US2964114A - Earth working implement and power lift mechanism therefor - Google Patents

Description

Dec. 13, 1960 w. J. MELDAHL EARTH WORKING IMPLEMENT AND POWER LIFT MECHANISM THEREFOR 4 Sheets-Sheet 1 Filed March 19, 1956 nvenfoz WALD EMAR J: MELDAHL Dec. 13, 1960 MELDAHL 2,964,114

EARTH WOR IN LEMENT AND POWER LIFT MECH SM THEREFOR Filed March 19, 1956 4 Sheets-Sheet 2 f7nuento1 WA LDEM 4 R J ME LDA HL Q'f-tat 115 Dec. 13, 1960 w. J. MELDAHL 2,964,114

EARTH WORKING IMPLEMENT AND POWER LIFT MECHANISM THEREFOR 4 Sheets-Sheet 3 Filed March 19, 1956 f7nuen ALDEMAR J. MEZDAHL Dec. 13, 1960 w. J. MELDAH 2,964,114

EARTH WORKING IMPLEMENT POWER LIFT MECHANISM THEREFOR Filed March 19, 1956 4 Sheets-Sheet 4 WA E DIgMAR i'h'ifibA HL awimfiamba CbHazn eg ilnited States Patent EARTH WDRKING IMPLEMENT ANDPOWER LIFTMECHANISM THEREFOR Waldemar J. Meldahl, Green Bay, Wis., assignor to J. I.

Case Company, Racine, Wis., a corporation of Wisconsin Filed Mar. 19, 195$,Ser. N... 572,541,

4 Claims. or. 172-487) in the direction of lighter weight, greater strength and rigidity, together with ease and economy of fabrication. Another object is to provide an advantageous arrangement of independent ground Working rigs carried by and propelled from the frame arrangement.

Another object is to provide an arrangementjof linkage for conveniently raising such rigs and adjusting the working depth thereof. V

Another object is to provide improvements in said mechanism which provide for advantageous operation of the usual self-interrupting power lift clutch. Another object is to provide improvements'in such a self-interrupting clutch to more properly adapt it to the special conditions commonly encountered when used with an implement of this type.

Other objects and advantages will appear from the following description in which like reference characters refer to the same parts throughoutvthe description and accompanying drawings in which:

Figure 1 is a perspective view of an implement embodying the invention taken from the rear and somewhat to the left.

Fig. 2 is a perspective view'on a largerscale, taken fromthe right side looking slightly tothe rear with parts removed and others broken away to show what lies v beneath. I

Fig. 3 is a right side elevation of a clutch indicated in Fig. 2 on alargerscale with parts removed. and others broken away. V Fig. 4 is a similar view but with other parts removed and certain underlying parts'sh-own in brokenlines.

Fig. 5 is a left side elevation of a portion of Fig. .4. Fig. 6is an elevation of the mechanism shown in Fig. 5 as seen from the left of Fig. 5.

Fig. 7 is an elevation of the mechanism shown in Fig. 5 as seen from the right of Fig. 5.

Fig. 8 is a view similar to Fig. 4 diagrammatic in I character and showing a modified form of the construction.

Fig. 9 is a similar view position.

Turning to Fig. 1, the machine comprises a frame, generally designated as F, carried by ground engaging wheels W1 and W2 and propelled by a drawbar D, frame F carrying a plurality of soil working rigs as R connected thereto by linkage systems L and raised and lowered by a power lift mechanism generally designated as P, frame showing the parts in'another F being attached to a tractor, not shown, through drawbar D, thereby propelling rigs R which are dropped into engagement with soil 'or lifted out of contact therewith 7 by mechanism Pas desired or as circumstances require.

Frame F comprises, in the present instance, a relatively large pipe or tube 10 having welded or otherwise fixed therewith a pair of supporting brackets 12 and 14 on which are journaled above-mentioned wheels W1 and W2, drawbar D being composed of suitable longitudinal members 16 fixed in a suitable manner to plates 18 and 20 also permanently united with tube 10. Drawbar D also has hitch plates 22 adjustably carrying a hitch pin assembly 24 which is of well-known type not necessary to further describe. With hitch assembly 24 connected to a tractor, the structure so far described will be stable and will travel along the ground behind the tractor.

Frame F carries, in the illustrative embodiment, three rigs R, which are essentially alike. Referring to the left hand rig as shown in Fig. 1, tube 10 has a substantially vertical member, in the present instance anoutwardly open channel 26, permanently united therewith and'having pivoted thereto at 28 and 30 respectively upper and lower parallel links 32 and 34. joined at their rearward extremities by a strut '36 forming part of a yoke-like member generally designated as 38. Yoke 38 has a strut portion 40'permanently united'to atool bar p'ortion 42 to. which above-mentioned strut portion 36 is" also connected in the neighborhood of apivotal connection 44 between above-mentioned link 34 and, strut 36. Link 32 is also connected to strut 36 at apivotal'connection 46. As will be apparent, since plate 26'and strut 36 are of substantially the same length, while, links 32 and 34 are also of substantially the same length, .these parts define a parallelogram-type of linkage wherein tool bar portion 42 may be raised and lowered relative to frame F with swinging of links 32 and 34 but substantially Without change in its angular relation to the ground. I

A companion link 48 to link 34 is pivoted to a bracket 50 and a companion link 52 to link 32 is pivoted to a bracket 54 permanently united to tube 10, links 48 and 52 being pivoted at their rearward ends to yoke 38 as in the case of links 32 and 34. In this way a stable arrange.- rnent'is provided supporting tool bar.42 for free up-anddown floating movement butmaintaining it at all times 'in a position substantially parallel to tube 10.

along with tool bar 42 arid [rig frame 56 as willbe apparent. It will also be apparent that, because of the parallel motion or fixed angular relation of toolbar 42 to the ground, the working angle of tools 66 will not be disturbed by any adjustments in the depth of working. Furthermore, since tools may be disposed at various points ahead of and behind each other, tools nearer and further from pivots'46 and 44 will nevertheless be raised and lowered substantially identical amounts when yoke 38 and toolbar 42 are adjusted up and down.

A rig frame generally designated as 68 defines a second or right-hand rig' located generally at the opposite end of tube 10 from rig frame 56, this right-hand rig being substantially identical with the left-hand rig just described so that further description of it is unnecessary. A 'third rig' frame 70, however, is located between those just described'and is fixed to a tool bar 72 which is carried on upper and lower parallel links 74 and 76 respectively on the left side and 78 and 80 on the right. Links 74 and .78 are pivotally connected to a yokeSZ having upwardly directed struts $4 and 86 extending '3 downwardly toand permanently united with tool bar 72. As will be apparent, yoke 82 and the several links form the elements of a parallelogram linkage, as in the case of yoke 38, so that gang frame 70 is free to move up and down while at the same time being caused to maintain a predetermined angular relation to the ground. The several rig frames, '68, and 70 are thus free to rise and fall or float and they are also [readily raised out of working position by suitable mechanism as follows.

A generally upwardly extending lever 88 is pivoted on a pin 90 engaged with above-mentioned plates 18 and 20 and may be rocked forward and back with substantial force by a mechanism to be described. Lever 88 is preferably fabricated of suitable structural elements and includes a pivot pin 92 to which are pivoted a plurality of extensible struts generally designated as 94, 96, and 98, one for each of rig frames 56, 68, and 70, strut 94 forming or being fixed with pivot 46, strut 96 being connected with theequivalent pivotal connection for the right-hand rig while strut 98 is anchored to a yoke 100 which connects with a pivotal connection .102 between yoke 82 and links 74 and 78. As will now be apparent, forward rocking of lever 88 will pull on struts 94, 96, and 98 and cause upward swinging of the three rig frames along with their respective parallel linkage sets.

Turning to Fig. ,2, struts 94, 96, and 98 are essentially similar and the description of one should sufiice for all. Strut 96 comprises an outer tubular section 104 having an eye or pivot bearing portion 106 journaledon abovementioned pivot 92. A rod portion 108-is slidable within tubularportion 104,- extending outwardly axially thereof and forming or in connection with a pivot 110, Fig. 1, corresponding to above-mentioned pivot 46. Tubular portion 104 provides a slot 112, Fig. 2, in which is slidable a cap screw or the like forming a motion limiting stop 114 engaged in rod 108. In this manner rod 108 is prevented from sliding entirely out of tubular portion 104, while the rod may slide further into tube 104 to the extent of the length of slot 112. Thus it is possible for a pull to be exerted through strut 96, whereas if a thrust develops in the strut, it may collapse or. telescope a limited amount to relieve the compression. A spring 116 is compressed between a collar-118 fixed on rod 108 and the end of tube 104, a washer 120 preferably being interposed as shown. In this way strut 96 is extended to its greatest possible length. I

Normally the weight of each rig and its linkage set will be imposed on its respective extensible strut and will put the strut in tension so that stop 114 willrest in the outer extremity of slot 112. Occasionally; however, the reaction of the ground, depending upon the type'and number of implements 66, will cause an upward tendency in the rig frame which will not only relieve the strut of any weight but may actually tend to compress the strut. Such force is yieldingly resisted by spring 116but if the force is sufficient the rig may rise with a compressing movement of spring 116 and with movement of stop 114 in slot 112 toward the right as seen in Fig. 2. There is thus, under these conditions, downward pressure on the implement tending to yieldingly hold it in the ground.

If the implement strikes a rock or other obstruction,

the rig is free to rise independently of the other rigs, with telescoping movement of the associated strut and without developing any destructive forces in the parts. We thus have a linkage which, by rocking movement in lever 88, will lift all three rigs simultaneously, whereas on the other hand the rigs are independent as far as floating movement is concerned and may rise to clear obstructions without any interference with each other. Furthermore, downwardpressure can be exerted on the rigs; as necessary without sacrificing this advantage.

A counterbalancing spring "122 is connected to a stud 124, Fig. 2, which is anchored and adjustable 'by means of a nut 126 engaging a portion of lever 88, the other end of spring 122 being anchored in any suitable manner I 4 to a bracket assembly 128 (Fig. l) fixed on drawbar D. Stud 124 may be adjusted to cause spring 122 to exert a continuous substantial pull on lever 88 so as to continuously tend to lift rigs R through struts 94, 96, and 98 and this pull may be adjusted from time to time by means of nut 126 as required by varying conditions.

Lever 88 may be rocked as necessary through a pitman link generally designated as 130 actuated by a crank 132 fixed on a shaft 134 carried in bearing brackets 136 and 138, shaft 134 being caused to rotate substantially one-half turn from time to time by a self-interrupting clutch generally designated as 140. Clutch 140 receives motion from ground wheel W2 through a sprocket 142 driving a chain 144 which also engages and drives a sprocket 146 constituting part of clutch 140.

Returning to a description of pitman link 130 and its connections, the link is bifurcated in character, and is provided with a slot 148 in which is slidable a trunnion pin 150 adjustable up and down in slot 148 by means of a screw 152. At its upper end link 130 is guided in an arcuate path about abovementioned pin 90 by means of swingable links 154 while other links 156, pivoted upon a pin 158 at theupper extremity of lever 88, connect with pin 150. At its lower end link 130 is journaled on a crankpin 160 (Fig. 1) on above-mentioned crank 132. With crank 132 in the position shown in Fig. 2,.for example, adjustment of screw 152 will cause movement of pm 150 with a maximum of swinging of links 156 and a minimum lengthwise component of movement, while with crank 132 in its lowered position, indicated in, dotted lines, links 156 will approach a position more nearly in line with link 130= so that adjustment of screw 152 will cause a reduced amount of swinging with an increased amount of lengthwise movement, thus providing an effective adjustment of working depth but resulting in a minimum amount of change in the raised position of the rigs. It will be apparent that lever 88 and links 154 and 156 approximate the action of a bell crank as related to pitman link 130 so that half turns of crank 132 will cause swinging of lever 88 to a forward position corresponding toa raised position of the rigs and to a rearward position corresponding to a lowered position of the rigs. Such movements are under the control of clutch 148.

Clutch 140, as best seen in Figs. 3 and 4, isof the type including a continuously rotating part driven by abovementioned sprocket 146, inthe present instance comprising a shell or cup member.16'2 providing a plurality of latch receiving recesses 164 continuously rotating by reason of the action of chain 144 and sprocket 146. A normally stationary part or latch plate 166 is fixed on shaft 134, on which portion 162, is journaled, and has'an outer peripheral cam track or surface 168 providing substantially diametrically'opposed detent notches 170' and 172,

a trip member or follower portion 174 being engaged in notch 172 as seen in Fig. 3. A latch actuatinggbar 176 is rockably mounted about shaft 134 and has a follower engaging surface 178 engaged with follower 174 and a similar surface 180 flush with the surface of notch 170 in the position of the parts shown in Fig. '3. Bar 176 is urged in a direction toencroach upon notches 170 and 172 by means of a spring 182 anchored on a pin 184 and engagedfwith a hook element 186 offset from shaft 134 so as to impose a turning effort on bar 176. Bar 176 is connected through a pivot 188, a link 190, and a pivot 192 with a latch lever 194 having a latchin'gportion 196 adapted to engage latch receiving recesses 164. It will be apparent that clockwise rocking of bar 176 will cause upward swinging of latch 194 and engagement of portion 196 with the nearest recess. Conversely, counterclockwise swinging of bar 176 will pull member 196 out of its recess for a declutched condition of normally stationaryplate 166.

Latch lever .194 is pivoted on a fulcrum or pin 198* fixed on plate 166 so that, when'latch'p'ortion 196 is engaged with any one of recesses 164, plate 166 will be caused to rotate synchronously with member 162, but when bar 176 is forced by follower 174 away from the margins of notches 170 and 172, vas seen in Fig. 3, latch portion 196 is pulled'out of recesses .164 so that portion 162 is free to rotate while plate 166 is locked by reason of engagement of follower 174 in .notch 172. It will be noted that the distance from pivot 198 to pivot 192 is substantially smaller than that from shaft 134 to pivot 188. As a result, a slight angular movement of bar 176 will cause a relatively great angular movement of latch lever 194. As well understood in the operation of this type of device, follower 174 is momentarily withdrawn from notch 172, whereupon spring 182 causes rocking of bar 176 and engagement of portion 196 as aforesaid to cause rotation of plate 166, clockwise in the embodiment disclosed. Follower 174 being immediately released, rides on'cam surface 168 until notch 17%) comes nearly into the position shown for notch 172 whereupon surface 180 of bar 176 (which now encroaches upon notch 170) encounters follower 174 and no longer rotates with plate 166, being prevented by contact with follower 174. A very few degrees of relative movement betweenbar 1-76 and plate 166 will cause multiplied movement of latch lever 194 and disengagement thereof from any recess 164 with which it happens to be engaged. Follower 174 is forcibly urged into the approaching notch as will be described and plate 166, now being free from'rotating element 162 is preferably forced by follower 174 a slight further amount until follower 174 seats in the approaching notch, thus locking plate 166 in the new position. The equivalent action, of course, occurs when follower 174 is momentarily moved out of notch 170. Plate 166- is therefore promptly freed from rotating member 162 so that follower 174 may cause the necessary slight additional rotation. In the past, certain difficulties have been encountered in this type of action.

Shaft 134, as heretofore described, is driven by plate 166 and actuates above mentioned link 136 through crank 132, and, as will be apparent, the downward thrust of link 130 upon crank 132 will cause a torque or tendency to rotate counterclockwise during the part of the rotation while link 130 is being raised and, if latch portion 196 is withdrawn from any detent recess 164 while crank 132 is in the act of raising link 130, crank 132 and consequently plate 166 is freed for rotating. Plate 166 will then tend to reverse unless forcibly held by follower 174. If this happens, a few degrees of reverse rotation will .cause reengagement of portion 196. with another recess 164, whereupon plate 166 will again be rotated in a clockwise direction until again released by the action of bar'176 contacting follower 174. Plate 166 will then again reverse and the action will continue with annoying clicking and substantial unnecessary wear and consumption of power. To avoid this, applicant has devised an arrangement whereby crank 132 may be adjusted so that it will cause maximum raising of link 130 or go over center at any desired point relatively to the point of engagement of follower 174, and in practice it isso adjusted as to reach the point where link 130 has just reached or gone'slightly beyond its point of maximum lifting efiort on rigs R at the time follower 174 engages notch-172. Thus, when latch portion 196 is disengaged, plate 166 will tend to rotate further rather than to reverse. Since the tendency of plate 166 to'reverse is removed, the aforesaid'clicking action will be avoided.

Crank132, as best seen in Figs. 5, 6, and 7, comprises a check portion 200, in the present instance welded or present instance, is contoured to fit about collar20 2 so as -to be pivotally guided thereon. Pin 160 extends ,in-

wardly through slot 204 and also through a clamping plate 208 on the opposite side'of cheek 200 from carrier plate 206 and is clamped'thereto .by means of a nut 210, the latter servingto clamp carrier plate 206 and pin 160 in fixed. position relatively to cheek 200. In order to more securely fasten pin 160, plate 206 extends beyond slot 204 and has a bolt 212 passing through a slot 214, in the present instance outwardly of slot 204 in crank cheek 20,0. Bolt 212-also passes, through clamping plate 2% and has a nut 216-engaging plate 208. With nuts 216 and 216 tightened, pin 160 is securely fastened in relation to cheek'2tl0. If it is desired to change the position of pin 160, this may be done with nuts 210 and 216 loosened, pin 160 shifting in substantially a true arc about shaft 134 as carrier plate 206 is guided by collar 202 and bolt 212 in slot 214. When the desired adjustment is reached, it is securely maintained by tightening nuts 210 and 216 as will be apparent. In this way a crank is provided which is adjustablein position relatively to its shaft but which is dependable in maintaining its adjustment inthe face of the rather severe shock loads imparted to it by the selfinterrupting clutch 140. p

Follower 174, as heretofore indicated, forms part of a trip member comprising in the present instance a lever arm 218 pivoted in a bearing portion 228 preferably supported in above-mentioned plate 138 disposed at a point in a line substantially tangent to the major portion of cam surface or track 168 so that lever 218, resisting any tendency to turn on the partof plate 166, is substantially in a condition of pure tension or compression. In other words, it is substantially on dead center as-related to the forces imposed upon it.

. As best seen in Fig. 2, lever portion 218 has a tension spring 222 connected therewith adjacent follower 174 and extending, when follower 174 is engaged in notch 172, at a large angle to lever arm 218 and anchored to a hook arrangement 224 adjustably'mounted on above-mentioned bracket 14, a nut 226 being operable to change the effective length of hook element 224 to adjust the tension or strength of spring 222. Spring 222 extends in a direction as nearly as practical suitable to provide a major component of force pulling follower 174 into notch 172 so that sufficient force is availabe to cause the slight turning of plate 166, hereinbefore described, as follower 174 seats in the .notch 172.

Lever arm 218 has a journal portion extending through bearing 220 and fixed to an arm 228 which extends upwardly and .rearwardly, and is connected with a rope or the like 230 extending to the tractor so that clutch 140 may be actuated by the tractor operator. A pull on rope 230 will rock arm 228' and accordingly arm 218, thereby removing follower174 from notch 1'72 and initiating actuation of the clutch. It will be noted that as lever arm 218 swings, the angle between spring 222' and lever 21% is materially reduced so that the pull of spring 222, while actually increased by the stretching of the spring, in view of the change in angle is reduced in its effect on the lever 218, approaching a dead center relation with lever 218 and its bearing 220. .In this way a relatively large force is developed tending to seat follower 174 in the notches 172 and 170, while avoiding the necessity for an excessive force or pull on rope 230.

Conditions vary in the application of this invention to various machines and to meet as many as possible of such variations, certain modifications are contemplated as indicated in Figs. 8 and 9. In this instance, a'clutch 145 has a modified form of plate 166 fixed on a shaft 134,

connecting with a crank of any suitable type 132*. A link is pivoted to'an arm 232 which will be assumed to be continuously biased in the direction indicated. In accordance with the principle explained in connection with f adjustable crank 132, the downward thrust resulting in link .130 with crank 132 over center as shown would result in favorable conditions as to latching of plate 166 when the motion of cluutch is interrupted. Conven= tionally, the position of clutch 14G corresponding to'the lowered position of arm 232 would place crank 132 ;1 80 degrees from the position shown in Fig. 8. This, however, assuming a continuous downward load on link '130, would result in a torque in crank 132. in a' reverse'd direction, the very dimculty which is avoided in the Fig. 8 position, this defect being corrected as follows.

Clutch 166 has a notch 172 engaged by a follower 174 to maintain the parts in position for a raised condi: tion in arm 232. Plate 166 also has a notch 17!] which is engaged by follower 174 for maintaining arm 232 in a lowered position as seen in Fig. 9. While conventionally the notches 170 and 172 are dimetrically'oppos'ed, in the case of clutch plate 166, notches 170 and 172 are less than 180 degrees apart, passing from notch 170 clockwise to notch 172 and, of course, more than 180 degrees apart passing in the same direction from notch 172 to notch 170 Thus with the parts arranged as shown crank 132 will turn less than 180 degrees when clutch 140 is actuated from the position in Fig. 8 to the position in Fig. 9. The weight of the load on arm 232 and link 130 therefore continues to urge crank 132 in a clockwise direction as will be apparent from Fig. 9, so that the difiiculty of undesired reversing of theclutch plate 165 and continuous disengaging and reengaging or clicking of the clutch is avoided. e I In other words, in view of the nondiametrical arrangement of notches 170 and 172*, crank 132 assuming it to be correctly adjusted in relation to plate i66 will be locked slightly past dead center when the load is raised and will be looked slightly before dead center when the load is lowered, both positions causing the load to tend to rotate the crank in a. forward direction rather than a reverse direction.

The operation of the mechanism is thought to be clear from the foregoing description and 'it is clear also that expedients have been provided for fully realizing the objects of the invention, and it is to be understood that the same is not intended to be limited by anything in the drawings or descriptions or, in fact, in any manner except as defined in the following claims.

What is claimed as new and desired of the United States is:

1. In a power lift implement of -the type including 'a mobile frame, an earth working rig element mounted on the frame for up-and-down adjusting movement respecby' Letters Patent tively into transport and earth working positions and mechanism for so moving said rig element; the combination in such mechanism, of a self-interrupting clutch including a constantly rotating part'and an intermittently rotating part and mechanism adapted, tdmomentarily a connection from said crank pin to said earth working rig element for lifting and lowering the latter in response to rotations of said crank.

2. In a power lift implement of the type including a mobile frame, an earth working rig element mounted on the frame for up-and-down adjusting movement respectively into transport and earth working positions and mechanism for so moving said rig element; the combination in suchmechanism, of a self-interrupting clutch including a constantly rotating part and an intermittently rotating part and mechanism adapted to momentarily connect the first mentioned part to the second mentioned part for rotation therewith, control means for said mechanism, means for raising and lowering said rig element from rotation of said second mentioned part including a crank pin eccentrically disposed in relation to the axis of rotation of said second mentioned part, a crank pin carrier plate having a portion guided for rotation about said axis, said crank pin being fixed on said carrier plate, clamping means engaged with said carrier plate and adapted. to clamp said carrier plate and said crank pin rigidly in one position relatively to said second mentioned part, said carrier plate and crank pin being shiftable to another angularly disposed position when said clamping means are disengaged, and a connection from said crank pin to said earth working rig element for lifting and lowering the latter inresponse to rotations of said crank.

connect the first mentioned part to the second mentioned part for rotation therewith, control means for said mechanism, means for raising and lowering said rig element from rotation of said second mentionedfpart including a shaft extending from .and fixed for rotation with said second mentioned part, a crank element on said shaft including a crank pin carried by said crank element eccentrically disposed in relation to the axis of rotation of said shaft, said crank including a cheek portion trans-- versely disposed with relation to said'shaft, a crank pin carrier plate juxtaposed withjsaid'cheek portion and having a portion guided for'rotatio'n about the axis of .said shaft, said check portion providing 'a' slot spaced from said shaft, said crank pin beingfixed onsaid carrier plate and having a portion extending through said slot, clamping means on said crank pin engaging the side of said check remote from said carrier plate, said cheek providing a second slot spaced radially from the first mentioned slot, and clamping means engaged with said carrier plate and in second slot, said clamping means being adapted to clamp said carrier plate and said crank pin rigidly in one position relatively to said check, said carrier plate and crank pin being 'shiftable to another position when said clamping means are disengaged, and

3. In a power lift implement of the type including a mobile frame, an earth working rig element mounted on the frame for up-and-down adjusting movement and mechanism for so moving said rig element, said rig element being constituted to impose on said mechanism a continuous load in one direction; the combination in such mechanism'of a self-interrupting clutch including a constantly rotating part and an intermittently rotating part, a crank connected for rotation with the intermittently ro- -ating part, and having a first dead-center position when said load is raised and a second dead-center position when 'said load is lowered, said positions being disposed substantially 180 degrees part, said intermittently rotating part having a pair of peripherally spaced detent means, a clutch tripping member engaged with one of said detent means for locking said intermittently rotatable member and said crank in a predetermined position, said tripping member being engageable in another position of said intermittently rotatable member, with the other detent means, one of said detent means being so located with relation to said tripping member as to place said crank, when engaged with said tripping member in a position slightly past dead center relatively to the direction of rotation of said clutch with the load in raised position, and the other detent being located substantially less than 180 degrees from the first in the direction opposite interrupted by engagement of said tripping member with said detents.

4. In a power lift implement constituted to unpose a continuous load in one direction; the combination of a self-interrupting clutchincluding a constantly rotating part and an intermittently rotating part, a crank connected for rotation with the intermittently rotating part, and having a first dead-centerposition when said load is raised and a I second .dead-center position when said load is lowered,

said positions being disposed substantially degrees apart, said intermittently rotating part having a pair of peripherally spaced detent means, a clutch tripping member engaged-with one of said detent means for locking said intermittently rotatable member and said crank in a predetermined-position, said tripping member being engageable in another position of said intermittently rotatable mcmberwith the other detent means, one of said detent means being so located with relation to said tripping member as to place said crank, when engaged with said tripping member in a position slightly past dead center relatively to the direction of rotation of said clutch with the load in raised position, and the other detent being located substantially less than 180 degrees from the first in the direction opposite to that of the rotation of said clutch.

References Cited in the file of this patent UNITED STATES PATENTS 10 i Harris May 27, 1919 Davis July 31, 1923 Hendricks et a1 Feb. 25, 1936 King Nov. 8, 1938 Strandlund Nov. 28, 1939 Strandlund Nov. 28, 1939 Scarlett et a1. June 27, 1944 Hyland et al Dec. 16, 1947 Oehler et al. Mar. 15, 1955 Aber June 5, 1956 FOREIGN PATENTS Germany Feb. 9, 1956 Great Britain Feb. 21, 1951 UNITED STATES PATENT @FFICE CERTIFICATION OF CORRECTION Patent No. 2,964,114 December l3 1960 Waldemar J, Meldahl It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected belows Column 7, line 71, before "second" insert said column 8 lines 36 and 37, for roating" read rotating same column, line 40, for "part" read apart Signed and sealed this 16th day of May 1961.

(SEAL) Attest:

ERNEST Wo SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

Images