(19)
(11) EP 1 593 645 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
02.05.2007 Bulletin 2007/18

(43) Date of publication A2:
09.11.2005 Bulletin 2005/45

(21) Application number: 05445026.7

(22) Date of filing: 01.05.2005
(51) International Patent Classification (IPC): 
B66F 9/22(2006.01)
F15B 11/048(2006.01)
(84) Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU MC NL PL PT RO SE SI SK TR
Designated Extension States:
AL BA HR LV MK YU

(30) Priority: 03.05.2004 SE 0401169

(71) Applicant: BT Industries
S-59581 Mjölby (SE)

(72) Inventors:
  • Bärnström, Joakim
    590 12 Linköping (SE)
  • Holler, Jimmy
    596 63 Skänninge (SE)

(74) Representative: Berglund, Erik Wilhelm 
Berglunds Patentbyra AB Aspebraten
590 55 Sturefors
590 55 Sturefors (SE)

   


(54) Hydraulic lifting device for a telescopically extendable fork lift truck mast


(57) Device at fork truck where in a telescopically extendable mast in the outermost or uppermost mast section is arranged a movement journaling of movement of the forks over the major part of the height of the uppermost mast section, and where lifting movements are achieved hydraulically by means of one or several hydraulic pistons (4) for the lifting of the mast sections and one or several other hydraulic pistons (3) for the lifting of the forks (8) in relation to the uppermost mast section (5). In the feed conduits to the hydraulic cylinders proportional valves 1, 2 are arranged in order to, at the transition shift between low lift movement and high lift movement and vice versa successively control the oil flow to and from the cylinders of the different systems respectively so that an unnoticeable transition and constant speed is obtained.







Search report