US3834671A - Lowering apparatus - Google Patents

Abstract

Apparatus for lowering a load from one level to a lower level (for example, for lowering a person to ground level from a burning building) which comprises a drum rotatable about an axle normally fixed in a frame. A cable is wound around the drum and rotation of the drum due to a load on the cable is retarded by the action of an annular cam inside the drum which co-operates with a piston and cylinder device to cause relative reciprocating movement between the cylinder and piston against the action of a retarding element therein, either the cam or the cylinder and piston device being fixed with respect to the support while the other is rotatable with the drum during unwinding of the cable.

Description

11] 3,834,671 1451 Sept. 19,1974

[541 LOWERING APPARATUS 200,653 7/1923 Great Britain 254/160 [76] in entor: God my L. M. Du Mesnil d 750,587 6/1956 Great Britain 254/158 Buisson, 44 bis, rue des, Versailles,

France Primary Examiner-Richard A. Schacher Assistant Examiner-Jeffrey V. Nase [22] Flledi 1972 Attorney, Agent, or FirmEric H. Waters; Alan K.

[21] Appl. No.: 281,018 Roberts, Julian H. Cohen [30] Foreign Application Priority Data [57] ABSTRACT Sept. 21, 1971 France 1. 71.33903 A pparatus for lowering a load from one level to a Jan. 24, 1972 France 72.02202 lower level p for lowering a person to [52] Us m 254/158 188/295 254/160 ground level from a burning building) which com- I 51] m AIGZb 1/12 prises a drum rotatable about an axle normally fixed in [58] Fieid 159 160 a frame. A cable is wound around the drum and rota- 1 g tion of the drum due to a load on the cable is retarded by the action of an annular cam inside the drum which co-operates with a piston and cylinder device to cause {56] References Cited relative reciprocating movement between the cylinder UNITED STATES PATENTS and piston against the action of a retarding element 1,761,311 6/1930 Redmond 254/158 therein, either the cam or the cylinder and piston del,9l2,953 Staats X vice being fixed respect to the support the 21154590 4/ 1939 P F 188/295 X other is rotatable with the drum during unwinding of 3,595,528 7/1971 V1rkk1 254/158 X the Cable.

FOREIGN PATENTS OR APPLICATIONS 175,591 6/1921 Great Britain .1 188/295 5 Clams 3 Drawmg figures Y:T 19 f #5 2 l l W PATENTEI] SEFl 01974 KHEU 2 [IF 3 PATENIE SEP 1 015m SHEET 3 [IF 3' LOWERING APPARATUS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an apparatus for lowering a load from one level to a lower level. The apparatus is of the type particularly useful for safely evacuating persons marooned on an upper story in a building which is on fire. It may also have other uses. In general it provides a means of rapidly lowering a person without risk of injury or an object without risk of damage from a higher level to a lower level. The invention is concerned with apparatus of the type comprising a drum, which is rotatable and carries a cable, and means of slowing down the rotation of the drum during the unwinding of the cable.

2. Description of the Prior Art Apparatus of the above general kind is known, for example from US. Pat. No. 2,091,418.

In certain apparatus of this type, the rotation of the drum is slowed by mechanical friction means. Their operation, however is irregular, entails wear, requires adjustment and servicing and, despite care, do not furnish results which are accurately reproducible.

In the aforesaid US. Patent, provision is made for the slowing-down of the rotation of the drum by the throttling of the flow of a fluid between one cylinder and another cylinder. The design of this apparatus nevertheless has the result that it is cumbersome and heavy as well as expensive to manufacture. Furthermore, the apparatus requires adjustment before use and there is a danger of fluid leaks. Although this US. Patent has been known since 1937, the apparatus described in it is not commercially known.

No apparatus of this kind has appeared to fulfil requirements up to the present time. Individual rescue devices are not generally to be found while, whenever a large fire occurs in a building, such as a store or an hotel, the fire claims numerous victims in the upper storys due to the impossibility of escaping through windows with the aid of a suitable apparatus.

The main object of the invention is to provide an apparatus for lowering a load from one level to another, which can constitute an individual rescue apparatus, which is compact, small in size, low in weight, easy to use and capable of being used without human supervision a number of times in succession.

Another important aim of the invention is to provide an apparatus which is simple in design, inexpensive to manufacture, needs no maintenance and requires no regulation before use. Simplicity, low price, the lack of the need for regulation and maintenance, and the almost complete elimination of wear are essential requirements for an apparatus intended to be an individual rescue means.

SUMMARY According to the invention, there is provided apparatus for lowering a load from one level to a lower level, comprising a support, a fastening means attached to the support, a hollow drum rotatable with respect to the support, a cable wound on the drum, and retarding means for retarding the rotation of the drum in the cable unwinding direction, the retarding means comprising at least one cam disposed internally of the drum and at least one cylinder arrangement including a cylinder, and a piston adapted to move relative to the cylinder against the action of a retarding element therein, either the cam or the cylinder arrangement being fixed with respect to the support while the other is rotatable with the drum during the unwinding of the cable, the profile of the cam being such that during the rotation of the drum it brings about relative reciprocating move ment between the cylinder and piston against the action of the retarding element.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view partly in elevation and partly in section of a form of construction of an apparatus according to the invention,

FIG. 2 is a view in section along line IIII in FIG. I, and

FIG. 3 is a view similar to FIG. 1 showing a modified construction of this apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus illustrated as an example in FIGS. 1 and 2 comprises a casing 1, which is in the form of a frame and which serves to support the entire mechanism.

The upper side of the frame 1 is provided with a hook 2, and the bottom side has an opening 3.

The two lateral sides of the frame carry a central shaft 7. The latter is able to turn about its axis, but at one end it projects from the frame and is provided with an operating square 7a. On this square 7a can be fitted a crank 4, which is provided, in line with the handle, with a movable locking finger 18. When the crank is in a certain position, the finger 1% can be engaged in a corresponding recess provided in the side of the frame, as shown in FIG. 1. In this way, the shaft 7 can be locked at will to prevent rotation in relation to the frame 1.

Inside the frame 1, the central shaft 7 supports a drum 5, on which is wound a cable 6 passing out through the opening 3. The free end of this cable is provided with a harness (not shown) when the apparatus is intended for the rescue of persons.

The drum 5 is mounted on the shaft 7 by means of two ball bearings 19, which are illustrated diagrmmatically in FIG. 1. The arrangement is such that when the finger 18 of the ctank 4ilocks the shaft 7 with respect to rotation, the drum 5 can turn about this shaft during the unwinding of the cable 6. When the finger 18 is released from its recess, the shaft 7 and the drum 5 can be turned in the opposite direction with the aid of the crank 4, whereby the cable is rewound onto the drum 5.

In this example, two cams which are adapted to rotate with the drum 5 are fixed to the interior of the drum. These are two annular cams 8 with inner operative surfaces. The cams are disposed transversely, being held by screws on the inner surface of the drum 5 surrounding the shaft 7.

Inside each annular cam 8, the shaft 7 is provided with a pair of perpendicularly related cylinders 20 connected end to end and disposed transversely, in the diametrical direction.

Each cylinder 20 contains a piston 21, which has a projecting end applied against the inner face of the corresponding cam 8.

The two chambers of the two cylinders are separated by a common transverse partition 22, but a passage 23 of small section establishes communication between the chambers 24 and 25, which are bounded respectively by the wall of the cylinders, the partition 22, and the pistons 21. The chambers 24, 25 are filled with oil and the pistons 21 are fitted in the cylinders for fluidtight sliding.

The profile of the cam is such that the pistons are forced to move with equal strokes, so as to increase and decrease, alternately and equally, the volumes of the chambers 24-, 25.

If desired, an adjustable throttling element (not shown) such as a needle screw, is provided to allow adjustment of the actual useful passage section 23 during the manufacture of the apparatus. In this way the rate of exchange of fluid between the chambers 24, 25 and, consequently the speed of displacement of the pistons and the retarding force applied to each cam 8, may be preset.

Each set of two cylinders, together with their pistons, constitutes a retarding means which acts on the corresponding movable cam 8 and limits the speed of this cam and consequently of the drum 5 during the unwinding of the cable 6. Through the action of this means, the speed at which a person attached to the cable by the harness at its free end is lowered can be pre-set to a selected value.

The number of sets of two cylinders disposed in the apparatus is not limited by the invention, and similarly the arrangement illustrated is not obligatory.

Each set comprising a cam, cylinders, and pistons, constitutes a retarding means capable of numerous modifications in respect of details.

For example, there could be only one cylinder arrangement, i.e., a cylinder with a piston and projecting piston rod, and the operative surface of the cam could be that of a slot in which the end of the piston rod would be engaged. The cam would then positively impart reciprocating movements to the piston, the retarding fluid being driven from one side and the other of this piston.

instead of being disposed transversely, the sets of two cylinders could be disposed longitudinally and fixed either on the cylinder 5 or on the shaft 7; the cams would then be disc type cams with an oblique operative face, disposed transversely and fixed either on the shaft 7 or on the cylinder 5.

FIG. 3 shows an example of a modification relating to the cylinder arrangement. Each cylinder contains a piston 26 having two opposite piston rods 27, 28. The two chambers 24, are bounded in the cylinder by a face of the piston 26 and the passage 23 is bored through the piston 26. The diameter of this passage is predetermined and requires no adjustment. This diameter naturally depends on the fluid used to fill the cylinder. Any incompressible fluid capable of acting as retarding element may be used; the diameter of the passage 23 should be determined in dependence on the properties of this fluid and the desired speed for a given weight.

As an example, with an apparatus constructed and tested with a drum of a diameter of 296 mm, using as retarding element oil produced by Societe Francaise ANTAR, grade Frigorifique No. l, viscosity 2 Engler, with an oil passage of a diameter of 2 mm, a speed of descent of the order of 0.80 m/sec. is obtained for a weight of about 80 kg.

FIG. 3 also shows that it is possible for parts such as balls, rollers, or similar parts reducing wear, to be fitted on the ends of the piston rods in contact with the cam 8.

In all cases, the force by which the ends of the piston rods are applied against the cams makes it possible for the cable 6 to be rewound on the drum 5 with the aid of the crank 4; i.e., the rotational driving of the shaft 7 permits the driving of the drum when there is no weight at the end of the cable; In consequence, it is not necessary for freewheel or disengaging means to be provided between the shaft 7 and the drum 5.

With a cable of'limited length, it would also be possible to replace the crank by a spring device effecting the automatic rewinding of the cable.

It is easy with the aid of any suitable known means (not shown) to provide a certain tightness for the piston rods in relation to the cylinder.

It can be seen that the apparatus of the invention is compact, that it requires no maintenance, and that it is subject only to very little wear. Being thus designed, its operation is regular and consistent. Adjustment having been made at the factory, the apparatus of the invention permits descent at a constant speed from start to finish, at a speed which is safe for persons whose weights range from 30 to kg. This is an important advantage for a rescue apparatus.

1 claim:

1. Apparatus for lowering a load from one level to a lower level, comprising a support, a fastening means attached to the support, a central shaft on said support, locking means for selectively locking the rotation of the shaft with respect to the support, a hollow drum rotatable about said shaft, a cable wound on the drum, said drum being rotatable in a unwinding direction of the cable and in the opposite winding direction of the cable, and retarding means for retarding the rotation of the drum in the cable unwinding direction, the retarding means comprising a cam means disposed internally of the drum and at least one cylinder arrangement including a cylinder, and a piston adapted to move relative to the cylinder against the action of an incompressible fluid contained therein, either said cam means being fixed with respect to the shaft while the cylinder arrangement is rotatable with the drum during the unwinding of the cable or the cylinder arrangement being fixed with respect to the shaft while the cam means is rotatable with the drum during the unwinding of the cable, the construction and profile of the cam means being such that during the rotation of the drum it brings about relative reciprocating movement between the cylinder and piston against the action of the incompressible fluid, said cylinder of the cylinder arrangement containing two variable volume chambers, each of which is bounded by a face of said piston, the incompressible fluid being in said chambers, these chambers being brought into communication with each other by a passage of reduced section,'said piston including two piston rods projecting out of the cylinder in opposite directions, the free end of each rod being applied against the surface of the cam means, the variations of volume of the chambers being equal and in opposite directions during the rotation of the drum.

2. Apparatus according to claim 1, wherein said cam means comprises at least one cam fixed to the inner face of the drum, while at least one cylinder arrangements is fixed to the central shaft.

tral shaft has an end which projects in relation to the support, said locking means comprising a crank including a movable locking finger adapted to engage in a hole provided in the support, the engagement of this finger with the support preventing the central shaft from rotating during the unwinding of the cable.

5. Apparatus according to claim 3, wherein the ends of the piston rods which co-operate with the corresponding cam include rolling means.

Claims (5)

1. Apparatus for lowering a load from one level to a lower level, comprising a support, a fastening means attached to the support, a central shaft on said support, locking means for selectively locking the rotation of the shaft with respect to the support, a hollow drum rotatable about said shaft, a cable wound on the drum, said drum being rotatable in a unwinding direction of the cable and in the opposite winding direction of the cable, and retarding means for retarding the rotation of the drum in the cable unwinding direction, the retarding means comprising a cam means disposed internally of the drum and at least one cylinder arrangement including a cylinder, and a piston adapted to move relative to the cylinder against the action of an incompressible fluid contained therein, either said cam means being fixed with respect to the shaft while the cylinder arrangement is rotatable with the drum during the unwinding of the cable or the cylinder arrangement being fixed with respect to the shaft while the cam means is rotatable with the drum during the unwinding of the cable, the construction and profile of the cam means being such that during the rotation of the drum it brings about relative reciprocating movement between the cylinder and piston against the action of the incompressible fluid, said cylinder of the cylinder arrangement containing two variable volume chambers, each of which is bounded by a face of said piston, the incompressible fluid being in said chambers, these chambers being brought into communication with each other by a passage of reduced section, said piston including two piston rods projecting out of the cylinder in opposite directions, the free end of each rod being applied against the surface of the cam means, the variations of volume of the chambers being equal and in opposite directions during the rotation of the drum.

2. Apparatus according to claim 1, wherein said cam means comprises at least one cam fixed to the inner face of the drum, while at least one cylinder arrangements is fixed to the central shaft.

3. Apparatus according to claim 1, wherein the cam means comprises two cams spaced apart in axial direction and fixed in a plane transverse to the inner face of the drum, each cam surrounding the cylinder which is disposed in diametrical direction and fixed to the central shaft, each said cylinder containing at least one piston including two of said piston rods extending in opposite directions, the free end of each of said rods being applied against the surface of the surrounding cam.

4. Apparatus according to claim 1, wherein the central shaft has an end which projects in relation to the support, said locking means comprising a crank including a movable locking finger adapted to engage in a hole provided in the support, the engagement of this finger with the support preventing the central shaft from rotating during the unwinding of the cable.

5. Apparatus according to claim 3, wherein the ends of the piston rods which co-operate with the corresponding cam include rolling means.

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