CA1237388A - Heavy load lifting apparatus - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

A heavy load lifting machine for elevating heavy loads off of and transporting heavy loads along the ground is disclosed. The machine includes a load lifting linkage having a special configuration for the linkage arms and lift rams to accommodate lifting objects in the range of forty tons or more and transporting the objects over the ground with minimal sway of the object during transport.

Description

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FLEL~ OF THE INVENTlOM
This invention relates to heavy load liftiny equipment which is particularly adapted to -the lifting of hea~y loads which may weigh in -the range of forty tons or 5 more.
_ACKGROUND OF THE INVENTION
A variety of forms of parallelogram type linkage devices are disclosed for lif-ting material. Ackermann, United States patent 3,018,011, discloses a fork lift 10 truck having a paral]elogram type linkage connected to the forks. A lift ram is connected intermediate the lower arm of each link to effect raising and lowering of the linkage. The upper arm of the linkage is formed by a hydraulic ram which controls tilting of the forks. This 15 arrangement may be satisfactory for lifting light loads.
However, with heavy loads such as in the range of 40 tons, extreme bending moments would develop in the ]ower arm due to the lift ram being pivotally connected intermediate the lower arm. The geometry of the 20 arrangemen-t, resulting from -the lift ram being connected to the lower arms of the linkage, requires considerable extension of the lift ram to elevate the forks. In orcler to minimize sway of the lifted article, plates are provided on each side of the vertical elements for the 25 Erames to ~ontain the vertical elements and prevent sway of the load. This places additional side hending moment.s on the vertical arms which could cause undue stresses in the frame if used to lift high tonnage loads.
Carter, United States patent 2,391,224, discloses a 30 parallelogram type linkage for a tractor loader. A frame is connected to the top of this linkage to control lifting of the linkage. The lift cyllnder for the frame is connected to the linkage and to the lifting Erame.
Although this arrangement may be suitable for low weigh-t 35 farm -tractor applications, due to the geometry of the lifting frame as connected to the parallelogram linkage for the fork results in e~treme bending moments in the parallelogram linkage and lifting frame. Furthermore, w:ith -the lifting frame atop -the paral:Lelogram linkage, visibili-ty forwardly of the tractor is hampered.
United States patent 2,656,058 discloses a type of paral.lelogram linkaye for lifting loads onto and off of a 5 truck. The frame consists of a single set of upper and lower arms forward of the frame. The lifting ram is positioned in a manner on the l.inkage to necessitate considerable extension and swing angle of the ram in lifting the forks. Such an arrangement, although 10 suitable for light loads in lifting materials onto and off the truck, is not acceptable for lifting high tonnage loadsO
United States patents ~,05~ 5 and 4,249,85~
disclose linkage mechanisms for lifting heavy loads.
15 ~Iowever in each arrangement, the lift cylinders are interconnected to the linkage mechanism in a manner which induces bending moments in the arms of the linkage when lifting heavy loads. United States patent 2,665,017 discloses a complex arrangement :involving parallelogram 20 linkage where the lift ram is interconnected to the arms of the parallelogram linkage. Due to its construction, extreme bending moments in the lifting arms result if the tractor loader is used to lift and manoeuvre hiyh tonnacJe objects.
Altho~lyh the pr.ior art patents have contemplated in many :Eorms the use o:E parallelogram linkages in lifting loads, no consideration has been given to the use of a parallelogram linkage in lifting high tonnage loads.
SUMMARY OF THE INVENTION
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According to an aspect of this invention, a heavy load lifting machine for elevating a heavy object off of and transporting the heavy object along the ~round comprises a motorlzed mobile vehicle having a structural load bearing frame~
The load-bearing frame has upright and base member means fixed relative to each other. The base member means extends forwardly of the upright member means. A
lifting linkage is secured to the frame comprising an outwardly extending upper arm and two outwardly extending lower arms of equal length. The upper arm has a first 3 ~3'73~

end pivo-ta:Lly connected to an upper central portion of the upright member means and each of the lower ~rms has a first end pivotally connected to a lower portion of the upright member means below -the first end of the upper 5 member. Carriage means is adapted for carrying the load comprising an upright frame to which a load-engaging means is connected. A second end of the upper arm is centrally pivotally connected to the carriage means frame and a second end of each of the lower arms is pivotally 10 connec-ted to the carriage means frame below the upper arm second end.
The lower arms include means for resisting sway in the lifting linkage when in use for carrying heavy loads.
Two lift hydraulic rams for the lifting linkage are 15 provided. Each ram has a first end pivotally connected to the base member means at a position intermediate the first and second ends of the lower arm. The ram has a second end pivotally connected to the carriage means frame to each side of the upper arm second end and alony 20 a pivotal axis defined by the pivotal connection of the upper member second end to the carriage means frame.
According to another aspec-t of the invent:ion, the load bearing frame may have riyid spaced-apart members provid:ing upright and base members fixed relative to each 25 other. The upper arm may be substitwted by two outwardly extending arms of e~ual length disposed to each side of a cen-tral portion of -the frame. Each of the upper arms has a first end pivotally connected to one of the upright members and each of the lower arms has a first end 30 pivotally connected to one of the upright members below the first ends of the upper members. A second end of each of the upper arms is pivotally connected to the carriage means frame. The second end of the ram is pivotally connected to the carriage means frame at the 35 pivotal connection of the second end of the upper memberO
According to a preferred aspect oE the invention, a tilt hydraulic ram may be used to interconnect the first end of the upper arm of the linkage to its pivo-t point of pivotal connection with the upright member of the suppor-tLrlg ~fame. Means may be included in the h~drauLic circuit for -the rams to absorb downwarcl shock loading on the lift:ing linkage during transport of the o~ject along the ground.
The heavy load lifting linkage, according to an aspect of this invention, may be mounted on a supportiny frame which may be other than a mobile frame such as found on a tractor body. E'or e~ample, the linkage may be mounted on a frame which is positioned so that the load 10 lifting linkage can elevate heavy loads from a first level to a second level on a repetitious basis.
~RIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention are shown in drawings, wherein:
Figure 1 is a perspec-tive view of the load lifting machine according to a preferred embodiment of the invention;
Figure 2 is a front elevation of the machine of Figure l;
Figure 3 is a top view of the machine of E'igure l;
Figure ~ is a side elevation Gf the machine of Figure l;
Figure 5 is an enlarged view of the lifting linkage as it is interconnected to the carriage frame for the 25 lift for~s;
E'igure 6 is a partial side elevation of the machine of Figure L exen~plifyinc~ tilting of the lif-t forks; and Figure 7 is a schematic view of the hydraulic system for the lifting, tilting and steering rams.
30 DETAILED DESCRIPI'ION OF THE PREFERRED E~BOD~MENTS
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The machine 10 of Figures 1, 2, 3 and 4 provides a system for lifting high tonnage loads, for example, in the range of up to forty tons or more and transporting those loads along rough terrain. The system is designed 35 in a manner to provide forward and lateral visibility at all elevation positions of the lifting linkage. This is accomplished by an arrangement for the linkage arms which are raised and lowered by special positioning oE the lift c~linders and interconnection to the lifting linkage.

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l-t is appreciated -that severa.L dif~erent arrangernents for the linkage arms may be used to accomplish the features of this invention. The machine 10, as shown in the drawings, exemplifies one embodiment 5 of the invention. The machine 10 is a mobile motorized vehi.cle having a tractor poxtion 12 with wheels 14 and a load bearing support frame 16 mounted on a tandem drive wheel arrangement 18. The load lifting linkage 20 is connected to the structural load bearing frame 16 of the 10 machlne 10 to provide for a raisiny and lowering of the carriage frame 22 to which load lifting elements, such as forks 24 may be connected. As shown in Figure 2, the tractor 12 has an operator cab 26 with forward window 28 and la-tera] windows 30 and 32 to provide complete 15 visibility in operating the lifting linkage 20. The carrier frame 22 comprises spaced-apart frame upright members 34 and 36. These upright carrier frame members are interconnected by cross-beams or members 38 and 40.
As shown in Figure 4, the fork 24 has a channel portion 20 42 which engages the upper ridge 41 of cross member 40.
The ].ower portion 44 of the fork 24 rests against the lower cross member 38 to thereby support a load lifted on the fork tangs 46.
The llfting linkage 20 of Figu,re 3 consists of two 25 upper arms 48 and S0 of eclual length and lower arms 52 and 5~ of equal l.ength. The lower arms 5Z and 5~ include an arrangernent to resist sway from side to side during transport. ~ccording to a preferred embodiment, the lower arms 52 and 54 converge towards one another in the 30 direction of carriage frame 22 relative to the upper arms 48 and 50. The upper arms 48 and 50 are essentially parallel to one another~ By arranging the lower arms so as to converge towards one another, the arms are placed in compression if there is a force inducing a lateral 35 sway in the lifting linkage. In turn, the lower arms then resist this sway. It is appreciated that the lower arms could also diverge away from one another in the direction of the carriage frame 22 relative to the upper arms 48 and 50. The same effect would be achieved in the 6 ~ t7~ ~ ~

lower arms dlverging for res:istiny lateral sway of the lifting linkage. It is also appreciated that -the lower arms may be placed paral.lel to one another and by suitable cross bracing between the two lower parallel 5 arms, lateral sway can be resisted.
As shown in Figures 1 and 4, the structural load bearing frame 16, as supported by the -tandem wheel arrangement 18, has rigid spaced-apart members in the form of base members 55 and 56 and upright members 57 and 10 58 on each side of the frame 16. The upper arms 48 and 50 are each connected at one end to the upright members 57 and 58 and at the other end to the carriage frame uprights 3~ and 36. The upright member 58 has at its upper portion a yoke 60 consisting of spaced-apart plates 15 62 and 64 as shown in Figure 3. The upper arm 50 at a first end 49 has a connector portion 66 with an eye through which connector bolt 68 extencls to provide for a pivotal connection of a connector portion 66 of the upper member 50 to a bearing in the upright member 58. At the 20 second end 69 of the upper member, as shown in Figure 3, it has secured there-to a yoke portion generally designated 70 and comprises spaced-apart plates 72 ancl 74. A pin 76, as shown in more detail in Fiyure 5, extends through the plates 72 and 74 to complete a 25 pivotal connection to a bearing in the upr:ic~ht :Erame member 34 oE the carriage 22. ~imi].arly, the first end 47 of the upper member 48 is pivota].ly connected to the uprlgh-t member 57 at connector portion 67. At the second end 71 of the upper member, it is pivotally connected to 30 the upright 36 by way of a similar yoke connector 70.
Each of the lower arms 52 and 5~ are pivotally connected to the upright members 58 of the support frame at a location below the point of connection of the first ends oE the uppe~ members 48 and 50. As shown in Figure 35 4, the lower member 54 is p.ivotally connected to the upright member 58 by way of a pin 73 extending through a bearing in the upright member 58 and through corresponding coupling 80 of the first end of the lower member 5~. The lower members 5~ and 54 converge towards 7 ~ 3~

one another ~or connec-tion to the cross-member A0 of -the carriage 22. The lower members 52 and 5~ are welded to a common plate 82 as shown in Figure 5, and which is pivotally connected to the cross-member 5~ by yokes 84 as 5 shown more readily in Figure 3, Each yoke 84 includes spaced-apart plates 86 and 88. The common plate 82 has two ou-twardly extending connectors 90 and ~2 which are received between the respective plates ~6 and 88 and connected thereto by the pin 9~, as shown in Figure 5.
In order to raise and lower the lifting linkage 20, two lift rams 96 and 98 of Figure 1 are interconnected between the vehicle frame and the linkage mechanism. A
first end of the lift ram 96 is pivotally connected at 100 to the base member 56 of the support frame 16. The 15 point of interconnection is intermediate and below the ends 80 and 82 of the lower member 54. According to this preferred embodiment of the invention, the point of ram interconnection is located approximately centrally between the :Eirst and second ends ~0, 82 o-f the

2~ respective lower member. As shown in Figure ~, the second end 102 of the lift ram 96 is pivotally connec-ted to the same pivot pins 76 orming the interconnection of t.he upper arm 50 to the carriage frame upright member 3~, Thus, the pivot axes for each second end o:E the hydraulic 25 ram are concentric with the plvot axes for the second erld 70 of each o:E the upper members ~8 and 50.
The tractor 12 is hinged:ly connected to the support frame 16 by way of an articulation connecti.on 104 which provides for both articulated steering of the machine 10 30 and oscillation of the tractor 12 relative to the load bearing frame 16. The articulated steering is controlled by a pair of hydraulic rams (not shown) in Figure ~, yet to be discussed with respect to Figure 7. By hydraulic controls a swinging action of the tractor 12 re]ative to 35 the load bearing frame 16 may be effected as shown by positions 12a and 12b in Figure 3. The load lifting linkage 20 is connected to the load bearing frame 16 of the machine in a manner to provide a parallelogram type linkage between the pivot points represented by pins 6~

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a~d 76 of ~he upper arms ancl pins 7~ and 9~ oE the lower arms. To provide additional strength in loading hearing characteristics for the lower arms, cross-bracing such as interconnecting tube 106 is provided to resist torsion 5 and lateral sway in the load lifting linkage induced by carrying a load on the forks 24.
As shown in Figure 4, the elevation of the forks 24 may be varied as indicated by arrow 108, by either extending or retracting the hydraulic rams 96 and 98.
10 From the position shown in Figure 4, extension of the rams 96 and 98 to the position 96a for the ram, upper arm position 50a and lower arm position 54a, the linkage rotates about the pivot points of this preferred parallelogram arrangement for the linkage system. By 15 positioning the hydraulic rams 96 and 98 with their po:Lnts to the load bearing frame 16 intermediate the length of the lower arms, minimal extension of the rams is required to provide a considerable height variation oE
the fork 24 as represented by arrow 108. Due to the 20 heavy load ]iEting requirements of the carriage frame, the less extension of the ram to provide considerable lifting of the heavy load results in less volume of hydraulic oil that has to be pumped into the rams 96 and 98. Furthermore, by positioning the rams in the manrler 25 shown in Eigure 4, the vert:Lcal lifting of the load is mQre ~eacl:ily accomplished in providing less s-train on the load bearing frame, because the rams are assuminy a more vertical position than would be the case if the lower end of the ram were connected more rearwardly at the upright 30 membexs 58 of the load bearing frame. According to this preferred arrangement, by converging the lower arms 52 and 54 in the manner shown in Figure 3, sufficient space is provided to locate the lifting rams 96 and 98 directly below and in line with the upper arms 48 and 50 to 35 increase the lifting capacity of the linkage arrangement.
In order to pick up some heavy objects off the ground, it is necessary to tilt the forks 24~ The upper arms 48 and 50 of the linkage arrangement may include tilt cylinders 108 and 11~ as shown ln Figure 3. The .. ~

cylinders ]U8 and 11~ are connec-ted to -the arrns 48 and 50 where the rod ends 66 and 67 of the rams 108 and 11~ are connected to the uprights 57 and 58 of the frame support structure 16. With the rams 108 and 114 provided in -the 5 upper arms 48 and 50, the rams then function to interconnect first ends 47 and 49 of the upper arms to the pivot points on the upright members 57 and 58 of the support frame. By extension and retraction of the rams 1~8 and 11~, the fork 24 may be tilted as demonstrated in 10 Figure 6 in the direction o:E arrows llU and 112 to a position 24a. By retracting the rams 108 and 114, the arms 50 move upwardly to the position shown at 50a. The carrier frame 22 is tilted about pin 94 to tilt the forks to the position 24a. During this tiltiny operation, the 15 lift ram 96 retains a constant length so -that the entire lift linkage 20 is pivoted upwardly about the pivot points on the frame 16. It is appreciated, however, that in some situations where tilting of the forks is not necessary, then the rams lU8 and 11~ are not required in 20 the upper arms 48 and 50.
The embodiment shown in Figure 6 provides a parallelogram-t~pe linkage arrangement for the upper and lower arms. It is understood, however, that tllting of the forks 24 ma~ be accentuated by adapting a 25 non-parallellogram~type arrangement for the upper and low~r arms. With reference to Figure 6, the distance between pivot pins 68 and 78 for the first en~s of the upper and lower arms may be less than the distance between the pivo-t pins 76 and 94 for the second ends oE
30 the upper and lower arms. By decreasing the distance between the pivotal pins 68 and 78, when the linkage mechanism is elevated by extension of rams 96 and 98, the upper arm has to swing further upwardly to permit upward swinging of the lower arms which results in pulling back 35 pivot point 76 further and thereby accentuating the tilt of the forks 24.
Thus by a manipulation of two sets of rams, a versatile, mobile load lifter for heavy objects of the forty ton range or more is provided.

r~eferriny to Figure 7, the hydraulic circuits ~or -the tilt and 1ift rams and for the steering rams is schema-tically shown. A master controller 1.16 is provided to control the flow of pressurized hydraulic fluid to the 5 tilt rams 108 and 114, the lift rams 96 and 98 and the steering rams 118 and 120. A pump 122 supplies pressurize~ hydraulic fluid to the master controller 116.
A reservoir 124 receives pressurized hydraulic fluid returned from the system. In accordance with standard 10 hydraulic systems, the pump 122 may withdraw fluid from the reservoir 124 in resupplying pressurized hydraulic fluid to the master controller 116. It is further appreciated that the master controller 116 includes valviny arrangements to properly control the flow of 15 hydraulic fluid in the system circuits. The valving arrangement are operated by control knobs..
The hydraulic circuit for the lift rams 96 and 98 include fluid lines 126 and 128. In line 126 is a flow divider 130 which ensures that all pressurized hydraulic 20 fluid, either going into the rams or being removed from the rams, is equally divided between the lift rams to ensure that the parallelogram linkage is always uniformly raised at both sides. The divider 130 may be of the standard ~ear Elow divider whi.ch splits the fluicl flow o~
2S line 1~6 and p.rovides equal fluid volume.s -to the closed ends 132 and 134 of the lift rams. The ram rods 136 and 133 are connected to the frame uprights 34 and 36 in the manner discussed with respect to Figure 5. When the master control is operated to release pressurized fluid 30 from the closed ends of the rams 96 and 9~, the flow divider 132 ensures that equal volumes of fluid flow out o:E the rams to ensure a uniform lowering of the linkage mechanism.
When the tilt cylinders 108 and 114 are used in 35 conjunction with the upper arms of the lifting linkage, the hydraulic fluid in the tilt ram circuits flow through lines 1~0 and 142. When it is desired to tilt the forks upwardly, the tilt rams are retracted. This is accomplished by providing pressurized hydraulic fluid in :L:i ~2~

line :L40 as div:ided be-tween the rams 108 anc( 11~ at tee intersection 144 to supply pressurized fluid to the rod ends ]46 and 148 of the tilt rams. The hydraulic fluid in the closed ends 150 and 152 flow out of the cylinders 5 to the tee 154 and return via line 142 to the reservoir 124 through the master control 116~ When it is desired to tilt the forks downwardly, pressurized fluid is provided in line 1~2 to extend the rams 1.08 and 114 where the hydraulic fluid flowing out of the rod sides 146 and 1~8 10 of the eylinders is returned to the reservoir 124 through the master controller.
Once the load is raised off of the ground and the forks 24 tilted to -the desired angular loeation, the wheels of the vehicle may drop into ruts or pass over 15 bumps whieh eauses a downward shoek loading on the forks 24 due to the weight of the object being earried. To avoid over stressing the link arms of the liftlng llnkage, a shock absorber ls provided for the rod ends 146 ancl 148 of the rams 108 and 114. The shoek absorber, 20 aecording to thls lnvention, eonsists of an aeeumulator 156 in the hydraulie eircuit 140 whieh has a eavity 158 filled with hydraulie fluid from line 1~0. ~ reclprocal dlvlder 160 separates a eompressible gas 162 :Erom th~
hydraulic fluid in eav.ty 158. When a downward shock ls 25 applied to the carrylng frame, the gas 162 ls compressecl due to the shock load attempting to extend the rods 162 and 16~ out of the rams 108 and 11~. However due to the master controller bloeking off llnes 1~0 and 142, the fluid eannot eseape so that the shoek is absorbed by 30 eompresslon of the gas 162 in the aeeumulator 156.
It is appreeiated that shoek loading of the frame may also be aceommodated by providing a shock absorber system in the lift rams, instead of with the tilt rams.
With referenee to Figure 7, an aeeumulator such as 156 35 used with the tilt rams can instead be placed in line 126 to absorb shoek loading by eompression of the gas eon-tained within the aeeumulator 156. It is understood, of eourse, that modifieation would also be have to be macde to the c3as aeeumulator to eompensate for the l2 ~ 3~

ad~i-tlonal load placecl on the lifting rams during raisiny and lowering of -the heavy loads.
The articulating s-teering for the vehic:le is effec-ted by -the steeriny rams 118 and 120 ~hich are 5 installed on both sides of the articulated connection for -the tractor and the load bearing frame. The rams are operated in reverse of each other so that when it is desired to turn in one direction, ram 118 is extended and ram 120 is retracted. Conversely when it is desired to 10 turn in the opposite direction, ram 118 is retrac-ted and ram 120 extended. Thus the circuitry for the steering rams is arranged to have line 166 communicate with the rod side 168 of ram llæ and the closed end 170 of ram 120. Line 172 communicates conversely with the closed 15 end 174 of ram 118 and the rod end 176 oE ram 120.
The structure of the lifting linkage, according to this invention, is capable of lifting very heavy loads and transporting them over rough terrain. Due to the articulated oscillating connection of the tractor 12 to 20 the support frame 16 and the tandem wheel arrangement 18, the load on the forks 24 remains reasonably level during transport. By locating the lift rams in the manner discussed with respect to Figure ~, considerable weigh-t can be raised and transported without placing bending 25 rnoments on the linkage arms. Instead, the members are r?laced :in tension or cornpression therehy optimizing their structural rigidity. As shown ln Figure 2, with the ability to raise and lower heavy loads, the linkage mechanism provides for unobstructed viewing forwardly of 30 the tractor cab 26 through the front windows. This is a significant advantage in the field of raising heavy loads due to the need to clearly see the area of opera-tion, so that industrial accidents are minimized.
The lower arms 5~ and 5~ converge towards the 35 carriage frame 22. This not only provides room for ~he lift rams 9~ and 98 as they extend from the base members of the support frame to the pivots points of the carrier upright members, but adds appreciably to the linkage resisting sway caused by movement of heavy loads over .

13 ~ 3~3 rouyh -terrain. By havlng the members 52 and 5~ welded -to a common p]ate 82 and the pla-te in turn pivotally connected to the carrier frame, sway is resisted by first of all the converging aspec-t of the arms and secondly, 5 the use of the common plate which increases resistance -to sway of the carrier 22 relative to the vehicle frame. To further strengthen the lower members in resisting sway and torsion, cross~bracing, such as at 106 as shown in Figure 3, may be added. By virtue of placing the lower 10 arms 52 and 54 in tension or compression, very heavy loads may be handled by the machine. At the same time, an overall lighter structure can be provided which is readily fabricated and easily mounted to the vehicle and yet provide unobstructed viewing forwardly of the 15 vehicle.
It is appreciated that the liEting mechanism may be mounted on a variety of mobile or stationary frames. For purposes of discussing the invention, the lifting linkage has been described with respect to a mobile frame.
20 ~Iowever in areas where it is only necessary to elevate heavy loads from one level to another without travel, it is possible to mount the system on some other form of stationary supporting structure. In o-ther circumstances, ~he llftincJ mechanism may be mounted on a rotary 25 turntable for a lifting heavy load and rotating the heavy load to a diEferent location.
It is appreciated that the upper arms for the lifting linkage may be substituted by a single upper axm which extends from a central region of the load bearing 30 frame to the central region of the carriage frame 2~. In this instance, the support frame 16 would consist of a base member means having the spaced-apart base members 56. An upright member means would include at least the lower portion of the upright members 58 to which the 35 lower arms 52 and 54 would be pivotally connected. Above this area, the pair of upright members 58 would be modified to provide a central abutment central of the vehicle and to which the first end of the single upper arm would be pivotally connected. Similarly, centrally 1~

oE the carri.~.lge :~rame 22 a fi~ed member would be pro~ided -to which a second end of -the single upper member wou].d be pivo-tally connected. The upper ends of the lift rams 96 and 98 would be pivotally connected to the carriage frame 5 22 to each slde of the single upper arm. The pitoval axes of the upper ends of the lift rams would be coincident with the pivotal axis of the connection for the single upper arm to the carriage frame 22. With this arrangement of two spaced-apart lower arms and the single 10 upper arm, the lifting linkage can continue to function in lifting heavy loads where all arms are placed in tension or compression during raising and lowering of the loads. A tilt cylinder, as u~ed with one of the upper arms as shown in the drawings, could also be used with 15 the single upper arm to provide tilting of the carriage frame 22.
It is also understood -that the lower arms may diverge rather than converge towards the carriage frame 22. The base portions of the upright 58 would be 20 modified to provide a centrally located member to which the first ends o~ the lower arms may be attached. The arms wou:Ld then diverge outside of the lifting rams 96 and 98 and be pivotally connected to the carriage frame below the pivot points oE the upper arms. Another 25 al-ternative to the arrangement for -the lower arms i5 that t:hey may be paralle]. to one another and include cross brac:i.ng which resists sway and torsion in -the lower arms when the system is in use. When the lower arms are provided parallel to one another, the lifting rams 96 and 30 98 are positioned so as to be either inside or outside of the lower arms so that there is no interference between the lower arms cross-bracing and the movement of the lifting rams.
Although preferred embodiments of the invention have 35 been described herein in detail, it will be understood by those skilled in the art that variations may be made thereto without departing from the spirit of the invention or the scope of the appended claims.

Claims (41)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A heavy load lifting machine for elevating a heavy object off of and transporting a heavy object along the ground, said machine comprising a motorized mobile vehicle having a structural load-bearing frame, said frame having upright and base member means fixed relative to each other, said base member means extending forwardly of said upright member means, a lifting linkage secured to said frame comprising an outwardly extending upper arm and two outwardly extending lower arms of equal length, said upper arm having a first end pivotally connected to an upper central portion of said upright member means, and each of said lower arms having a first end pivotally connected to a lower portion of said upright member means below said first ends of said upper member, carriage means adapted for carrying a load comprising an upright frame to which a load engaging means is connected, a second end of said upper arm being centrally pivotally connected to said carriage means frame and a second end of each of said lower arms being pivotally connected to said carriage means below said upper arm second end, said lower arms including means for resisting sway in said lifting linkage when in use for carrying heavy loads, two lift hydraulic rams for said lifting linkage, each said ram having a first end pivotally connected to said base member means intermediate said first and second ends of said lower arm and said ram having a second end pivotally connected to said carriage means frame to each side of said upper arm second end and along a pivotal axis defined by said pivotal connection of said upper member second end.

2. A machine of claim 1, wherein said means for resisting sway in said lifting linkage comprises arranging said lower arms to converge relative to each other towards said carriage means frame.

3. A machine of claim 1, wherein said means for resisting sway in said lifting linkage comprises arranging said lower arms to diverge relative to each other towards said carriage means frame.

4. A machine of claim 1 or 2, wherein said lower arms included cross-bracing means for interconnecting said lower arms intermediate their first and second ends.

5. A machine of claim 1, wherein said means for resisting sway in said lifting linkage comprises arranging said lower arms parallel to each other, said lower arms include cross-bracing means for interconnecting said lower arms intermediate their first and second ends.

6. A machine of claim 1, wherein said frame has rigid spaced-apart members, each said member having upright and base members fixed relative to each other, said upper arm being substituted by two outwardly extending arms of equal length disposed to each side of a central portion of said frame, each of said upper arms having a first end pivotally connected to one of said upright members and each of said lower arms having a first end pivotally connected to one of said upright members below said first ends of said upper members, a second end of each of said upper arms being pivotally connected to said carriage means frame, said ram having said second end pivotally connected to said carriage means frame at said pivotal connection of said second end of a respective said upper member.

7. A machine of claim 6, wherein the arrangement of said upper and lower arms is such to form a parallelogram-type load lifting linkage.

8. A machine of claim 6, wherein said means for resisting sway in said lifting linkage comprises arranging said lower arms to converge relative to each other towards said carriage means frame.

9. A machine of claim 6, wherein a tilt hydraulic ram interconnects said first end of each said upper arm to its point of pivotal connection with said upright member, said rams for said upper arms tilting said carriage means frame when actuated.

10. A machine of claim 9, wherein a hydraulic circuit supplies and removes pressurized hydraulic fluid to and from said tilt rams, means included in said hydraulic circuit for said tilt rams for absorbing downward shock loading on said tilt rams during transporting of a heavy object along the ground.

11. A machine of claim 10, wherein said means for absorbing shock loading on said tilt rams comprises an accumulator cylinder having a confined compressible gaseous medium for absorbing downward shock loading on said tilt rams.

12. A machine of claim 6, wherein a hydraulic circuit which supplies and removes pressurized hydraulic fluid to and from said lift rams includes means for absorbing downward shock loading on said lift rams during transporting of a heavy object along the ground.

13. A machine of claim 8, wherein a tilt hydraulic ram interconnects said first end of each said upper arm to its point of pivotal connection with said upright member, said rams for said upper arms tilting said carriage means frame when actuated.

14. A machine of claim 13, wherein a hydraulic circuit supplies and removes pressurized hydraulic fluid to and from said tilt rams, means included in said hydraulic circuit for said tilt rams for absorbing downward shock loading on said tilt rams during transporting of a heavy object along the ground.

15. A machine of claim 14, wherein said means for absorbing shock loading on said tilt rams comprises an accumulator cylinder having a confined compressible gaseous medium for absorbing downward shock loading on said tilt rams.

16. A machine of claim 8, wherein a hydraulic circuit which supplies and removes pressurized hydraulic fluid to and from said lift rams includes means for absorbing downward shock loading on said lift rams during transporting of a heavy object along the ground.

17. A machine of claim 6, wherein a hydraulic circuit supplies and removes pressurized hydraulic fluid to and from said lift rams, means included in said hydraulic circuit for said lift rams for equally dividing flow of hydraulic fluid to and from said lift rams to ensure thereby a level lifting and lowering of said lifting linkage.

18. A machine of claim 6, wherein said vehicle has articulated steering as effected by an articulated connection between a tractor section and said structural load bearing frame.

19. A machine of claim 18, wherein said structural load bearing frame is supported above ground by a tandem wheel arrangement.

20. A machine of claim 8, wherein said upper arms are essentially parallel to each other.

21. A machine of claim 20, wherein said first ends of said lower arms are spaced apart essentially the same width as said first ends of said upper arms.

22. A machine of claim 21, wherein said second ends of said converging lower arms are secured to a common plate means, said plate means being pivotally connected to said carriage means frame below said second ends of said upper members.

23. A machine of claim 6, wherein said carriage means frame comprises spaced apart essentially upright frame members interconnected by a cross-member means, each of said second ends of said upper arms being pivotally connected to one of said upright frame members, said plate means being pivotally connected to said cross-member means.

24. A heavy load lifting linkage for attachment to a supporting frame, said linkage comprising an upper arm and two lower arms of equal length, carriage means adapted for carrying a load comprising an upright frame to which a load engaging means is connected, a first end of said upper arm being adapted for pivotal connection to a supporting frame, a first end of each of said lower arms being adapted for pivotal connection to a supporting frame below and to each side of said first end of said upper member, a second end of said upper arm being centrally pivotally connected to said carriage means frame and a second end of each of said lower arms being pivotally connected to said carriage means frame below said second end of said upper member, said lower arms including means for resisting sway in said lifting linkage when in use for carrying heavy loads, two lift hydraulic rams for said lifting linkage, each said ram having a first end adapted for pivotal connection to a supporting frame and a second end adapted for pivotal connection to said carriage means frame to each side of said upper arm second end and along a pivotal axis defined by said pivotal connection of said second end of said upper member, said ram being of a length to locate said ram first end for pivotal connection to a supporting frame intermediate said first and second ends of said lower arm.

25. A heavy load lifting linkage of claim 24, wherein said means for resisting sway in said lifting linkage comprises arranging said lower arms to converge relative to each other towards said carriage means frame.

26. A heavy load lifting linkage of claim 24, wherein said means for resisting sway in said lifting linkage comprises arranging said lower arms to diverge relative to each other towards said carriage means frame.

27. A heavy load lifting linkage of claim 24, wherein said means for resisting sway in said lifting linkage comprises arranging said lower arms parallel to each other, said lower arms include cross-bracing means for interconnecting said lower arms intermediate their first and second ends.

28. A heavy load lifting linkage of claim 24, wherein said upper arm is substituted by two outwardly extending arms of equal length, each of said upper arms having a first end pivotally connected to a supporting frame, a second end of each of said upper arms being pivotally connected to said carriage means frame, said ram having said second end pivotally connected to said carriage means frame at said pivotal connection of said second end of said supper member.

29. A heavy load lifting linkage of claim 24, wherein the arrangement of said upper and lower arms is such to form a parallelogram-type load lifting linkage.

30. A heavy load lifting linkage of claim 29, wherein said means for resisting sway in said lifting linkage comprises arranging said lower arms to converge relative to each other towards said carriage means frame.

31. A heavy load lifting linkage of claim 23, wherein a tilt hydraulic ram interconnected said first end of each said upper arm to its point of pivotal connection with a supporting frame, said rams for said upper arms tilting said carriage means frame when actuated.

32. A heavy load lifting linkage of claim 31, wherein a hydraulic circuit supplies and removes pressurized hydraulic fluid to and from said tilt rams, means included in said hydraulic circuit for said tilt rams for absorbing downward shock loading on said tilt rams during transporting of a heavy object along the ground.

33. A heavy load lifting linkage of claim 32, wherein said means for absorbing shock loading on said tilt rams comprises an accumulator cylinder having a confined compressible gaseous medium for absorbing downward shock loading on said tilt rams.

34. A heavy load lifting linkage of claim 28, wherein a hydraulic circuit which supplies and removes pressurized hydraulic fluid to and from said lift rams includes means for absorbing downward shock loading on said lift rams during transporting of a heavy object along the ground.

35. A heavy load lifting linkage of claim 30, wherein a tilt hydraulic ram interconnects said first end of each said upper arm to its point of pivotal connection with said upright member, said rams for said upper arms tilting said carriage means frame when actuated.

36. A heavy load lifting linkage of claim 35, wherein a hydraulic circuit supplies and removes pressurized hydraulic fluid to and from said tilt rams, means included in said hydraulic circuit for said tilt rams for absorbing downward shock loading on said tilt rams.

37. A heavy load lifting linkage of claim 36, wherein said means for absorbing shock loading on said tilt rams comprises an accumulator cylinder having a confined compressible gaseous medium for absorbing downward shock loading on said tilt rams.

38. A heavy load lifting linkage of claim 37, wherein said means for absorbing shock loading on said tilt rams comprises an accumulator cylinder having a confined compressible gaseous medium for adborsing downward shock loading on said tilt tams.

39. A heavy load lifting linkage of claim 30, wherein a hydraulic circuit supplies and removes pressurized hydraulic fluid to and from said lift rams, means included in said hydraulic circuit for said lift rams for equally dividing flow of hydraulic fluid to and from said lift rams to ensure thereby a level lifting and lowering of said lifting linkage.

40. A heavy load lifting linkage of 30, wherein said second ends of said converging lower arms are secured to a common plate means, said plate means being pivotally connected to said carriage means frame below said second ends of said upper members.

41. A heavy load lifting linkage of claim 30, wherein said carriage means frame comprises spaced apart essentially upright frame members interconnected by a cross-member means, each of said second ends of said upper arms being pivotally connected to one of said upright frame members, said plate means being pivotally connected to said cross-member means.