a suitable protective enclosure which may be entirely substantially transparent to the radiation from the transmitter or which may be relatively opaque to such radiation and have merely a window e.g. of aluminium or brass, substantially transparent to the radiation and positioned to permit the beam from the transmitter to be incident upon the radiation-sensitive element of the detector. While as has been explained above the equipment is especially suitable for controlling the movement of the coal charging car away from the coal bunker of a coal carbonising installation, it will be apparent that the equipment has many other applications such as in blast-furnace charging installations, quarries and generally in industrial installations for transferring material from a container to a car or like movable receptacle which must remain stationary until the ow of material from the container has been cut off.

We claim:

1. In a material transfer installation, in combination, a material-storage container, a material-receiving car which has to be moved into -aligned position with a discharge chute of such container in order to convey material from the container to the car and to be moved out of said aligned position to transfer the conveyed material, equipment comprising a transmitter for projecting a beam of electromagnetic radiation to a detector sensitive to such radiation, and a detector sensitive to said radiation with means operable by said detector and adapted to prevent movement of said car when same is positioned to receive material from said discharge chute and the intensity of the radiation incident upon such detector is below a predetermined value; said transmitter and detector being so located in operative relationship to said chute when the car is positioned that said beam will be intercepted by a part on a door of the chute to reduce the intensity of radiation incident on the detector when the door controlling the ow of material through said discharge chute is open, the radiation projected by the transmitter having an energy such that when the beam is intercepted by said part as aforesaid, the radiation incident upon said detector will be reduced below said predetermined value, but such, that the beam will penetrate smoke, dust and other atmospheric obstructions between the transmitter and detector Without reducing below said predetermined value the intensity of radiation incident upon the latter.

2. In a material transfer installation, in combination. a material-storage container, a material-receiving car which has to be moved into aligned position with a discharge chute of such container in order to convey material from the container to the car and to be moved out of said aligned position to transfer the conveyed material, equipment comprising a transmitter for projecting a beam of electromagnetic radiation having an energy within the range 0.005 to 150 mev. (million electron volts) to a detector sensitive to such radiation, a detector sensitive to said radiation, and means operable by said detector and adapted to prevent movement of said car when the same is positioned to receive material from said discharge chute and the intensity of radiation incident upon such detector is below a predetermined value; said transmitter and detector being so located in operative relation to said chute at least when the car is positioned in coal-receiving relation to said chute that said beam is intercepted by a part on the door of the chute to reduce the intensity of radiation incident on the detector below said predetermined value, when a door controlling the tlow of material through the discharge chute is open.

3. In a coal carbonizing installation, in combination, a coal bunker equipped with a plurality of discharge chutes for conveying coal from the bunker, transfer hoppers on a charging car, which car is movable into position relative to the bunker to locate the hopper in the path of ow of coal from the discharge chutes to fill the hoppers, and which car is movable out of said position to a different location for charging the coal from the hoppers into coal carbonizing chambers, equipment comprising a transmitter for projecting a beam of electromagnetic radiation having an energy within the range 0.005 to mev. (million electron volts) to an associated detector sensitive to such radiation, and a detector sensitive to said radiation with means operable by said detector and adapted to prevent movement of said car when same is positioned for its hopper to receive coal from said chutes and the intensity of radiation incident upon the detector is below a predetermined value; said transmitter and detector being so located relative to the discharge chutes that a beam of said radiation is intercepted by a part on the chutes which reduces the intensity of radiation incident upon the detector below said predetermind value when the car is positioned as aforesaid for its hoppers to receive coal from the chutes, and a door controlling at least one of said chutes is operable for the flow of coal to the hoppers on the car.

4. The equipment of claim 3, wherein the bunker has a plurality of discharge chutes arranged in at least one row, and in which the transmitter is disposed for projecting a beam of radiation parallel with a row of said chutes for interception by parts on the chutes that are movable into the path of the beam upon the opening of any chute-controlling door in such row for outow of coal therefrom.

5. The equipment of claim 4, wherein the bunker has at least two rows of discharge chutes, a transmitter disposed for projecting its beam of radiation parallel with and between the centerlines of adjacent rows of chutes for interception by parts on the chutes of both rows upon the opening of a chute in either of said rows when the car is still in coal receiving position.

6. The equipment of claim 5 and which includes a shutter associated with each said chute as the part thereon for movement into beam-intercepting position upon opening of such chutes.

7. The equipment of claim 3, in which said transmitter projects a beam of radiation having an energy within the range 0.05 to 15 mev.

8. The equipment of claim 3, in which said transmitter projects a beam of radiation having an energy within the range 0.5 to 1.5 mev.

9. The equipment of claim 3, in which said transmitter includes a radioactive substance as the source of said beam.

10. The equipment of claim 9, in which said radioactive substance is selected from the group consisting of the isotope cobalt (60) and caesium (137) sulphate.

11. The equipment of claim 3, in which said transmitter and said detector are located in lixed. positions with respect to the bunker.

12. The equipment of claim 1l, which includes an electric motor on the car for moving same and an electric power source external of the car providing power for said motor, in which said detector controls the transmission of power from said source to the car.

13. The equipment of claim 3, and which includes an electric motor on the car, and in which said transmitter and said detector are located on the car in positions for said beam from the transmitter to be intercepted by the opening of a discharge chute door when the car is positioned to receive coal from the bunker.

References Cited in the tile of this patent UNITED STATES PATENTS 2,317,175 Burdick Apr. 20, 1943 2,572,687 Anderson et al Oct. 23, 1951 FOREIGN PATENTS 801,117 Great Britain Sept. 10, 1958