US3842997A - Lifting device - Google Patents

Lifting device Download PDF

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Publication number
US3842997A
US3842997A US00411395A US41139573A US3842997A US 3842997 A US3842997 A US 3842997A US 00411395 A US00411395 A US 00411395A US 41139573 A US41139573 A US 41139573A US 3842997 A US3842997 A US 3842997A
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US
United States
Prior art keywords
platform
power cylinder
rocking lever
lifting
parallelogram arm
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00411395A
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English (en)
Inventor
G Sprikkelman
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
MARIBA BV
Original Assignee
AVO INTERN TRANSPORT
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Filing date
Publication date
Application filed by AVO INTERN TRANSPORT filed Critical AVO INTERN TRANSPORT
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Publication of US3842997A publication Critical patent/US3842997A/en
Assigned to VON WIENWALD, A.E. SCHAEFFER, TRUSTEE reassignment VON WIENWALD, A.E. SCHAEFFER, TRUSTEE COURT APPOINTMENT (SEE DOCUMENT FOR DETAILS). AUG 25, 1981 Assignors: JUDGE OF THE DISTRICT COURT OF ZUTPHEN, FOR AVO INTERN TRANSPORT B.V., BANKRUPT
Assigned to MARIBA B.V. reassignment MARIBA B.V. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: AVO INTERN TRANSPORT B.V., IN BANKRUPTCY, BY: A.E. SCHAEFFER, TRUSTEE
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60P—VEHICLES ADAPTED FOR LOAD TRANSPORTATION OR TO TRANSPORT, TO CARRY, OR TO COMPRISE SPECIAL LOADS OR OBJECTS
    • B60P1/00—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading
    • B60P1/44—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading having a loading platform thereon raising the load to the level of the load-transporting element
    • B60P1/4414—Vehicles predominantly for transporting loads and modified to facilitate loading, consolidating the load, or unloading having a loading platform thereon raising the load to the level of the load-transporting element and keeping the loading platform parallel to the ground when raising the load

Definitions

  • a lifting device for instance fitted as a lifting platform assembly to a truck, consisting of a lifting platform and one or more parallelogram-shaped articulated rod-systems, by which rods or arms this platform is directly or indirectly pivotingly connected to a carrying structure fitted to the truck chassis.
  • One parallelogram arm is capable of telescoping and the platform is driven and controlled by a hydraulic power system.
  • the platform has four positions--lifted approximately vertically at maximum height, lifted horizontally at maximum height, lowered horizontally on ground and lowered in downward sloping position on ground.
  • a single power cylinder means performs all three functions.
  • the pivot point of one parallelogram arm is connected to the carrying structure through a rocking lever, and the power cylinder is pivotingly attached to this rocking lever.
  • PATENTEDncrzzxsn SHEET 2 OF 4 7 7 l9 "AV A ⁇ V/T ⁇ me no 6' PATENTED 3.842.987
  • This invention relates to a lifting device, for instance fitted as a lifting platform assembly to a truck, consisting of a lifting platform, one or more parallelogramshaped articulated rod-systems, by which rods or arms this platform directly or indirectly being pivotingly connected to a carrying structure, this structure being fitted to for instance a truck chassis, one parallelogram arm being capable of telescoping, the platform being driven and controlled by a hydraulic power system, the platform having four positions lifted approximately vertically at maximum height, lifted horizontally at maximum height, lowered horizontally on ground and lowered in downward sloping position on ground and, in doing so, three different motions (three func tions), a single power cylinder means being applied to perform all three functions, the pivoting point of one parallelogram arm viewing the carrying structure being connected to the carrying structure through a rocking lever, and the connection of the power cylinder viewing the carrying structure being pivotingly attached to this rocking lever.
  • Lifting devices of this kind are known in the art having a variety of forms and can for instance be applied to railway carriages, agricultural apparatus, trucks, aircraft, stationary installations and on all these places, where the extending parallelogram-shaped articulated rod-system can be accommodated without trouble.
  • German Offenlegungsschrift Pat. No. 1,580,379 describes a device which is basically similar to the one of this application. It also makes use of one power cylinder to perform all three functions. It has also got a rocking lever between the carrying structure and the end of one of the parallelogram arms and the power cylinder. The position of the pivoting point of the rocking lever is such that a special clamp must be withdrawn to enable the lifting platform to be lowered into the downward sloping position.
  • the positions 1, 2, 3 and 4 should be exactly the shifting points between the motions X, Y and Z.
  • the motions X, Y and Z may not shift unobserved into each other, in order to possess over a selective control system.
  • the fixed pivoting point of the rocking-lever on the carrying structure is positioned between the point of connection of the lower parallelogram arm and the point of connection of the power-cylinder on the rocking lever.
  • the point of connection of the power piston viewing the lifting platform can be located on two different places. According to the first possibility this point is located on that part of the lower telescoping parallelogram arm, which is nearest to the lifting platform. According to the second location, this point of connection of the power piston can be located on the short parallelogram arm which is part of the lifting platform or may be the carrying parallelogram arm to the lifting platform. For the first solution there is less power required to lift the platform from the horizontal position at maximum height to the vertical position at maximum height, but a locking latch must be fitted to the telescoping parallelogram arm to avoid any risk that the telescoping arm would telescope-out during the horizontal lifting procedure. This, in fact, would cause serious danger and should therefore be banished out.
  • the second solution is absolutely safe without a locking latch over the telescoping arm, but requires a higher pressure in the power cylinder, to move the lifting platform from the horizontal into the vertical position.
  • the first solution means for automatically locking the latch during all lifting actions of the platform can be fitted. Only for the vertically positioning of the platform, unlocking of the latch should be done by hand as a separate action. By choosing the second solution this complication is avoided.
  • top-pressure in this system can only be reached when a lower set safety valve or other liftlimiting device is unlocked.
  • a safety margin which is used during the lifting activities with or without loads, an unforeseen and unwanted move over X from position 2 to position 1 is impossible. Only an intented action will make the move over X possible.
  • position 1 the lifting platform forms a closing wall of the cargo hold of the truck. If the platform is locked in this position, the hydraulic system can be unloaded, resulting in position I being a rest position. Also position 4 is a rest position, in which the hydraulic system can be unloaded.
  • the power cylinder according to this invention is single acting and pushing and therefore of the utmost simplicity. If it is useful for reasons of occupied place or cost, to make use of two or more smaller power cylinders instead of one large, then this is possible by connecting the power cylinders mechanically and hydraulically parallel to each other. The total stroke should remain unaltered, to make possible all motions.
  • the blocking latch of the telescopic parallelogram arm is unloaded during almost all normal service positions and situations. This is an advantage and contrary to most of the other locking devices in previous art lifting apparatus.
  • the platform When the platform is wanted to be placed vertically, i.e., from position 2 to position 1, this is done with an unloaded platform. Also in this situation the locking latch is unloaded, therefore unlocking is easily performed. Due to the horizontal working position of the platform, the telescope will always automatically telescope-in, resulting in an automatic locking of the latch thanks to its own weight.
  • the unlocking means is spring-loaded in its rest-position, in which the locking latch is locked. By moving the unlocking means into the unlocking position, the latch will be unlocked, freeing the telescope to move out.
  • the stroke of the power cylinder should be chosen sufficiently long, to enable the angle over which the platform can be pivoted from position 3 to position 4, to be larger than the top angle of the platform.
  • the top or point of the platform can touch the ground, also when the ground being not absolutely horizontal. It is, however, of greater importance, that the lifting platform will be held horizontal between position 3 and position 2, in order not to enlarge the risk that the load should fall off.
  • the lifting platform stays parallel to the truck floor during lifting and lowering, resulting in a sloping lifting platform when the truck floor also is sloping.
  • This disadvantage is avoided according to the invention, by the rocking lever, which performs the dislocation of one of the points of connection of the parallelogram-shaped rod-systern. having an adjustable stop.
  • a small hydraulic power cylinder could be placed between the stop and the rocking lever.
  • the control of it can take place separately, but it may also be integrated or even automated. If the platform might come to rest with its sharp end on a platform-quay, and in case the level of the truck would fall due to compressing its springs, part of the weight will come to rest on the platform and the whole lifting platform assembly, this being not wanted and even dangerous.
  • the main power cylinder can stay locked in that position to carry the load, the sharp end of the platform remaining free to move up and down within certain limits.
  • the lifting platform When putting the lifting platform into service from the rest position 1, the lifting platform will have to descend but also rotate into the horizontal position. In order to make sure that this action will take place automatically, without risking accidents or incorrect human actions, according to the invention the lifting platform should fulfil the requirement that there should be a minimum distance between the center of gravity of the unloaded platform and the line through the pivoting point of the platform.
  • This formula reads: r S-cosda [l/a +b -(l-l'/l') Sinda]. (The symbols can be found in the FIGS.).
  • FIG. 1 shows a lifting platform according to the invention in the'approximately vertical position at maximum height, being position 1.
  • FIG. 2 shows the same lifting platform as in FIG. I, in the horizontal position at maximum height, being position 2.
  • FIG. 3 shows the lifting platform in the horizontal position on the ground, being position 3.
  • FIG. 4 shows the lifting platform in downward sloping position on the ground, being position 4.
  • FIG. 5 shows schematically the mechanism for the static calculation.
  • FIG. 6 shows schematically the four different positions of the lifting platform and the three motions or functions through which the platform moves.
  • FIG. 7 shows the same lifting platform as in the previous figures, but without locking latch and with alternative position of the point of connection of the power cylinder viewing the platform, with the platform.
  • FIG. I the rear side of the truck is indicated with l, 2 being the chassis member, 3 the trucks loading floor, 4 the end of the loading floor and 5 the carrying structure to the chassis for the lifting device.
  • the lifting platform 6, with a closed load side 6' and a generally open ground side 6" is supported on the parallelogram arms 7 and 8, forming part of the parallelogramshaped articulated rodsystem.
  • the lifting platform is pivotingly connected to the parallelogram arms 7 and 8, these arms being themselves coupled to the carrying structure 5 at the pivoting points 11 and 12.
  • the lower parallelogram arm 8 can telescope in and out at 13, the telescoped-in position being limited by means of a shoulder 14.
  • the hydraulic power cylinder 15, being single acting and pushing, is equiped with a single connection 16 for the pressure medium.
  • the piston rod 17 is extending.
  • the pivoting points 18 and 19 act as reaction points for the power cylinder.
  • the point 18 is situated on a short distance from the pivoting point on the lower parallelogram arm 8.
  • the pivoting point 19 is situated at one end of the rocking lever 20, the pivoting point 12 of the lower parallelogram arm being connected to the other end of the rocking lever 20.
  • the fixed pivoting point 21 is located between the points 19 and 12, about which the rocking lever 20 can rotate.
  • the part of the rocking lever 20 situated between the pivoting point 21 and the point of connection 12 with the parallelogram arm 8, is indicated with 22.
  • the rocking lever 20 To take up the reaction forces during the lifting procedure, the rocking lever 20 must rest against the stop 23. If it is wanted, for instance whenever the loading floor 3 of the truck is sloping forward or backward instead of being horizontal, the position of the rocking lever 20 is made adjustable by means of the adjusting bolts 24 in relation to the stop 23, to be able to adjust during the lifting procedure the loading side 6' of the platform 6 exactly horizontally. By doing so, it is possible to adjust the line through the centers of the pivoting points 11 and 12 towards the loading floor 3 at an angle, which deviates from 90.
  • the telescoping parallelogram arm 8 is telescopedin against the shoulder 14 and is locked by the automatic latch 25.
  • the latter is urged in position 2 by the unlocking means 26, which is connected to the car rying structure, into the locked position, if the latch might not have been come into the locked position automatically due to wear or dirt.
  • the unlocking means 26 By voluntary unlocking the latch 25 by the unlocking means 26, it can be un locked, after which the platform can be positioned vertical from position 2 into position 1. In the vertical or nearby vertical position 1, the whole lifting platform assembly can be locked with the help of, nonillustrated, latches 27, in order to unload the hydraulic system.
  • the lifting platform will descend a little at the unlocking of the latches 27 and after that it will remain in that position, borne by the since then compressed hydraulic medium. If there can bleed hydraulic medium through the control device, the piston rod 17 will move into the cylinder l5, fluid bleeding away through connection 16. Then the lifting platform will begin to descend and to rotate from the vertical to the horizontal position. About half way the total lifting height, the platform will arrive at the horizontal position, the latch 25 locking automatically the telescopic parallelogram arm 8.
  • the stroke of the cylinder 15 should be made sufficiently long, to have some spare stroke left to compensate for possible deviations from the horizontal level of the ground.
  • the lifting platform being unloaded or loaded (within the limits set by the strength of the design), has no influence on the working cycle as described above.
  • the lifting cycle takes place in the reciprocal sequence.
  • the latch 25 will come to rest against the unlocking device 26.
  • a part of the control and safety system may be connected to the unlocking device 26 by means of switches or valves. If the latch might not have locked the telescope during the above-described startup due to wear or dirt, then it will at this very moment be urged into the locked position.
  • the latch 25 can be unlocked, to start with motion X by continued expelling the piston out from the power cylinder 15.
  • the lifting platform can be blocked in this position by means of the not illustrated latches 27. Furthermore it is possible to fit non-illustrated latches, to lock the lifting platform also in position 2.
  • FIG. 7 shows an alternate preferred embodiment of the lifting device according to the invention.
  • the locking latch 25 and its unlocking means 26 can be dropped, resulting in a simpler and cheaper product. This can only safely be done, if the pivoting point 18, being the point of connection of the power cylinder at its side viewing the platform, will be moved to a position between the pivoting points 9 and 10, being the points of connection between the two long parallelogram arms and the short parallelogram arm near the platform.
  • both embodiments of the lifting device according to the invention are safe under all circumstances and able to perform in the correct sequence all movements.
  • the pressure levels in the hydraulic medium are so different during the motions Z and Y that there exists a sufficient big margin to meet with unforeseen circumstances, as may be formed by eg pivoting points with abnormal friction due to wear or lack of service.
  • a lifting platform for instance fitted as lifting platform assembly to a truck, a lifting platform, one or more parallelogram-shaped articulated rod-systems, by which rods or arms this platform is directly or indirectly pivotingly connected to a carrying structure fitted to the truck chassis, one parallelogram arm being capable of telescoping, and the platform being driven and controlled by a hydraulic power system, the platform having four positions: lifted approximately vertically at maximum height; lifted horizontally at maximum height; lowered horizontally on ground; and lowered in downward sloping position on ground and, in doing so, three different motions, a single power cylinder means being applied to perform all three motions, the pivot point of the lower parallelogram arm being connected to the carrying structure through a rocking lever, and the power cylinder means being pivotingly attached at one end to this rocking lever, characterized in that the power cylinder means is single acting and pushing, and the fixed pivot point of the rocking lever on the carrying structure is located between the point of connection of the lower parallelogram arm and the point of connection of the power cylinder means on the
  • the single power cylinder means comprises a plurality of two or more single acting pushing power-cylinders mechanically and hydraulically connected in parallel and functioning together as one power cylinder.

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Forklifts And Lifting Vehicles (AREA)
US00411395A 1972-11-01 1973-10-31 Lifting device Expired - Lifetime US3842997A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL727214777A NL150067B (nl) 1972-11-01 1972-11-01 Hefinrichting.

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US3842997A true US3842997A (en) 1974-10-22

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ID=19817281

Family Applications (1)

Application Number Title Priority Date Filing Date
US00411395A Expired - Lifetime US3842997A (en) 1972-11-01 1973-10-31 Lifting device

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US (1) US3842997A (fr)
BE (1) BE806780A (fr)
NL (1) NL150067B (fr)

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4111317A (en) * 1977-08-29 1978-09-05 Robinson Morris D Platform lift
EP0006225A1 (fr) * 1978-06-14 1980-01-09 Vereinigte Metallwerke Ranshofen-Berndorf AG Dispositif de levage
US4780044A (en) * 1987-02-03 1988-10-25 Elskamp Hendrika J Device for controlling a loading platform for transport vehicles
US4787809A (en) * 1987-03-13 1988-11-29 Iowa Mold Tooling Company, Incorporated Hydraulic lift gate
US4930973A (en) * 1989-03-30 1990-06-05 Waltco Truck Equipment Co., Inc. Tiltable tailgate lift
US5118246A (en) * 1989-03-24 1992-06-02 Philippe Saussard Elevating tailgate for vehicle and process of handling it
US5941677A (en) * 1994-07-26 1999-08-24 Eco Global Patents B.V. Loading platform
US6019567A (en) * 1998-03-23 2000-02-01 Lift Technologies, Inc. Slidable load lifting system
US6082958A (en) * 1996-05-21 2000-07-04 Sorensen Hydraulik, Zweigniederlassung, Ulfborg, Filial Af Sorensen Hydraulik Gmbh, Tyskland Lift-type loading platform system
US6164895A (en) * 1999-04-07 2000-12-26 Croswell; Edward M. Trailer hitch mounted lifting attachment
US20080211254A1 (en) * 2005-06-16 2008-09-04 Peter Maier Leichtbau Gmbh Tailgate
US20100124479A1 (en) * 2008-11-17 2010-05-20 D.M. Brooks Global, Inc. Lift assembly for a vehicle
US8132281B1 (en) * 2011-01-27 2012-03-13 Lift-U, Division Of Hogan Mfg., Inc. Fold out ramp
US8250693B1 (en) 2011-01-27 2012-08-28 Lift-U, Division Of Hogan Mfg., Inc. Fold out ramp
US8375496B1 (en) 2011-01-27 2013-02-19 Lift-U, Division Of Hogan Mfg., Inc. Fold out ramp
CN106744561A (zh) * 2017-01-18 2017-05-31 重庆华伟工业（集团）有限责任公司 一种辅助上下车装置
US20170217270A1 (en) * 2016-01-29 2017-08-03 Joseph DelMaestro Hitch mounted cargo lifting device
US11613197B1 (en) * 2020-02-05 2023-03-28 Felling Trailers, Inc. Folding trailer ramp with powered full extension and soft ground contact

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4111317A (en) * 1977-08-29 1978-09-05 Robinson Morris D Platform lift
EP0006225A1 (fr) * 1978-06-14 1980-01-09 Vereinigte Metallwerke Ranshofen-Berndorf AG Dispositif de levage
US4780044A (en) * 1987-02-03 1988-10-25 Elskamp Hendrika J Device for controlling a loading platform for transport vehicles
US4787809A (en) * 1987-03-13 1988-11-29 Iowa Mold Tooling Company, Incorporated Hydraulic lift gate
US5118246A (en) * 1989-03-24 1992-06-02 Philippe Saussard Elevating tailgate for vehicle and process of handling it
US4930973A (en) * 1989-03-30 1990-06-05 Waltco Truck Equipment Co., Inc. Tiltable tailgate lift
US5941677A (en) * 1994-07-26 1999-08-24 Eco Global Patents B.V. Loading platform
US6082958A (en) * 1996-05-21 2000-07-04 Sorensen Hydraulik, Zweigniederlassung, Ulfborg, Filial Af Sorensen Hydraulik Gmbh, Tyskland Lift-type loading platform system
US6019567A (en) * 1998-03-23 2000-02-01 Lift Technologies, Inc. Slidable load lifting system
US6164895A (en) * 1999-04-07 2000-12-26 Croswell; Edward M. Trailer hitch mounted lifting attachment
US20080211254A1 (en) * 2005-06-16 2008-09-04 Peter Maier Leichtbau Gmbh Tailgate
US9090200B2 (en) * 2005-06-16 2015-07-28 Peter Maier Leichtbau Gmbh Tailgate
US20100124479A1 (en) * 2008-11-17 2010-05-20 D.M. Brooks Global, Inc. Lift assembly for a vehicle
US8132281B1 (en) * 2011-01-27 2012-03-13 Lift-U, Division Of Hogan Mfg., Inc. Fold out ramp
US8181300B1 (en) * 2011-01-27 2012-05-22 Lift-U, Division Of Hogan Mfg., Inc. Fold out ramp
US8250693B1 (en) 2011-01-27 2012-08-28 Lift-U, Division Of Hogan Mfg., Inc. Fold out ramp
US8375496B1 (en) 2011-01-27 2013-02-19 Lift-U, Division Of Hogan Mfg., Inc. Fold out ramp
US20170217270A1 (en) * 2016-01-29 2017-08-03 Joseph DelMaestro Hitch mounted cargo lifting device
US10421324B2 (en) * 2016-01-29 2019-09-24 Joseph DelMaestro Hitch mounted cargo lifting device
CN106744561A (zh) * 2017-01-18 2017-05-31 重庆华伟工业（集团）有限责任公司 一种辅助上下车装置
US11613197B1 (en) * 2020-02-05 2023-03-28 Felling Trailers, Inc. Folding trailer ramp with powered full extension and soft ground contact

Also Published As

Publication number Publication date
NL150067B (nl) 1976-07-15
BE806780A (fr) 1974-02-27
NL7214777A (fr) 1974-05-03

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Legal Events

Date Code Title Description
AS Assignment

Owner name: MARIBA B.V.,ALMELO, THE NETHERLANDS

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:AVO INTERN TRANSPORT B.V., IN BANKRUPTCY, BY: A.E. SCHAEFFER, TRUSTEE;REEL/FRAME:004231/0876

Effective date: 19830712

Owner name: VON WIENWALD, A.E. SCHAEFFER, TRUSTEE

Free format text: COURT APPOINTMENT;ASSIGNOR:JUDGE OF THE DISTRICT COURT OF ZUTPHEN, FOR AVO INTERN TRANSPORT B.V., BANKRUPT;REEL/FRAME:004231/0863

Effective date: 19811112