EP0585282A1 - Chariot elevateur pour couloirs etroits - Google Patents

Chariot elevateur pour couloirs etroits

Info

Publication number
EP0585282A1
EP0585282A1 EP19920909897 EP92909897A EP0585282A1 EP 0585282 A1 EP0585282 A1 EP 0585282A1 EP 19920909897 EP19920909897 EP 19920909897 EP 92909897 A EP92909897 A EP 92909897A EP 0585282 A1 EP0585282 A1 EP 0585282A1
Authority
EP
European Patent Office
Prior art keywords
line
steering
truck
pressure
valve
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.)
Withdrawn
Application number
EP19920909897
Other languages
German (de)
English (en)
Inventor
Frederick Leslie Brown
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.)
Translift Material Handling Ltd
Original Assignee
Translift Material Handling Ltd
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 Translift Material Handling Ltd filed Critical Translift Material Handling Ltd
Publication of EP0585282A1 publication Critical patent/EP0585282A1/fr
Withdrawn legal-status Critical Current

Links

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
    • B66F9/07568—Steering arrangements
    • 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
    • B66F9/10—Masts; Guides; Chains movable in a horizontal direction relative to truck
    • B66F9/105—Articulated, i.e. front chassis with wheels and mast rotatable relative to rear chassis with wheels

Definitions

  • This invention relates to narrow aisle lift trucks which are intended for use in industrial warehouses and the like.
  • the loads, often palleted are inserted at right angles to the face of the stack in spaces in the honeycomb cell-like arrangement of the faces of the storage racks, and extracted in like manner.
  • the aisle is to be kept relatively narrow.
  • a truck for use in these narrow aisles has the truck in two parts with a central pivot. There are four wheels in the usual two parallel-axle relationship.
  • the front part of the truck carries the mast, forks and load, and the rear part carries the driver, propulsion motor and counterweight to balance the load. Loads and counterweights of one or two tonnes are commonplace.
  • Steering is effected by turning the front part as a whole about the pivot axis.
  • chain drive is used from a steering motor on the rear part. In such a truck it is possible for the front part to be at 90 degrees or even more to the rear part.
  • both rear wheels are driven, the rear part always attempts to travel in a straight line normal to the axis of the rear wheels, but when the front wheels are at 90 degrees they are in the worst possible position since their axis is parallel to the attempted direction of movement of the rear part of the truck. So the wheels skid sideways with a high rate of tyre wear. At less extreme angles of the two parts, the tyres may grip the road, but the forces applied may tend to displace the steered wheels in the steered direction ( oversteer ) and this applies forces to the steering mechanism.
  • the value of the feedback forces depend upon the steered angle and are most severe in the manoeuvrein; necessary for load insertion and extraction.
  • a narrow aisle lift truck of the kind comprising a truck body mounted on a pair of driven wheels, a mast structure carrying lift forks xounted on a pair of non-driven front wheels, a centre pivot between the body and mast, and steering means for varying the angle of the body to the mast, is characterised in that steering forces are transmitted front a driver's steering control to the steered part via a one way transmission device which prevents oversteer and feedback forces applied to the steering mechanism.
  • a and D there are two pilot inputs to relief valve F. namely A and D: there is a ratio between the pressures required to open the relief valve via the different sources. If the ratio is 10:1 it requires ten times the pressure in port D to open it than in port A. A ratio of about 10 to 1 is preferred. If there is no pressure in lines L or R the steering angle is held constant by check valves 1 and 2 and relief valves E and F in the closed positions.
  • turns to the right are achieved by oil leaving the steering unit at port R via line B and following the opposite path to that in a left turn, i.e. via one-way valve 2, and pilot operation of relief valve E via branch B.
  • Certain other events such as accidental impact between the steered part and an obstacle or the driver sensing oversteer, and attempting to correct by steering in the opposite direction can also apply excess loads to the hydraulic system by reaction of the motor against the hydraulic fluid.
  • the forces acting on the parts may drive the steered part in the opposite direction to that of the steering force. For example if trie steering force is turning the truck to the left the line via port L and valve 1 is pressurised. An impact in the same direction will cause a pressure surge in that line which could damage the motor, result in burst hoses or fittings, or damage the chain and gears.
  • this damage is avoided by the bypass system.
  • the corresponding relief valve opens to exhaust fluid in that line.
  • valve F is opened by line A
  • valve E is opened by the bypass C when the pressure in the left steer line exceeds the normal operating pressure by the mentioned ratio.
  • the use of a ratio such as 10:1 ensures that normal variations in hydraulic pressure do not cause undesired relief
  • the 10 to 1 or other ratio may be achieved by balancing pressure applied to pistons of different area in control valves or by adjustable check valves for example.
  • the one-way valves, relief valves and connections may all be provided in a single unit, called a motion control valve.
  • An alternative steering system uses a pair of hydraulic rams extending between the pivoted parts. Eitherto these have, or may have been, single acting, in that in order to steer the truck fluid has been supplied to one end of one ram and the other ram has been open to exhaust.
  • oversteer forces effectively extend the pressurized ram in the same direction as the pressurized fluid and there may be only light spring face provided in that ram to resist this.
  • the invention may be applied to this arrangement in generally the same way as described for the steering motor, in which case exhaust of fluid from the opposite ram would be prevented or controlled thus providing a resistance to the oversteer movement.
  • double acting rams can be used in which fluid flow to one end of one ram is via the pump for steering, flow from the opposite end of the same ram is via a motion control valve to prevent undesired rapid movement of the steering and likewise the ram, and with recirculation of fluid from one end to the other of the second ram via a further restrictor or motion control valve as a further check against undesired steering movements.
  • the invention can also be applied with non-hydraulic means.
  • non-hydraulic means For example using a pair of oppositely directed free wheel devices on the main- pivot with disc brakes or like friction means to act as the transmission clutch between one or other of the steered parts.
  • a positive movement of the steering wheel by the driver will declutch the free wheel which prevents movement in the desired direction only during the time when the steering wheel or tiller is actively moved.
  • the steering will be held in the set position but is capable of movement against the resistance of the disc brakes so as to give the desirable feel to the steering.

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)

Abstract

Un chariot élévateur pour couloirs étroits comporte une commande hydraulique de direction avec des moyens d'interdiction de survirage par réaction entre les roues et le sol. Lors d'un virage à gauche, le liquide hydraulique s'écoule par le conduit A vers le moteur et est évacué du moteur par le conduit opposé B et par une soupape de surpression F qui s'ouvre sous la pression dans le conduit A. Lorsque l'angle de direction reste constant, aucune pression ne règne dans le conduit A, et la soupape F est fermée, de sorte que les efforts éventuels tendant à solliciter la direction d'un côté ou de l'autre sont contrés par les soupapes unidirectionnelles sur le conduit A et par la soupape de surpression fermée F. Les soupapes de dérivation C et D sont agencées pour s'ouvrir de sorte que, dans le cas par exemple où un choc accidentel aurait augmenté la pression dans l'un des deux conduits, la soupape de surpression appropriée s'ouvre, protégeant ainsi le circuit contre tout endommagement.
EP19920909897 1991-05-24 1992-05-11 Chariot elevateur pour couloirs etroits Withdrawn EP0585282A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9111285 1991-05-24
GB919111285A GB9111285D0 (en) 1991-05-24 1991-05-24 Narrow aisle lift truck

Publications (1)

Publication Number Publication Date
EP0585282A1 true EP0585282A1 (fr) 1994-03-09

Family

ID=10695572

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19920909897 Withdrawn EP0585282A1 (fr) 1991-05-24 1992-05-11 Chariot elevateur pour couloirs etroits

Country Status (3)

Country Link
EP (1) EP0585282A1 (fr)
GB (2) GB9111285D0 (fr)
WO (1) WO1992020612A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB0312343D0 (en) 2003-05-30 2003-07-02 Translift Engineering Ltd Fork lift truck
GB0822585D0 (en) 2008-12-11 2009-01-14 Translift Bendi Ltd Articulated vehicles

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1551481A (en) * 1977-01-12 1979-08-30 Ford Motor Co Hydraulic valve assembly
US4310062A (en) * 1980-01-22 1982-01-12 International Harvester Company Hydrostatic steering arrangement
GB8719175D0 (en) * 1987-08-13 1987-09-23 Translift Material Handling Lt Narrow aisle lift truck
US5188248A (en) * 1990-04-27 1993-02-23 Gehl Company Stabilizing cylinder for a rough terrain forklift

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9220612A1 *

Also Published As

Publication number Publication date
WO1992020612A1 (fr) 1992-11-26
GB2255941A (en) 1992-11-25
GB9111285D0 (en) 1991-07-17
GB2255941B (en) 1994-10-19
GB9210125D0 (en) 1992-06-24

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Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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17P Request for examination filed

Effective date: 19931122

AK Designated contracting states

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Designated state(s): DE GB

17Q First examination report despatched

Effective date: 19950428

STAA Information on the status of an ep patent application or granted ep patent

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18D Application deemed to be withdrawn

Effective date: 19950909