CA1170633A - Emergency descent device - Google Patents

Abstract

EMERGENCY DESCENT DEVICE
ABSTRACT OF THE DISCLOSURE
This invention relates to a fire escape for high rise buildings. Cables are automatically lowered from the roof of the building, and once they have descended, brake apparatus is slipped over each cable to be used from various levels of the building. A person is suspended from each brake apparatus, and is controllably lowered to the ground. Since the brake apparatus can be attached anywhere along the cable without prethreading, a plurality of persons can be lowered at the same time, and the same cable can be used repeatedly by many people.

Description

02 This application is a division of Canadian application 03 Serial No. 376,970 filed May 6th, 1981.
04 This invention relates to apparatus used to facilitate 05 emergency descent by persons trapped at an elevated position in 06 high rise buildings.
07 Fires in high-rise buildings pose major difficulties 08 for persons trapped at high levels. Fire engine ladders normally 09 can rise only a limited number of stories. Interior stairwells often not only become blocked with smoke, but provide a conduit 11 for smoke to rise to the top of a building, thus shutting off 12 means for persons to escape. In cases where the building 13 has window balconies, or when persons in the building are able to 14 find their way to the roof, helicopters are used to evacuate otherwise trapped persons. However it is often difficult to 16 obtain sufficient numbers of helicopters to service a large 17 building housing a large number of persons, such as a high-rise 18 hotel. Consequently there have been many disasters in which 19 people have been seriously hurt or killed jumping from windows many stories high, to the ground.
21 The present invention provides an emergency decent 22 device which is both effective and safe. According to the 23 present invention, cables are automatically unwound from the roof 24 of a building past windows or balconies, to the ground, the cables being released automatically when the fire alarm rings.
26 Within each room, or at central locations, an apparatus is made 27 available, one to a person, which is coupled to the cable, to 28 which apparatus a seat which can be hitched to a belt surrounding 29 the person is connected. A plurality of persons at different floor levels along one cable all can use the cable at the same 31 time. Once a user is on the seat, a brake control is released, 32 allowing friction members in the apparatus to ride along the 33 cable at a speed which is controllable by the user. As more 34 people descend on a single cable, the descent rate of the uppermost users is slow automatically, thus compensating for a 36 greater number of people using one cable.
37 The use of friction members to lower a person down a 38 cable is not new, and indeed was invented a great many years 39 ago. However such apparatus was not practical for a number of reasons to be described below.
41 In Canadian Patent No. 65,498 to H.W. Racey, applied 6~

02 for on December 1, 1899, a controllable descent device using a 03 rope or cable is described. However the rope or cable must be 04 threaded through the descent device, in a complex operation, and 05 consequently each descent device is permanently attached 06 to the rope or cable. The number of persons which can use a rope 07 or cable is thus predetermined by the number of friction devices 08 attached thereto, and in an emergency, it is virtually impossible 09 to attach more devices to the rope or cable. Due to the complex apparatus, utilizing five wheels within a housing, regular 11 maintenance appears to be necessary at the site at which it is 12 attached to the rope, thus being labour intensive and costly.
13 The apparatus itself is a complex mechanism, and thus is not 14 inexpensive. Besides the cost, the danger of not facilitating the descent of more than a predetermined number of users due to 16 the requirement of pre-threading, is dangerous in itself.
17 In Canadian Patent 44,042, by ~ucretia Lester, issued 18 August 24, 1893, a descent device of much simpler construction is 19 shown. This device utilizes a pair of cooperatively shaped convoluted surfaces which clamp around a rope, friction slowing 21 the descent of the user. In the event that the user accidentally 22 stops squeezing the friction devices together, a camming effect 23 results, stopping the downward descent of the user.
24 However the structure of the apparatus is such that as with Canadian Patent 88,189, the device must be prethreaded on 26 the rope, and additional friction devices cannot be added at the 27 time of emergency, once the rope has dropped, with the attendant 28 danger to persons who are left with insufficient numbers of such 29 friction devices.
Canadian Patent 57,608 to W.B. Wilson dated 31 September 28, 1897 describes a different form of emergency 32 descent device to that of Patent 44,042, and appears to be fairly 33 inexpensive and controllable. However this apparatus suffers 34 from the same problem as the ones described above, in that it must be threaded on the rope prior to lowering of the rope, since 36 the rope passes through apparatus.
37 The present invention is a relatively inexpensive 38 emergency descent device by which persons can be controllably 39 lowered down a rope, but it can be attached to the rope at any 11170~3 02 position on the rope, after the rope has been lowered.
03 Consequently any number of friction devices can be attached, 04 limited only by the number of such devices available.
05 Consequently a central depository of such devices can be 06 distributed disproportionately along the building, as might be 07 needed by congregations of persons in the building. A
08 substantial improvement in the factor of safety afforded persons 09 within such buildings is thus provided. Further, the devices can be distributed upon registration or entry of persons to the 11 building, allowing their use whereby the persons might be in the 12 event of fire.
13 According to the present invention, a cable is slipped 14 sideways between a pair of friction devices, and the friction devices are moved toward each other using a brake control, 16 preferably in the form of a screw. As the brake devices close 17 toward each other, clamping the cable, a cable guide closes over 18 the entrance of the cable between the friction devices, and the 19 cable is thus held between guides on both sides of the friction devices, as they are clamped around the cable. The brake control 21 closes the friction devices until the full weight of a person can 22 be supported on the cable. A seat is attached to the lower 23 portion of the apparatus, and the person sits in the seat, 24 attaching the seat cables to his belt, or fastening a belt attached to the cables around his waist. He then swings clear of 26 the building, supported by the cable. Release of the brake 27 control in small degrees allows the friction members to slide 28 over the cable, lowering the person slowly to the ground and to 29 safety.
As more persons attach similar apparatus to the cable 31 below, and place their weight on the cable, the upper portions of ~32 the cable tightens, thus increasing the tension of the cable ~33 against the friction members. Automatic compensation against 34 persons suspended higher descending into persons suspended lower is thus provided.
36 In general, the invention is an emergency descent 37 device comprised of a pair of friction members having 38 cooperatively shaped adjacent convoluted surfaces, apparatus for ~39 adjusting the space between the surfaces, a first cable guide 6:~3 02 extending from one member to the other on one side thereof for 03 retaining a cable between the convolutions of the surfaces, and a 04 second cable guide extending from one member to the other on the 05 other side thereof, when the surfaces are a first predetermined 06 distance apart in which the convolutions are substantially 07 enfolded, and extending from the one member toward, but not as 08 far as the other when the convolutions are a second predetermined 09 distance apart in which the convolutions are not substantially enfolded. The cable can thus be slipped between the surfaces and 11 between the first and second cable guides when the surfaces are 12 the second distance apart, but is retained therebetween when the 13 surfaces are adjusted to the first distance apart.
14 A better understanding of the invention will be obtained by reference to the detailed description below, and to 16 the following drawings, in which:
17 Figure 1 is a schematic side view of a building, with 18 the invention in use, 19 Figure la is a detail of a magnetic brake which releases the cable used in the invention, 21 Figure 2 is a schematic perspective, with some parts 22 distorted in size, used to illustrate the invention, and 23 Figure 3 is a schematic perspective, with some parts 24 distorted in size, used to illustrate a further embodiment of the invention.
26 Turning first to Figure 1, a building 1 is shown, having 27 a plurality of balconies 2, which illustrate~ generally a high-rise 28 building. A cable reel 3, on which preferably steel cable of eg. 1/4 29 or 3/8th thickness cable is wound, is rotatably mounted on the roof of the building. The cable 6 passes through a magnetic brake 4, and 31 over a rotatable reel 5, and has a weight 7 attached to its end.
32 When the building fire alarm operates, it releases the 33 brake, thus allowing the weighted end of the cable 6 to pull it 34 down from the reel to the ground. The amount of cable wound on the reel is just sufficient to reach the ground, and the reel end 36 of the cable is fastened to the hub of the reel.
37 While an electric motor could have been used to unwind 38 the reel, it is preferred to use a weight, since fire alarm 39 systems are often connected to emergency power supplies which do not have the capacity to drive such apparatus as reel motors, but 41 which would have sufficient capacity to release a self latching ~ .3 02 magnetic brake. The remaining operation of the unwinding 03 function of the reel is thus rendered free of the supply of any 04 power, gravity causing the cable to unwind to its proper 05 position.
06 Persons standing on each of the balconies can now 07 descend on the cable. An emergency descent device 8 is slipped 08 over the cable, and its brake is closed. This effectively locks 09 the device to the cable, and the user attaches a seat, sits on it, and releases the brake slowly. He then descends down the 11 rope.
12 As can be seen in Figure 1, a plurality of emergency 13 descent devices with users attached are descending at the same 14 time down a single rope. Clearly more than one person from each level can use the same cable, and a plurality of persons from 16 different levels can use the same cable.
17 Further, if additional persons find their way to one 18 cable from other areas of the building, additional descent 19 devices can be attached easily, merely by slipping them on the cable. This is distinguished from the prior art descent devices 21 described earlier, in which only a predetermined number of such 22 devices could be used on a single cable, those which had been 23 prethreaded on the rope or cable. In the prior art, once the 24 cable has been lowered, no additional descent devices can be added, thus establishing a dangerous condition since there would ~26 be no additional devices available for use once the prethreaded 27 devices have been used up.
28 Figure la is a detail of the magnetic brake. The brake 29 is comprised of a pair of steel armatures 10, which are normally magnetically latched together, closing on the cable 6. If 31 desired, a pair of brake pads 11 operated by the armatures can be 32 used, thus clamping the cable 6 against movement. With the cable 33 entirely wound on the reel except for the weighted end, which ~34 hangs over the reel 5 which is cantilevered past the top of the ~35 building, it is held in position by the magnetically latched 36 relay.
37 As soon as the fire alarm rings, current is passed 38 along wires 12 to the magnetic brake relay coil, thus releasing 39 the armatures, which then latch open. The brake thus releases 1.~7(:)6:~3 02 the cable 6, allowing the weight 7 to draw it down to the ground.
03 It is preferred that a plurality of such reels and 04 cables should be provided, e.g., in a 230 unit apartment having ~5 11 f:Loors, 21 cables could be utilized around the building.
06 Turning now to Figure 2, the details of the preferred 07 embodiment of the descent device is shown. A pair of friction 08 members 15 and 16, preferably each cut from a two inch by four 09 inch nominal cross-section piece of hardwood, about 10 inches long, have cooperatively shaped adjacent convoluted surfaces 17 11 and 18, for frictionally pressing on the cable. In one 12 successful prototype, a central five inch length convex section 13 protruded from friction member 16, toward a cooperatively shaped 14 convex section in friction member 15, each of the sides of the concave and convex sections cut at about a 45 degree angle.
16 A first cable guide is located on one side of the 17 friction members, which could be a flat piece of aluminum or 18 steel fastened on one friction member and extending substantially 19 across the side of the other friction member. However, in the preferred embodiment, a pair of bolts 19 and 20 are used, which 21 are located to one side of the friction members along the length 22 thereof. The bolt is preferably fastened in one friction member, ~23 e.g. friction member 15, and each passes through a corresponding ;24 hole 21 and 22 in friction member 16, in order that friction ~25 member 16 should slide along the bolts. Also, preferably the 26 opposite sides of the friction members are faced with steel or ~27 aluminum plates 23 and 24, which provides firm bearing surfaces 28 for the ends of the bolts, which could otherwise bite into the 29 wood of the friction members.
A keeper, or nut locked to the end of bolts 19 and 20 ~;31 retains friction member 16 on the bolts; otherwise the loosened 32 apparatus could come apart.
~33 A screw member, preferably in the form of a bolt 25, 34 with a keeper or locknut 25A, extends through both friction mem-~35 bers 15 and 16. Preferably the bolt 25 should have a manually 36 operable end, for turning the bolt. The bolt passes through fric-~37 tion member 16, and is threaded to end plate 23, whereby rotation 38 of the bolt 25 causes friction members 15 and 16 to draw together.
39 A second cable guide is attached at the other side of 06~

02 friction members 15 and 16. In the preferred embodiment, the 03 guide is comprised of a pair of bolts 26 and 27 which pass 04 through friction member lS, only part way across the gap between 05 both friction members. Preferably the bolts extend from the 06 inward portion of the concave section of friction member 15, and 07 approximately to the outward upper portions of friction member 0~ 15.
09 Consequently, when friction members 15 and 16 are at a first predetermined position apart, with the convex portion of 11 friction member 16 spaced from the ends of bolts 26 and 27, the 12 cable can be passed between the ends of bolts 26 and 27 and the 13 convex surface of friction member 16, against bolts 19 and 20.
14 Friction members 15 and 16 are then drawn together by turning bolt 25, causing bolts 26 and 27 to close to friction member 16.
16 Bolts 26 and 27 then pass into coaxial holes 28 and 29 in 17 friction member 16, thus allowing friction members 15 and 16 to 18 be drawn closer and tighter on cable 6, without interference to 19 bolts 26 and 27. However bolts 26 and 27 have effectively locked the cable within the convoluted regions between the friction 21 members 15 and 16. The control bolt 25 is thus turned until the 22 cable 6 is effectively locked therebetween.
23 A pair of eye bolts 30 and 31 are fixed adjacent the 24 bottoms of the friction members, and can be bolted to plates 23 and 24, or to the friction members themselves. The eyes of the 26 eye bolts extend outwardly opposite each other. A pair of 27 swivelling snap shackles 32 and 33 are detachably affixed to the 28 eye bolts, and seat cables 34 and 35 are respectively connected 29 to the snap shackles, using, e.g., nicopress sleeves. In a successful prototype, the seat cables were 1/16th inch diameter 31 stainless steel cable.
32 The cables are connected via "Y" branches under a seat 33 36. In the aforenoted successful prototype, the seat was 34 fabricated of 1/4 inch thickness plywood. In order to take the strain off the plywood seat when a person is seated thereon, it 36 is preferred to cross the branched seat cables underneath.
37 A pair of belt loops 37 and 38, each having a hole 38 through which a corresponding cable 34 and 35 passes, and an 39 elongated slot for accommodating a belt, is attached to the l~''t'~6. ~3 02 individual seat cables 34 and 35. The belt loops can be made of 03 aluminum.
04 In operation, once the friction members have been 05 clamped around the cable 6, the user attaches a belt through the 06 belt loops, and draws the plywood seat against his posterior.
07 The belt which is used can be either his own belt, or a belt 08 which is supplied with the apparatus and is normally looped 09 through the belt slots.
After the plywood seat is drawn against his posterior, 11 the user leans over the balcony or window adjacent which the 12 cable 6 with the friction members clamped thereto is located, and 13 attaches the snap shackles 32 and 33 to eye bolts 30 and 31. The 14 user then places all his weight on the seat, and is held in position by the belt. The user can also steady himself by 16 holding onto seat cables 34 and 35.
17 The user, now suspended by means of the friction 18 members being clamped on cable 6, unscrews brake control bolt 25 19 until the friction members begin sliding on cable 6. If the descent is too slow, the brake control bolt 25 is turned in one 21 direction, loosening the friction members, and if the descent is 22 too fast, the brake control bolt can be turned in the opposite 23 direction, thus tightening the friction members.
24 Of course, rather than having an eye bolt or thumb screw adjustment end to bolt 25, a lever could be used, for ease 26 of adjustment.
27 It should be noted that the forces on friction members 28 15 and 16 when a user is seated on seat 36 is to close or tighten ~29 the bottom of the pair of friction members, thus effectively causing a slowing of descent.
31 Also, as users are hung from cable 6 below, the cable 32 tightens, thus causing additional pressure on convoluted services 33 17 and 18, also effectively aiding the slowing of descent.
34 It is believed that the use of the present invention will facilitate the saving of a great many lives which otherwise 36 could be lost due to fire in high-rise buildings.
37 A person understanding the principles of the present 38 invention may now conceive of changes or other embodiments, using 39 the principles of the present invention. A11 are considered to 11706,~3 02 be w:ithin the sphere and scope of the invention as defined in the 03 claims appended hereto.

, , , :

16.~;~

03 Referring now to Figure 3, which shows a further 04 embodiment, it should be noted that it is not necessary to 05 utilize two bolts or dowels 26 and 27 as shown in Figure 2; only 06 one dowel 40 can be used. Should the friction members 15 and 16 07 tilt about the plane which contains the cable, the cable will be 08 retained between the guide formed by dowel 40 and the upper or 09 lower opposite guides 19 and 20.
Further, the guide shown in Figure 2 formed by a bolt 11 19 can be threaded into one of the friction members e.g., as 12 shown at reference 41 in Figure 2, the bolt passing unthreaded or 13 threaded with opposite bias through friction member 16. The 14 portion of the bolt extending outside friction member 16 opposite to the threaded portion can be fixed to a crank 42, and held 16 thereto for example by a cotter pin 43. A square hole in the 17 crank and a square head on the bolt 19 fitted into the hole of 18 the crank, held together by the cotter pin, will sufice. A
19 stopper nut, or large outside diameter washer 44 held under the head of the bolt or by a spacer from the crank bears against the 21 friction member 16, allowing friction member 15 to be drawn 22 toward friction member 16 as the crank is turned. In this 23 embodiment bolt 25 ( Figure 2) can be dispensed with.
24 It has also been found that cooperating convoluted adjacent surfaces of the friction members are not necessary, in ~26 the embodiment shown in Figure 3. The adjacent surfaces of the ~27 friction members are plane in form, thus reducing their cost 28 considerably.
29 In operation, the crank is turned so as to widen the space between the friction members, causing the end of dowel ~or 31 bolt) 40 to become outwardly spaced from the adjacent surface of 32 friction member 16. The apparatus is then applied to the cable 33 so that the cable bears against bolts 19 and 20. The crank is 34 then turned to narrow the space between the friction members, and the dowel 40 becomes inserted into a cooperating hole 45 in 36 friction member 16 in a similar manner to the embodi~ent of 37 Figure 2, thus retaining the cable between the guides formed by 38 elements, 40, 19 and 20 within the apparatus.

.33 02 The crank is further turned until both friction members 03 make friction contact with the cable. The seat or other 04 suspension apparatus is attached to eye bolts 30 and 31, and when 05 weight is applied thereto, pressure is as a result applied to the 06 lower portions of the friction members, forcing them together.
07 This causes increased energy to be absorbed as the apparatus 08 slides down the cable. The speed of descent can be controlled by 09 adjusting the force between the friction members by turning crank 42 in either clockwise or counterclockwise direction.
11 The friction members can be faced with leather brake 12 pads, or the brake pads can be eliminated and aluminum blocks can 13 be used as friction members 15 and 16.

Claims (16)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. An emergency descent device comprised of a pair of friction members having cooperatively shaped adjacent convoluted surfaces, means for adjusting the space between the surfaces, first cable guide means extending from one member to the other on one side thereof for retaining a cable between the convolutions of said surface, and second cable guide means extending from one member to the other on the other side thereof when the surfaces are a first predetermined distance apart in which the convolutions are substantially enfolded, and extending from said one member toward, but not as far as the other when the convolutions are a second predetermined distance apart in which the convolutions are not substantially enfolded, whereby said cable can be slipped between said surfaces and between the first and second cable guide means when the surfaces are said second distance apart, and be retained therebetween when the surfaces are adjusted to said first distance apart, said first cable guide means being in the form of a pair of dowel shaped members fixed adjacent mutually opposite ends on said one side of one friction member and directed toward the other friction member, and slideably passing through holes in the other friction member, whereby the lateral positions of the friction members are fixed relative to each other as the friction members are adjusted in distance therebetween.

2. An emergency descent device as defined in claim 1, in which the dowel shaped members are formed of bolts, each passing completely through said other friction member when said friction members are said second distance apart, and having friction member retaining means ixed to the ends of said bolts.

3. An emergency descent device as defined in claim 2, in which said retaining means are formed of nuts locked to said bolts, each having a diameter greater than the diameter of an associated one of said holes.

4. An emergency descent device as defined in claim 1, 2 or 3, in which the second cable guide means are in the form of a second pair of dowel shaped members fixed adjacent the other side of one of the friction members and pointed toward the other, and located in at least one concave section of its convoluted surface, said other friction member having coaxially located holes for slideably accommodating said second pair of dowel shaped members.

5. An emergency descent device as defined in claim 1, in which the means for adjusting is comprised of screw means threaded between the pair of friction members for adjusting the spacing between the friction members and thereby frictionally clamping a cable extending therebetween, when the screw means is turned.

6. An emergency descent device as defined in claim 5, in which the friction members are comprised of blocks of hardwood.

7. An emergency descent device as defined in claim 5 or 6, further including means for shackling a seat cable to one end of each of the friction members.

8. An emergency descent device as defined in claim 5 or 6, further including a seat retaining cable having its ends shackled to one end of each of the friction members, the cable adjacent each end forming the leg of a Y, a seat for accommodating a user, the arms of each Y passing through holes adjacent opposite corners of the seat and extending continuous under the seat.

9. An emergency descent device as defined in claim 5 or 6, further including a seat retaining cable having its ends shackled to one end of each of the friction members, the cable adjacent each end forming the leg of a Y, a seat for accommodating a user, the arms of each Y passing through holes adjacent opposite corners of the seat and extending continuous and crossing diagonally under the seat.

10. An emergency descent device as defined in claim 1 in which the dowel shaped members are formed of bolts, each passing completely through said other friction member when said friction members are said second distance apart, and having nuts locked to the end of said bolts, each having a diameter greater than the diameter of an associated one of said holes; the second cable guide means are a second spaced pair of dowel shaped members fixed adjacent the other side of one of the friction members and pointed toward the other, and located in a concave section of its convoluted surface, said other friction member having coaxially located holes for slideably accommodating said second pair of dowel shaped members, the means for adjusting is comprised of screw means threaded between the pair of friction members for adjusting the spacing of the friction members and thereby frictionally clamping a cable extending therebetween when the screw means is turned, the friction members being comprised of blocks of hardwood having opposite disposed external stiff metal facing panels fixed to their surfaces through which said bolts extend, and a seat retaining cable having its ends shackled to one end of each of the friction members, the cable adjacent each end forming the leg of a Y, a seat for accommodating a user, the arms of each Y passing through holes adjacent opposite corners of the seat and extending continuous and crossing diagonally under the seat.

11. An emergency descent device as defined in claim 10, further including means retained by the seat retaining cable adjacent each end for accommodating a belt for passing around a user.

12. An emergency descent device as defined in claim 6 or 10, further including an emergency descent cable for passing between the convoluted surfaces and being retained between the first and second cable guide means, a descent cable reel fixed to the roof and adjacent the edge of a building, and a descent cable brake means adapted to be released in the event of a fire alarm, whereby the descent cable can be unreeled from the cable reel toward the ground, and one or a plurality of the friction members can frictionally slide down the cable with a user suspended therefrom.

CLAIMS SUPPORTED BY SUPPLEMENTARY DISCLOSURE

13. An emergency descent device comprised of a pair of friction members having cooperatively shaped adjacent surfaces, means for adjusting the space between the surfaces, first cable guide means extending from one member to the other on one side thereof for retaining a cable between the surfaces, and second cable guide means extending from one member to the other on the other side thereof when the surfaces are a first predetermined distance apart and extending from said one member toward, but not as far as the other when the surfaces are a second predetermined distance apart whereby said cable can be slipped between said surfaces and between the first and second cable guide means, and be retained therebetween when the surfaces are adjusted to said first distance apart, said first cable guide means being in the form of members fixed adjacent mutually opposite ends on said one side of one friction member and directed toward the other friction member, and means for retaining the lateral positions of the friction members relative to each other as the friction members are adjusted in distance therebetween.

14. An emergency descent device comprised of a pair of friction members having cooperatively shaped adjacent surfaces, means for adjusting the space between the surfaces, first cable guide means extending from one member to the other on one side thereof for retaining a cable between the surfaces, and second cable guide means extending from one member to the other on the other side thereof when the surfaces are a first predetermined distance apart and extending from said one member toward, but not as far as the other when the surfaces are a second predetermined distance apart whereby said cable can be slipped between said surfaces and between the first and second cable guide means, and be retained therebetween when the surfaces are adjusted to said first distance apart, said first cable guide means being in the form of members fixed adjacent mutually opposite ends on said one side of one friction member and directed toward the other friction member, means for retaining the lateral positions of the friction members relative to each other as the friction members are adjusted in distance therebetween, and means for attaching a body supporting member to the frictional members.

15. An emergency descent device as defined in claim 14 in which the means for adjusting the space between the surfaces is comprised of a screw.

16. An emergency device as defined in claim 1, 13 or 14, further including an emergency descent cable for passing between said surfaces and being retained between the first and second cable guide means, a descent cable reel fixed to the roof and adjacent the edge of a building, and a descent cable brake means adapted to be released in the event of a fire alarm, whereby the descent cable can be unreeled from the cable reel toward the ground, and one of a plurality of the friction members can frictionally slide down the cable with a user suspended therefrom.