EP0061451B1 - High visibility lift apparatus - Google Patents

High visibility lift apparatus Download PDF

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Publication number
EP0061451B1
EP0061451B1 EP19810901362 EP81901362A EP0061451B1 EP 0061451 B1 EP0061451 B1 EP 0061451B1 EP 19810901362 EP19810901362 EP 19810901362 EP 81901362 A EP81901362 A EP 81901362A EP 0061451 B1 EP0061451 B1 EP 0061451B1
Authority
EP
European Patent Office
Prior art keywords
movable
lifting
load sharing
set forth
uprights
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
Application number
EP19810901362
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0061451A4 (en
EP0061451A1 (en
Inventor
Milford D. Mcveen
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.)
Caterpillar Industrial Inc
Original Assignee
Caterpillar Industrial Inc
Towmotor Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Caterpillar Industrial Inc, Towmotor Corp filed Critical Caterpillar Industrial Inc
Publication of EP0061451A1 publication Critical patent/EP0061451A1/en
Publication of EP0061451A4 publication Critical patent/EP0061451A4/en
Application granted granted Critical
Publication of EP0061451B1 publication Critical patent/EP0061451B1/en
Expired legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B66—HOISTING; LIFTING; HAULING
    • B66F—HOISTING, LIFTING, HAULING OR PUSHING, NOT OTHERWISE PROVIDED FOR, e.g. DEVICES WHICH APPLY A LIFTING OR PUSHING FORCE DIRECTLY TO THE SURFACE OF A LOAD
    • B66F9/00—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes
    • B66F9/06—Devices for lifting or lowering bulky or heavy goods for loading or unloading purposes movable, with their loads, on wheels or the like, e.g. fork-lift trucks
    • B66F9/075—Constructional features or details
    • B66F9/08—Masts; Guides; Chains

Definitions

  • the invention relates to load moving devices such as mast assemblies. More particularly, the invention relates to such devices using a pair of lifting elements to elevate the load.
  • a common application of such apparatus is as the mast assembly for a fork lift truck or other material handler.
  • the mast assembly generally contains two fixed uprights attached to the vehicle with a movable upright mounted on each of the fixed uprights by rollers.
  • a carriage carrying load engaging forks is mounted for movement on the movable uprights.
  • the movable uprights and carriage can be selectively elevated to retrieve or place loads as desired.
  • the present invention provides an apparatus in accordance with claim 1 of the appended claims.
  • a mast assembly such as for use on a lift truck or cargo handling device, can thus utilize a load sharing member to provide free lift in which the carriage moves without the movable uprights being moved.
  • Such free lift facilitates easy transporting of loads while maintaining high visibility for an operator which might otherwise be hampered by elevated movable uprights or a separate jack to control only the carriage for free lift.
  • apparatus 10 which, for example, is a mast assembly, such as is used on a lift truck or container handling vehicle.
  • the mast assembly shown detached from the associated vehicle and as would be normally seen looking from the operator station of the vehicle, includes a first member, such as movable upright assembly 12 and a second member, such as a carriage 14.
  • the movable upright assembly has first and second movable uprights 16, 18 which are connected one to the other at their upper ends 20, 22 by a cross member 23.
  • the movable uprights are mounted on and movable relative to first and second fixed uprights 24, 26, respectively which define a stationary frame 28.
  • the fixed uprights are spaced one from the other and are interconnected by a top support member 29 and a bottom support member 30.
  • the movable uprights are movably mounted on the fixed uprights by rollers 31" (two lower ones of which are shown in outline in Fig. 1), for example, as is commonly practiced in the art.
  • the carriage is mounted on and movable relative to the first and second movable uprights such as illustrated by lower rollers 31" and engages loads to be carried on, for example, forks (not shown) connected thereto.
  • first and second lifting elements 32, 34 shown as first and second jacks 36, 38 which are hydraulically actuated single acting cylinders.
  • Each of the jacks has a movable lifting portion or rod 40, 42 and a stationary or housing portion 44, 46.
  • the housing portions are each fixed relative to the frame 28 by connection to the bottom support member 30.
  • a load sharing member 48 is connected to and between the rods which are each controllably movable relative to their related housing portions between a first and second position. At their first or retracted positions, the carriage is movable and the movable upright assembly is free from being movable, and at their second, extended travel positions both the movable upright assembly and the carriage are movable.
  • Jack operation as by hydraulic controls, is well known in the art.
  • Means 50 such as a flexible tension member or chain 52, is provided for interconnecting the rod 40, 42 of the jacks 36, 38 and the carriage 14 for moving the carriage 14 through actuation of the jacks.
  • the chains 52', 52" are connected to the fixed uprights 24, 26 through respective brackets 54, 56 extending from said uprights across the jacks.
  • Each of the chains passes about a sheave 58, 60 connected to the load sharing member 48 and is connected to the carriage 14. It wi.ll be seen, therefore, that in response to moving at least one of the rods of the jacks, elevational movement of the carriage will be controlled.
  • the chains can also be connected directly to the housing portions 44, 46 of the jacks.
  • pins 62, 64 are positioned through respective rods 40, 42 of the first and second jacks 36, 38 and the load sharing member 48 to form a slightly loose connection between the jacks and the load sharing member.
  • Each of said rods has a stepped end portion defining a seat 66 (one of which is shown in Fig. 2) which is positioned immediately adjacent and in contactable relationship with shoulders 70 on the load sharing member.
  • the seats are preferably tapered or conical to be self-centering for maintaining full contact between the related seats and shoulders when said load sharing member is pivotally moved about the related one of the pins relative to its interconnected rod.
  • the load sharing member 48 will be urged into abutting engagement with the movable upright assembly 12.
  • Guide means 74 such as a first guide pin 78' and a first guide arm 80', maintains preselected alignment of the load sharing member and the movable upright assembly in moving toward such engagement.
  • the guide arm which is shown as an integral portion of the load sharing member, has a sleeve portion positioned about and slidable along the pin in response to moving its related rod 40 between its retracted and extended positions.
  • a second guide pin 78" and guide arm 80" are also shown associated with the opposite end of the load sharing member from the first pin and arm.
  • first and second bushings 81', 81" each positioned loosely about a respective guide pin, and an engaging pad 82 divided between the two ends 84, 86 or, alternately, brackets of the cross member 23.
  • stops 88', 88" such as a cotter key or roll pin positioned transversely through each of the guide pins at their lowermost portions, are engageable by the load sharing member upon its downward travel.
  • the mast assembly 10 is used to elevate loads supported by the carriage 14 for retrieval, transport and storage purposes.
  • the present invention provides free lift of the carriage, in which the carriage is movable to raise a load, such as to an elevation required for driving an associated vehicle, while the movable uprights 16, 18 are not moved above the level of the fixed uprights 24, 26.
  • the carriage 14 is shown at its lowermost travel position at which the rods 40, 42 of the first and second jacks 36, 38 are as fully retracted as is allowable relative to the maximum permissible carriage movement downwardly.
  • the movable uprights 16,18 rest upon the fixed uprights 24, 26, such as through stops connected to and extending from the fixed uprights 24, 26, which prevent the movable uprights 16, 18 from extending below the fixed uprights 24, 26.
  • the movable uprights do not extend above the fixed uprights in such retracted positions of the jacks.
  • the load sharing member 48 is positioned a preselected distance D (Fig. 2) from the engaging pad 82 of the movable upright assembly 12.
  • Such distance D defines one-half of the free lift of the carriage in that for each unit of travel of the sheaves 58, 60 the carriage 14 moves two of such units.
  • movement of the load sharing member through a distance greater than said distance D will cause the movable upright assembly to be elevated above the fixed uprights 24, 26.
  • the carriage 14 and movable uprights 16,18 are moved by activating the first and second jacks 36, 38, which are preferably connected in parallel to a pressurized fluid source (not shown) such as a hydraulic pump.
  • a pressurized fluid source such as a hydraulic pump.
  • the carriage is movable through twice the preselected distance D by extending the rods to move the chains 52 past their respective sheaves 58, 60 to, in effect, pull the carriage upwardly.
  • the movable uprights remain stationary in that the rods 40, 42 and the load sharing member 48 are free from any moving connection or engagement with said uprights.
  • the load sharing member 48 is movable relative to the movable upright assembly 12 guided by the guide arms 80 moving freely along their respective guide pins 78.
  • the guide arms 80 through the bushings 81 contact the engaging pad 82.
  • the load sharing member is resultingly movable with the movable upright assembly upon further extension of the rods 40, 42.
  • the carriage also continues its elevational movement, as the load sharing member and movable upright assembly move one with the other, owing to the continuing upward movement of the sheaves 58, 60 and the continuing movement of the chains 52 about their respective sheaves.
  • the bushings 81 preferably of an elastomeric or plastic material, absorb shock and noise occurring during engagement of the guide arms and the engaging pad.
  • Lowering of the carriage is generally simply accomplished by retracting the jack rods 40, 42 to let the force of gravity resultingly lower the movable upright assembly 12 which is resting upon the load sharing member 48. However, if the movable upright assembly 12 hangs up, the load sharing member through the guide arms 80', 80" moves along the guide pins 78', 78" until it engages the stops 88', 88" at the lowermost portions of the guide pins. Further retraction of the rods pulls on the movable uprights 16, 18 through the guide pins to break loose the movable upright assembly, or to correct a mis- sequencing problem in which the movable uprights do not move downwardly together.
  • the load applied on the carriage 14 will not be centered and unequal forces will be exerted through the chains 52 before the jacks 36, 38 are extended to initially move the carriage.
  • the parallel hydraulic connection between the jacks 36, 38 maintains essentially equal fluid operating pressure in each one.
  • the jack experiencing the least resistance through tension in its related chain tends initially to be the first to move, which motion causes the carriage 14 to cock to one side.
  • the load sharing member 48 partially moves about its connection to the rod of the jack not being extended.
  • the load sharing member 48 thereby continuously attempts to equally distribute the load between the jacks 36, 38 and maintain equal chain tension. It will be apparent therefore that the movable upright assembly is initially movable in response to only at least one of rods being extended, although the other side of the load sharing member will quickly contact the upright assembly owing to the small differential existing from the unequal rod movement.
  • the jacks are mounted at their housing portions 44, 46 through a flexible connection with the fixed uprights 24, 26. This tends to facilitate unequal movements between the jacks.
  • Such flexible mounting also frees the guide arms 80 and pins 78 from some of the loads encountered during operation and accommodates forces experienced by the jacks particularly at extended rod positions.
  • the mast assembly 10 as disclosed provides numerous desirable features particularly useful in lift trucks or cargo handlers.
  • the load sharing member 48 permits the use of two hydraulic jacks nested in close proximity to the uprights 16, 18 and 24, 26 for maximum visibility around said uprights, such as where the jacks are mounted behind the uprights so as to not further interfere with an operator's forward line of sight.
  • the load sharing member also maximizes free lift of the carriage 14 without any movement of the movable uprights 16, 18 or the necessity for a separate jack for moving the carriage.
  • the absence of their movement during free lift facilitates using longer movable uprights without any need to extend them relatively far below the bottom support member 30, which can interfere with unrestricted movement of the mast assembly 10.

Landscapes

  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Structural Engineering (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Forklifts And Lifting Vehicles (AREA)
EP19810901362 1980-10-03 1980-10-03 High visibility lift apparatus Expired EP0061451B1 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1980/001326 WO1982001181A1 (en) 1980-10-03 1980-10-03 High visibility lift apparatus

Publications (3)

Publication Number Publication Date
EP0061451A1 EP0061451A1 (en) 1982-10-06
EP0061451A4 EP0061451A4 (en) 1983-05-16
EP0061451B1 true EP0061451B1 (en) 1986-04-23

Family

ID=22154583

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19810901362 Expired EP0061451B1 (en) 1980-10-03 1980-10-03 High visibility lift apparatus

Country Status (4)

Country Link
EP (1) EP0061451B1 (enrdf_load_stackoverflow)
JP (1) JPS57501477A (enrdf_load_stackoverflow)
DE (1) DE3071579D1 (enrdf_load_stackoverflow)
WO (1) WO1982001181A1 (enrdf_load_stackoverflow)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB9022002D0 (en) * 1990-10-10 1990-11-21 Fielden Engineers Limited Improvements in or relating to fork lift trucks

Family Cites Families (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2089143A (en) * 1936-03-13 1937-08-03 Severn A White Elevator cable equalizer
DE871423C (de) * 1950-04-23 1953-03-23 Miag Fahrzeugbau G M B H Foerderkarren mit den hoehenverstellbaren Lastentraeger und den ausfahrbaren Traggestellteil nacheinander betaetigender Hubeinrichtung
FR1138828A (fr) * 1955-10-07 1957-06-20 Yale & Towne Mfg Co Mécanisme de montage de la plateforme et des montants dans un chariot élévateur
DE1043946B (de) * 1957-02-15 1958-11-13 Yale & Towne Mfg Co Hubwagen mit hebbarem Lasttraeger an einem Staender, der an einem Hauptstaender senkrecht hebbar ist
FR2275987A2 (fr) * 1973-05-30 1976-01-23 Lucas Gustave Nouveau dispositif de prelevement de produits ensiles adaptables a une remorque ou a une benne portee
US4030568A (en) * 1976-03-24 1977-06-21 Caterpillar Tractor Co. High visibility mast for lift trucks
US4010825A (en) * 1976-04-05 1977-03-08 Towmotor Corporation Lift chain equalizing device
US4219302A (en) * 1978-02-13 1980-08-26 Towmotor Corporation Cylinder arrangement for raising a carriage and uprights of a mast
US4191276A (en) * 1978-03-06 1980-03-04 Cascade Corporation High-visibility two-stage mast assembly for lift trucks
WO1980000434A1 (en) * 1978-08-17 1980-03-20 Bushiki Kaisha Toyoda Jidoshok Device for loading and unloading lift truck
JPS55151498A (en) * 1979-05-09 1980-11-26 Toyoda Automatic Loom Works Mast device in fork lift truck

Also Published As

Publication number Publication date
JPS57501477A (enrdf_load_stackoverflow) 1982-08-19
EP0061451A4 (en) 1983-05-16
DE3071579D1 (en) 1986-05-28
WO1982001181A1 (en) 1982-04-15
EP0061451A1 (en) 1982-10-06

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