US2417492A - Lifting and pulling mechanism - Google Patents

Description

Match ,8, s. HINCHCLIFFE 2,417,492

LIFTING AND PULLING MECHANISM Filed July 5, 1945 I3 I70 F/GS. I i

F/6.6. 4 E L" 2a l J v 49 L ti INCHCLIFFE,

Attorneys,

Patented Mar. 18, 1947 UNITED STATES PATENT: OFFICE Application 11113? 1945-, Ser'ialNo'. 603,339 In Great Britain Jiily"21-,- 1944 9 Claims. (01. 254-467) This invention relates. to lifting. and. pulling mechanism.

The object of the invention. is: to provide a lifting and pulling gear which will be compact and for its size capable of carrying substantially greater loads than hitherto. Another object of the invention is to provide an intermittent or ratchet type of lifting and pulling mechanism in which a practically infinite ratchet movement may be obtained so that loads may be lifted: or lowered with greater delicacy or adjustment than has hitherto been possible. A further object is to provide improved. freedom of chain movement in such ratchet form of the mechanism.

The mechanism according to the invention comprises a lifting; shaft rotatable in a casing and having rigidly mounted thereon: achain sprocket for carrying the. lifting chain, and a driving member for turning thesaid shaft, while interposedb'etween the said driving'member and the casing, and in resilientrubbing contact with the latter, is a clutch member whichisi'ri threaded engagement with the said shaft in. such a manner that when the driving. member is turned to-take the load, the movement of the shaft tends to retract the said clutchmember and so relieve the pressure betweenit and the: casing,.but when the. driving member is' released from turning. effort, and so tends to move in the opposite direction, its movementtends to increasethe pressure between the clutch member. and the casing.. so that the shaft is'held.

The resilient contact between'theclutch memher and the casing may be effected: by resilient means interposed between the driving member and the clutch member and. connecting the: two members so as to form a resilient connection between them with the result that asrthe driving member is moved the clutch: member is resiliently pushed or pulled around with it and is thus always ready for engagement with the easing when the driving member ceases to'exert any driving efiort, and-to disengage when thei driving effort is resumed.

According to one form of the invention the mechanism is operated by means of a double pawl and ratchet the onepawl and-ratchet being adapted to operate the shaft in one direction'and the other pawl and ratchet to operatethe clutch in the opposite direction, and in a preferred form of such double ratchet mechanism the 'pawls-comprise radially slidable pawl members mountedin two angularly spaced radial casings. projecting from a housing enclosingaratchet wheelon the shattand the: clutch memb'er on which are formed ratchetv teeth in oppositevforma'tionto those of the ratchet wheel, the said pawl casings having arranged between them' a common transverse cylindrical casing? containing; a rotatable locking member having formed thereon circumferential grooves into which project portions of the said pawls. and also a segmental recess which leaves a solid segmental l portion the ends of. which form abutments which are adaptedto engage shoulders on the outer portions of the pawls to withdraw the one or the other pawl from engagement with its respective ratchet teeth according to the sition of: thesaid lockingmember; the other pawl being free tooperate.

The invention will now" be described by way of example with reference to theaccompanying drawings which show a ratchet form of themechanism;

In: the said drawings Fig. 1 is a sectional plan taken on the lineL-I of Fig. 2.

Fig; 2 is asection on: the line H ll of. Fig. 1.

Fig. 3 is an outsideelevation.

Fig. 4 is a section on the line IVIV of Fig. 1.

Fig. 5 is a section on the line V-V of Fig. 3.

Fig. 6- is a partial section on the 1ine'VI--'VI of 4.

Referring more particularly to the drawings, the mechanism comprisesa casing l in which is mounted alifting drivingshaft 2 whose one end projectsint'o the casing and has rigidly mounted? thereon a chain sprocket 3-." The end' of the shaft 2 inside the-casing. I hasajournal thereon which is carried-in a bearing portion-4a integral with a detachable cover plate 4" which encloses the sprocket 3 insid'e the casing. The casing: l is open' at. its lower portion to allow ofthe passage of the" lifting chain: whose centre line is indicated at 5 and having a hook 511 attached thereto. Collars 2a, 2b are: formed on this portion of the shaft to" prevent its moving. axially relatively to the l casing.-

The projecting portion-r of the lifting. shaft has formed thereon a multi=start thread 20 for a portion of its. length; The: outer adj acent portion 2d of: the shaftis: reduced to'- receive aratchet wheel 6 is keyed to: the said shaft. This ratchet wheel constitutes the driving member" of the mechanism. Between the ratchet Wheel- 6 andthe: casing I a.-c1utchlmcmber 1 is arranged in threaded engagement: with the multi-s'tart thread zc th'e'said c1uteh rhe'mbe1 being of slightlyle'ss' diameter than-that'- (if the ratchet wheel 6*.- Ratchet teeth In areircmred on the peri hery ot the ciutcn member 1i Ine teetii or' the clutch I own axes.

member I and ratchet wheel 6 are oppositely arranged. Two or more clutch discs 8, 9 keyed respectively to the shaft 2 and casing I are interposed between the clutch member I and the casing I to form a plate clutch according to known form, friction rings I being interposed between the clutch member I, discs 8 and 9 and the casing I.

The mid portion of the shaft 2 is preferably supported in an oil-less bush II, that is to say an oil secreting bush, to avoid lubrication difiiculties.

A common ratchet arm I2 is mounted about the clutch member I and the ratchet wheel 6 with corresponding pawls I3, I4 which tak the form of cylindrical members slidably mounted in corresponding angularly spaced radial cylinv drical casings Ia, I5b in a common housing I5 which is integral with the ratchet arm I2, the said casings projecting from a housing I6 enclosing the ratchet wheel 6 and the clutch member I, while between and integral with the casings I511, I512 there is arranged a common transverse cylindrical housing I5c in which is rotatably mounted a cylindrical locking member I! having formed thereon circumferential grooves I'Ia, I'Ib (Fig. 5) into which project flat portions of the pawls I3 and I4 respectively. The pawls are thus prevented from rotating about their A transverse segmental recess He is cut out of the locking member I! for nearly its total width so as to leave a solid segmental portion the ends of which form abutments which are adapted to engage one or other of the shoulders on the pawls I 3, I4 formed by their flats, ac-

cording to the position of the member I! which is -so that the lower end of its segmental portion has-abutted against the outer shoulder of the clutch member pawl I l and as a result has forced it out of engagement with the teeth on the clutch -member, the final movement of the arm I8 causing the end of the segment to move past the pawl shoulder so that the pawl I4 is positively locked without any tendency for its spring to turn the member II. At the same time the upper end of the segmental portion has moved inwards beyond the inner limit of the shoulder on the pawl I3 which is thus in the space He, so that the said pawl is free to operate. In order to ensure against unintentional turning of the member I! near the ends of the segmental portion nicks are formed at Hot, I'Ie with which the pawl shoulders are adapted to engage under the pressure of their springs.

The assembly of the above pawl control device is exceedingly simple and is effected prior to the passing of the casing I6 over the ratchet wheel and clutch member. The locking member I! is first inserted and is located in its correct lateral position by means of a locating screw 49 having a reduced inner portion which is an accurate sliding fit in one of the circumferential grooves say I'll) as shown. It is necessary to have the member I! correctly located in order to ensure the free reciprocating movement of the pawls in the grooves Ila, I'Ib in which their fiat portions are easy sliding fits. The member I! is then turned so that the space I'Icycoin- 4 cides with the interior of one of the casings I5a, I5b, so that its respective pawl I3 or I4 and its spring may be inserted therein so that its shoulder is within the space lie. The member I! is then turned until the space Ilc coincides with the interior of the other casing when the other pawl and its spring are inserted in the said casing, the first pawl having as a result of such movement been forced further along the casing by the end of the segmental portion of the member IT. The member I1 is then turned until the bore for receiving the arm I8 comes between the stops I5d and IE6 and the said arm inserted. The arm I8 thus locks the member H from turning far enough to release the pawls beyond their predetermined limits of travel, so that the member I1 in its turn acts as an effective lock for the pawls. The whole assembly is thus effectively held by means of the arm I8 and the locating screw I9.

The driving shaft 2 is further reduced to form a screw-threaded portion 2e which receives a holding down nut 20 which is iournalled and flanged to retain a hand wheel 2i for effecting continuous movement of the mechanism when paying in or out of the chain has to be effected. The said hand wheel has a segmental slot 2Ia for accommodating a lateral pin 22 which projects from the clutch member I through a segmental slot 6a in the ratchet wheel 6, and for accommodating a similar pin 23 on the ratchet wheel 6 arranged at a small angle from the pin 22. The nut 20 is locked to the spindle by means of a pin 24 or other locking means. The ratchet wheel 6 has a concentric boss 61) around which is wrapped a helical spring 25 of which the one end is connected to the clutch member pin 22 and the other end to the ratchet wheel pin 23.

The operation of the mechanism is as follows: when it is desired to lift a load, the ratchet wheel pawl I3 is engaged with the ratchet wheel 6, and the clutch pawl I4 disengaged as above described. The lever I2 is then operated so that the ratchet wheel 6 is driven and the shaft 2 is turned. Owing to the clutch member I being pressed against a friction ring I0 and disc 9, it tends to lag, and as the shaft 2 turns, its screw thread 20 tends to bring the clutch member I out of engagement with the casing I by releasing the pressure on the clutch discs 8 and 9, so that the shaft 2 is free to operate. The rotation of the shaft 2 tends to withdraw the clutch member I which then, owing to the resilient connection of the spring 25, trails after the ratchet wheel 6 and is thus maintained out of effective engagement with the casing I, it actually making a light rubbing contact. When the lever is released the tendency of the shaft 2 to move in the opposite direction under the load, at once, owing to such rubbing contact, draws the clutch member 1 into engagement with the casing I through the clutch plates 8, 9. The shaft 2, and consequently the load, is thus held against turning during the return movement of the operating lever I'2. On reversing the lever again, the same sequence of movements of the mechanism occurs, and so on throughout the lifting period.

When it is desired to lower a load, the pawl operating device is operated so that the ratchet wheel pawl I3 is withdrawn and the clutch pawl I4 engaged with the ratchet teeth la on the clutch member I. From the above description it will be seen that when the shaft 2 is stationary the clutch member I is always engaged, so that the WU -=load is" :held. To zlowep ltherload; the 1- operating wlever 12- ismovedrin' the direction reverse to that ofllifting. .';This causes the clutch member 1 tdisengage withxthei casing I so: that the. shaft; 2

free .to: turn, :zbutjas the turning of the shaft? 2 .1

abea-done vquickly by turning the hand wheel 2L The-effect of this is to engage one or other of the lateral pins.22,-.23 projecting fromthe clutch member "l andthe ratchetwheel 6 respectively.

.. For example,if-itisedesiredto lower the hook,

the-pawls l3, l4 aresetasfor lowering a' load, "that-is toasay so-thatthe ratchet wheel pawl i3 disengages and the clutch member pawl Men- ,g-ages. .The hand wheel 2| is then turned in an anticlockwise direction.

end of the slot 2Ia. against the pin 22 and has,

.This brings the lower .the effect of withdrawing the clutch member .and pressing it against the ratchet whee1 so that .Zthe. shaft is turned. This turning continues as along as the hand wheel turns. Directly the hand .wheel 2| is arrested, ,theclutch member 1 engages "the casing I. and further paymentout of '.the chain is prevented. .If it is desired to draw in'the hook, .then the. clutch pawl M is disengaged, the ratchet wheel pawl i3 is engaged, and

the hand wheel 2! .is turned in a clockwise di-j rection. This hasthe ifect of bringing the upper end of the sloti-2ala against theratchet wheel pin 23, so turning the ratchet wheel 6, which has the f-urther--e1fect ofrelieving the clutch pressure and freeing the shaft 2, the clutch member "l,

thereafterturning with the. ratchet wheel 6 owing to its being trailed by the spring 25. The movement of the shaft 2 continues so long as the hand wheel "2 l-is rotated-,- but directly the movement of thet'ihand swheeltlisearrested, then the weightof the hook tends to .turn the shaft 2 in the reverse direction with the immediate result that thenlutchmember? again fully engages with the casing I.

1;" Editing andpullingmechanism comprising rigidly mounted on said shaft, said ratchet wheel having a segmental slot .formed' therein, a clutch "tmember interposed between saidratchet wheeliand w'said casing, said clutch member being: inresilient 1rubbingxcontact.withxsaid casing .and'in threaded zengagementzwith saidshaft, ratchetteeth on said 2101..

:lsitely disposed to those. on. said ratchet. wheel,

clutch member, .said ratchet nteethibeing oppov:oppositely disposed pawls. adapted to engageqsaid ..:ratchet wheel and clutch memberv respectively, a common. oper'atingmember for individually re- :tracting ;said pawls,. alpin' projecting laterally from said clutch. memberrinto the slotein said .ratchetcwheel, a second; pin projecting laterally mfrom saidyratchet wheelinto the samerplane as said clutch pin, and resilient connecting means 220 arranged between said .pins. so that said clutch member follows the movementofasaidxratchet wheel.

"2. The; mechanism according to, claim. 1, comprisingahand wheel rotatably mounted on said 'drivingshafasaid hand wheel havingna .seg-

rmental slot 'for accommodating said ratchet while in the other direction the otherend of the $5101}: abuts against the ratchet, pin and socturns the shaft and withdraws theclutch member.

..3. ,The mechanism accordingto claim 1 comprisin a housing enclosing the ratchet wheel and clutch member, pawl casings projecting from said housing; said pawl members being slidably mount- ;ed insaid pawl casings and adapted respectively .toengage the ratchet ,wheel and .clutch memabers, a: commontransverse cylindrical casing arranged between said pawl casings, a rotatable locking memberin said transverse casing, said locking member having formed thereon circumferential grooves into which project portions of said .pawls, saidlocking member also having formedtherein asegmental recess which leaves 1 a solid segmentalportion the ends of which form The pitch of the thread is to be such that the clutch member 1 will not revolve when the shaft 2 is turned in the proper direction provided the friction surfaces are originally in contact. This will depend upon the friction and radius of the friction rings [0 and the friction. and radius of the thread.

It will be seen thatflwith a relatively small mechanism substantially heavy loads may be handled, for the reason that once the dimensions of its main members-the casing and the shafthave been decided upon according to the maximum load to be handled, the remaining members may be easily accommodated without affecting the width and diameter of the mechanism. Further, with the form of clutch described, the disengagement thereof requires a minimum of effort by the operator. The advantage of this is particularly noticeable in lowering operations; for in the usual form of clutch comprising a relatively heavy clutch engaging spring whose presabutments, shoulders on the outer portions or" said pawls, said shoulders being adapted to abut against said abutments to withdraw said pawls alternatively from engagement with their respective teeth according to the position of said locking member.

4. The mechanism according to claim 1, comprising a housing enclosing the ratchet wheel and clutch member, pawl casings projecting from said housing, said pawl members being slidably mounted in said pawl casings and adapted respectively to engage the ratchet wheel and clutch members, said pawl members having flats formed thereon, a common transverse cylindrical casing arranged between said pawl casings, a rotatable locking member in said transverse casing, said locking member having formed thereon circumferential grooves into which project said flats of said pawls, said locking member also having formed therein a segmental recess which leaves a solid segmental portion the ends of which form abutments, shoulders on the outer portions of said pawls, said shoulders being adapted to abut against said abutments to withdraw said pawls alternatively from engagement with their respective teeth according to the position of said locking member.

5. The mechanism according to claim 1, comprising a housing enclosing the ratchet wheel and clutch member, pawl casings projecting from said housing, said pawl members being slidably mounted in said pawl casings and adapted respectively to engage the ratchet wheel and clutch members, a common transverse cylindrical casing arranged between said pawl casings, a rotatable locking member in said transverse casing, said locking member having formed thereon circumferential grooves into which project portions of said pawls, said locking member also having formed therein a segmental recess which leaves a solid segmental portion the ends of which form abutments, shoulders on the outer portions of said pawls, said shoulders being adapted to abut against said abutments to withdraw said pawls alternatively from engagement with their respective teeth according to the position of said locking member, said segmental portion being nicked near its ends for engagement with said pawl shoulders.

6. The mechanism according to claim 1, coniprising a housing enclosing the ratchet wheel and clutch member, pawl casings projecting from said housing, said pawl members being slidably mounted in said pawl casings and adapted respectively to engage the ratchet wheel and clutch members, a common transverse cylindrical casing arranged between said pawl casings, a rotatable locking member in said transverse casing, said locking member having formed thereon circumferential grooves into which project portions of said pawls, and a pin in said transverse casing projecting a sliding fit in one of said grooves, said locking member also having formed therein a segmental recess which leaves a solid segmental portion the ends of which form abutments, shoulders on the outer portions of said pawls, said shoulders being adapted to abut against said abutments to withdraw said pawls alternatively from engagement with their respective teeth according to the position of said locking member.

'1; The mechanism according to claim 1, comprising a housing enclosing the ratchet wheel and clutch member, pawl casings projecting from said housing, said pawl members being slidably mounted in said pawl casings and adapted respectively to engage the ratchet wheel and clutch means for limiting the angular movement of said arm so that portions of said segmental portion are always in said pawl casings, and the whole assemblage effectively locked, said locking member having formed thereon circumferential grooves into which project portions of said pawls, said locking member also having formed therein a segmental recess which leaves a solid segmental portion the ends of which form abutments, shoulders on the outer portions of said pawls, said shoulders being adapted to abut against said abutments to withdraw said pawls alternatively from engagement with their respective teeth according to the position of said locking member.

8. The mechanism according to claim 1, comprising multiple plate clutch means interposed between said clutch member and said casing, said plate clutch means comprising non-rotatable plate means on said casing, other plate means rotatable with said shaft and further plate means rotatable with said clutch member.

9. The mechanism according to claim 1, comprising multiple plate clutch means interposed between said clutch member and said casing, said plate clutch means comprising non-rotatable plate means on said casing, other plate means rotatable with said shaft and further plate means constituted by the face of said clutch member adjacent said stationary plate means.

SIDNEY HINCHCLIFFE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,937,331 Cofiing Nov. 28, 1933 FOREIGN PATENTS Number Country Date 70,491 Germany Aug. 23, 1893

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