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EP0716040B1 - Free stroke damping - Google Patents

Free stroke damping Download PDF

Info

Publication number
EP0716040B1
EP0716040B1 EP19950850205 EP95850205A EP0716040B1 EP 0716040 B1 EP0716040 B1 EP 0716040B1 EP 19950850205 EP19950850205 EP 19950850205 EP 95850205 A EP95850205 A EP 95850205A EP 0716040 B1 EP0716040 B1 EP 0716040B1
Authority
EP
European Patent Office
Prior art keywords
mast
switch
piston rod
carriage
sensor
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
EP19950850205
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0716040A1 (en
Inventor
Rune Svensson
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.)
BT Industries AB
Original Assignee
BT Industries AB
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 BT Industries AB filed Critical BT Industries AB
Publication of EP0716040A1 publication Critical patent/EP0716040A1/en
Application granted granted Critical
Publication of EP0716040B1 publication Critical patent/EP0716040B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime 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
    • B66F9/20—Means for actuating or controlling masts, platforms, or forks
    • 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 diameters of the hydraulic cylinders that take care of the movements of the different parts is chosen in such a way that with the cylinders coupled in parallel, at a lifting movement of the lifting forks at first these will be lifted in relation to the mast by a carriage carrying the forks being moved in relation to the first or inner mast part, that is the one that on the extending of the mast is situated on top. In this way the weight that has to be lifted when the lifts are low is minimized.
  • the above object can however be solved without any electrical or hydraulic connections having to be drawn via the lifting mast.
  • a free stroke lifting device including a piston for the free stroke that hangs down with the piston rod downwards, the outer end of the piston rod carrying a pulley for a lifting chain for the load forks that first runs down to the pulley and around this and up again to a pulley arranged in the mast part in which the carriage is moveable and therefrom down to the load fork carrying carriage.
  • This known construction has among other things the advantage that a movement for the load forks is obtained that is the double of the work stroke of the hydraulic cylinder.
  • control means for the motor can be placed in the above described way no long and expensive arranging of connecting leads out through and along the mast to the load fork carriage is necessary.
  • the mast parts will always be retraced first before the free stroke is reversed, this due to the different weights and the different activation pressures of the hydraulic cylinders in the mast and the one controlling the free stroke.
  • the shocklike contact on the movement downwards can therefor also be dampened by for instance using the engine in the lowering direction to control the oil flow from the hydraulic cylinders.
  • a reduction of the engine speed means a braking of for the mast parts so that these have a reduced contact energy when they reach their lowest position.
  • If desired means may be arranged on the load fork carriage itself also for the cooperation with the same switch that is actuated by the free stroke piston so that this movement also is braked close to its lower end position.
  • the activation of the switch may be such that reduction only exists on movement downwards of the fork carriage and not at movement upwards or movement speed restrictions may be arranged only to be active at lowering.
  • Fig 1 shows schematically mast and fork carriage in the lowermost position of the forks
  • fig 2 the position shortly before the end of the free stroke
  • fig 3 a started lifting of the mast
  • fig 4 the maximum uplifted position of the fork carriage.
  • the truck in the drawings includes a frame on which a mast constituted by three parts, of which one 2 is fastened to the frame.
  • a mast part 2 fastened to the frame an additional mast part 3 is slidable journaled heightwise and supports in turn yet another in this intermediate mast part movable mast part 4.
  • the mast can execute a telescopic movement with a great lifting height.
  • a carriage 5 is arranged carrying load forks.
  • the carriage 5 is by means of a cylinder 7 and a chain 6 running over a pulley 8 arranged in the outer end of the piston rod movable over essentially the entire height of the inner mast section.
  • the cylinder 7 for the movement of the load fork carriage in the mast section 4 is suspended in this up side down and the pulley carrying rod end reaches almost to the lower end of the inner mast section when it is fully extended.
  • a switch 11 is arranged, provided with a roller 12 in the end of an arm 13.
  • the roller 12 can be actuated by a likewise in the frame or in the frame mounted mast part 2 vertically movable rod 14, that is pretensioned by means of a spring.
  • the lower end of the free stroke piston will when the piston gets close to its lower end position act on the rod that in turn act on the switch 11 that in turn either reduce the drive speed of the hydraulic pump (at lifting) or restrict the open cross section of a proportional valve controlling the lowering flow of the hydraulic oil from the cylinder.
  • the control of the movement may in an alternative embodiment include a magnetic sensor or switch means that have its status altered when a magnet on the piston rod passes the sensor.

Landscapes

  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Structural Engineering (AREA)
  • Civil Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Forklifts And Lifting Vehicles (AREA)
EP19950850205 1994-11-28 1995-11-24 Free stroke damping Expired - Lifetime EP0716040B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9404118A SE505606C2 (sv) 1994-11-28 1994-11-28 Anordning, vid en gaffeltruck, för dämpning av stötar och slag i lyftrörelsen
SE9404118 1994-11-28

Publications (2)

Publication Number Publication Date
EP0716040A1 EP0716040A1 (en) 1996-06-12
EP0716040B1 true EP0716040B1 (en) 2000-04-12

Family

ID=20396137

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19950850205 Expired - Lifetime EP0716040B1 (en) 1994-11-28 1995-11-24 Free stroke damping

Country Status (3)

Country Link
EP (1) EP0716040B1 (sv)
DE (1) DE69516250T2 (sv)
SE (1) SE505606C2 (sv)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19710556C2 (de) * 1997-03-14 1999-03-11 Jungheinrich Ag Ausfahrbare Mastkonstruktion für einen Hubwagen
CN102431936A (zh) * 2011-12-19 2012-05-02 苏州先锋物流装备科技有限公司 一种具有限位功能的堆垛车
AU2015318258B2 (en) 2014-09-15 2019-02-14 Crown Equipment Corporation Lift truck with optical load sensing structure

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1174262B (de) * 1958-04-28 1964-07-16 Clark Equipment Co Hublader mit einem ausfahrbaren und neigbaren Hubmast
US3486333A (en) * 1968-03-26 1969-12-30 Clark Equipment Co Upright control system for use in a lift truck
DE2926657A1 (de) * 1979-07-02 1981-01-15 Jungheinrich Kg Hubmast fuer hublader
US5022496A (en) * 1989-12-05 1991-06-11 Crown Equipment Corporation Slowdown during staging of a turret stockpicker
JP2716876B2 (ja) * 1991-04-01 1998-02-18 三菱重工業株式会社 フォークリフトの制御装置

Also Published As

Publication number Publication date
DE69516250T2 (de) 2000-08-10
SE9404118D0 (sv) 1994-11-28
SE9404118L (sv) 1996-05-29
SE505606C2 (sv) 1997-09-22
DE69516250D1 (de) 2000-05-18
EP0716040A1 (en) 1996-06-12

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