EP0769625A2 - A rotary fluid actuator - Google Patents
A rotary fluid actuator Download PDFInfo
- Publication number
- EP0769625A2 EP0769625A2 EP96115678A EP96115678A EP0769625A2 EP 0769625 A2 EP0769625 A2 EP 0769625A2 EP 96115678 A EP96115678 A EP 96115678A EP 96115678 A EP96115678 A EP 96115678A EP 0769625 A2 EP0769625 A2 EP 0769625A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- actuator according
- actuator
- piston
- sliding block
- sliding blocks
- 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- Withdrawn
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Classifications
-
- 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
- F15B15/02—Mechanical layout characterised by the means for converting the movement of the fluid-actuated element into movement of the finally-operated member
- F15B15/06—Mechanical layout characterised by the means for converting the movement of the fluid-actuated element into movement of the finally-operated member for mechanically converting rectilinear movement into non- rectilinear movement
- F15B15/068—Mechanical layout characterised by the means for converting the movement of the fluid-actuated element into movement of the finally-operated member for mechanically converting rectilinear movement into non- rectilinear movement the motor being of the helical type
Definitions
- the present invention relates to a rotary fluid actuator comprising a body defining a cylindrical chamber in which a piston can slide axially, a surface of the piston having at least one helical groove for cooperating with guide means which include a sliding block of complementary shape for each groove, each sliding block being supported by the body of the actuator.
- the sliding blocks are in the form of blocks, each block being complementary with a portion of the respective helical groove and having a central hole, normally a through-hole, for the engagement of an articulation pin fixed radially relative to the body of the actuator.
- the material constituting each sliding block has to have good resistance to mechanical stresses since the structure of the sliding block is weakened in the narrow sections adjacent the hole and because the forces produced by the actuator in operation, which are sometimes very intense, are concentrated in these regions.
- a practically essential solution is therefore to use high-strength steel for the construction of the sliding blocks.
- this involves the risk of the sliding blocks seizing in the respective helical grooves in the event of malfunction due, for example, to a lubrication fault, with consequent serious damage to the helical grooves and hence to the entire main piston of the actuator, since the main piston is also normally made of steel.
- the main object of the present invention is to propose an actuator of the type indicated above which is free of the aforementioned problems.
- each sliding block is fixed to the body of the actuator.
- the sliding blocks using weaker materials, that is, materials having less mechanical strength than those used previously and, in particular, with less mechanical strength than the material used for the construction of the piston so that, in the event of seizure, only the sliding blocks are damaged and not the main piston.
- each sliding block is mounted on the body removably so that it can be replaced quickly in the event of damage.
- the sliding blocks are preferably made of an anti-friction material.
- a double-acting, rotary fluid actuator normally a hydraulic actuator, according to the invention, also known as a helical actuator
- the actuator 1 can be used in machines of various kinds when it is necessary to convert the power generated by the pressure of a fluid into a mechanical power which enables one or more members to be rotated about an axis, for example, through a predetermined angle of between 0° and 360°.
- the actuator 1 is advantageously used in devices associated with vehicles for lifting and tipping refuse bins, for example, of the type described in the Applicant's Italian patent application No. T095A000462.
- the actuator 1 comprises a cylindrical body 3 including a tubular outer wall 5 and a tubular inner wall 7 sealingly mounted for rotation relative to the wall 5.
- An annular piston 13 is slidable axially and sealingly in a cylindrical chamber 9 defined between the walls 5 and 7. Ducts 9a and 9b, for the admission and discharge of the fluid used to bring about the movement of the piston 13, open in the opposite ends of the chamber 9.
- the piston 13 which is normally made of steel, has a plurality of helical grooves 15, for example three grooves, on its radially outer surface, which grooves have the same pitch and are thus spaced equiangularly, and each of which is engaged by a respective sliding guide block 18 fixed to the body 3 and having a shape complementary to a portion of the respective groove 15.
- each sliding block 18 is made in one piece, that is, integrally with an arcuate base portion 19 having the function of a support element for the active portion of the sliding block 18, that is, the portion which is intended to engage the respective groove 15.
- Both the groove 15 and the active portion of the sliding block 18 preferably have trapezoidal sections transverse the axis of the actuator 1, with respective sides converging substantially towards this axis.
- the sliding blocks 18 and the respective arcuate base portions 19 can advantageously be made of an anti-friction material such as bronze or of a self-lubricating plastics material but, in any case, of a material less strong than that constituting the cylinder 13.
- each base portion 19 which faces towards the axis of the actuator 1 is wider than the active portion of the block 18 so that it constitutes a portion of the wall of the cylindrical chamber 9.
- the sliding blocks 18 are mounted removably on the body 3 so that they can easily be replaced in the event of damage.
- they are carried by a support ring 20 which is connected to the wall 5 of the body 3, also removably, in a substantially central portion thereof.
- the wall 5 comprises two symmetrical tubular portions 5a, to each of which a respective connecting flange 22 is anchored at one end.
- the ring 20 is thus fixed between the flanges 22 by means of clamping screws 25.
- the ring 20 is shaped so as to define internally a seat which houses the support elements 19 of the sliding blocks 18 and clamps them radially relative to the piston 13 so that they can engage the grooves 15 correctly.
- the ring 20 may also contribute to the angular restraint of the sliding blocks 18 relative to the ring.
- it has a number of recesses 27 equal to the number of sliding blocks 18, the recesses being arranged around its inner periphery and each having a shape corresponding to the base portion 19 of a block 18, and opposed pairs of radial shoulder walls 27a.
- each block 18 is clamped axially relative to the body 3 by opposed radial end faces 23 of the flanges 22 so that the flanges 22 act as axial shoulders for the base portions 19.
- the seat defined by the ring 20 for housing the blocks 18 consists of a single annular seat delimited radially by a circular wall 28 concentric with the axis of the piston 13.
- the wall 28 provides for the radial clamping of the base portions 19 abutting it and, in both cases, the portions 19 are restrained angularly by means of elongate members which extend axially from the connecting flanges 22 towards the blocks 18.
- these members are constituted by cylindrical pins 30 which engage axial holes formed both in the portions 19 and in the flanges 22.
- these members are constituted by axial appendages 24 which extend integrally from the connecting flanges 22 beyond the faces 23 and are intended to be interposed to act as angular shoulders between adjacent base portions 19.
- the radially inner surface of the piston 13 has a plurality of axial grooves 35, for example three grooves, each of which is engaged by a guide element 37 which may be constituted by an axial rib projecting radially from a sleeve 40 fixed in a position intermediate two symmetrical tubular portions 7a of the wall 7.
- Each tubular portion 7a defines an inner cylindrical chamber 42 which is inside and coaxial with the chamber 9 and in which a respective auxiliary, double-acting, linear piston 44, rigidly connected to a hollow rod 46, can slide.
- the rods 46 project outside the actuator 1 so as to be able to control the movement of a handling member (not shown in the drawings) keyed to each of them and constituted, for example, by a gripping arm transverse the axis of the actuator.
- the auxiliary pistons 44 are opposed, that is, both facing towards the sleeve 40, and ducts for the admission/discharge of a fluid open into the opposite ends of the chambers 42.
- the admission of fluid under pressure to both of the chambers 42 through a first common duct 48 formed so as to extend radially through the ring 20 and the piston 13 and both radially and axially through the sleeve 40 enables the pistons 44 to be moved apart, bringing about an axial extension of the portion of the actuator 1 which is rotatable relative to the body 3, so that the handling members keyed to the ends of the rods 46 projecting from the actuator 1 are moved apart telescopically.
- the supply of fluid under pressure through a pair of interconnected ducts 50 causes the pistons 44 to move towards one another, thereby reducing the axial distance between the handling members at the ends of the rods 46.
- a splined shaft 54 which extends axially through the sleeve 40 and is fixed thereto by means of a transverse pin 56 engages corresponding axial holes formed through the pistons 44 so that the pistons 44 and hence the hollow rods 46 can slide relative to one another but remain fixed together for rotation.
- each end of the actuator 1 there is also an annular head 58 which is free to rotate relative to the body 3 and is connected rigidly and removably to a respective tubular portion 7a by means of axial screws 59.
- Each head 58 is drilled to allow the respective rod 46 to extend through it and a sliding bearing 60 and sealing rings 62 are interposed between it and the rod 46.
- the body 3 may comprise ducts 64, 66 in the vicinity of the heads 58 for the supply of fluid to any tools carried by the handling members fixed to the rods 46.
- the ducts 64, 66 open in respective annular chambers formed in the vicinity of the ends of the body 3 and facing the rods 46 radially so as to surround them.
- ducts 68 formed in the heads 58 open radially into the respective annular chamber and open axially from the heads for the connection of an external distribution pipe (not shown in the drawings).
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Actuator (AREA)
- Braking Arrangements (AREA)
Abstract
Description
- The present invention relates to a rotary fluid actuator comprising a body defining a cylindrical chamber in which a piston can slide axially, a surface of the piston having at least one helical groove for cooperating with guide means which include a sliding block of complementary shape for each groove, each sliding block being supported by the body of the actuator.
- In known actuators of the type indicated above, the sliding blocks are in the form of blocks, each block being complementary with a portion of the respective helical groove and having a central hole, normally a through-hole, for the engagement of an articulation pin fixed radially relative to the body of the actuator. In this known solution, the material constituting each sliding block has to have good resistance to mechanical stresses since the structure of the sliding block is weakened in the narrow sections adjacent the hole and because the forces produced by the actuator in operation, which are sometimes very intense, are concentrated in these regions.
- A practically essential solution is therefore to use high-strength steel for the construction of the sliding blocks. However, this involves the risk of the sliding blocks seizing in the respective helical grooves in the event of malfunction due, for example, to a lubrication fault, with consequent serious damage to the helical grooves and hence to the entire main piston of the actuator, since the main piston is also normally made of steel.
- The main object of the present invention is to propose an actuator of the type indicated above which is free of the aforementioned problems.
- This object is achieved by virtue of the fact that each sliding block is fixed to the body of the actuator.
- By virtue of this characteristic, it is no longer necessary to form holes in the sliding blocks since they do not have to be articulated about pins and hence the sliding blocks are no longer structurally weakened by holes or narrow sections, which previously had a great bearing on the selection of the construction material.
- It is therefore possible to construct the sliding blocks using weaker materials, that is, materials having less mechanical strength than those used previously and, in particular, with less mechanical strength than the material used for the construction of the piston so that, in the event of seizure, only the sliding blocks are damaged and not the main piston.
- Moreover, since it is possible to use a weaker material than in the past, the operations necessary to produce the sliding blocks, which are normally carried out by means of numerically-controlled machines, are quicker and the overall cost of the sliding blocks is thus reduced.
- Advantageously, each sliding block is mounted on the body removably so that it can be replaced quickly in the event of damage.
- The sliding blocks are preferably made of an anti-friction material.
- Further characteristics and advantages of the present invention will become clearer from the following detailed description, given with reference to the appended drawings, provided purely by way of non-limiting example, in which:
- Figure 1 is an elevational view of an actuator according to the invention, sectioned longitudinally,
- Figure 2 is an elevational cross-section taken on the line II-II of Figure 1,
- Figure 3 is a perspective view of a sliding block of the actuator according to the invention,
- Figure 4 is a view similar to Figure 1 of a portion of the body of an actuator according to a first variant of the invention,
- Figure 5 is an elevational cross-section taken on the line V-V of Figure 4,
- Figure 6 is a view similar to Figure 1 of a portion of the body of an actuator according to another variant of the invention, and
- Figure 7 is an elevational cross-section taken on the line VII-VII of Figure 6.
- With reference initially to Figures 1 to 3, a double-acting, rotary fluid actuator, normally a hydraulic actuator, according to the invention, also known as a helical actuator, is indicated 1. The actuator 1 can be used in machines of various kinds when it is necessary to convert the power generated by the pressure of a fluid into a mechanical power which enables one or more members to be rotated about an axis, for example, through a predetermined angle of between 0° and 360°. In particular, the actuator 1 is advantageously used in devices associated with vehicles for lifting and tipping refuse bins, for example, of the type described in the Applicant's Italian patent application No. T095A000462.
- The actuator 1 comprises a cylindrical body 3 including a tubular outer wall 5 and a tubular inner wall 7 sealingly mounted for rotation relative to the wall 5. An
annular piston 13 is slidable axially and sealingly in a cylindrical chamber 9 defined between the walls 5 and 7. Ducts 9a and 9b, for the admission and discharge of the fluid used to bring about the movement of thepiston 13, open in the opposite ends of the chamber 9. - The
piston 13, which is normally made of steel, has a plurality ofhelical grooves 15, for example three grooves, on its radially outer surface, which grooves have the same pitch and are thus spaced equiangularly, and each of which is engaged by a respectivesliding guide block 18 fixed to the body 3 and having a shape complementary to a portion of therespective groove 15. - In particular, each
sliding block 18 is made in one piece, that is, integrally with anarcuate base portion 19 having the function of a support element for the active portion of thesliding block 18, that is, the portion which is intended to engage therespective groove 15. - Both the
groove 15 and the active portion of thesliding block 18 preferably have trapezoidal sections transverse the axis of the actuator 1, with respective sides converging substantially towards this axis. - The sliding
blocks 18 and the respectivearcuate base portions 19 can advantageously be made of an anti-friction material such as bronze or of a self-lubricating plastics material but, in any case, of a material less strong than that constituting thecylinder 13. - The surface of each
base portion 19 which faces towards the axis of the actuator 1 is wider than the active portion of theblock 18 so that it constitutes a portion of the wall of the cylindrical chamber 9. - The sliding
blocks 18 are mounted removably on the body 3 so that they can easily be replaced in the event of damage. In particular, they are carried by asupport ring 20 which is connected to the wall 5 of the body 3, also removably, in a substantially central portion thereof. For this purpose, the wall 5 comprises two symmetricaltubular portions 5a, to each of which a respective connectingflange 22 is anchored at one end. Thering 20 is thus fixed between theflanges 22 by means of clampingscrews 25. - The
ring 20 is shaped so as to define internally a seat which houses thesupport elements 19 of thesliding blocks 18 and clamps them radially relative to thepiston 13 so that they can engage thegrooves 15 correctly. - The
ring 20 may also contribute to the angular restraint of thesliding blocks 18 relative to the ring. In this case, as shown in Figure 2, it has a number ofrecesses 27 equal to the number ofsliding blocks 18, the recesses being arranged around its inner periphery and each having a shape corresponding to thebase portion 19 of ablock 18, and opposed pairs ofradial shoulder walls 27a. - Moreover, each
block 18 is clamped axially relative to the body 3 by opposedradial end faces 23 of theflanges 22 so that theflanges 22 act as axial shoulders for thebase portions 19. - According to the structural variants shown in Figures 4, 5,6 and 7, the seat defined by the
ring 20 for housing theblocks 18 consists of a single annular seat delimited radially by acircular wall 28 concentric with the axis of thepiston 13. In this case, thewall 28 provides for the radial clamping of thebase portions 19 abutting it and, in both cases, theportions 19 are restrained angularly by means of elongate members which extend axially from the connectingflanges 22 towards theblocks 18. - According to the variant shown in Figures 4 and 5, these members are constituted by
cylindrical pins 30 which engage axial holes formed both in theportions 19 and in theflanges 22. - According to another variant shown in Figures 6 and 7, these members are constituted by
axial appendages 24 which extend integrally from the connectingflanges 22 beyond thefaces 23 and are intended to be interposed to act as angular shoulders betweenadjacent base portions 19. - The radially inner surface of the
piston 13 has a plurality ofaxial grooves 35, for example three grooves, each of which is engaged by aguide element 37 which may be constituted by an axial rib projecting radially from asleeve 40 fixed in a position intermediate two symmetrical tubular portions 7a of the wall 7. - Each tubular portion 7a defines an inner
cylindrical chamber 42 which is inside and coaxial with the chamber 9 and in which a respective auxiliary, double-acting,linear piston 44, rigidly connected to ahollow rod 46, can slide. Therods 46 project outside the actuator 1 so as to be able to control the movement of a handling member (not shown in the drawings) keyed to each of them and constituted, for example, by a gripping arm transverse the axis of the actuator. - The
auxiliary pistons 44 are opposed, that is, both facing towards thesleeve 40, and ducts for the admission/discharge of a fluid open into the opposite ends of thechambers 42. In particular, the admission of fluid under pressure to both of thechambers 42 through a firstcommon duct 48 formed so as to extend radially through thering 20 and thepiston 13 and both radially and axially through thesleeve 40, enables thepistons 44 to be moved apart, bringing about an axial extension of the portion of the actuator 1 which is rotatable relative to the body 3, so that the handling members keyed to the ends of therods 46 projecting from the actuator 1 are moved apart telescopically. Conversely, the supply of fluid under pressure through a pair of interconnectedducts 50 causes thepistons 44 to move towards one another, thereby reducing the axial distance between the handling members at the ends of therods 46. - A splined shaft 54, which extends axially through the
sleeve 40 and is fixed thereto by means of atransverse pin 56 engages corresponding axial holes formed through thepistons 44 so that thepistons 44 and hence thehollow rods 46 can slide relative to one another but remain fixed together for rotation. - Thus, if fluid is supplied under pressure to the actuator 1 through the
duct other duct piston 13 is caused to slide inside the chamber 9 and is simultaneously rotated about the axis of the actuator, guided by means of thegrooves 15 and thesliding blocks 18. Owing to the engagement of theguide elements 37 in theaxial grooves 35, this rotation brings about a corresponding rotation of the unit comprising thesleeve 40, the splined shaft 54, the tubular portions 7a and theauxiliary pistons 44 and, in particular, of therods 46 with the handling members keyed to their ends outside the actuator 1. - At each end of the actuator 1 there is also an
annular head 58 which is free to rotate relative to the body 3 and is connected rigidly and removably to a respective tubular portion 7a by means ofaxial screws 59. Eachhead 58 is drilled to allow therespective rod 46 to extend through it and a sliding bearing 60 andsealing rings 62 are interposed between it and therod 46. - The body 3 may comprise
ducts heads 58 for the supply of fluid to any tools carried by the handling members fixed to therods 46. In this case, theducts rods 46 radially so as to surround them. Moreover,ducts 68 formed in theheads 58 open radially into the respective annular chamber and open axially from the heads for the connection of an external distribution pipe (not shown in the drawings).
Claims (18)
- A rotary fluid actuator comprising a body (3) defining a cylindrical chamber (9) in which a piston (13) can slide axially, a surface of the piston (13) having at least one helical groove (15) for cooperating with guide means which include a sliding block (18) of complementary shape for each groove (15), each sliding block (18) being supported by the body (3) of the actuator (1), characterized in that each sliding block (18) is fixed to the body (3) of the actuator (1).
- An actuator according to Claim 1, characterized in that each sliding block (18) is mounted removably on the body (3).
- An actuator according to Claim 1 or Claim 2, characterized in that the section of each groove (15) transverse the axis of the piston (13) is trapezoidal, the sides of each groove (15) converging substantially towards the axis of the piston (13).
- An actuator according to Claim 2 or Claim 3, characterized in that each sliding block (18) is integral with an arcuate support element (19).
- An actuator according to Claim 4, characterized in that a surface of each arcuate support element (19) from which the respective sliding block (18) projects constitutes a portion of the wall of the cylindrical chamber (9).
- An actuator according to any one of Claims 2 to 5, characterized in that the sliding blocks (18) are made of an anti-friction material.
- An actuator according to Claim 6, characterized in that the anti-friction material is bronze.
- An actuator according to Claim 6, characterized in that the anti-friction material is a self-lubricating plastics material.
- An actuator according to any one of Claims 1 to 6, characterized in that the piston (13) has a plurality of radially outer and equiangularly spaced helical grooves (15), and in that the respective sliding blocks (18) are carried by a support ring (20) connected to the body (3) in a substantially central portion thereof.
- An actuator according to Claim 9, characterized in that the support ring (20) has a seat (27; 28) for housing the arcuate support elements (19) of the sliding blocks (18), axial restraint means (23) and angular restraint means (24; 27; 30) being provided for restraining the sliding blocks (18) relative to the support ring (20).
- An actuator according to Claim 10, characterized in that the axial restraint means for the sliding blocks (18) are constituted by end faces (23) of a pair of flanges (22) for connecting the support (20) to the body (3) of the actuator (1).
- An actuator according to Claim 11, characterized in that the housing seat consists of a plurality of recesses (27) disposed around the periphery of the cylindrical chamber (9) and each having a shape corresponding to a respective support element (19) of a sliding block (18).
- An actuator according to Claim 11, characterized in that the housing seat consists of an annular seat (28) delimited radially by a circular wall concentric with the axis of the piston (13), the annular seat (28) being able to house the support elements (19) of the sliding blocks (18) in abutment with the circular wall, and in that the angular restraint means for the support elements comprise elongate members (24; 30) which extend from the connecting flanges (22) axially relative to the piston (13).
- An actuator according to Claim 13, characterized in that the elongate members are pins (30) which engage corresponding axial holes formed in the support elements (19) of the sliding blocks (18) and in the connecting flanges (22).
- An actuator according to Claim 13, characterized in that the elongate members are axial appendages (24) of the connecting flanges (22) which are intended to be interposed to act as shoulders between adjacent support elements (19).
- An actuator according to any one of Claims 1 to 15, characterized in that the piston (13) is annular and its radially inner surface has at least one axial groove (35) for engagement by a guide element (37) projecting radially from an internal, axially extensible unit which comprises a pair of opposed linear fluid actuators (7, 44, 46) aligned with one another.
- An actuator according to Claim 16, characterized in that each linear actuator comprises an auxiliary piston (44) connected to a respective control rod (46) to which a handling member is keyed outside the actuator (1), guide means (54) being provided for keeping the auxiliary pistons (44) fixed for rotation with one another.
- An actuator according to Claim 17, characterized in that it comprises a pair of annular end heads (58) through which respective control rods (46) extend, each head (58) being connected rigidly and removably to one end of the axially extensible unit and being in abutment with an end of the body (3), with freedom to rotate.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
IT95TO000781A IT1281373B1 (en) | 1995-10-02 | 1995-10-02 | ROTARY FLUID ACTUATOR |
ITTO950781 | 1995-10-02 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0769625A2 true EP0769625A2 (en) | 1997-04-23 |
EP0769625A3 EP0769625A3 (en) | 1998-06-03 |
Family
ID=11413845
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP96115678A Withdrawn EP0769625A3 (en) | 1995-10-02 | 1996-09-30 | A rotary fluid actuator |
Country Status (2)
Country | Link |
---|---|
EP (1) | EP0769625A3 (en) |
IT (1) | IT1281373B1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1238166A1 (en) * | 1999-11-23 | 2002-09-11 | 1994 Weyer Family Limited Partnership | Hydraulic collection tool |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE8103188U1 (en) * | 1981-08-27 | Eckart GmbH & Co KG, 6490 Schlüchtern | Pressure fluid operated swivel motor | |
DE7511630U (en) * | 1977-10-27 | Niederheide, Gustav, 4322 Sprockhoevel | ||
US2765778A (en) * | 1954-09-17 | 1956-10-09 | Julian E Gerry | Hydraulic actuated steering mechanism |
DE1052913B (en) * | 1957-08-30 | 1959-03-12 | Karl Marx Stadt Maschf | Hydraulic feed device, especially for peeling knives in centrifuges |
US3731546A (en) * | 1971-12-01 | 1973-05-08 | Sundstrand Corp | Power operable pivot joint |
US4373426A (en) * | 1978-11-13 | 1983-02-15 | Weyer Paul P | Rotary actuator |
DE8601050U1 (en) * | 1986-01-17 | 1986-03-27 | Post, Hermann, 6480 Wächtersbach | Pressure fluid operated swivel motor |
-
1995
- 1995-10-02 IT IT95TO000781A patent/IT1281373B1/en active IP Right Grant
-
1996
- 1996-09-30 EP EP96115678A patent/EP0769625A3/en not_active Withdrawn
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1238166A1 (en) * | 1999-11-23 | 2002-09-11 | 1994 Weyer Family Limited Partnership | Hydraulic collection tool |
EP1238166A4 (en) * | 1999-11-23 | 2003-07-30 | 1994 Weyer Family Ltd Partners | Hydraulic collection tool |
US6612051B2 (en) | 1999-11-23 | 2003-09-02 | 1994 Weyer Family Limited Partnership | Hydraulic collection tool |
Also Published As
Publication number | Publication date |
---|---|
IT1281373B1 (en) | 1998-02-18 |
ITTO950781A0 (en) | 1995-10-02 |
EP0769625A3 (en) | 1998-06-03 |
ITTO950781A1 (en) | 1997-04-02 |
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