US3262520A

US3262520A - Trackless hoist with safety stop

Info

Publication number: US3262520A
Application number: US397344A
Authority: US
Inventors: Frederick H Bond; Laurence C Pilvelis
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-09-17
Filing date: 1964-09-17
Publication date: 1966-07-26
Anticipated expiration: 1983-07-26

Description

July 26, 1966 Filed Sept. 17, 1964 F. H. BOND ETAL TRACKLESS HOIST WITH SAFETY STOP 3 Sheets-Sheet 1 M A 7702/1/15 V5 y 1966 F. H. BOND ETAL TRACKLESS HOIST WITH SAFETY STOP 3 Sheets-Sheet 2 Filed Sept. 17, 1964 y 26, 1966 F. H. BOND ETAL 3,262,520

TRACKLESS HOIS'l WITH SAFETY STOP Filed Sept 17, 1964 3 Sheets-Sheet 5 INVENTORS. 7 6 Ream/0K 17.5mm

L a HEE/VGE 6. PM VEL /s BY 3,262,520 Patented July 26, 1966 3,262,520 TRACKLESS HOIST WITH SAFETY STOP Frederick H. Bond, Brockton, and Laurence C. Pilvelis, Methuen, Mass., assignors to the United States of America as represented by the Secretary of the Navy Filed Sept. 17, 1964, Ser. No. 397,344

12 Claims. .(Cl. 187-88) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the pay-v ment of any royalties thereon or therefor.

This invention relates to trackless hoists for load carriers by which a' load may be raised or lowered as desired. Various safety devices have been provided for hoists using tracks or guides for the load carrier, to arrest descent of the carrier and load if there is, for any reason, a failure in the raising and lowering apparatus, but heretofore no simple and satisfactory safety device has been avaliable for trackless hoists. In loading and unloading ships, for example, trackless hoists are in common use, yet protectionagainst undesired descent of the carrier and its load, if any, is urgent.

An object of this invention is to provide a trackless hoist for a load carrier, which will automatically become effective to stop descent of the carrier if the hoist cable for the carrier becomes slack, for any reason, and is unable to support the carrier and any load on it,'which does not greatly add to the cost of the hoist or require radical changes in its design or mode of operation, which requires no special attention to make it effective, which adds a safety construction to trackless hoists which is relatively simple, practical, dependable and inexpensive.

Other objects and advantages will appear from the following description of an example of the invention, and the novel features will be particularly pointed out in connection with the appended claims.

In the accompanying drawings:

FIG. 1 is a side elevation of the essentials of a trackless hoist embdoying a safety construction in accordance with this invention;

FIG. 2 is a perspective of many of the parts of the safety addition with the parts in their inactive positions;

FIG. 3 is a similar view, but with the same parts in the positions occupied and effective to prevent descent of the carrier when the hoist cable is unable to hold the carrier;

FIG. 4 is a perspective of the wedge or wedge member used as a safety part;

FIG. 5 is another perspective of the same part to show another face thereof;

FIG. 6 is a perspective of one part of the guide;

FIG. 7 is a perspective of another part of the guide; and

FIG. 8 is a sectional elevation taken approximately along the line 8-8 of FIG. 1, and illustrating details by which the lower end of the arresting cable is secured to the tensioning device.

In the illustrated embodiment of the invention, and referring particularly to FIG. 1, a load carrier 10 is formed of a metal frame with means, not shown, for carrying a load that is to be raised or lowered. This frame on its upper part carries a pulley or sheave, not shown, that is rotatably mounted in a housing 11 that opens upwardly. A flexible hoist cable in the nature of an articulated chain 12 passes downwardly into the housing 11, around beneath the pulley in that housing, and then rises in a direction generally parallel to the downwardly extending chain stretch. A hoist 13 is suspended from a support 14, and one stretch of the chain 12 is anchored to the housing of the hoist, and the other stretch of the chain extends into the housing of the hoist and there is connected to a power operated drum by which the chain may be paid out or wound up to lower or raise the load carrier 10. This is all old and hence is not described in greater detail. If the chain should fail to hold the carrier, the carrier could fall, and since there is no track which could be used as part of a safety device, some safety provision is important.

The safety provision in accordance with this invention, employs a flexible cable 15 that may be a wire rope, which is secured at one end to the support 14 and depends there-from alongside of, but spaced somewhat from the chain 10. The load carrier 10 is provided on its upper part with a guide 16 downwardly through which the cable 15 passes. The lower end of cable 15 is secured to the inside face of an end flange 17 of a spool-shaped drum 18 by the U-bolt 19 as shown in provided within it of a spring motor, not shown, which urges the drum to rotate continuously in a direction to wind the cable 15 thereon, and hence as the load carrier 10 is raised and lowered by the chain 12, the drum 18 will wind up or pay out the cable 15 and keep it reasonable taut at all times.

The guide 16 (see FIGS. 2 to 7) includes a somewhat U-shaped back block 20 (FIG. 6) which is secured to the load carrier frame by machine screws 21 that pass upwardly through a part of the carrier 10 and are threaded into the bottom of the block 20 (FIG. 2). The opposite side faces of the block 20 have channels 22 that extend vertically from end to end and a 'U-shaped cover plate 23 has ribs 24 on the inside faces of the arms of that plate near the open face between the arms. The cover plate slides downwardly over the open front of the block 20, with ribs 24 sliding in the channels 22. When the cover plate is so attached to the block 20, a plurality of machine screws 25 pass through the cover plate and are threaded into the block 20 to prevent endwise sliding of the cover plate 23 on the block 20.

Vertically slidable within the guide between the cover plate 23 and the block 20 is a wedge member or wedge 26, shown in two different perspectives in FIGS. 4 and 5. approximately half cylinder channel for the full length of the wedge, and the wall of this channel has spiral groove indentation sections 28 corresponding to the spiral ribs in the surface of the stranded wire rope used as the cable 15. The inside rear face of the block 20 has a groove or channel 29 running vertically from end to end of the block in alignment with the channel 27 in the wedge 26. The

channels

27 and 29 together are somewhat complementary and of a size to fit and grip the cable 15 where the wedge is moved upwardly in the guide. Since the wedge, except for the channel 27, is tapered vertically, with its thicker end lowermost, when ever the ridge is in a lower position, such as shown in FIGS. 1 and 2, the channel 27 is away from the cable 15 so that the cable may pass freely through the guide, but whenever the wedge is moved upwardly into a position shown in FIG. 3, it is also shifted toward the block 20, and its channel 27 contacts cable 15 and presses it against the rear channel 29, to grip the cable 15 firmly and prevent its movement through the guide. This will anchor the load carrier firmly to the cable and prevent descent of the carrier independently of the hoist.

To enable movement of the wedge 26 vertically in the guide, the cover plate 23 is provided with a notch 30 in its lower edge leading to the wedge. A bell crank lever 31 is pivoted at 32 to the face of the cover plate 23, and one arm of this bell crank has a pin 33 that extends through the notch 30 and into and slides in a horizontally elongated recess or cavity 34 in the wedge 26. As the bell crank lever 31 r 26 vertically in the guide 16. The bell crank lever 31 FIG. 8. The drum 18 is in its face towards the block 20, extending vertically rocks on its pivot it will shift the wedge is operated by mechanism that is controlled by the tautness of the hoist cable 12.

A pair of arms and 36 are pivoted together intermediate of their ends, by pivot 37, and extend generally vertically with their upper end between the descending and rising stretches of the chain cable 12, as shown in 1 FIGS. 1 and 2. The lower end of the arm 36 is pivoted by pin 38 to a boss 39 on the upper face of the load carrier 10, and the lower end of the other arm 35 has a terminal 40 forwardly extending to a position a little in front of the plane of the exposed face of the cover plate 23. The face end of this terminal 40 is connected by a link 41 to the other arm of the bell crank lever 31. This link is adjustable in length and is formed of end to end sections that are coupled by two universal joints 42. The connection of link 41 to the bell crank lever is by a pivot pin 43.

A helical compression spring 44 is disposed between V the lower pair of

arms

35 and 36 and urge the lower ends of these arms apart. These arms may have cups 45 facing one another in which the ends of the spring 44 are received and confined against displacement. The upper ends of the

arms

35 and 36 are pivoted by pivot pins 46 to

individual shoes

47 and 48 that are disposed between and bear against the inner faces of the rising and descending stretches of the hoist cable 12. The spring 44 in urging about the lower ends of the

arms

35 and 36 will also urge apart the upper ends of the same arms and hence urge apart the

shoes

47 and 48, but engagement of the shoes with the stretches of the chain or cable 12 prevents this separation of the shoes. When the

arms

35 and 36 are so held against separation by chain 12, the link 41 holds the bell crank lever 31 and wedge 26 in the inactive positions shown in FIG. 2 where the wedge does not grip the cable 15. A leaf spring 49 (FIGS. 2 and 3) is flexed and secured, under flexed condition, at its ends to the

shoes

47 and 48 and also urges these shoes apart as shown in FIG. 3.

Under normal conditions the chain 12 is under tension as the load carrier 10 is raised and lowered by operation of the hoist device 13, and as the carrier moves up and down in the guide the wedge 26 is in its lowermost position and does not grip the arresting cable or wire rope 15. The tensioning device, of which the drum 18 and its spring (not shown) are a part, will normally take up slack in the arresting cable 15 as the carrier moves up and down and keep the cable 15 taut. The

shoes

47 and 48 are pressed by

springs

44 and 49 against the descending and rising stretches of the cable 12'and this causes the wedge 26 to be held normally in its lower position out of gripping engagement with cable 15. Should the hoist cable or chain 12 break or become slack for any reason, the

springs

44 and 49 will be free to press the

shoes

47 and 48 apart, as shown in FIG. 3 and this will cause arm 35 to rock, and operate link 41 to rock the bell crank lever 31 and elevate the wedge 26 into gripping contact with the arresting cable 15. This will anchor the carrier 10 to the cable 15 and prevent descent of the carrier, thus acting as a safety device that automatically becomes effective to prevent descent of the load carrier if the hoist cable fails, for any reason, to support the carrier. Thus by this relatively simple addition to a typical trackless hoist, a very valuable safety feature is added.

The hoist cable 12 may be a flexible wire rope or metal chain, and the term cable is intended to include both. The arresting cable 15 may be a stranded flexible wire rope or any other cable or rope.

It will be understood that various changes in the details, materials and arrangements of parts, which have been herein described and illustrated in order to explain the nature of the invention, maybe made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims.

We claim: I

1. A safety device for a trackless hoist of the type in which a load carrier is suspended and selectively raised and lowered by a flexible cable hoist in which the cable depends from a support, passes around a pulley on said carrier, returns back toward said support, and is connected to a hoist by which it is selectively paid out and retracted to lower and raise said carrier, which comprises the combination therewith of:

(a) a flexible, rope-like arresting cable secured to and depending from said support and guided through a part of said carrier,

(b) tensioning means mounted on said carrier and to which arresting cable is connected after passing said guide part of said carrier, for keeping said arresting cable taut as said carrier is raised and lowered, and

(0) means on said carrier and having a controlling part disposed between the depending and rising stretches of said hoist cable normally held in inactive condition by the tautness of said cable stretches, but operable for automatically gripping said arresting cable and preventing descent of said carier whenever either stretch of said hoist cable becomes slack and releases said controlling part.

2. The device according to claim 1, wherein said guide part of said carrier has a Wedge member which is movable into and out of gripping engagement with said arresting cable by said controlling part, and said last mentioned means has means operable upon release of said controlling part for forcing said wedge member into gripping engagement with said arresting cable and preventing descent of said carrier.

3. A safety device for application to a trackless hoist of the type in which a load carrier is selectively raised and lowered by :a flexible hoist cable that has one stretch which descends from a support a portion which passes around a pulley on said carrier and another stretch that rises approximately parallel to said one stretch, and by which the carrier may normally be raised and lowered, which comprises:

(a) a flexible, rope-like arresting cable for attachment to said support to depend adjacent to said hoist cable,

(b) a guide for mounting on said carrier and through which said arresting cable passes,

(c) tensioning means for mounting on said carrier below said guide and to which the lower end of said arresting cable is connected after it passes through said guide and automatically operable to take up slack in said arresting cable as the carrier is raised and lowered;

(d) said guide having a wedge member movable therein into and out of wedging engagement with said arresting cable,

(e) means mountable on said carrier, having a controlling part disposed between said hoist cable stretches, and normally held inactive by the tautness of said cable stretches, and also having mechanism connecting said part and said wedge member and operable when said part is released by slackness in either stretch of said hoist cable for forcing said wedge member into gripping engagement with said arresting cable and taking "over support of said carrier from said arresting cable.

4. A trackless hoist for a load carrier which comprises:

(a) said carrier (b) a support, I

(c) a flexible hoist cable with one stretch depending from said support, a portion passing around said pulley, and another stretch rising toward said support along side of said depending stretch,

(d) a hoist caried by said support, connected to said rising stretch and operable selectively to pay out and retract said one stretch of said cable to raise and lower said carrier,

having a pulley,

(e) a flexible arresting cable connected to and depend ing from said support,

(f) said carrier having a guide through which said arresting cable passes and a tensioning device below said guide forkeeping the arresting cable taut as the carrier is raised and lowered, and said guide having therein a wedge member operable therein into anld1 out of wedging engagement with said arresting ca e,

(g) means having a follower yieldingly urged against one of said stretchesof the hoist cable, and a connection from the follower to said wedge member, for normally holding said wedge member out of wedging engagement with said arresting cable in said guide when said hoist cable is taut and for operating said wedge member under said yielding urge into wedging engagement with said arresting cable when said one of said stretches becomes slack and allows movement of said follower further toward that slack stretch.

5. A trackless hoist for a load carrier, which comprises (a) said carrier having a pulley,

(b) a support,

(c) a flexible hoist cable depending from said support passing around said pulley, rising from said pulley and connected to a hoist that winds and unwinds it to raise and lower said carrier,

(d) :a flexible arresting cable connected to and depending from said support,

(e) a tensioning device on said carrier connected to the lower end of said cable and operable to keep said arresting cable taut as said carrier is raised and lowered by said hoist cable,

(f) a guide caried by said carrier and through which said arresting cable passes downwardly before it reaches said tensioning device and having therein a wedge member movable in the length wise direction of the arresting cable into and out of gripping engagement with the arresting cable,

(g) means disposed between the descending and rising stretches of said hoist cable and yieldingly urged under pressure with contact, with both of said stretches,

(h) a connection from said means to said wedge memher for normally holding said wedge member out of gripping engagement with said arresting cable, but operable by movement of said means, when slack in one of said stretches of hoist cable enables movement of said means, to move said wedge member into gripping contact with the arresting cable and prevent descent of said carrier.

v 6. The hoist according to claim 5, wherein:

(a) said means includes a pair of arms pivoted together intermediate of their ends, extending generally parallel to said stretches of said hoist cable and at one end of the pair having shoes disposed between said stretches and bearing against those stretches, the other end of one of said arms being pivoted to said carrier, and the other end of the other of said arms having a mechanical connection to said wedge member for operating it into gripping relation with said arresting cable when slack in one of said stretches of hoist cable enables separation of said shoes, and p (b) means acting between said pair of. arms for yieldingly urging said arms to rotate on their pivoted connection to one another and to said carrier, when the slack in one of said hoist cable stretches permits it, in a direction to move said wedge member into gripping engagement with said arresting cable.

7. The hoist according to claim 6, wherein:

(a) said mechanical connection includes a lever pivoted to the carrier and at one part having a pin and slot connection to said wedge member, and

(b) a link connecting another part of said lever to said other end of said other of said arms.

8. A trackless hoist for a load carrier which comprises:

(a) said carrier,

(b) a support,

(0) a hoist cable depending from said support and connected to said carrier and by operation of which said carrier selectively may be raised and lowered,

(d) a flexible arresting cable anchored to and depending from said-support adjacent to said hoist cable,

(e) a tensioning device on said carrier to which the lower end of said arresting cable is secured and by which the arresting cable is kept taut as said carrier is raised and lowered by said hoist cable,

(f) a guide carried by said carrier and through which said anchoring cable passes to said tensioning device, said guide having a safety member operable into and out of gripping engagement with said arresting cable,

(g) means including an element pressed against said hoist cable and connected to said safety member for operating the latter into gripping contact with said arresting cable to prevent descent of said carrier when slackness in said hoist cable permits movement of said element further in its direction toward said hoist cable, and

(h) means yieldingly urging said element continuously in a direction toward said hoist cable and into pressing engagement against that hoist cable, for moving said safety member into gripping engagement with said arresting cable when said hoist cable becomes slack and unable to support said carrier.

9. The hoist according to claim 8 wherein:

(a) said hoist cable has descending and rising stretches arrayed side by side,

(b) said first mentioned means employs a pair of arms pivoted together intermediate of their ends and extending in a direction along a stretch of said hoist cable,

(c) the corresponding ends of said arms at one end of the pair having shoes disposed between said descending and rising stretches and bearing against such stretches, the other end of one of said arms being pivoted to said carrier,

((1) a mechanical connection from the other end of said other of said arms, to said safety member for operating said safety member into gripping engagement with said arresting cable when slack in one of said hoist cable stretches permits relative separation of said shoes, and

(e) means acting between said arms for urging them yieldingly in directions to press said shoes against said hoist cable stretches and operate said safety member when said shoes separate due to slack in one of said hoist cable stretches.

10. The hoist according to claim 9, wherein:

(a) said mechanic-a1 connection is link pivoted to said other of said arms and to said safety member.

11. The hoist according to claim 8, whereinf (a) said tensioning device is a drum to which an end of the arresting cable is anchored and spring operated in a rotary direction to wind the arresting cable thereon when the carrier is rising and to unwind it when the carrier is descending.

12. The hoist according to claim 8, wherein (a) said safety member is a wedge slidable in the guide in a direction upwardly along the arresting cable and progressively into gripping engagement with the said arresting cable, and Y (b) said first mentioned means, when activated by slack in a hoist cable stretch, moving said wedge in said upward direction to grip the arresting cable and prevent descent of the carrier.

(References on following page) 8 References Cited by the Examiner 2,348,090 5/ 1944 Otto 20061.18 2,419,518 4/1947 Eichinger 20061.18 UNITED STATES PATENTS 2,550,839 5/1951 Martin 18788 820,637 5/1906 Gable et a1. 187-88 187 88 EVON C. BLUNK, Primary Examiner.

1,163,237 12/1915 Iron 1,177,170 3/1916 Butts 187-88 ANDRES H. NIELSEN, Examiner.

Claims

1. A SAFETY DEVICE FOR A TRACKLESS HOIST OF THE TYPE IN WHICH A LOAD CARRIER IS SUSPENDED AND SELECTIVELY RAISED AND LOWERED BY A FLEXIBLE CABLE HOIST IN WHICH THE CABLE DEPENDS FROM A SUPPORT, PASSES AROUND A PULLEY ON SAID CARRIER, RETURNS BACK TOWARD SAID SUPPORT, AND IS CONNECTED TO A HOIST BY WHICH IT IS SELECTIVELY PAID OUT AND RETRACTED TO LOWER AND RAISE SAID CARRIER, WHICH COMPRISES THE COMBINATION THEREWITH OF: (A) A FLEXIBLE, ROPE-LIKE ARRESTING CABLE SECURED TO AND DEPENDENDING FROM SAID SUPPORT AND GUIDED THROUGH A PART OF SAID CARRIER, (B) TENSIONING MEANS MOUNTED ON SAID CARRIER AND TO WHICH ARRESTING CABLE IS CONNECTED AFTER PASSING SAID GUIDE PART OF SAID CARRIER, FOR KEEPING SAID ARRESTING CABLE TAUT AS SAID CARRIER IS RAISED AND LOWERED, AND (C) MEANS ON SAID CARRIER AND HAVING A CONTROLLING PART DISPOSED BETWEEN THE DEPENDING AND RISING STRETCHES OF SAID HOIST CABLE NORMALLY HELD IN INACTIVE CONDITION BY THE TAUTNESS OF SAID CABLE STRETCHES, BUT OPERABLE FOR AUTOMATICALLY GRIPPING SAID ARRESTING CABLE AND PREVENTING DESCENT OF SAID CARRIER WHENEVER EITHER STRETCH OF SAID HOIST CABLE BECOMES SLACK AND RELEASES SAID CONTROLLING PART.