CA2086379A1 - Safety winch - Google Patents
Safety winchInfo
- Publication number
- CA2086379A1 CA2086379A1 CA 2086379 CA2086379A CA2086379A1 CA 2086379 A1 CA2086379 A1 CA 2086379A1 CA 2086379 CA2086379 CA 2086379 CA 2086379 A CA2086379 A CA 2086379A CA 2086379 A1 CA2086379 A1 CA 2086379A1
- Authority
- CA
- Canada
- Prior art keywords
- axle
- drive
- rotation
- ratchet wheel
- main axle
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66D—CAPSTANS; WINCHES; TACKLES, e.g. PULLEY BLOCKS; HOISTS
- B66D1/00—Rope, cable, or chain winding mechanisms; Capstans
- B66D1/02—Driving gear
- B66D1/04—Driving gear manually operated
- B66D1/06—Safety cranks for preventing unwanted crank rotation and subsequent lowering of the loads
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66D—CAPSTANS; WINCHES; TACKLES, e.g. PULLEY BLOCKS; HOISTS
- B66D5/00—Braking or detent devices characterised by application to lifting or hoisting gear, e.g. for controlling the lowering of loads
- B66D5/32—Detent devices
- B66D5/34—Detent devices having latches
Abstract
SAFETY WINCH
ABSTRACT OF THE DISCLOSURE
A winch, for example, for winding in and paying out a cable attached to a person in a hazardous situation, for example underground, comprises a pair of axles mounted on a frame, one of the axles carrying the cable drum for rotation therewith. Two safety brakes are provided, one on each axle, and each including a cam actuated clutch so that rotation of the drum in the pay-out direction is only allowed when the axles are driven in the pay-out direction.
A handle for driving the axles includes two hand grasp portions for different mechanical advantage. The handle can be located at two different positions on a drive sprocket on one of the axles or on a second drive sprocket freely rotatable on the first axle for different drive ratios.
ABSTRACT OF THE DISCLOSURE
A winch, for example, for winding in and paying out a cable attached to a person in a hazardous situation, for example underground, comprises a pair of axles mounted on a frame, one of the axles carrying the cable drum for rotation therewith. Two safety brakes are provided, one on each axle, and each including a cam actuated clutch so that rotation of the drum in the pay-out direction is only allowed when the axles are driven in the pay-out direction.
A handle for driving the axles includes two hand grasp portions for different mechanical advantage. The handle can be located at two different positions on a drive sprocket on one of the axles or on a second drive sprocket freely rotatable on the first axle for different drive ratios.
Description
BACKG~OUND OF THE INVENTION
, This invention relates to a safety winch of a type particularly, but not exclusively designed for paying out and reeling in a cable attached to a person when entering a hazardous zone so the person can be extracted by the winch if necessary.
It is well known that persons entering hazardous situations such as underground pipelines, storage containers and the like can encounter difficulties such as poisonous fumes which can place the person in difficulty or even causing unconsclousness. In such a situation it is necessary for the person to be extracted from the danger wlthout the necesslty of a second person entering the same zone and possibly befalling the same fate.
As safety consciousness has developed, therefore, it has been necessary to attach to persons entering such a zone a cable attached to a harness worn by the person with the cable extendlng to a sultable hoist system whlch allows the cable to be reeled in and the person extracted from the dangerous situatlon. Many winches are available which provlde sufficient power to allow the person to be extracted including llfting the person vertlcally, should thls be neco~sary. Hand wlnches of thls type are available whlch can develop ~ufflclent force from hand operatlon to wlthdraw ~ ~: 2086379 the person. These winches generally include a brake mechanism so that the cable is prevented from being rapidly paid out should the winch be inadvertently released, for example when lifting the person from an underground location. It will of course be appreciated that, should the winch be released or the brake fail, the person can be dropped with the possibility of causing injuries beyond those already sustained.
Conventional winches are therefore unsatisfactory as they do not provide sufficient fail safe operation and euch they do not have the flexibility of drive arrangements to enable the winch to be operated in a manner which avoids lnterferlng with the normal operation of the person while ln the dangerous location but yet provides the ability to extract the person and to generate sufficient power to ensure that the person can be properly lifted.
According ~o the a first aspect of the invention there is provided a safety winch compri~ing a main frame, a cablo, a main axle, a secondary axle, means mounting the main axle and the ~econdary axle on the main frame each for rotatlon about a respoctlve one of two parallel axles, a drum mounted on the main axle for rotation therewlth in a flr~t directlon to cause pay-out of sald cable and ln a ~-cond dlrectlon to cause reel ln of ~ald cable, chaln drl~e m-ano for communlcatlng rotatlon of each of the maln axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the secondary axle, and a safety brake arrangement operable to prevent rotation of the main axle in said first direction, the safety brake arrangement comprising first safety brake means mounted on the main axle and second safety brake means mounted on the secondary axle, each of the first and second safety brake means being arranged to allow rotation of the main axle in said second direction to cause reel in of the cable and being arranged to prevent rotation of the main i~
axle ln said flr~t direction except when the main axle is drlven from sald chain drlve means ln sald flrst dlrectlon.
Accordlng to a second aspect of the lnventlon there 18 provlded a safety wlnch comprlslng a maln frame, a cable, a main axle, a secondary axle, means mounting the main axle ~
and the secondary axle on the main frame each for rotation about a respectlve one of two parallel axes, a drum mounted. . 1 :
on the maln axle for rotatlon therewlth ln a flrst dlrection ~:~
to cause payout of sald cable and ln a second directlon to cause reel ln of sald cable, chain drive means for communlcatlng rotatlon of each of the main axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the socondary axle, and a safety brake arrangement operable to provent rotatlon of the maln axle in oald flrst dlrection, I
said safety brake assembly comprising a ratchet wheel mounted on the main axle for rotation about the axis of the main axle relative to the main axle, a pawl mounted on the frame and cooperating with the ratchet wheel to prevent rotation thereof in said first direction, a drive member receiving drive from said chain drive means and mounted on the main axle for rotation about the axis of the main axle, friction pad means between the drive member and the ratchet wheel and cam means between the main axle and the drive member allowing limited rotational movement between the main axle and the drive member and operable in said second dlrectlon of movement of the drive member to cause the frictlon pad means to form a frictional connection between the drlve member and the ratchet wheel to communicate drive from the drive member to the ratchet wheel and operable in said flrst direction of movement of the drive member to move the frlction pad mean~ axially to separate sald frictional connection to allow rotation of the drive member and the main axle relatlve to the ratchet wheel.
According to the third aspect of the invention, there is provided a safety winch compri~ing a main frame, a cable, a main axle, a secondary axle, mean~ mounting the maln axle and the secondary axle on the maln frame each for rotatlon about a respectlve one of two par~llel axes, a drum mounted on the maln axle for rotatlon therewith ln a first ~` 20~6379 :.
direction to cause payout of said cable and in a second direction to cause reel in of said cable, chain drive means for communicating rotation of each of the main axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the secondary axle, and a safety brake arrangement operable to prevent rotation of the main axle in the said first direction, a first sprocket mounted on the secondary axle at an end thereof opposite to said chain drive means, a drive ~procket mounted on said main frame, a chain communicating drive from the drive ~procket to the first sprocket, each of sald flrst aprocket and said drive sprocket having means thereon for engagement with said handle means for communication of manual drive thereto from said handle means, the drive sprocket and the first sprocket being arranged such that a drive ratio between the drive sprocket and the maln axle i8 different from a drive ratio between the flr~t sprocket and the main axle.
One embodiment of the invention will now be de~cribed in con~unction with the accompanying drawings in which:
D~SCRIP~ION OF TNF DRAWINGS
Flgure 1 i~ a ~chematic plan vlew of a wlnch Accordlng to the pre~ont lnvontlon.
Flgure 2 ls a front elevatlonal vlew of the winch of Figure 1 showing the handle attached to the second operating location.
Figure 3 is a view along the lines 3-3 of Figure 1 showing the construction of the ratchetk and pull arrangement.
DETAILED DESCRIPTION
The winch comprises a main frame generally indicated at 10 including a bace plate 11 and a plurality of upstanding walls. The upstanding walls include a first side wall 12 extending along the full length of one side of the base frame 11. A ~econd side wall 13 lies parallel to the flrst slde wall and extends along the base plate to a posltion approxlmately mldway along the base plate at which lt la connected to a transverse wall 14. A further slde wall portlon 15 extends from the transverse wall parallel to the slde wall 12 but spaced lnwardly from the side wall portlon 13. An end wall 16 pa~rallel to the transverse wall 14 closes the frame.
Acros~ the frame is provided a firsit main axle 17 and a secondary axle 18 which lie parallel, horizontal and parallel to the transver6e wall 14. Each of the axles is ! aupport on bearlngsi 19 mounted in the respective side walls.
The main axle 17 thus is positioned on one cide of the tran~ver~e wall 14 and a ~econdary axle 18 i~ posltioned on th- oth-r sld- of the tran~v-rse wall 14. The maln axle 17 , " ~ ~
~ - 7 -carries a cable drum 20 with end walls 21 defining a cylindricl receptacle for a cable 22 to be wound thereon.
The cable is arranged and attached to the drum 60 that the rotation of the drum in the clockwise direction as 6hown in Figure 2 causes the cable to be wound onto the drum and rotation of the drum in the counter clockwise direction causes the cable to be paid out.
On the left hand end of the axle 17 is mounted a drive sprocket 23 which is connected to the axle so as to communicate drive to the axle and vice versa. On the left hand end of the axle 18 is provided a second sprocket 24 whlch i8 mounted on the axle for rotation therewith. A
chain 25 communicates drive between the sprockets 23 and 24.
At the rlght hand end of the shaft 18 iB provided a first drlve sprocket 26 which again i~ attached to the axle 18 for co-rotation therewith. A second drive sprocket 27 is mounted on the shaft.17 but is carried thereon by bearlngs 28 whlch allow the sprocket to rotate freely relative to the axle 17. A chaln 29 communicates drive between the sprockets 26 and 27.
On the front face of each of the drive sprockets 26 and 27 iB provlded a mountlng bracket 30. The mounting bracket 30 iB arranged to receive a removeable handle 31 B0 thlo can be attached to a selected one of the brackets 30, r-mov-d from that bracket and roplaced on the other of the 208~379 brackets as required. The handle 31 includes an end portion 32 for attachment to the bracket 30 so that the end portion 32 rotates about the axis of the respective axle. The handle thus extends radially outwardly from the axle and provides a first hand grip portion 33 at a first di tance spaced from the axle and a second hand grip portion 34 at a ~econd greater distance from the axle. Thus the operator can grasp the hand grip portion 34 which requires a larger arc of rotation of the hand while driving the handle. This provides greater mechanical advantage and thus 3110ws the operator to apply a greater force. The hand grip portion 33 bolng pooltloned radlally lnwardly requires only a much ~h~llower arc of the movement of the hand with a significantly reduced mechanical advantage for high speed drive of the handle. The bracket 30 lncludes a slot 30A
parallel to the end of the handle for receiving the end therein. The outer face of the slot 30A hao a hole 30B
through whlch a spring mounted pin 30C on the handle can pro~ect to lock the handle end 32 within the slot.
In addltion, the ~prockets 23, 24, 26 and 27 have different numbers of drlve teeth so as to provide a different drive ratio when the handle is applied to the ~procket 26 as opposed to the drive ratio when the the handle io applled tho ~prookot 27. Thus in one example the ~prock-t 27 ha~ 38 teeth and the ~procket 26 ha~ 19 teeth prov~ding a drive ratio of 2 to 1. The sprocket 24 ln thls example has 10 teeth and the sprocket 23 has 40 teeth providing a ratio of 4 to 1. Thus when the handle is applied to the sprocket 26, the drive ratio from the handle to the axle 17 is governed wholly by the sprockets 24 and 23 and thus i6 at a ratio of 4 to 1. When the handle is appliex to the sprocket 27, the ratio of drive from the handle to the axle 17 is 2 to 1 since the ratio is reduced from the sprocket 27 to the sprocket 26 and then increased from the sprocket 24 to the sprocket 23. The mounting of the sprocket 27 on the axle 17 does not provide any drive communication between those elements except through the drlve chaln as descrlbed above, but provide~ a convenient locatlon for mountlng the sprocket 27 in a limlted space since the sprockets 27 and 23 are then aligned allowing the outer housing to be malntained at a minimum.
In order to provide yet further flexibility for the drlve ~y~tem, wlth the handle removed, a chain drive pulley of the type used in overhead doors can be used and mounted on the bracket 30. This provides therefore a chain ~uapended from the chain drlve pulley so the chain can be pulled over the pulley to apply a drlve actlon to the required sprocket through the bracket 30.
In a yet further arrangement, a bevelled gear drive arrangement can be connected to the bracket 30 wlth the bevel gear recelvln0 drlve ~rom a secon~ bevel gear mounted on the end plate 16 and attached to 8 handle. In thl~ way ~ ':
- '- 20~637~
the handle can rotate about an axle at right angles to the axles 17 and 18 ~o that the device can be driven from that position when required.
In order to prevent inadvertent release of the cable when fully wound in or while winding or paying out of the cable, there are provided a first and a second safety brake arrangement 40, 41. The safety brake arrangement 40 is mounted on the axle 17 and cooperates with the frame adjacent the axle 17 o as to halt rotation of the axle in a pay out direction. the 6econd safety brake arrangement 41 act6 a6 a back-up to the first 6afety brake arrangement in . . .
case of a fallure of the fir~t. In operation, as will be apparent from the descrlption hereinafter, the first safety brake arrangement is that which is normally operating while the second 6afety brake arrangement is normally released in the pay-out operation.
The ~afety brake arrangement~ are ~ubatantially identlcal and each comprl6es a ratchet wheel 42 having ratchet teeth 43. The ratchet teeth cooperate with a pawl 44 mounted on a ~haft 45 pivotally attached to the frame ad~acent the ratchet wheel. The pawl 44 i~ shaped to engage lnto the ratchet teeth to prevent rotation of the ratchet wheel 42 in a direction to hold the ratchet wheel again6t rotatlon in the pay-out dlrectlon. Thus a~ vlewed from the ad~acent end o the shaft 18, the ratchet wheel 42 18 prevented from rotatlng ln the counter clockwlse directlon.
20~S379 As viewed from the adjacent end of the axle 17, the ratchet wheel 42 i8 prevented from ro~ating in a cloekwise direction.
The pawl 44 is actuated from the engaged position shown in Figure 3 to a release positioned spaced away from the ratchet teeth 43 by a spring wire 46 which has an end hook portion 47 engaged through a hole in the pawl 44. The spring wire 46 includes a circular hoop portion 48 which is wrapped around a drum 49 attached to and co-rotating with the ratchet wheel 42. Thus it will be appreciated that rotation of the ratchet wheel in the clockwise direetion a shown in Figure 3 eauses the spring hoop 48 to be rotated by the drum 49 in a direetlon to push the pawl away from the ratehet teeth to allow the rotation of the rateh wheel in the elockwise direetion to eontinue without the pawl riding over the ratehet teeth. Rotation of the drum in the eounter eloekwi~e dlreetion causes the hoop 48 to pull the spring in the eounter elockwise direction pulling the pawl into engagement with the ratchet teeth to engage into the ratchet position.
Each of the ratchet wheels is mounted on its respective axle by bearings allowing free rotation between the axle and the ratehet wheel. The ratehet wheel is however engaged wlth the axle through a frletlon pad 50 earrled on the ~aee of the ratehet wheel between the ratehet wheel and a plate 60 fixed on the axle on the inside of the ~ 2086379 ratchet wheel A second friction pad 61 i6 located between the outer face of the ratchet wheel and the inside face of the adjacent drive sprocket The ratchet wheel, brake pad 50 and 61 and the drive sprocket are normally frictionally interconnected into engagement so that normally the ratchet wheel is attached to the respective axle for co-rotation therewith ~hus the pawl and ratchet arrangement normally allow the rotation of the axles in a direction to wind up the cable onto the drum but prevent rotation of the axles in the opposed direction to allow pay-out of the cable In the event therefore that the handle is released durlng wlnd-up of the cable or the cable is pulled, for oxample by a fall of the person attached to the cable, then the cable 1B prevented from belng pulled out by the ratchet wheel and the pawl mounted on the axle 17 In order to pay out the cable, therefore, it i6 nece~sary to release the brake and thls 18 effe~cted by rotatlon of the sprocket 23 ln a dlrection to pay out the cabl- Between the ~procket and the ratchet wheel i8 provided a cam drive arrangement 53 which allows limited rotatlon of the sprocket relatlve to the ratchet wheel AB
the sprocket 1B thus driven ln the dlrectlon to pay out the cable, the sprocket moves relative to the ratchet wheel, as the ratchet wheel is held, and the cam drive member 53 pu~h-~ th- ratch-t wheol away from the sprocket to release the brake action between the frlction pad 61 and the lnslde surface of the sprocket and between the friction pad 50 and the fixed plate 60. As soon as the friction coupling is relesed, the sprocket and the axle together with the drum are free to rotate in the pay-out direction allowing the pay-out action to take place.
However, as soon as movement occurs between the axle and the sprocket, this causes the cam member 53 to re-engage the friction brake pads to hold the axle and and therefore the drum against further movement. The rotation of the drum is thuR limited to the amount of rotation of the drive ~procket and automatically prevents any further rotatlon beyond that deliberately applied by the operator.
The same effect is carried out at the secondary Aafety brake 41 but because of the lncreased drive ratio at the second safety brake, this release of the friction pad from the sprocket 26 occurs earlier and to a greater extent ~o that the main control of the movement of the drum i9 carrled wholly by the first ~afety brake 40.
The drive arrangement for the drum and the safety brake arrangement including the secondary safety brake, provide a highly effective arrangement for winding and paying out the cable while at all times prevent the cable from being released rapidly. The device is therefore partlcularly useful for attachment to a per60n in a hazardouo locatlon, for example underground, so that the person can be pulled in by the winch arrangement including lifting the person from an underground location without any danger of the person being dropped should the winch be inadvertently released. The device does not in any way rely upon a single pawl and thus provides a fail-safe arrangement necessary for the protection of human life. -Since various modifications can be made in my invention as hereinabove described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanylng specification shall be interpreted as lllustratlve only and not ln a limiting sense.
, This invention relates to a safety winch of a type particularly, but not exclusively designed for paying out and reeling in a cable attached to a person when entering a hazardous zone so the person can be extracted by the winch if necessary.
It is well known that persons entering hazardous situations such as underground pipelines, storage containers and the like can encounter difficulties such as poisonous fumes which can place the person in difficulty or even causing unconsclousness. In such a situation it is necessary for the person to be extracted from the danger wlthout the necesslty of a second person entering the same zone and possibly befalling the same fate.
As safety consciousness has developed, therefore, it has been necessary to attach to persons entering such a zone a cable attached to a harness worn by the person with the cable extendlng to a sultable hoist system whlch allows the cable to be reeled in and the person extracted from the dangerous situatlon. Many winches are available which provlde sufficient power to allow the person to be extracted including llfting the person vertlcally, should thls be neco~sary. Hand wlnches of thls type are available whlch can develop ~ufflclent force from hand operatlon to wlthdraw ~ ~: 2086379 the person. These winches generally include a brake mechanism so that the cable is prevented from being rapidly paid out should the winch be inadvertently released, for example when lifting the person from an underground location. It will of course be appreciated that, should the winch be released or the brake fail, the person can be dropped with the possibility of causing injuries beyond those already sustained.
Conventional winches are therefore unsatisfactory as they do not provide sufficient fail safe operation and euch they do not have the flexibility of drive arrangements to enable the winch to be operated in a manner which avoids lnterferlng with the normal operation of the person while ln the dangerous location but yet provides the ability to extract the person and to generate sufficient power to ensure that the person can be properly lifted.
According ~o the a first aspect of the invention there is provided a safety winch compri~ing a main frame, a cablo, a main axle, a secondary axle, means mounting the main axle and the ~econdary axle on the main frame each for rotatlon about a respoctlve one of two parallel axles, a drum mounted on the main axle for rotation therewlth in a flr~t directlon to cause pay-out of sald cable and ln a ~-cond dlrectlon to cause reel ln of ~ald cable, chaln drl~e m-ano for communlcatlng rotatlon of each of the maln axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the secondary axle, and a safety brake arrangement operable to prevent rotation of the main axle in said first direction, the safety brake arrangement comprising first safety brake means mounted on the main axle and second safety brake means mounted on the secondary axle, each of the first and second safety brake means being arranged to allow rotation of the main axle in said second direction to cause reel in of the cable and being arranged to prevent rotation of the main i~
axle ln said flr~t direction except when the main axle is drlven from sald chain drlve means ln sald flrst dlrectlon.
Accordlng to a second aspect of the lnventlon there 18 provlded a safety wlnch comprlslng a maln frame, a cable, a main axle, a secondary axle, means mounting the main axle ~
and the secondary axle on the main frame each for rotation about a respectlve one of two parallel axes, a drum mounted. . 1 :
on the maln axle for rotatlon therewlth ln a flrst dlrection ~:~
to cause payout of sald cable and ln a second directlon to cause reel ln of sald cable, chain drive means for communlcatlng rotatlon of each of the main axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the socondary axle, and a safety brake arrangement operable to provent rotatlon of the maln axle in oald flrst dlrection, I
said safety brake assembly comprising a ratchet wheel mounted on the main axle for rotation about the axis of the main axle relative to the main axle, a pawl mounted on the frame and cooperating with the ratchet wheel to prevent rotation thereof in said first direction, a drive member receiving drive from said chain drive means and mounted on the main axle for rotation about the axis of the main axle, friction pad means between the drive member and the ratchet wheel and cam means between the main axle and the drive member allowing limited rotational movement between the main axle and the drive member and operable in said second dlrectlon of movement of the drive member to cause the frictlon pad means to form a frictional connection between the drlve member and the ratchet wheel to communicate drive from the drive member to the ratchet wheel and operable in said flrst direction of movement of the drive member to move the frlction pad mean~ axially to separate sald frictional connection to allow rotation of the drive member and the main axle relatlve to the ratchet wheel.
According to the third aspect of the invention, there is provided a safety winch compri~ing a main frame, a cable, a main axle, a secondary axle, mean~ mounting the maln axle and the secondary axle on the maln frame each for rotatlon about a respectlve one of two par~llel axes, a drum mounted on the maln axle for rotatlon therewith ln a first ~` 20~6379 :.
direction to cause payout of said cable and in a second direction to cause reel in of said cable, chain drive means for communicating rotation of each of the main axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the secondary axle, and a safety brake arrangement operable to prevent rotation of the main axle in the said first direction, a first sprocket mounted on the secondary axle at an end thereof opposite to said chain drive means, a drive ~procket mounted on said main frame, a chain communicating drive from the drive ~procket to the first sprocket, each of sald flrst aprocket and said drive sprocket having means thereon for engagement with said handle means for communication of manual drive thereto from said handle means, the drive sprocket and the first sprocket being arranged such that a drive ratio between the drive sprocket and the maln axle i8 different from a drive ratio between the flr~t sprocket and the main axle.
One embodiment of the invention will now be de~cribed in con~unction with the accompanying drawings in which:
D~SCRIP~ION OF TNF DRAWINGS
Flgure 1 i~ a ~chematic plan vlew of a wlnch Accordlng to the pre~ont lnvontlon.
Flgure 2 ls a front elevatlonal vlew of the winch of Figure 1 showing the handle attached to the second operating location.
Figure 3 is a view along the lines 3-3 of Figure 1 showing the construction of the ratchetk and pull arrangement.
DETAILED DESCRIPTION
The winch comprises a main frame generally indicated at 10 including a bace plate 11 and a plurality of upstanding walls. The upstanding walls include a first side wall 12 extending along the full length of one side of the base frame 11. A ~econd side wall 13 lies parallel to the flrst slde wall and extends along the base plate to a posltion approxlmately mldway along the base plate at which lt la connected to a transverse wall 14. A further slde wall portlon 15 extends from the transverse wall parallel to the slde wall 12 but spaced lnwardly from the side wall portlon 13. An end wall 16 pa~rallel to the transverse wall 14 closes the frame.
Acros~ the frame is provided a firsit main axle 17 and a secondary axle 18 which lie parallel, horizontal and parallel to the transver6e wall 14. Each of the axles is ! aupport on bearlngsi 19 mounted in the respective side walls.
The main axle 17 thus is positioned on one cide of the tran~ver~e wall 14 and a ~econdary axle 18 i~ posltioned on th- oth-r sld- of the tran~v-rse wall 14. The maln axle 17 , " ~ ~
~ - 7 -carries a cable drum 20 with end walls 21 defining a cylindricl receptacle for a cable 22 to be wound thereon.
The cable is arranged and attached to the drum 60 that the rotation of the drum in the clockwise direction as 6hown in Figure 2 causes the cable to be wound onto the drum and rotation of the drum in the counter clockwise direction causes the cable to be paid out.
On the left hand end of the axle 17 is mounted a drive sprocket 23 which is connected to the axle so as to communicate drive to the axle and vice versa. On the left hand end of the axle 18 is provided a second sprocket 24 whlch i8 mounted on the axle for rotation therewith. A
chain 25 communicates drive between the sprockets 23 and 24.
At the rlght hand end of the shaft 18 iB provided a first drlve sprocket 26 which again i~ attached to the axle 18 for co-rotation therewith. A second drive sprocket 27 is mounted on the shaft.17 but is carried thereon by bearlngs 28 whlch allow the sprocket to rotate freely relative to the axle 17. A chaln 29 communicates drive between the sprockets 26 and 27.
On the front face of each of the drive sprockets 26 and 27 iB provlded a mountlng bracket 30. The mounting bracket 30 iB arranged to receive a removeable handle 31 B0 thlo can be attached to a selected one of the brackets 30, r-mov-d from that bracket and roplaced on the other of the 208~379 brackets as required. The handle 31 includes an end portion 32 for attachment to the bracket 30 so that the end portion 32 rotates about the axis of the respective axle. The handle thus extends radially outwardly from the axle and provides a first hand grip portion 33 at a first di tance spaced from the axle and a second hand grip portion 34 at a ~econd greater distance from the axle. Thus the operator can grasp the hand grip portion 34 which requires a larger arc of rotation of the hand while driving the handle. This provides greater mechanical advantage and thus 3110ws the operator to apply a greater force. The hand grip portion 33 bolng pooltloned radlally lnwardly requires only a much ~h~llower arc of the movement of the hand with a significantly reduced mechanical advantage for high speed drive of the handle. The bracket 30 lncludes a slot 30A
parallel to the end of the handle for receiving the end therein. The outer face of the slot 30A hao a hole 30B
through whlch a spring mounted pin 30C on the handle can pro~ect to lock the handle end 32 within the slot.
In addltion, the ~prockets 23, 24, 26 and 27 have different numbers of drlve teeth so as to provide a different drive ratio when the handle is applied to the ~procket 26 as opposed to the drive ratio when the the handle io applled tho ~prookot 27. Thus in one example the ~prock-t 27 ha~ 38 teeth and the ~procket 26 ha~ 19 teeth prov~ding a drive ratio of 2 to 1. The sprocket 24 ln thls example has 10 teeth and the sprocket 23 has 40 teeth providing a ratio of 4 to 1. Thus when the handle is applied to the sprocket 26, the drive ratio from the handle to the axle 17 is governed wholly by the sprockets 24 and 23 and thus i6 at a ratio of 4 to 1. When the handle is appliex to the sprocket 27, the ratio of drive from the handle to the axle 17 is 2 to 1 since the ratio is reduced from the sprocket 27 to the sprocket 26 and then increased from the sprocket 24 to the sprocket 23. The mounting of the sprocket 27 on the axle 17 does not provide any drive communication between those elements except through the drlve chaln as descrlbed above, but provide~ a convenient locatlon for mountlng the sprocket 27 in a limlted space since the sprockets 27 and 23 are then aligned allowing the outer housing to be malntained at a minimum.
In order to provide yet further flexibility for the drlve ~y~tem, wlth the handle removed, a chain drive pulley of the type used in overhead doors can be used and mounted on the bracket 30. This provides therefore a chain ~uapended from the chain drlve pulley so the chain can be pulled over the pulley to apply a drlve actlon to the required sprocket through the bracket 30.
In a yet further arrangement, a bevelled gear drive arrangement can be connected to the bracket 30 wlth the bevel gear recelvln0 drlve ~rom a secon~ bevel gear mounted on the end plate 16 and attached to 8 handle. In thl~ way ~ ':
- '- 20~637~
the handle can rotate about an axle at right angles to the axles 17 and 18 ~o that the device can be driven from that position when required.
In order to prevent inadvertent release of the cable when fully wound in or while winding or paying out of the cable, there are provided a first and a second safety brake arrangement 40, 41. The safety brake arrangement 40 is mounted on the axle 17 and cooperates with the frame adjacent the axle 17 o as to halt rotation of the axle in a pay out direction. the 6econd safety brake arrangement 41 act6 a6 a back-up to the first 6afety brake arrangement in . . .
case of a fallure of the fir~t. In operation, as will be apparent from the descrlption hereinafter, the first safety brake arrangement is that which is normally operating while the second 6afety brake arrangement is normally released in the pay-out operation.
The ~afety brake arrangement~ are ~ubatantially identlcal and each comprl6es a ratchet wheel 42 having ratchet teeth 43. The ratchet teeth cooperate with a pawl 44 mounted on a ~haft 45 pivotally attached to the frame ad~acent the ratchet wheel. The pawl 44 i~ shaped to engage lnto the ratchet teeth to prevent rotation of the ratchet wheel 42 in a direction to hold the ratchet wheel again6t rotatlon in the pay-out dlrectlon. Thus a~ vlewed from the ad~acent end o the shaft 18, the ratchet wheel 42 18 prevented from rotatlng ln the counter clockwlse directlon.
20~S379 As viewed from the adjacent end of the axle 17, the ratchet wheel 42 i8 prevented from ro~ating in a cloekwise direction.
The pawl 44 is actuated from the engaged position shown in Figure 3 to a release positioned spaced away from the ratchet teeth 43 by a spring wire 46 which has an end hook portion 47 engaged through a hole in the pawl 44. The spring wire 46 includes a circular hoop portion 48 which is wrapped around a drum 49 attached to and co-rotating with the ratchet wheel 42. Thus it will be appreciated that rotation of the ratchet wheel in the clockwise direetion a shown in Figure 3 eauses the spring hoop 48 to be rotated by the drum 49 in a direetlon to push the pawl away from the ratehet teeth to allow the rotation of the rateh wheel in the elockwise direetion to eontinue without the pawl riding over the ratehet teeth. Rotation of the drum in the eounter eloekwi~e dlreetion causes the hoop 48 to pull the spring in the eounter elockwise direction pulling the pawl into engagement with the ratchet teeth to engage into the ratchet position.
Each of the ratchet wheels is mounted on its respective axle by bearings allowing free rotation between the axle and the ratehet wheel. The ratehet wheel is however engaged wlth the axle through a frletlon pad 50 earrled on the ~aee of the ratehet wheel between the ratehet wheel and a plate 60 fixed on the axle on the inside of the ~ 2086379 ratchet wheel A second friction pad 61 i6 located between the outer face of the ratchet wheel and the inside face of the adjacent drive sprocket The ratchet wheel, brake pad 50 and 61 and the drive sprocket are normally frictionally interconnected into engagement so that normally the ratchet wheel is attached to the respective axle for co-rotation therewith ~hus the pawl and ratchet arrangement normally allow the rotation of the axles in a direction to wind up the cable onto the drum but prevent rotation of the axles in the opposed direction to allow pay-out of the cable In the event therefore that the handle is released durlng wlnd-up of the cable or the cable is pulled, for oxample by a fall of the person attached to the cable, then the cable 1B prevented from belng pulled out by the ratchet wheel and the pawl mounted on the axle 17 In order to pay out the cable, therefore, it i6 nece~sary to release the brake and thls 18 effe~cted by rotatlon of the sprocket 23 ln a dlrection to pay out the cabl- Between the ~procket and the ratchet wheel i8 provided a cam drive arrangement 53 which allows limited rotatlon of the sprocket relatlve to the ratchet wheel AB
the sprocket 1B thus driven ln the dlrectlon to pay out the cable, the sprocket moves relative to the ratchet wheel, as the ratchet wheel is held, and the cam drive member 53 pu~h-~ th- ratch-t wheol away from the sprocket to release the brake action between the frlction pad 61 and the lnslde surface of the sprocket and between the friction pad 50 and the fixed plate 60. As soon as the friction coupling is relesed, the sprocket and the axle together with the drum are free to rotate in the pay-out direction allowing the pay-out action to take place.
However, as soon as movement occurs between the axle and the sprocket, this causes the cam member 53 to re-engage the friction brake pads to hold the axle and and therefore the drum against further movement. The rotation of the drum is thuR limited to the amount of rotation of the drive ~procket and automatically prevents any further rotatlon beyond that deliberately applied by the operator.
The same effect is carried out at the secondary Aafety brake 41 but because of the lncreased drive ratio at the second safety brake, this release of the friction pad from the sprocket 26 occurs earlier and to a greater extent ~o that the main control of the movement of the drum i9 carrled wholly by the first ~afety brake 40.
The drive arrangement for the drum and the safety brake arrangement including the secondary safety brake, provide a highly effective arrangement for winding and paying out the cable while at all times prevent the cable from being released rapidly. The device is therefore partlcularly useful for attachment to a per60n in a hazardouo locatlon, for example underground, so that the person can be pulled in by the winch arrangement including lifting the person from an underground location without any danger of the person being dropped should the winch be inadvertently released. The device does not in any way rely upon a single pawl and thus provides a fail-safe arrangement necessary for the protection of human life. -Since various modifications can be made in my invention as hereinabove described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without departing from such spirit and scope, it is intended that all matter contained in the accompanylng specification shall be interpreted as lllustratlve only and not ln a limiting sense.
Claims (13)
1. A safety winch comprising a main frame, a cable, a main axle, a secondary axle, means mounting the main axle and the secondary axle on the main frame each for rotation about a respective one of two parallel axles, a drum mounted on the main axle for rotation therewith in a first direction to cause pay-out of said cable and in a second direction to cause reel in of said cable, chain drive means for communicating rotation of each of the main axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the secondary axle, and a safety brake arrangement operable to prevent rotation of the main axle in said first direction, the safety brake arrangement comprising first safety brake means mounted on the main axle and second safety brake means mounted on the secondary axle, each of the first and second safety brake means being arranged to allow rotation of the main axle in said second direction to cause reel in of the cable and being arranged to prevent rotation of the main axle in said first direction except when the main axle is driven from said chain drive means in said first direction.
2. The winch according to Claim 1 wherein each of said safety brake means comprises a ratchet wheel mounted on the respective axle for rotation about the respective axis relative to the respective axle, a pawl mounted on the frame and cooperating with the ratchet wheel to prevent rotation thereof in said first direction, a drive member mounted on the respective axle for rotation about the respective axis, friction pad means mounted between the drive member and the ratchet wheel and cam means between the axle and the drive member allowing limited rotational movement between the axle and the drive member and operable in said second direction of movement of the drive member to cause the friction pad means to form a frictional connection between the drive member and the ratchet wheel to communicate drive from the drive member to the ratchet wheel and operable in said first direction of movement of the drive member to move the friction pad means axially to separate said frictional connection to allow rotation of the drive member and the axle relative to the ratchet wheel.
3. The winch according to Claim 1 wherein the first safety brake means is mounted on the main axle at the chain drive means and wherein the driver member of the first safety brake means comprises a sprocket for receiving drive communication from the chain drive means.
4. The winch according to Claim 1 wherein the second safety brake means is mounted on the secondary axle at an end thereof spaced from the chain drive means and wherein the drive member of the second safety brake means comprises means for engagement with said handle means.
5. The winch according to Claim 4 wherein the drive member of the second safety brake means comprises a sprocket for receiving drive communication from a chain and wherein there is provided a drive sprocket for driving the chain, the drive sprocket having means thereon for engagement with the handle means, the drive sprocket and the drive member of the second safety brake means being arranged such that the drive ratio to the main axle when the handle is on the drive sprocket is different from the drive ratio to the main axle when the handle is on the drive member of the second safety brake means.
6. The winch according to Claim 5 wherein the drive sprocket is mounted on the main axle for free rotation relative thereto.
7. The winch according to Claim 1 wherein the handle means includes a handle end around which the handle rotates, a first hand grasp member mounted on the handle at a first spacing from the handle end and a second hand grasp member spaced at a greater distance from the handle end.
8. The winch according to Claim 2 including a spring engaged around a surface of the ratchet wheel and rotatable thereby around the respective axis, the spring being arranged to engage the pawl such that rotation of the ratchet wheel in the second direction causes the pawl to be moved out of engagement with the ratchet wheel and wherein rotation of the ratchet wheel in the first direction causes the pawl to be moved into engagement with the ratchet wheel
9. A safety winch comprising a main frame, a cable, a main axle, a secondary axle, means mounting the main axle and the secondary axle on the main frame each for rotation about a respective one of two parallel axes, a drum mounted on the main axle for rotation therewith in a first direction to cause payout of said cable and in a second direction to cause reel in of said cable, chain drive means for communicating rotation of each of the main axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the secondary axle, and a safety brake arrangement operable to prevent rotation of the main axle in said first direction, said safety brake assembly comprising a ratchet wheel mounted on the main axle for rotation about the axis of the main axle relative to the main axle, a pawl mounted on the frame and cooperating with the ratchet wheel to prevent rotation thereof in said first direction, a drive member receiving drive from said chain drive means and mounted on the main axle for rotation about the axle of the main axle, friction pad means between the drive member and the ratchet wheel and cam means between the main axle and the drive member allowing limited rotational movement between the main axle and the drive member and operable in said second direction of movement of the drive member to cause the friction pad means to form a frictional connection between the drive member and the ratchet wheel to communicate drive from the drive member to the ratchet wheel and operable in said first direction of movement of the drive member to move the friction pad means axially to separate said frictional connection to allow rotation of the drive member and the main axle relative to the ratchet wheel.
10. The winch according to Claim 9 including a spring engaged around a surface of the ratchet wheel and rotatable thereby around the respective axis, the spring being arranged to engage the pawl such that rotation of the ratchet wheel in the second direction causes the pawl to be moved out of engagement with the ratchet wheel and wherein rotation of the ratchet wheel in the first direction causes the pawl to be moved into engagement with the ratchet wheel.
11. A safety winch comprising a main frame, a cable, a main axle, a secondary axle, means mounting the main axle and the secondary axle on the main frame each for rotation about a respective one of two parallel axes, a drum mounted on the main axle for rotation therewith in a first direction to cause payout of said cable and in a second direction to cause reel in of said cable, chain drive means for communicating rotation of each of the main axle and the secondary axle to the other of the main axle and the secondary axle, handle means for manually driving the secondary axle, and a safety brake arrangement operable to prevent rotation of the main axle in the said first direction, a first sprocket mounted on the secondary axle at an end thereof opposite to said chain drive means, a drive sprocket mounted on said main frame, a chain communicating drive from the drive sprocket to the first sprocket, each of said first sprocket and said drive sprocket having means thereon for engagement with said handle means for communication of manual drive thereto from said handle means, the drive sprocket and the first sprocket being arranged such that a drive ratio between the drive sprocket and the main axle is different from a drive ratio between the first sprocket and the main axle.
12. The winch according to Claim 1 wherein the drive sprocket is mounted on the main axle for free rotation relative thereto.
13. The winch according to Claim 11 wherein the handle means includes a handle end around which the handle rotates, a first hand grasp member mounted on the handle at a first spacing from the handle end and a second hand grasp member spaced at a greater distance from the handle end.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2086379 CA2086379A1 (en) | 1992-12-29 | 1992-12-29 | Safety winch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2086379 CA2086379A1 (en) | 1992-12-29 | 1992-12-29 | Safety winch |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2086379A1 true CA2086379A1 (en) | 1994-06-30 |
Family
ID=4150915
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2086379 Abandoned CA2086379A1 (en) | 1992-12-29 | 1992-12-29 | Safety winch |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2086379A1 (en) |
-
1992
- 1992-12-29 CA CA 2086379 patent/CA2086379A1/en not_active Abandoned
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| Date | Code | Title | Description |
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| FZDE | Dead |