EP0622331B1 - A lifting unit for the forks of lift trucks - Google Patents
A lifting unit for the forks of lift trucks Download PDFInfo
- Publication number
- EP0622331B1 EP0622331B1 EP94200679A EP94200679A EP0622331B1 EP 0622331 B1 EP0622331 B1 EP 0622331B1 EP 94200679 A EP94200679 A EP 94200679A EP 94200679 A EP94200679 A EP 94200679A EP 0622331 B1 EP0622331 B1 EP 0622331B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- chamber
- piston
- forks
- fluid
- duct
- 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
Links
Images
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
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B15/00—Fluid-actuated devices for displacing a member from one position to another; Gearing associated therewith
- F15B15/20—Other details, e.g. assembly with regulating devices
- F15B15/22—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke
- F15B15/222—Other details, e.g. assembly with regulating devices for accelerating or decelerating the stroke having a piston with a piston extension or piston recess which throttles the main fluid outlet as the piston approaches its end position
Abstract
Description
Claims (9)
- A lifting unit (11), for the forks (12) of lift trucks (10), having at least one single-acting hydraulic cylinder (18; 19) kinematically connected to the forks (12) and comprising a cylindrical body (30) in which slides a piston (31) which is integral with an actuating rod (33), the forks (12) being lifted as a result of the hydraulic cylinder (18; 19) being supplied with working fluid and the forks (12) being lowered by gravity, discharging the working fluid, wherein between the piston (31) and a base (36) of the cylindrical body (30) is defined a first internal chamber (44) communicating with at least one duct (39) for the inflow and outflow of the working fluid; wherein between the rod (33) and the cylindrical body (30) is defined a second internal chamber (45) opposite the first chamber (44) with respect to the piston (31) and communicating with the said first chamber (44); and wherein first interception means are provided which, during an end-of-travel stroke of the piston (31) towards the said base (36), determine a narrowing of the cross-section of the fluid outflow from the first chamber (44) to the fluid inflow and outflow duct (39), and wherein second interception means are provided which, during the opposite end stroke, determine a narrowing in the cross-section of the discharge of the fluid outflow from the second chamber (45) to the first chamber (44), characterised in that, the first interception means comprise a tang (37) which is either integral with the base (36) of the cylindrical body (30) or with the piston, and which is coupled, with clearance, with a through hole located either in the piston (31) opening on one side into the rod (33) or located in the base of the cylindrical body, there being accommodated in the tang (37) a duct (42), which communicates on one side with the said fluid inflow and outflow duct (39) or opens into the rod and on the other side opens out on the exterior of the tang (37) in the direction of the through hole (38).
- A lifting unit according to Claim 1, wherein the first chamber (44) communicates with the fluid inflow and outflow duct (39) through at least one main passage (42) and at least one auxiliary passage (46,47) provided with check valve means (51-53) which prevent the fluid flow from the first chamber (44) to the fluid inflow and outflow duct (39); wherein the second chamber (45) communicates with the first chamber (44) through at least one main passage (48) and at least one narrow auxiliary passage (49); and wherein the first interception means (37,38) limit fluid discharging from the first chamber (44) to the fluid inflow and outflow duct (39) through the respective main passage (42) during the said end-of-travel stroke of the piston (31) towards the base (36), and the second interception means (34) prevent the discharge of fluid from the second chamber (45) to the first chamber (44) through the respective main passage (48) during the opposite end-of-travel stroke.
- A lifting unit according to Claim 1, wherein the through hole (38) has a narrow portion (50) such that a narrow passage is formed between the tang (37) and the hole (38); and wherein the tang (37) and the hole (38) have a corresponding upper and lower flaring respectively.
- A lifting unit according to Claim 2, wherein the auxiliary passage (46,47) relative to the first chamber (44) is provided in the base (36) of the cylindrical body (30); and wherein the check valve means comprise a ball valve member (51) which rests on a seat (52) of a duct (47) of said auxiliary passage and which is retained in said duct (47) by a pin (53) transversely inserted in the duct (47).
- A lifting unit according to any of the Claims 2, 3, 4, wherein the actuating rod (33) is hollow and its interior communicates with the first chamber (44); wherein the said rod (33) has a plurality of through holes (48) each of which forms the said main passage relative to the second chamber (45); and in which the said second interception means comprise a bush (34) which is disposed between the rod (33) and the cylindrical body (30) and which impedes the said through holes (48) during the opposite end-of-travel stroke.
- A lifting unit according to Claim 5, wherein a plurality of auxiliary passages relative to the second chamber (45) are formed in the piston (31), and comprise through transversal ducts (49) each having a portion with a narrow cross-section and communicating with the second chamber (45) through the space between the piston (31) and the cylindrical body (30).
- A lifting unit according to any of the preceding Claims, wherein a central hydraulic cylinder (18) kinematically connected to the forks (12) and a pair of side hydraulic cylinders (19) kinematically connected to the central hydraulic cylinder (18) through a telescopic frame (13) are provided.
- A lifting unit according to any of the Claims 1 to 6, wherein a single hydraulic cylinder kinematically connected to the forks is provided.
- A lifting unit according to any of the Claims 1 to 6, wherein a pair of side hydraulic cylinders kinematically connected to the forks through a telescopic frame is provided.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ITMI930528 | 1993-03-19 | ||
ITMI930528A IT1272114B (en) | 1993-03-19 | 1993-03-19 | FORK LIFTING UNITS IN FORKLIFTS |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0622331A1 EP0622331A1 (en) | 1994-11-02 |
EP0622331B1 true EP0622331B1 (en) | 1998-09-30 |
Family
ID=11365414
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94200679A Expired - Lifetime EP0622331B1 (en) | 1993-03-19 | 1994-03-16 | A lifting unit for the forks of lift trucks |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0622331B1 (en) |
AT (1) | ATE171695T1 (en) |
DE (1) | DE69413593T2 (en) |
ES (1) | ES2123704T3 (en) |
IT (1) | IT1272114B (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE19710556C2 (en) * | 1997-03-14 | 1999-03-11 | Jungheinrich Ag | Extendable mast construction for a pallet truck |
DE29707639U1 (en) * | 1997-04-28 | 1997-08-21 | Still Gmbh | Hydraulic cylinder with shock protection |
DE19802119A1 (en) * | 1998-01-21 | 1999-07-22 | Still Wagner Gmbh & Co Kg | Industrial truck with a lifting device |
US6557456B2 (en) | 2001-05-24 | 2003-05-06 | The Raymond Corporation | Cushioned actuator |
DE10214864C5 (en) * | 2002-04-04 | 2009-12-17 | Linde Material Handling Gmbh | Hydraulic cylinder with cushioning |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR1414638A (en) * | 1964-11-25 | 1965-10-15 | Appalette | Adjustable hydraulic end-of-stroke shock absorber for plunger hydraulic cylinders |
FR2024747A1 (en) * | 1969-05-02 | 1970-09-04 | Lati Ste | |
US4006666A (en) * | 1975-05-22 | 1977-02-08 | Towmotor Corporation | Cushioning device for a hydraulic jack |
DE3146845A1 (en) * | 1981-11-26 | 1983-06-01 | Wabco Steuerungstechnik GmbH & Co, 3000 Hannover | DEVICE FOR STOPPING THE WORKING PISTON OF A DOUBLE-ACTING WORK CYLINDER |
US4476960A (en) * | 1982-08-09 | 1984-10-16 | Towmotor Corporation | Adjustable chain anchor for lift trucks |
US4706781A (en) * | 1985-02-28 | 1987-11-17 | Kabushiki Kaisha Toyoda Jidoshokki Seisakusho | Fluid-operated cylinder with cushioning flow rate control valve means |
-
1993
- 1993-03-19 IT ITMI930528A patent/IT1272114B/en active IP Right Grant
-
1994
- 1994-03-16 ES ES94200679T patent/ES2123704T3/en not_active Expired - Lifetime
- 1994-03-16 DE DE69413593T patent/DE69413593T2/en not_active Expired - Fee Related
- 1994-03-16 AT AT94200679T patent/ATE171695T1/en active
- 1994-03-16 EP EP94200679A patent/EP0622331B1/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
DE69413593D1 (en) | 1998-11-05 |
EP0622331A1 (en) | 1994-11-02 |
ITMI930528A1 (en) | 1994-09-19 |
DE69413593T2 (en) | 1999-03-18 |
ATE171695T1 (en) | 1998-10-15 |
ES2123704T3 (en) | 1999-01-16 |
IT1272114B (en) | 1997-06-11 |
ITMI930528A0 (en) | 1993-03-19 |
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