Emergency mine elevator

[57] ABSTRACT

An emergency escape hoist assembly installed adjacent a mine shaft. The assembly has a cage and associated hoist mechanism normally parked in a retracted position relative to the mine shaft. The cage and hoist mechanism can be operated from push-button switches either at the mine level, at the hoist or at ground level. When the cage is called, a main power unit is energized and the cage and hoist mechanism are moved so as to position the cage over the shaft. The cage then descends and stops at the mine level. Personnel board the cage and push the hoist button, causing the cage to ascend. The cage stops at ground level and then the entire unit returns to its normal parked position. The mechanism is controlled by limit switches with necessary electrical and hydraulic interlocks to assure proper sequence of operations.

Claims, 13 Drawing Figures

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Patented Sept. 11, 1973

3,757,701

Sheets-Sheet 1

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INVENTORS.

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Patented Sept. 11, 1973

3,757,701

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Patented Sept. 11, 1973

3,757,701

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INVENTORY.

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ATTORNEYS.

Patented Sept. 11, 1973

3,757,701

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Sheets-Sheet 5

Electric power Source

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Patented Sept 11, 1973

3,757,701

Sheets-Sheet 6

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3,757,701

EMERGENCY MINE ELEVATOR

This invention relates to emergency escape devices, and more particularly to an emergency elevator device to allow personnel to escape from a mine shaft under emergency conditions.

A main object of the invention is to provide a novel and improved emergency escape elevator device to permit miners or other personnel to escape from a mine under emergency conditions, the escape device being relatively simple in construction, being arranged so that it is normally in a non-obstructing relationship with respect to its associated mine shaft, and being operable to automatically move into working position when its use is required.

A further object of the invention is to provide an improved automatic emergency escape elevator assembly which is normally positioned beside or near a mine shaft and which, when called, will move over the mine shaft, lower a cage to the mine bottom and stop to allow personnel to board the cage, after which such personnel can again energize the apparatus so as to cause it to raise the cage and the personnel therein to the surface, after which the apparatus returns to a retracted position.

A further object of the invention is to provide an improved automatic emergency escape hoist apparatus for a mine, the apparatus combining the features of automatic horizontal mobility and vertical hoisting in proper sequence without requiring the use of an attendant or operator, the apparatus involving inexpensive components, being relatively compact in size, being reliable in operation, and providing a means for the rapid escape of personnel from a mine under emergency conditions.

A still further object of the invention is to provide an improved emergency mine escape elevator device which is installed beside or near a mine shaft, and which is arranged so that no portion thereof is normally over the mine shaft, whereby the apparatus is not normally in the path of possible explosive forces, and thus, in its normal position, is not subject to damage and will not be rendered inoperative and unuseable by the sudden occurrence of emergency conditions causing explosions, or the like

A still further object of the invention is to provide an improved automatic emergency escape apparatus providing a means of escape for personnel from a mine shaft, the apparatus employing a unique arrangement of components providing a high degree of reliability of operation and employing automatic control elements which accurately limit the movement of the parts thereof in a manner to provide a high degree of safety in operation and rapid action thereof when called upon under emergency conditions.

A still further object of the invention is to provide an improved emergency mine elevator employing an escape cage which is normally located in a retracted position relative to the associated mine shaft and which is moved to an overlying position with respect to the shaft when the device is placed in operation, the apparatus being provided with safety stop means to insure against over-travel when the cage is moved over the mine shaft, which is provided with means to prevent possible tipping or overturning of the cage during operation, and which is further provided with means to control the gravitational and other forces developed thereby so as to give a high degree of stability to the apparatus and to make it safe to operate.

Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:

FIG. 1 is a vertical cross-sectional view taken through the ground adjacent a mine shaft and showing a typical improved emergency mine elevator assembly according to the present invention, the parts thereof being shown in parked positions.

FIG. 2 is a vertical cross-sectional view similar to FIG. 1, but showing the parts of the emergency elevator apparatus in operated position with its cage lowered to mine level.

FIG. 3 is an enlarged cross-sectional view taken substantially on the line 3—3 of FIG. 2.

FIG. 4 is a longitudinal vertical cross-sectional view taken substantially on the line 4—4 of FIG. 3.

FIG. 5 is an enlarged fragmentary vertical crosssectional view taken substantially on the line 5—5 of FIG. 4.

FIG. 6 is an enlarged fragmentary elevational view of the cage member employed in the emergency mine elevator assembly of FIGS. 1 to 5.

FIG. 7 is a horizontal cross-sectional view taken substantially on the line 7—7 of FIG. 6.

FIG. 8 is a bottom plan view of the cage member taken substantially on the line 8—8 of FIG. 6.

FIG. 9 is a fragmentary vertical cross-sectional view taken substantially on the line 9—9 of FIG. 6.

FIG. 10 is a schematic diagram showing the hydraulic circuit of the emergency mine elevator apparatus illustrated in FIGS. 1 to 9.

FIG. 11 is a block diagram schematically indicating the electrical circuit connections of the electrically operated components of the system illustrated in FIG. 10, as employed in the emergency mine elevator apparatus of FIGS. 1 to 9.

FIG. 12 is a schematic block diagram showing the general layout of the electrical components of FIG. 11.

FIG. 13 is a schematic block diagram, generally similar to FIG. 12, but showing the schematic layout of components in a modification of the present invention wherein the apparatus employs only electrical components instead of employing the hydraulic components of FIG. 12.

Referring to the drawings, 11 generally designates an improved emergency mine elevator assembly constructed in accordance with the present invention. The assembly 11 is illustrated as a typical installation adjacent to the vertical shaft portion 12 of a mine, for example, of a mine wherein said vertical shaft portion communicates with at least one horizontal bottom shaft portion 13 in the manner illustrated in FIG. 2. The elevator assembly 11 is mounted on a suitable horizontal supporting plate or slab 14 located adjacent to and extending laterally from the top rim of the vertical mine shaft portion 12.

Mounted on the supporting slab 14 are the parallel guide rails 15, 15 extending for the length of the slab 14 and terminating adjacent the vertical mine shaft portion 12. Upstanding stop blocks 16,16 are secured on the rails 15,15 adjacent the rim of the vertical shaft portion 12, as shown in FIGS. 1,2,3 and 4. Designated at 17 is a platform member provided with conventional supporting wheels 18 which engage on the rails 15 and thereby support the platform 17 for horizontal move3,757,701 ment, for example, for movement from a retracted position relative to the vertical mine shaft portion 12, to an extended position such as that shown in FIG. 2.

Thus, the platform 17 may be normally in the retracted position thereof shown in FIG. 1, but may be extended, in a manner presently to be described, to the position thereof shown in FIG. 2, wherein the leftward supporting wheels 18 engage the stop blocks 16.

Mounted on the slab 14 midway between the rails 15, 15 at the right portion thereof, as viewed in FIGS. 3 and 4, is an upstanding longitudinally extending I-beam 19 which is suitably anchored to the slab 14 and which is employed as a safety hold-down beam to retain platform 17 in a horizontal position. Thus, said platform is provided with a pair of depending opposing, substantially L-shaped members 20,20 whose horizontal arms engage slidably beneath the opposite margins of the top flange of the I-beam 19 and constrain the platform 17 to move in a horizontal direction, as is apparent from FIG. 5.

Designated at 21 is an elongated cylinder which has one end thereof connected to a depending abutment member 23 carried by platform 17 and has a piston provided with a piston rod 63 extending from the opposite end of the cylinder and connected to an upstanding block 22 secured to the slab 14. The cylinder 21 may be of substantial length so that its piston has a rather long stroke, for example, of the order of 8 feet. Thus, the cylinder 21 is employed as the means for retracting and extending the platform 17 horizontally in a manner presently to be described.

Rigidly secured to the left end of the platform 17, as viewed in FIGS. 1 to 4, is an upstanding frame-like enclosure 24 which extends vertically upwardly from the plane of platform 17 and which is suitably braced, for example, by inclined strut members 25 and suitable horizontal tie bars 26, as shown in FIG. 4. Thus, the upstanding vertical frame-like enclosure 24 is rigidly secured to the platform 17 and is braced so that it has an axis perpendicular to the plane of the platform.

Mounted on the right end portion of platform 17, as viewed in FIGS. 1 to 4, is a housing 27 containing a hoist assembly 28 which may be of a conventional type having a hydraulic driving motor 29 which is drivingly connected to a cable reel 30 and which is provided with a hydraulically operated brake assembly 31. The housing 27 also contains a conventional hydraulic power unit 32 which may comprise a pump 33 driven by an electric motor 34, and which may include a suitable reservoir 35 for hydraulic fluid, as well as other necessary components of a conventional hydraulic power unit. Thus, as shown in FIG. 10, the unit may include an electrically energized heater 36 immersed in the reservoir 35, and various other conventional components presently to be described.

The hoist reel 30 has wound thereon a hoist cable 37 which engages over a pulley 38 journaled on the top of the upstanding frame-like enclosure 24 and has its end suitably secured to the top end of an elevator cage 39 normally contained within the frame-like enclosure 24, as illustrated in FIG. 4.

As shown in FIGS. 1, 2 and 4, the lower portion of the frame-like enclosure 24 is provided with suitable wire mesh or chain link panels 40 on all of the sides ' thereof with the exception of the side opening toward the platform 17.

As shown in FIGS. 6 to 9, the cage 39 comprises a generally cylindrical framework having top and bottom main structural sections shown at 41 and 42. Thus, the bottom section 42 comprises a circular band 43 having a diametral cross bar 44 of I-beam shape and having additional cross bar elements of I-beam shape 45 extending perpendicular to the diametral cross bar 44 and rigidly connecting said cross bar to the circular band 43. Rigidly secured on the frame elements 43, 44 and 45 is a circular floor plate 46. Secured to the bottom surfaces of the bar members 45 are respective square plates 47, located adjacent the outer band 43, as shown in FIG. 8, and secured to each plate 47 is a depending buffer spring 48, said springs 48 serving as cushioning elements for cushioning the bottom ends of the travel of the cage 39 when it descends to the level of the horizontal mine shaft portion 13, as will be presently described.

The upper cage frame section 41 is generally similar to the lower frame section 42 and comprises a circular band 49 provided with a pair of parallel spaced, substantially diametrally extending channel bars 50,50 arranged in the manner illustrated in FIGS. 7 and 9, namely, with their webs parallel and spaced apart in the manner illustrated in FIG. 9. The respective channel members 50 are rigidly connected to the circular outer band 49 by I-beams 51 extending perpendicular to the channel members 50 and having rigid connections at their end, for example, by welding, or the like, with band 49 and channel members 50.

The cable 37 is provided at its end with an eye bracket 52 through which extends a horizontal bolt member S3 connecting the webs of the channel members 50, 50 at the intermediate portions thereof, as shown in FIGS. 6 and 9, providing a pivotal connection of member 52 to the top frame structure 41. A bracket member 63 is clamped to the cable 37 a substantial distance above the connector 52 and respective stabilizing chains 54, 54 connect opposite lugs 55, 55 of bracket 63 with respective horizontal bolts 56 extending through the webs of the channel members 50, 50 symmetrically located on opposite sides of the cable fastening bolt 53.

The top and bottom frame sections 41 and 42 are rigidly connected by a plurality of vertical cage bars 57 which are provided with upwardly and inwardly inclined top extensions 58 whose top ends are rigidly connected with a circular band 59 at the top end of the cage. As shown in FIG. 8, the members 57 may be of channel shape and are preferably arranged with their flanges directed outwardly. Any desired number of vertical members 57 may be employed, for example, six equally spaced members in the typical design illustrated in the drawings. The intermediate portions of the vertical cage bars 57 are rigidly connected to a circular rail band 60 with one portion thereof between a pair of vertical cage bars 57 being cut off to define a doorway, and a chain 61 being employed as a closure for such doorway, the chain having at least one detachable end to allow access into and out of the cage.

The vertical frame-like enclosure 24 is suitably formed to define a doorway 62 which is registrable with the doorway of the cage when the cage is in its elevated position, for example, the position thereof shown in FIGS. 3 and 4, to allow the occupants of the cage to emerge therefrom onto the platform 17.

3,757,701

As above described, the wheel stops 16 are located so as to position the enclosure 24 over the vertical mine shaft portion 12 when the platform is moved to its extended position, namely, the position thereof shown in FIGS. 2,3 and 4. In the normal position of the apparatus, for example, that shown in FIG. 1, the cage structure 39 is supported substantially entirely within the enclosure 24, and at a sufficient height to clear slab 14, so that it may be freely moved to its operating position, namely, the position of FIG. 2 when the platform is extended. As will be further apparent from FIG. 1, the cage 39 is supported at a sufficient height so that it not only clears the slab 14, but also the parts carried by and projecting upwardly from said slab, as well as the top rim of the casing of the vertical mine shaft portion 12.

The apparatus also includes a main control cabinet 64, which may be located at any convenient position, for example, in the hoist housing 27, and which serves as a means to furnish controlled energization to the various electrical components of the apparatus as well as a junction box for making the necessary electrical connections between the source of electrical power and the various components of the apparatus.

It will be noted that the vertical frame bars 57 and their upwardly convergent extensions 58 define skid members which will slide along the wall of the vertical mine shaft portion 12, and are smoothly engageable with said wall to prevent hang-ups during hoisting. The upwardly convergent top end elements 58 permit easy entry of the cage into the hoist tower frame 24. The buffer springs 48, provided at the bottom of the cage, absorb shocks when the cage reaches the level of the horizontal mine shaft portion 13. The cable 37 is preferably of a non-spin type so as to give a controlled ride under emergency conditions.

As will be preferably explained, the hoist drum 30 is provided with braking means including an emergency brake drum 64' directly fastened to the reel drum 30. The braking mechanism is controlled by a hydraulic cylinder 66, with means to automatically apply the brake when the hoist is stopped. The hydraulic hoist motor 29 may be of the direct gear type, coupled to the hoist reel by flexible coupling means 67. The hoisting speed and cycle are automatically controlled by a conventional hoist control 168 having a fly ball speed governor 169 and a gear driven cam wheel 64 which controls acceleration, deceleration, stopping and time for each portion of the cycle. As will be presently explained, electrical interlocks with the valves controlling the hydraulic motor insure proper operation.

As will be apparent from FIGS. 1, 2 and 4, the hoist tower or enclosure 24 is of sufficient height to completely contain the cage assembly 39 and to provide for a reasonable amount of over-travel thereof.

Referring now to FIG. 1®, it will be seen that the outlet of the pump 33 is connected to a hydraulic line 68 connected through respective conventional reversing valve assemblies 69 and 70 to the hoist motor 29 and to the cage positioning cylinder 21. The reversing valve assembly 69 has respective operating solenoids A and B. When solenoid B is energized, the valve assembly 69 operates to provide downward movement of the hoist cage, and conversely, when solenoid A is energized, the valve assembly operates to provide for upward movement of the hoist cage. Thus, the valve assembly 69 controls the direction of flow of hydraulic fluid in the circuit containing the hydraulic motor 29. Similarly, the cylinder control valve assembly 70 has respective operating solenoids E and F to control the direction of hydraulic fluid furnished to the circuit containing the cylinder 21. When solenoid F is energized, the valve assembly 7® operates to cause the cylinder 21 and platform 17 to be moved to the position of FIG. 2, and conversely, when solenoid E is energized, the valve assembly causes retraction of platform 17 to the position of 1.

The hydraulic circuit containing the cylinder 21 is provided with respective conventional flow control valve devices 71 and 72 utilizing to control the speed of movement of the cylinder 21, piston rod 63, and therefore, the speed of extension and retraction of the cage assembly. A conventional reducing valve assembly 73 is provided in the connection between pressure line 68 and valve assembly 70 which may be adjusted to allow the hydraulic circuit of the cylinder 21 to operate at lower than system pressure, inasmuch as full system pressure will not be required for the operation of cylinder 21.

The hydraulic circuit containing the hoist motor 29 is provided with dual relief valves 74 and 75, with replenishing check valves 76 and 77, as shown in FIG. 10. This fluid circuit also contains a conventional holding counterbalance valve 78 and includes a control valve 79 having an operating solenoid S. The valve 79 has connected thereacross a conventional choke block flow control valve device 8© acting as a pressure compensating device.

A conventional relief valve 81 is connected between hydraulic line 68 and reservoir 35, and a dump valve 82 is connected between valve 81 and the reservoir, said valve 82 being provided with the operating solenoid V. The valve arrangement including the relief valve 81 and the dump valve 82 is of a conventional type and is such that when the hydraulic lines 83 and 84 leading respectively to the reversing valve assemblies 69 and 70 are blocked, the pressure fluid from line 68 will return to reservoir 35. Energization of valve solenoid V will block return through dump valve 82.

A dump valve 85 is also connected to line 68 through a conventional flow control device 86, the dump valve 85 having the operating solenoid D. Fluid pressure line 84 is connected to the brake cylinder 66 through a branch circuit 88 including a speed-controlling reducing valve 89, a check valve 90, a brake control valve assembly 91 and a further speed controlling valve device 92. The valve assembly 91 has an operating solenoid K. As shown, the valve assembly 91 normally connects cylinder 66 to the reservoir, and under these conditions braking force is applied to drum 64'. In order to release such braking force, solenoid K must be energized, to allow pressure fluid to flow to cylinder 66.

As is diagrammatically illustrated in FIG. 11, energization of the various solenoids is provided from a suitable power supply source and conventional wiring in the control cabinet 64. Respective push button switch assemblies 95, 96 and 97 are provided for controlling the operation of the system. Push button switch assembly 95 is located in a conveniently accessible location in the housing 27. Push button switch assembly 96 is located at ground level on the frame-like enclosure 24 at a position conveniently accessible to occupants of the cage 39 when said cage is in its elevated position, such as that shown in FIG. 4. Push button switch assembly 97 is located at the horizontal mine shaft portion 13

3,757,701 adjacent the landing position of cage 39 when it has completed its downward travel.

Conventional circuitry is provided, not shown, for energizing solenoids V and F responsive to actuation of one of the push buttons, for example, “lower” push button of any one of the push button assemblies 95,96 or 97. Thus, for example, the “lower” push button is shown at 101 for the hoist push button assembly 95. The other push button assemblies 96 and 97 have corresponding “lower” push buttons. Said assemblies also have “hoist” push buttons 102 which are employed to elevate the cage 39, in a manner presently to be described.

Thus, as above described, with the motor 34 energized, actuation of any of the push buttons 101 causes energization of solenoids V and F, causing cylinder 21 to be extended, namely, to move to the position of FIG. 2, moving the tower 24 over the vertical mine shaft 12. When the cylinder 21 reaches its limit of travel, it operates a limit switch 93 which causes solenoid F to become deenergized and causes solenoids B and S to become energized, solenoid V remaining energized, to start downward movement of the hoist. The choke block device 80 connected across valve 79 is adjustable to allow adjustment of acceleration of the hoist either 25 down or up.

It will be understood that when the hoist motor 29 becomes energized, the brake cylinder 66 simultaneously receives pressure hydraulic fluid, by the energization of the solenoid K. Braking action is controlled by ³θ the provision of respective “on” and “off” limit switches 98 and 99 which are employed in a conventional manner to provide an electrical interlock between the brake and motor control solenoids.

As above mentioned, when the tower 24 reaches the position of FIG. 2, the solenoids B and S are energized to cause motor 29 to be operated in a direction to lower the cage 39. The cage descends, tripping a “slow down” limit switch 106 which is suitably wired so as to deenergize solenoid S and energize solenoid D, to start slow down by controlled flow out of the motor by way of pressure-compensated flow control device 86.

When the cage 39 reaches its bottom limiting position, it actuates a limit switch 107 which is suitably wired so as to deenergize solenoid B, and after a time delay to deenergize solenoids V and D. The cage 39 is thus stopped in its lowered position, for loading.

Suitable wiring is provided so that when any one of the “hoist” push buttons 102 is actuated, solenoids V, A and S are energized, causing the motor 29 to be activated in a direction to raise the cage 39. As the cage 39 approaches its uppermost position, it trips a limit switch 108 which is wired so that its activation energizes solenoid D, to thereby deny flow of pressure hydraulic fluid to the motor 29. An upper limit switch 109 is provided, being engageable by the cage 39 as it reaches its landing position in tower 24. Limit switch 109 is suitably wired so as to deenergize solenoid A responsive to actuation thereof, and after a time delay to deenergize solenoids V, S and D. Thus, as the cage 39 rises and approaches its top limit of travel, it slows down by tripping the “slow down” limit switch 108, and thereafter is stopped in its top landing position by actuating the top limit switch 109. As will be apparent from FIG. 10, the deenergization of solenoids A and S cut off fluid flow in the motor circuit and deenergization of the solenoids D and V cause the output flow from the pump 33 to be returned to the reservoir through the relief valve 81.

Suitable circuitry is provided for energizing solenoids E and V when the cage 39 is in its upper landing position, whereby to retract the platform 17 from the position of FIG. 2 to the position of FIG. 1. Thus, a suitable control switch may be provided for energizing solenoids E and V at this time, whereby to return platform 17 to its starting position, shown in FIG. 1. This circuit is further controlled by a limit switch 94, engageable by suitable means, for example, a projection on cylinder 21, so as to deenergize solenoids E and V at the end of the retraction stroke.

As above mentioned, at the completion of the escape operation, the solenoids E and V are energized to retract the platform 17 to the non-operating position thereof shown in FIG. 1. This may be done by the provision of a suitable energizing circuit which can be controlled manually, for example, by a push button switch, connected to the solenoids E and V. This circuit may include the limit switch 94, which is arranged to be actuated responsive to the completion of the retraction movement of the cylinder 21, for example, by employing a projection on the cylinder to actuate said limit switch. Thus, the limit switch 94 operates to deenergize the solenoids E and V at the end of the retraction movement of platform 17 in substantially the same manner in which solenoid F becomes deenergized by the actuation of limit switch 93 at the completion of the forward movement of cylinder 21, except that in this case the solenoid V remains energized and the solenoids D and S become energized.

In the alternative form of the invention illustrated in FIG. 13, electric power means is used to operate the various parts of the apparatus. Thus, an electric motor 21' is attached to the platform 17 in any suitable manner, the shaft of the motor 21' being provided with a pinion gear 201 which meshes with a rack bar 202 secured to the fixed slab 14. The rack bar 202 extends in the direction of intended movement of the platform 17, the platform being supported on rails 15, as in the previously described form of the invention and being provided with retaining means 19, 20, as previously described. The hoist drum 28 is driven by a reversible electric motor 29' energized through the main control unit 64' and being reversibly operable through circuits controlled by the “lower” push buttons 101 and the “hoist” push buttons 102, providing reversible operation of motor 29' similar to reversible operation of the hydraulic motor 29 provided in the previously described form of the invention.

The energizing circuits for the motor 21' are controlled by respective limit switches 93 and 94 so that ₅₅ motor 21' becomes deenergized automatically by the actuation of limit switch 93 by suitable abutment means on platform 17 when the platform reaches its forward limit of travel, and similarly, when electric motor 21' is energized for retracting the platform it be₆₀ comes deenergized by the engagement of suitable abutment means on platform 17 with the limit switch 94 when the platform reaches the end of its retracted path of travel. The rack bar 202 may be fastened to any suitable portion of the stationary structure beneath the platform 17, for example, to the retaining beam member 19.

The hoist motor 29' may be automatically deenergized at the limits of travel of the cage 39, for example,

3,757,701 by the provision of suitable limit switches 108 and 109 located to slow down and deenergize the hoist motor 29 when it approaches ground level, and by other limit switches, not shown, similar to the limit switches 106 and 107 of the previously described embodiments of the invention located adjacent the lower limit of travel of the cage 39 and arranged to be actuated thereby as the cage approaches and finally reaches its lower limit of travel, namely, reaches the horizontal mine shaft portion 13. The hoist drum 28 is provided with suitable braking means interlocked with the motor 29' in a conventional manner. Thus, the drum 28 may be provided with an emergency brake drum 204 engaged by a brake band 205 whose tension is controlled by a solenoid 206 whose plunger is connected to the brake band 205 for applying braking force to the brake band and whose limits of travel are controlled in a conventional manner by the provision of limit switches 98' and 99' connected in the circuit of the braking solenoid 206.

The mode of operation of the embodiment shown in FIG. 13 is generally similar to that of the previously described form of the invention, the motor 21' being energized in a direction to move the platform 17 to the position of FIG. 2 responsive to the actuation of any one of the “lower” push buttons. The motor 21' is automatically deenergized when it reaches the position of FIG. 2 and the motor 29' becomes energized in a direction to lower the cage 39, becoming denergized when the cage has reached its lowermost position, such as that shown in FIG. 2. When a “hoist” push buttom 102 is actuated, motor 29' becomes energized in a direction to raise the cage and automatically becomes deenergized by the action of limit switches 108 and 109 to position the cage at its upper limit of travel, for example, that shown in FIG. 4. Subsequently, motor 21' may be energized to retract platform 17 to its original nonoperating position, such as that shown in FIG. 1.

It will be understood that within the spirit of the present invention any conventional hoist assembly, either hydraulically driven or driven by an electric motor, may be employed to raise and lower the passenger cage. Also, within the spirit of the present invention, this hydraulically or electrically powered hoist assembly may be employed in conjunction with either the hydraulically operated platform-shifting means shown in FIGS. 1 to 12 or with the electrically powered platform shifting means shown in FIG. 13.

While certain specific embodiments of an improved emergency mine elevator have been disclosed in the foregoing description, it will be understood that various modifications within the spirit of the invention may occur to those skilled in the art. Therefore, it is intended that no limitations be placed on the invention except as defined by the scope of the appended claims.