US3787032A

US3787032A - Self-releasing and self-lowering block

Info

Publication number: US3787032A
Application number: US00283394A
Authority: US
Inventors: P Bagby
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-08-24
Filing date: 1972-08-24
Publication date: 1974-01-22
Anticipated expiration: 1991-01-22

Abstract

A self-releasing, self-lowering block adapted to rest upon a horizontal support cable. A vertically extending hoisting cable extends about the support cable, through sheaves in the block, and is retained within pivoted sections of the block. A release element attached to the hoisting cable can be raised to effect release of the pivoted sections so that they may move apart and allow the block to drop off the support cable and slide down the hoisting cable. Certain ones of the sheaves of the block are laterally offset to impart a drag upon the block and slow its descent.

Description

llnited States Patent [191 Bagby 1 SELF-RELEASING AND SELF-LOWERING BLOCK [76] Inventor: Percy R. Bagby, 27844 Conestoga Dr., Rolling Hills, Calif. 90274 22 Filed: Aug. 24, 1972 [21] App]. No.: 283,394

[52] U.S. Cl 254/190, 254/192, 254/196, 254/197, 24/132, 294/83 [51] Int. Cl B66d 1/28, B66d 5/32 [58] Field of Search 254/190 R, 192, 193, 197, 194, 254/195, 196; 294/83 R; 24/132 R 3/1959 Livingston 254/197X 1 Jan. 22, 1974 610,172 9/1898 Dotson 254/193 Primary Examiner-Richard E. Aegerter Assistant Examiner-Jeffrey V. Nase [57] ABSTRACT A self-releasing, self-lowering block adapted to rest upon a horizontal support cable. A vertically extending hoisting cable extends about the support cable, through sheaves in the block, and is retained within pivoted sections of the block. A release element attached to the hoisting cable can be 'raised to effect release of the pivoted sections so that they may move apart and allow the block to drop off the support cable and slide down the hoisting cable. Certain ones of the sheaves of the block are laterally offset to impart a drag upon the block andslow its descent.

6 Claims, 9 Drawing Figures PAIENTED JAN 2 2 I974 SHEEY 1 BF 2 FIGW5 SELF-RELEASING AND SELF-'LOWERING BLOCK BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates to a self-releasing, selflowering block, and more particularly to such a block which is releasable by means of a release element attachable to a cable trained through the block.

2. Description of the Prior Art I There are many situations in which it is necessary to support men and material for work upon cable mounted equipment or the like located at relatively great heights and in relatively inaccessible positions. One method utilizes a block which is attached to the cable which mounts the equipment. A hoisting cable trained through the block is then used to raise an equipment cab or the like carrying the men and their working materials. Once the work is completed the equipment cab is easily lowered to-the ground, but detachment of the block from the support cable is difficult. Preferably the block should be remotely actuable to drop off the support cable, and its rate of descent should be at a controlled rate to avoid injuring personnel and damaging the block. Various devices have been advanced in the prior art to accomplish these goals, but none have been entirely satisfactory.

SUMMARY According to the present invention, a block is provided which comprises a pair of hinged sections of generally U-shape adapted to rest upon a support cable. The block sections include a plurality of sheaves about which a hoisting cable can be trained. The hinged block sections are held together in closed position by a releas able arm underlying the support cable. However, upon attachment of a release element to the hoisting cable, and hoisting of the release element into engagement with the release arm the block sections are allowed to be pivoted apart by the continued pulling of the hoisting cable. The outwardly pivoted block sections are thus pulled over and slide off the support cable.

Certain ones of the sheaves on the block sections are laterally offset in the release position of the block to form a loop in the hoisting cable, and thereby impose a drag to slow the descent of the block to the ground. Once the block has reached the ground, the hoisting cable need only be opened to form a free end which" can be pulled over the support cable. 1

Other objects and features of the invention will become apparent from consideration of the following description taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a block according to the present invention;

FIG. 2 is a longitudinal cross-sectional view of the block of FIG. 1, the release arm being shown in its latched position;

FIG. 3 is a view similar to FIG. 2, but illustrating the release arm being moved toward its release position;

FIG. 4 is an enlarged view taken along the line 4-4 of FIG. 3;

FIG. 5 is an enlarged view taken along the line 5-5 of FIG. 1;

FIG. 6 is an elevational view of the block of FIG. I, with the release am being located in the position illustrated in FIG. 3;

FIG. 7 is a view similar to FIG. 6, but illustrating the release arm in its fully released position, with the block sections pivoted farther apart;

FIG. 8 is a view similar to FIG. '7, but illustrating the block sections pivoted almost completely apart, and further illustrating the support cable just prior to disengagement of the block therefrom; and

FIG. 9 is a view similar to FIG. 8, but illustrating the block released from the support cable and descending toward the ground at a slowed rate.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is illustrated a self-releasing, self-lowering block 10 according to the present invention and comprising, generally, a main block section 12 of inverted U-shape having a longer leg on one side, and a secondary block section 14 constituting a downward continuation of the opposite short side of the main block section 12. The section 12 includes a pair of spaced apart pivot brackets 16 which support a pintle 18, whereby the

sections

12 and 14 are pivotable relative to one another from the closed position illustrated in FIG. 2 to the open position illustrated in FIG. 9.

The block 10in the particular application described herein is adapted for disposition upon a horizontally oriented support-cable 20, the cable 20 extending through the U-shaped support passage or central opening defined by the

block sections

12 and 14 in their closed position.

The block 10 is utilized to raise and lower men and equipment from the ground to the elevated position of the support cable 20 for working upon cable mounted fittings or equipment such as insulators, where the cable 20 constitutes part of alarge antenna for example.

A cab (not shown) carrying the men and equipment is attached to a hoisting cable 22 which is disposed through the block 10. As will be seen, the hoisting cable 22 also forms a partof the mechanism for effecting the spreading apart movement of the

block sections

12 and 14 toward their release position.

The main block section 12 is formed by a pair of

side plates

24 and 26 secured-together and maintained in spaced apart relation by a plurality of nut and bolt assemblies 28 located adjacent the upper outer margins of the

plates

24 and 26. The

plates

24 and 26 each include an integral, axially outwardly extending flange 30. In addition, an arcuate reinforcing member 32 of inverted U-shape is welded to the undersides of the flanges 30, extending axially of the block 10 parallel to the axis of the support cable 20'. A U-shape member 34 made of rubber is adhered to the adjacent surfaces of the member 32 and flange 30,the resilient wearing surface of the member 34 beingadapted to engage the support cable 20 without damage to the cable.

As best viewed in FIG. 2, the right leg of the U-shape member. 34 is longer and slotted at 38 to receive a release arm 48, as will be seen. The slot 38 is in communication with the open area between the spaced

side plates

24 and 26 of the main block section 12.

A pair of

side plates

40 and 42 are pivotally mounted to the pintle 18 and appear to be downward extensions of the left sides of the

plates

24 and 26. However, the place where the

plates

40 and 42 abut against the

plates

24 and 26 constitutes the hinge joint of the block in its closed position.

The pivot brackets 16 supporting the pintle 18 are welded to the main

block side plates

24 and 26, as best illustrated in FIG. 1.

The

side plates

40 and 42 include flanges 44 located opposite the slotted leg 36, and one of these flanges 44 is provided with a slot 46, as best seen in FIG. 2, to enable the release arm 48 to extend therethrough.

' the release arm 48 is located below the support cable 20, and extends across the central opening defined between the

block sections

12 and 14 in their closed position, as best seen in FIG. 2. The arm 48 is pivotedly supported at one extremity by a pivot pin 50 which is carried by the secondary

block side plates

40 and 42. The opposite, free extremity of the release arm 48 is biased downwardly by a torsion spring 52 disposed upon the pivot pin 50. One extremity of the spring 52 is engaged upon the upper margin of the arm 48, and the other extremity is engaged upon an abutment or pin 54 carried by the secondary block section 14. The free extremity of the release arm 48 is downwardly offset to form a latch portion 56 which is disposed through a slot or locking detent 58 in the side plate flange 30, and also extends into the space between the

side plates

24 and 26.

In operation, the release arm 48 is pivotable upon the pin 50, and normally has the latch portion 56 thereof in engagement with the lower margin of the locking detent 58. This prevents the

block sections

12 and 14 from pivoting outwardly about the axis of the pintle 18.

A vertically extending release pin 60 located in the space between the

plates

24 and 26 is carried for vertical slidable movement by a pair of vertically spaced trunnions 62 which are attached to the adjacent surface of the flange 30. The upper end of the pin 60 is provided with a flattened end or head adapted to engage the lower end of the latch portion 56 to raise it when the opposite or lower end of the pin 60 is engaged by a release element 64, as will be described subsequently.

The hoisting cable 22 is trained upwardly between the main

block side plates

24 and 26, between a pair of confronting pulleys or sheaves 66, then around three sheaves 68 at the top of the block 10, and then downwardly between the

plates

40 and 42 and between a pair of confronting sheaves 70. All of the

sheaves

66, 68, and 70 rotate about axes generally parallel to the axes of support cable and pintle l8, and support and guide the cable 20 through the block 10.

In a typical operation in which, for example, the support cable 20 is a large antenna, and work has to be done on insulators (not shown) carried by the antenna, the block 10 is first mounted at one end of the cable. The block is then moved down the cable to the proper location with the hoisting cable 22 in position. Next, the cable 22 is used to hoist the men and equipment to the work site.

Once the work is completed, the hoisting cable 22 .is operated to lower the men and equipment to the ground. The release element 64 is then attached to the cable 22. It constitutes an enlargement or obstruction for actuating the release pin 60 and can be formed by any suitable means. As best seen in FIG, 5, the element 64 of the present embodiment comprises a pair of

semicylindrical portions

72 and 74 having integral sleeve half-sections 76 and 78 which together define a central, vertically oriented passage 80 to receive the cable 22. A pair of nut and bolt assemblies 82 are provided to securely clamp the half-sections 76 and 78 onto the hoisting cable 22, as will be apparent.

After the release element 64 is attached to the cable 22, the cable 22 is used to hoist the release element 64 until it abuts against the headed lower end of the release end 60 and moves it upwardly, as seen in FIG. 3. Continued pulling upon the cable 22 causes the release element 64 to upwardly move the pin 60, which in turn moves the latch portion 56 into alignment with the locking 58. In addition, the continued pulling tends to push up the main block section 12 about the pintle 18. This causes the locking detent 58 to move outwardly of the latch portion 56, enabling the bias of the spring 52 to urge the release arm 48 to its-most downward position, as seen in FIG. 7. FIG. 7 also illustrates the continued upward and outward pivoting of the main block section 12 in response to continued downward pulling upon the opposite run of the hoisting cable 22.

FIG. 8 shows the pivoted position of the main block section 12 just prior to the time that the orientation of the block sections relative to the cable 20 allows the block 10 to-fall off the cable 20. Once the block 10 has dropped off the cable 20, as seen in FIG. 9, the only constraint preventing the block 10 from plummeting to the ground is the drag imposed on the cable 22 by the engagement thereof by the

sheaves

66, 68 and 70. Certain ones of these sheaves are laterally offset relative to the others, as seen in FIG. 9, so that a bight or loop is formed in the cable 22 sufficient to develop a drag that slows the otherwise rapid descent of the block 10 to the ground.

To complete the operation, the hoisting cable loop is opened-at some point to provide a free end which can be pulled over and free of the support cable 20.

From the foregoing it is seen that the block 10 is selfreleasing, by operation of the release element 64 upon the release pin 60, and self-lowering, by reason of the frictional drag imparted by the presence and location of the

sheaves

66, 68 and 70.

Various modifications and changes may be made with regard to the foregoing detailed description without departing from the spirit of the invention. It will be apparent that recitation of the support cable 20 is merely exemplary, and that the block 10 is adapted for similar operation with respect to any element disposed through the block opening. In addition, the term cable" as used herein is intended to comprehend analagons lines, such as ropes, chains and the like.

I claim:

1. A self-releasing, self-lowering block for mounting upon a cable disposed over a support member, said block comprising:

first and second block 'sections defining a downwardly opening support passage, said first block section being disposed upon one vertical run of a cable, said second blockvsection being mounted to said first block section for upward pivotal movement from a closed position in which said support passage opens downwardly and an open position in which said support passage opens upwardly whereby, upon location of a cable means in said support passage, said block sections are supported by such cable means in said closed position, and whereby said block sections drop off said cable means in said open position, said block sections including sheaves adjacent said support passage for training a cable up one side of said support passage, over said support passage, and down the other side of said support passage, certain of said sheaves on said first block section being laterally offset in said open position relative to certain of said sheaves on said second block section whereby a cable trained through said sheaves does not lie in a straight line in said open position; and

release means including an arm disposed across said support passage in said closed position, said arm being selectively operable for' movement away from said support passage.

2. A self-releasing, self-lowering block according to claim 1 wherein said sheaves include a pair of oppositely disposed sheaves in the lower extremity of said second block section whereby forcible engagement of said second block section by an obstruction on a'cable trained through said oppositely disposed sheaves tends to pivot said second block section toward said open po sition. v

3. A self-releasing, self-lowering block according to claim 1 wherein said release arm is pivotally mounted to one of said block sections and projects at its free extremity into locking engagement with the other of said block sections, said release means including a release pin normally out of engagement with said release arm, but movable into engagement with said release arm upon engagement of said release pin by an release element on a cable trained through'said sheaves whereby said release arm is pivoted out of said locking engagement.

4. A self-releasing, self-lowering block according to claim 1 wherein said release means includes bias means engaged upon said release arm and tending to pivot said release arm out of said locking engagement.

5. In combination with a hoisting cable disposed up and over a generally horizontally oriented cable means,

a self-releasing, self-lowering block comprising:

first and second block sections assembled to define an inverted U-shape structure having a downwardly opening support passage through which said cable means extends to support said block sections, said first block section being disposed upon one vertical run of said cable, said second block section being mounted to said first block section for upward pivotal movement from a closed position in which said support passage opens downwardly and an open position in which said support passage opens upwardly whereby said block sections are enabled to drop off said cable means, one of said block sections including a locking detent, said block sections including sheaves adjacent said support passage for training a hoisting cable up one side of said support passage, over said support passage, and down the other side of said support passage, certain of said sheaves on said first block section being laterally offset in said open position relative to certain of said sheaves on said second block section whereby the hoisting cable does not lie in a straight line in said open position; and

a release arm pivotally carried by one of said block sections and normally'projecting across said sup; port passage in said closed position and in engaged relation with said detent; and

a release pin carried by one of said block sections and actuable by an release element on said cable to pivot said release pin out of said engaged relation with said detent whereby said second block section is freely pivotable toward said open position.

6. A self-releasing, self-lowering block according to claim 5 and including bias means engaged upon said release arm and tending to move said release arm away from said support passage when said release arm is out of said engaged relation-with said detent.

Claims

1. A self-releasing, self-lowering block for mounting upon a cable disposed over a support member, said block comprising: first and second block sections defining a downwardly opening support passage, said first block section being disposed upon one vertical run of a cable, said second block section being mounted to said first block section for upward pivotal movement from a closed position in which said support passage opens downwardly and an open position in which said support passage opens upwardly whereby, upon location of a cable means in said support passage, said block sections are supported by such cable means in said closed position, and whereby said block sections drop off said cable means in said open position, said block sections including sheaves adjacent said support passage for training a cable up one side of said support passage, over said support passage, and down the other side of said support passage, certain of said sheaves on said first block section being laterally offset in said open position relative to certain of said sheaves on said second block section whereby a cable trained through said sheaves does not lie in a straight line in said open position; and release means including an arm disposed across said support passage in said closed position, said arm being selectively operable for movement away from said support passage.

2. A self-releasing, self-lowering block according to claim 1 wherein said sheaves include a pair of oppositely disposed sheaves in the lower extremity of said second block section whereby forcible engagement of said second block section by an obstruction on a cable trained through said oppositely disposed sheaves tends to pivot said second block section toward said open position.

3. A self-releasing, self-lowering block according to claim 1 wherein said release arm is pivotally mounted to one of said block sections and projects at its free extremity into locking engagement with the other of said block sections, said release means including a release pin normally out of engagement with said release arm, but movable into engagement with said release arm upon engagement of said release pin by an release element on a cable trained through said sheaves whereby said release arm is pivoted out of said locking engagement.

5. In combination with a hoisting cable disposed up and over a generally horizontally oriented cable means, a self-releasing, self-lowering block comprising: first and second block sections assembled to define an inverted U-shape structure having a downwardly opening support passage through which said cable means extends to support said block sections, said first block section being disposed upon one vertical run of said cable, said second block section being mounted to said first block section for upward pivotal movement from a closed position in which said support passage opens downwardly and an open position in which said support passage opens upwardly whereby said block sections are enabled to drop off said cable means, one of said block sections including a locking detent, said block sections including sheaves adjacent said support passage for training a hoisting cable up one side of said support passage, over said support passage, and down the other side of said support passage, certain of said sheaves on said first block section being laterally offset in said open position relative to certain of said sheaves on said second block section whereby the hoisting cable does not lie in a straight line in said open position; and a release arm pivotally carried by one of said block sections and normally projecting across said support passage in said closed position and in engaged relation with said detent; and a release pin carried by one of said block sections and actuable by an release element on said cable to pivot said release pin out of said engaged relation with said detent whereby said second block section is freely pivotable toward said open position.

6. A self-releasing, self-lowering block according to claim 5 and including bias means engaged upon said release arm and tending to move said release arm away from said support passage when said release arm is out of said engaged relation with said detent.