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 inven ⁇ tion 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.
• an apparatus has a frame, a first member mounted on and movable relative to said frame, and a second member mounted on and movable relative to said first member.
• First and second lifting elements are connected to the frame and each have a lifting or extendable portion movable between first and second positions. At the first positions, the second member is movable while the first member is free from being movable. At the second positions, said first and second members are both movable.
• a load sharing member is connected to the lifting portions of both lifting elements and is movable relative to the first member in response to at least one of the lifting portions moving from its first toward its second position. The load sharing member is movable with the first member in response to at least one of said lifting portions being at its second position.
• a mast assembly has first and second fixed uprights and first and second movable uprights mounted on and movable along the first and second fixed uprights.
• a carriage is mounted on and movable relative to said first and second movable uprights.
• a load sharing member is connected to lifting portions or rods of first and second jacks which have housing positions fixed relative to the fixed uprights. The load sharing member is movable with and in response to moving the jacks between their first positions at which said load sharing member is movable relative to the movable uprights and their second positions at which said load sharing member is movable with the movable uprights.
• a chain is connected to the carriage and one of the fixed uprights and passes about a sheave mounted to the load sharing member.
• a mast assembly such as for use on a lift truck or cargo handling device, utilizes the 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.
• Fig. 1 is a diagrammatic rear view of a mast assembly incorporating one embodiment of the present invention and as might be viewed when removed from, for example, a lift truck;
• Fig. 2 is a diagrammatic view taken along line II-II and showing a portion of the mast assembly of Fig. 1 in greater detail.
• 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 a 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. Simi ⁇ larly, the carriage is mounted on and movable relative to the first and second movable uprights such as illus ⁇ trated 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 con- trollably movable relative to their related housing portions between a first and second position.
• 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 will 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 adja ⁇ cent 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 pivotly 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.
• 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 re ⁇ quired 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 car ⁇ riage 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 load sharing member 48 is positioned a preselected distance D (Fig. 2) from the engaging pad 82 of the movable upright assembly 12.
• 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 pressur ⁇ ized fluid source (not shown) such as a hydraulic pump.
• a pressur ⁇ ized 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 en- gagement with said uprights.
• the load sharing member 48 in response to raising the carriage 14 through its free lift distance, 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 con ⁇ tinues 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.
• 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 retrac- tion 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 missequencing 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. Unequal tension forces remain on the chains until the carriage rollers associated with the movable upright assembly 12 move transversely through the cocking motion a suf ⁇ ficient distance to engage the movable uprights 16,18 to develop lateral or side thrust loads in the rollers.
• the load sharing member 48 thereby contin- uously 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 exist ⁇ ing from the unequal rod movement.
• the mast assembly 10 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.

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• 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)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22154583

Family Applications (1)

Country Status (4)

Cited By (1)

Citations (3)

Family Cites Families (8)

• 1980
  • 1980-10-03 EP EP19810901362 patent/EP0061451B1/en not_active Expired
  • 1980-10-03 WO PCT/US1980/001326 patent/WO1982001181A1/en active IP Right Grant
  • 1980-10-03 JP JP81501730A patent/JPS57501477A/ja active Pending
  • 1980-10-03 DE DE8181901362T patent/DE3071579D1/de not_active Expired

Patent Citations (3)

Non-Patent Citations (1)

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