US 2933157 A
Description (OCR text may contain errors)
April 19, 1960 J. R. HUBER DEVICE FOR CONTROLLED SLIDING ON A ROPE Filed March 22, 1957 2 Sheets-Sheet l XJ ZQQM By "M ATTORNEY April 19, 0 J. R. HUBER 2,933,157
DEVICE FOR CONTROLLED SLIDING ON A ROPE Filed March 22, 1957 2 Sheets-Sheet 2 "MM $84M A TTOR'NEY United States Patent DEVICE FOR CONTROLLED SLIDING ON A ROPE John Richard Huber, Holicong, Pa., assiguor to Eastern Rotorcraft Corporation, Doylestown, Pa., a corporation of Pennsylvania Application March 22, 1957, Serial No. 647,885
4 Claims. (Cl. 188-651) This invention relates to rope engaging devices and is more particularly concerned with devices which will provide controlled sliding of a load along a rope member.
Devices of this nature are particularly useful in providing for the lowering of personnel from aircraft after a crash landing or for use in escape from a building in case of fire or other emergency. Such devices are also useful in lowering cargo loads where a rate of descent slower than a free fall is required to prevent damage.
The main object of the present invention is to provide a simple and light weight device which will support a weight such as a person while permitting a relatively constant rate of descent down a rope under the influence of the weight. The invention includes the provision of rope engaging mechanism which automatically develops braking action which increases with increased load thereby controlling the descent speed to a value within the range for which it is designed regardless of variation in the Weight.
A secondary object of the invention is to provide a device for controlled sliding along a rope having a construction which will permit more than one of the devices to be used simultaneously in series on the same rope member.
How these and other objects and advantages of the invention are attained will be clear by reference to the drawings in which- Figure 1 is a general elevational view of a device according to the present invention showing it supporting a weight of a rope.
Figure 2 is an enlarged front elevational viewer the device illustrated in Figure 1 .having'a portion-of the frame removed to show the interior construction.
Figure 3 is a sectional view of the device taken in the direction of arrows 3-3, Figure 2.
Figure 4 is a front elevational view generally similar to Figure 2 but illustrating an alternative form of device.
Figure 5 is a side elevational .view of the device of Figure 4.
Referring to the figures it will be seen that in Figure 1 a rope is shown attached to a supporting ring 11, the device 12 being supported on the rope for downward sliding movement under load. As illustrated, a looped load strap 13 is connected to the device 12 and is proportioned in this example as a wrist strap to permit a person to hang securely by the strap with one hand.
The details of construction of the device 12 will be more clearly seen by reference to Figures 2 and 3. A frame 14, which is in the form of a deep channel, supports therein a rope engaging and load transfer member illustrated as an elongated beam 15. Beam 15 is supported by a pivot 16 in frame 14 and one end of the beam 15 has a smooth rounded surface 17 around which the rope 10 extends as it passes through the frame 14 and out to the upper loaded portion of the rope. The unloaded portion of the rope is indicated at 10a. The opposite end of the beam 15 from the rounded portion 17 is shown at 18 where it is in position to apply a force to a brake I some circumstances the aircraft may come to rest with.
shoe 19 which engages the rope 10 at the point where the unloaded portion of the rope 10a moves into the device 12 as it passes through during a descent operation. The shoe 19 is supported against displacement in the direction of rope travel by means of a rod 20 which passes through slotted openings 21 in the frame 14. These slotted openings permit the brake shoe 19 to move toward or away from the rope as required to change the applied pressure thereon. A guide bushing 22 is supported in the frame 14 to guide the rope 16 along the frame 14 to prevent a lateral component of rope load from being applied to the brake shoe. A rounded entry lip 23 is provided on the frame 14 to give smooth flow of the rope into the device.
The strap 13 which supports the load is attached to the frame 14 by means of elongated opening 24. A metal reinforcement member 25 is provided to protect the strap against damage from the metal edges of the frame. It will be noted that the opening 24 is located in a position so that the strap load as indicated by arrow 26 is generally in line with the loaded portion. of the rope. Arrow 27 indicates the tension of the rope load and it will be observed that under an increased load that the force developed against the end 17' will cause movement of the beam 15 as indicated by the dotted outline 15a. This movement in turn increases the pressure at the end 18 of the beam with consequent increase inapplication of braking load against the rope. It will be noted that the rope turns around the end 17 off the beam 15 approximately through a right angle. The combination of rope tension forces produces a moment about the pivot 16 which will be proportionate to the load in the which provides increased force at the brake application point.
With the proportioning of the mechanism shown in Figure 2, a suitable rate of descent for lowering personnel.
from disabled aircraft after a crash is provided. Under the escape openings at a height of 12 or more feet above the ground. The use of a rope with the device shown permits relatively rapid descent of persons from the aircraft at a speed which will prevent injury on ground contact. The device also reduces the possibility of injury resulting from rope burns or loss of grip on the rope. The device illustrated is able to absorb in heat the energy required for a fairly rapid descent (at rates from 5 to. 12 feet per second) for heights up to 30 feet or more without damage to the parts of the device. For use with the device nylon rope is preferred because of the resilience as well as the surface characteristics which combine to give smooth flowing action as the rope passes. through the device thus eliminating any jerkiness or variation in speed caused by inconsistencies in the rope structure.
The device 29 shown in Figures 4 and 5 performs the same general function as that shown in Figure 2 but is constructed to provide more satisfactorily for the simultaneous use of more than one device on the rope. A frame 30 supports a snubbing drum 31 around which the rope 10 makes a complete turn. The drum 31 is provided with side flanges 32 which extend and form an arm 33 projecting down into the frame 30. The flanges 32 are attached to the drum 31 by means of a suitable fastening such as a rivet 34 and the assembly of drum 31 and arm 33 is supported in the frame 30 by means of pivot member 35. At the lower end of arm 33 a brake shoe 36 is supported in position in the frame 30 by the rod 37 extending through slots 38 in a position where the brake shoe can press against the rope as it enters the frame 30.
The load strap 13 is supported in the frame 30 by means of the opening 39 which is located close to the arm 33 and the point of entry of the portion of rope 10a where the brake pressure is applied. In this position the strap 13 also supports the load substantially in line with the loaded portion of the strap 10.
With the construction shown in Figures 4 and 5 the rope flows through the device from the brake shoe 36 to the drum 31 where it passes around the drum and the loaded end of the rope leaves the strap tangentially at a point approximately one complete turn from the portion of the rope inside the device. The snubbing action of the drum 31 causes the portion of the rope between V the brake shoe 36 and the drum 3110 have a substantially and after it is passed around the drum. Thus increase in load will cause increase in braking force and vice versa. As a result, the velocity at which the rope flows through the device will remain fairly constant regardless of the load which is being supported. Because the snubbing action of the drum causes a considerable reduction in tension in the rope after it has passed around it less braking action is required to produce the same rate of descent developed in the device of Figure 2. Therefore, the mechanical advantage required between the drum and the arm applying the load to the brake shoe is less than that required in the previous form of the device.
It will be noted that the direction of inflow in Figure 4 I of .rope portion 10a is approximately in line with the direction of the outflow portion ofthe rope at 10. Since there is little change in the resultant direction of the ropethe addition of a second load in series with a device of Figure 4 will have little or no detrimental effect on the operation of the device. The tension in the rope member will 'be increased but the difference in tension between the brake shoe and the outfiowing portion 10 of the rope will be a direct result of the load introduced by the device. Any tension already in the inflowing rope 10a will of course be added to the weight carried in frame 30 to produce the total tension at the loaded portion of the rope 10.
From the foregoing it will be evident that I have provided a relatively simple and light-weight braking device for attachment to a rope to permit the control of the descent speed of a load along the rope. By the provision of braking action proportional to the load being carried the speed of movement along the rope can be maintained within the desired limits even thouglrthe weight carried by the device may vary. This is important in connection with the use of the device for lowering personsrto the ground from an aircraft after a crash or from a structure in case of emergency since the device when used for these purposes must be capable of carrying people of diiferent weights without dangerous increase in velocity of descent. The devices illustrated are capable of being used many times without causing damageto the rope. Thus a relatively light weight A" nylon rope having an ultimate strength capacity of 1200 lbs. may be repeatedly used with safety for personnel escape purposes.
I claim: 7
1. A device for attachment to a rope to provide controlled sliding of a load thereon, said device having'a frame incorporating attachment means for connecting a load thereto, a rope deflecting and load transfer member in the form of a snubbing drum around which the rope extends one complete turn, a mounting pivot supporting said snubbing drum in said frame, said frame having a portion to react against a rope passing through the frame, an arm rigidly attached to said drum and extending therefrom and a rope engaging brake shoe member supported at the end of arm adjacent said reaction portion of said frame, said drum having its motion limited by virtue of the engagement of said brake shoe member with a rope in position adjacent the reaction portion of said frame.
2. A device in accordance with claim 1 in which the distance from the end of said arm to said mounting pivot is greater than the distance from said mounting pivot to the point of .tangency of the loaded portion of the rope on said drum.
3. A device in accordance with claim 1 in which said load attachment means is located near the end of'sai-d arm. a
4. A device for attachment to a rope to provide controlled sliding of a load thereon, said device having a frame, attachment means on said frame for connecting a load thereto, a rope snubbing drum having a capacity for holding at least one complete wrap ofrope, an arm rigidly attached to said drum, a support for said drum at one end of said frame including ,a pivot member engaging said drum in concentric relationship, said arm extending into said frame, a brake shoe located at the end .of said arm to engage a rope where it passes between said frame and said shoe, said pivot member being located to cause said arm to apply pressure to said brake shoe by virtue of the load and friction developed in a rope moving around said drum.
References Cited in the file of this patent UNITED STATES PATENTS Johnson Oct. 17, 1939 www- A -4m