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
  • B66F9/082—Masts; Guides; Chains inclinable

Definitions

• This invention relates generally to controllably tiltable load lifting mast assemblies and more particularly to mounting arrangements for the tilt cylinders on the mast assemblies of lift trucks.
• Lift trucks are commonly provided with tilt cylinders for permitting controlled fore and aft tipping of a lift mast on the lift truck.
• the tilt cylinders are connected directly to vertical beams which constitute a part of a support frame for the lift mast.
• the tilt cylinders also serve to strengthen the support frame against twisting or "wrack" of the vertical beams caused by unbalanced loadings.
• tilt cylinders positioned substantially above the operator. This is disadvantageous in that it unduly obstructs the operator's vision. This tilt cylinder placement can also permit oil to leak onto the operator or onto a windscreen of the lift truck.
• the present invention is di rected to overcoming one or more of the problems set forth above.
• a load lifting device which has a supportive structure and a suppo rt frame pivotally attached thereto.
• the support frame includes two substantially vertical beams connected one to the other by a crossmember. At least one beam has a projection member which projects outboard therefrom.
• An extens ible means having a first and a second end is connected by its second end to the projection member at a point a spaced distance from said one beam. The first end of the extensible means is connected to the supportive structure.
• Fig. 1 is a diagrammatic isometric view of a lift truck incorporating an embod iment of the present invention
• Fig. 2 is a diagrammatic top plan view of the lift mast of the lift truck of Fig. 1 detailing the connection of the tilt cylinders to the lift mast.
• a lift mast embodying the principles of the present invention, is generally indicated by the reference numeral 10.
• the lift mast is utilized on a work vehicle 14 such as a lift truck.
• a support frame 16 for the lift mast 10 is pivotally mounted at pivot points 18 on the work vehicle 14 so as to be pivotable fore and aft with respect thereto.
• the support frame 16 supports a load engaging carriage 19.
• the support frame 16 includes two upwa rdl y extending beams 20, each having an outboard edge 21, which serves as a guide and supports for the carriage 19. These beams 20 are parallel to a central axis 42 therebetween.
• each beam 20 is connected by a c rossmember 22 for aiding in maintaining them in relatively rigid spaced apart relationship.
• the crossmember 22 is connected between upper end portions 23 of the beams 20.
• this crossmember 22 has first and second end portions 24,26 each extending outboard from the corresponding beam 20.
• Each end portion 24,26 has a connecting plate 28 rigidly attached thereto at a connecting surface 30 which is an outboardmost reg i on of each end po rti on 24,26.
• a tilt cylinder 32 having a first end portion 34 and a second end portion 36 is pivotally connected by its second end portion 36 to each connecting plate 28. As shown in Fig. 1 the first end portion 34 of each tilt cylinder 32 is pivotally connected to the work vehicle 14.
• the tilt cylinders 32 are so positioned so as to be parallel one to the other.
• the tilt cylinders 32 extend sufficiently far that the first end portions 34 thereof are located aft of an operator's station 38 which itself is af t of the lift mast 10.
• the first and second end portions 24,26 may be located on discrete pro j ect i on members (not shown) each rigidly connected to and projecting outboardly from a respective one of said beams 20. This would obviate the need for d i r ectl y connecting the tilt cylinders 32 to the crossmember 22.
• this embodiment would be essentially the same as that previously described, having the tilt cylinders 32 mounted on projections provided by the crossmember itself.
• each of the tilt cylinders 32 By rigidly connecting each of the tilt cylinders 32 to the support frame 16 at a position substantially outboard from the corresponding beam 20 a number of advantageous results are obtained.
• inertial loadings In the operation of a lift truck unbalanced and often substantial fore and aft loadings are often imposed upon the beams 20, as for example when the lift truck changes translational speed or turns a sharp corner while transporting a load.
• transient loadings are termed "inertial loadings" in the art and can either cause both beams 20 of the support frame 16 to move identically and synchronously as in the former example or cause torque of the joined beams 20 about the central axis 42 parallel and intermediate the beams 20 as in the latter example.
• the angle of "wrack” for this case is less than half that of the case for non-offset tilt cylinders 32.
• tilt cylinders 32 whose resistance to displacement is, for small displacements, a linear function of the magnitude of displacement locating the connection points 30 each half again as far outboard from the corresponding beam 20 as the center-to-center distance between the beams would cause the angle of "wrack" for a given inertial loading to be decreased by a factor of nearly 4.
• Such a drastic improvement would allow a decrease in needed beam 20 crossbracing, beam 20 rigidity, and other advantages as would be recognized by one skilled in the art.
• tilt mast 10 with the offset tilt cylinders 32 Another of the substantial advantages yielded by the tilt mast 10 with the offset tilt cylinders 32 is that the tilt cylinders need not be as powerful as would be necessary were there no offset. This is due to the fact that offset tilt cylinders will be countering decreased forces. Additionally, outward placement of the tilt cylinders 32 increases upward visibility for the operator. Also, this outward placement makes it less likely that hydraulic fluid leaks from the tilt cylinders 32 will contact the operator or a windshield on the lift truck. Other aspect, objects and advantages of the present invention of this invention can be obtained from a study of the drawings, claims and the disclosure.

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)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

Family

ID=22154692

Family Applications (1)

Country Status (4)

Cited By (3)

Citations (5)

Family Cites Families (4)

• 1980
  • 1980-12-19 JP JP56501921A patent/JPS57501959A/ja active Pending
  • 1980-12-19 WO PCT/US1980/001703 patent/WO1982002188A1/en not_active Application Discontinuation
  • 1980-12-19 EP EP19810901400 patent/EP0067152A4/en not_active Withdrawn
• 1981
  • 1981-09-14 NO NO813127A patent/NO813127L/no unknown

Patent Citations (5)

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