CN213159330U

CN213159330U - Central lifting mechanism of mahjong machine

Info

Publication number: CN213159330U
Application number: CN202022048123.6U
Authority: CN
Inventors: 陈屹
Original assignee: Hangzhou Jingshi Electronics Co ltd
Current assignee: Hangzhou Jingshi Electronics Co ltd
Priority date: 2020-09-17
Filing date: 2020-09-17
Publication date: 2021-05-11
Anticipated expiration: 2030-09-17

Abstract

The utility model relates to a central lifting mechanism of a mahjong machine. Solves the technical problem of poor transmission stability of the central lifting mechanism of the mahjong machine in the prior art. Including central lift barrel, central lift seat, the lift disk body, central lifter, central lift bracket, lift driving motor, the lift rocking arm, the motor reference column, motor mounting bracket and motor frame demountable installation structure, central lift bracket locates central lifter lower extreme through the fixed cover of location structure, central lift bracket circumference outside has vertical guide plate, vertical guide plate upper end has horizontal guide plate, horizontal guide plate lower extreme has horizontal lifting face, vertical guide plate keeps away from central lift bracket one side and has the vertical spacing face of face looks vertically with horizontal lifting. Has the advantages that: the installation stability of the central lifting motor is improved, and shaking is not easy to generate; the stability of the lifting rocker arm in the lifting center lifting bracket process is ensured, the transmission process is reliable, and the phenomenon of shaking is not easily generated in the lifting process.

Description

Central lifting mechanism of mahjong machine

Technical Field

The utility model belongs to the technical field of amusement equipment, a mahjong machine is related to, especially, relate to a mahjong machine center elevating system.

Background

Mahjong is a popular tool for people as a recreational tool and is listed as a sports event. The traditional playing method is to manually code and shuffle the cards, and in order to save the shuffling time, a series of mahjong machines with the automatic shuffling function appear on the market. The central disk of the existing automatic mahjong machine needs to be lifted up through the central lifting mechanism when the mahjong is shuffled, so that the mahjong tiles can be pushed into the mahjong machine from a table top, and therefore, the central lifting mechanism of the mahjong machine is an important component of the automatic mahjong machine. The central lifting mechanism of the existing mahjong machine has a plurality of defects, for example, the failure rate is high, the transmission stability is poor, the installation stability of a driving motor is poor, the lifting process is easy to generate shaking phenomenon and the like, so that the central lifting mechanism of the mahjong machine is undoubtedly influenced greatly.

In order to solve the deficiencies of the prior art, various solutions have been proposed. For example, chinese patent document discloses a central lifting mechanism of a mahjong machine [ application No.: 201220355595.9], comprising a central lifting shaft connected with the round door seat, a central shaft seat connected with the central lifting shaft in a sliding way and a lifting motor arranged on the central shaft seat, wherein the lower part of the central lifting shaft is provided with a lifting platform, the output shaft of the lifting motor is provided with a lifting crank, one end of the lifting crank is fixed on the output shaft of the lifting motor, and the other end of the lifting crank is provided with a crank pushing wheel attached to the bottom surface of the lifting platform.

Although the scheme relieves the problems of poor transmission stability and high failure rate of the central lifting mechanism of the mahjong machine to a certain extent, the scheme still has the following problems: the installation of the driving motor is not firm enough, the installation stability of the motor is poor, and the lifting process is easy to cause the problems of shaking and the like.

Disclosure of Invention

One of the purposes of the utility model is to provide a central lifting mechanism of a mahjong machine; the technical problems that the installation stability of a central lifting motor of a mahjong machine is poor and the like in the prior art are solved.

In order to achieve the above purpose, the utility model adopts the following technical proposal: the central lifting mechanism of the mahjong machine comprises a central lifting seat, wherein the upper end of the central lifting seat is provided with a cylindrical central lifting cylinder body, a central lifting rod is movably arranged in the central lifting cylinder body in a penetrating way, the upper end of the central lifting rod is connected with a central lifting bracket positioned at the lower end of the central lifting seat, a lifting driving motor is arranged at the lower end of the central lifting seat, and a lifting rocker arm linked with the central lifting bracket is arranged on an output shaft of the lifting driving motor, center lift bracket be the annular and locate central lifter lower extreme through the fixed cover of location structure, center lift bracket circumference outside vertical guide plate that has vertical setting, just vertical guide plate upper end horizontal guide plate that has the extension and level setting towards the center lift bracket outside, horizontal guide plate lower extreme horizontal guide plate face that supports mutually with the lifting of lift rocking arm, vertical guide plate keep away from center lift bracket one side and have with horizontal lifting face looks vertically spacing face.

In foretell mahjong machine center elevating system, central lift bracket circumference outside lifting mount pad has, just vertical guide rail plate form in lifting mount pad one side, horizontal guide rail plate perpendicular to vertical guide rail plate and form in lifting mount pad middle part one side, just central lift bracket, lifting mount pad and vertical guide rail plate and horizontal guide rail plate even formula structure as an organic whole.

In the central lifting mechanism of the mahjong machine, the lifting mounting seat is internally provided with a plurality of reinforcing ribs, and the horizontal lifting surface is connected with the vertical limiting surface through the arc-shaped transition part.

In foretell mahjong machine center elevating system, location structure including set up at central lifting bracket lower extreme circumference inboard and be the spacing portion of curved arc, central lifter lower extreme support and lean on in the spacing portion of arc, just central lifting bracket circumference two locating holes that correspond the setting each other have, central lifter lower extreme radially be equipped with the radial hole corresponding with the locating hole, and a locating lever is fixed in proper order and is worn to locate in locating hole and radial hole.

In foretell mahjong machine center elevating system, center lift seat up end be equipped with a plurality of vertical settings and be located the fender frame reference column in the center lift barrel circumference outside, center lift seat lower extreme be equipped with the slide-spindle that is located the center lift bracket circumference outside and is the U-shaped and keep off the frame, just slide-spindle keep off frame upper end through keeping off a demountable installation structure setting in the uncovered mouth of center lift seat lower extreme and with keep off the frame reference column and link to each other, and slide-spindle keeps off and slides through the spacing subassembly of direction between frame and the center lift bracket and link to each other.

In foretell mahjong machine center elevating system, motor frame demountable installation structure including setting up the motor mounting hole in motor mounting bracket upper end, the motor reference column run through in central lift seat, motor mounting hole and motor reference column circumference inboard motor locating hole corresponding, just motor mounting hole and motor locating hole pass through motor positioning bolt and link to each other, motor reference column circumference first strengthening rib has, just motor reference column and first strengthening rib an organic whole be formed into on central lift seat.

In foretell mahjong machine center elevating system, motor mounting bracket be narrow structure under wide, lift driving motor set up in motor mounting bracket one side just lift driving motor's output shaft pass motor mounting bracket, just motor mounting bracket circumference strengthen the frame.

In foretell mahjong machine center elevating system, fender frame demountable installation structure keep off the frame installation department that the frame outside extension set up including setting up in the sliding shaft fender frame upper end both sides and towards the sliding shaft fender, fender frame installation department on be equipped with and keep off the frame mounting hole, fender frame reference column run through in central lift seat, fender frame mounting hole and fender frame reference column circumference inboard keep off the frame locating hole corresponding, just fender frame mounting hole and fender frame locating hole link to each other through keeping off a frame positioning bolt, fender frame reference column circumference second strengthening rib has, just fender frame reference column, second strengthening rib, central lift barrel all link to be the integral type structure with central lift seat.

In the central lifting mechanism of the mahjong machine, the guide limiting assembly comprises strip-shaped guide grooves which are respectively arranged on two sides of the sliding shaft baffle frame and axially extend, and guide bearings which are arranged in the strip-shaped guide grooves in a sliding manner are respectively arranged at two ends of the positioning rod.

In foretell mahjong machine center elevating system, the circumference outside of central lift seat uncovered department be equipped with the lift seat mounting panel, just the lift seat mounting panel on be equipped with a plurality of lift seat locating holes, just central lift barrel upper end threaded connection have an annular locking dish.

Compared with the prior art, the utility model has the advantages of:

1. the central lifting seat is compact in structure and small in size, and meanwhile, the motor, the sliding shaft baffle frame and the central lifting seat are firmly connected by extending the positioning columns on the upper end face of the central lifting seat, so that the mounting stability of the central lifting motor is improved, and the central lifting seat is not easy to shake;

2. the horizontal lifting surface and the vertical limiting surface form an L-shaped structure, so that the stability of the lifting rocker arm in the lifting center lifting bracket process is ensured, the transmission process is reliable, and the phenomenon of shaking is not easily generated in the lifting process.

Drawings

Fig. 1 is a schematic structural diagram of the present invention;

FIG. 2 is an exploded view of the structure of the present invention;

fig. 3 is an exploded view of another perspective of the present invention;

fig. 4 is a schematic structural view of the central lifting bracket of the present invention;

fig. 5 is a schematic view of another perspective of the center lift bracket of the present invention;

in the figure, a central lifting seat 1, a central lifting cylinder 11, a motor positioning column 12, a baffle frame positioning column 13, a sliding shaft baffle frame 14, a lifting seat mounting plate 15, a lifting seat positioning hole 16, an annular locking disc 17, a central lifting rod 2, a lifting disc body 21, a central lifting bracket 3, a vertical guide rail plate 31, a vertical limiting surface 311, a horizontal guide rail plate 32, a horizontal lifting surface 321, a lifting mounting seat 33, a reinforcing rib 331, an arc transition part 332, a lifting driving motor 4, a lifting rocker arm 41, a motor mounting frame 42, a reinforcing frame 421, a motor frame detachable mounting structure 5, a motor mounting hole 51, a motor positioning hole 52, a first reinforcing rib 53, a positioning structure 6, an arc limiting part 61, a positioning hole 62, a radial hole 63, a positioning rod 64, a baffle frame detachable mounting structure 7, a baffle frame mounting part 71, a baffle frame mounting hole 72, a baffle frame positioning hole 73, a second reinforcing rib 74, a guide limiting component, A strip-shaped guide groove 81 and a guide bearing 82.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

As shown in figures 1-5, the central lifting mechanism of the mahjong machine comprises a central lifting base 1 with a cylindrical central lifting cylinder 11 at the upper end, a central lifting rod 2 with the upper end connected with a lifting disc body 21 is movably arranged in the central lifting cylinder 11 in a penetrating way, the lower end of the central lifting rod 2 is connected with a central lifting bracket 3 positioned at the lower end of the central lifting base 1, a lifting driving motor 4 is arranged at the lower end of the central lifting base 1, a lifting rocker arm 41 linked with the central lifting bracket 3 is arranged on an output shaft of the lifting driving motor 4, the central lifting base 1 is rectangular box-shaped, the upper end of the central lifting base 1 is closed, the lower end is open, a plurality of vertically arranged motor positioning columns 12 are arranged on the upper end surface of the central lifting base 1, the motor positioning columns 12 are connected with a motor mounting rack 42 positioned in an open mouth at the lower end of the central lifting base 1 through a motor rack detachable mounting structure 5, and the, center lift bracket 3 is the annular and fixes the cover through location structure 6 and locate 2 lower extremes of center lifter, 3 circumference outsides of center lift bracket have the vertical guide plate 31 of vertical setting, and vertical guide plate 31 upper end has the horizontal guide plate 32 that extends and the level sets up towards the center lift bracket 3 outside, horizontal guide plate 32 lower extreme has the horizontal lifting face 321 that leans on mutually with the lifting portion of lift rocking arm 41, vertical guide plate 31 keeps away from center lift bracket 3 one side and has vertical spacing face 311 mutually perpendicular with horizontal lifting face 321. In this embodiment, through at 1 up end an organic whole of center lift seat and form motor reference column 12, realize firm the linking to each other of motor mounting bracket 42 and center lift seat 1, the installation stability of center lift motor has been improved, difficult production rocks, and simultaneously, horizontal lifting face 321 and vertical spacing face 311 form L shape structure, stability when having guaranteed lifting rocker arm 41 and the contact of horizontal lifting face 321, the stability of center lift bracket lift in-process has been improved, the transmission process is reliable, difficult production rocks among the lift in-process.

Preferably, the lifting seat mounting plate 15 is arranged on the outer circumferential side of the opening of the central lifting seat 1, a plurality of lifting seat positioning holes 16 are formed in the lifting seat mounting plate 15, the upper end of the central lifting cylinder 11 is in threaded connection with an annular locking disc 17, and the central lifting seat 1 is mounted and fixed through the lifting seat mounting plate 15 during actual mounting.

Further, the lifting mount 33 is disposed on the outer circumferential side of the central lifting bracket 3 in this embodiment, the vertical guide plate 31 is formed on one side of the lifting mount 33, the horizontal guide plate 32 is perpendicular to the vertical guide plate 31 and is formed on one side of the middle of the lifting mount 33, and the central lifting bracket 3, the lifting mount 33, the vertical guide plate 31 and the horizontal guide plate 32 are connected to form an integrated structure. Preferably, the lifting mounting seat 33 has a plurality of ribs 331 therein, and the horizontal lifting surface 321 is connected with the vertical limiting surface 311 through an arc-shaped transition portion 332. Adopt the integral type structure, can improve central lift bracket 3's structural strength like this, avoid because phenomena such as fracture, damage that central lift bracket 3 one side atress caused.

In order to realize firm linking to each other of center lift bracket 3 and center lifter 2, location structure 6 here just is the spacing portion 61 of curved arc including setting up 3 lower extreme circumference inboards in center lift bracket, 2 lower extremes of center lifter support and lean on the spacing portion 61 of arc, and 3 circumferences in center lift bracket have two locating holes 62 that correspond the setting each other, 2 lower extremes in center lifter radially be equipped with the corresponding radial hole 63 of locating hole 62, and a locating lever 64 is fixed in proper order and is worn to locate in locating hole 62 and radial hole 63.

Furthermore, in order to ensure the stability of the central lifting bracket 3 during lifting, a plurality of blocking frame positioning columns 13 which are vertically arranged and are positioned on the circumferential outer side of the central lifting barrel 11 are arranged on the upper end surface of the central lifting seat 1, a U-shaped sliding shaft blocking frame 14 which is positioned on the circumferential outer side of the central lifting bracket 3 is arranged on the lower end of the central lifting seat 1, the upper end of the sliding shaft blocking frame 14 is arranged in an open port at the lower end of the central lifting seat 1 through a blocking frame detachable mounting structure 7 and is connected with the blocking frame positioning columns 13, and the sliding shaft blocking frame 14 is connected with the central lifting bracket 3 in a sliding mode through a guiding limiting assembly 8.

Preferably, the blocking frame detachable installation structure 7 includes blocking frame installation parts 71 which are arranged on two sides of the upper end of the sliding shaft blocking frame 14 and extend towards the outer side of the sliding shaft blocking frame 14, blocking frame installation parts 71 are provided with blocking frame installation holes 72, the blocking frame positioning columns 13 penetrate through the central lifting seat 1, the blocking frame installation holes 72 correspond to the blocking frame positioning holes 73 on the circumferential inner side of the blocking frame positioning columns 13, the blocking frame installation holes 72 are connected with the blocking frame positioning holes 73 through the blocking frame positioning bolts, the blocking frame positioning columns 13 are circumferentially provided with second reinforcing ribs 74, and the blocking frame positioning columns 13, the second reinforcing ribs 74, the central lifting barrel 11 and the central lifting seat 1 are connected into an integrated structure. By adopting the structure, the sliding shaft blocking frame 14 can be firmly connected with the central lifting seat 1, and meanwhile, the thickness of the central lifting seat 1 does not need to be increased.

The guiding and limiting assembly 8 here includes strip-shaped guiding grooves 81 respectively disposed on both sides of the sliding shaft blocking frame 14 and extending axially, and the two ends of the positioning rod 64 respectively have guiding bearings 82 slidably disposed in the strip-shaped guiding grooves 81.

The motor frame detachable mounting structure 5 in this embodiment includes a motor mounting hole 51 disposed at the upper end of the motor mounting frame 42, the motor positioning column 12 penetrates through the central lifting seat 1, the motor mounting hole 51 corresponds to a motor positioning hole 52 on the circumferential inner side of the motor positioning column 12, the motor mounting hole 51 is connected to the motor positioning hole 52 through a motor positioning bolt, the motor positioning column 12 has a first reinforcing rib 53 in the circumferential direction, and the motor positioning column 12 and the first reinforcing rib 53 are integrally formed on the central lifting seat 1. Preferably, the motor mounting bracket 42 has a structure that the top is wide and the bottom is narrow, the lifting driving motor 4 is disposed at one side of the motor mounting bracket 42, the output shaft of the lifting driving motor 4 penetrates through the motor mounting bracket 42, and the motor mounting bracket 42 has a reinforcing frame 421 at the circumference. Obviously, the adoption of the structure can firmly connect the motor mounting frame 42 with the central lifting seat 1, and meanwhile, the thickness of the central lifting seat 1 does not need to be increased.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications, additions and substitutions for the specific embodiments described herein may be made by those skilled in the art without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Although the center lift base 1, the center lift cylinder 11, the motor positioning post 12, the stopper positioning post 13, the slide shaft stopper 14, the lift base mounting plate 15, the lift base positioning hole 16, the annular lock plate 17, the center lift lever 2, the lift disc body 21, the center lift bracket 3, the vertical guide plate 31, the vertical stopper surface 311, the horizontal guide plate 32, the horizontal lifting surface 321, the lifting mounting seat 33, the reinforcing rib 331, the arc transition portion 332, the lift driving motor 4, the lift rocker arm 41, the motor mounting bracket 42, the reinforcing frame 421, the motor bracket detachable mounting structure 5, the motor mounting hole 51, the motor positioning hole 52, the first reinforcing rib 53, the positioning structure 6, the arc stopper portion 61, the positioning hole 62, the radial hole 63, the positioning rod 64, the stopper bracket detachable mounting structure 7, the stopper mounting portion 71, the stopper mounting hole 72, the stopper positioning hole 73, the second reinforcing rib 74, the positioning hole 73, the positioning hole for the motor bracket, The terms guide stop assembly 8, bar guide slot 81, guide bearing 82, etc., do not exclude the possibility of using other terms. These terms are used merely to more conveniently describe and explain the nature of the present invention and should not be interpreted as imposing any additional limitations that are contrary to the spirit of the present invention.

Claims

1. A central lifting mechanism of a mahjong machine comprises a central lifting seat (1) with a cylindrical central lifting cylinder body (11) at the upper end, a central lifting rod (2) with the upper end connected with a lifting disk body (21) is movably arranged in the central lifting cylinder body (11) in a penetrating way, the lower end of the central lifting rod (2) is connected with a central lifting bracket (3) positioned at the lower end of the central lifting seat (1), a lifting driving motor (4) is arranged at the lower end of the central lifting seat (1), a lifting rocker arm (41) linked with the central lifting bracket (3) is arranged on an output shaft of the lifting driving motor (4), the central lifting seat (1) is rectangular box-shaped, the upper end of the central lifting seat (1) is closed, the lower end of the central lifting seat is open, a plurality of vertically arranged motor positioning columns (12) are arranged on the upper end face of the central lifting seat (1), and the motor positioning column (12) is connected with a motor mounting rack (42) positioned in an opening at the lower end of the central lifting seat (1) through a motor rack detachable mounting structure (5), the lifting driving motor (4) is arranged on the motor mounting rack (42), the central lifting bracket (3) is annular and is fixedly sleeved at the lower end of the central lifting rod (2) through a positioning structure (6), the outer side of the circumference of the central lifting bracket (3) is provided with a vertical guide rail plate (31), and the upper end of the vertical guide rail plate (31) is provided with a horizontal guide rail plate (32) which extends towards the outer side of the central lifting bracket (3) and is horizontally arranged, the lower end of the horizontal guide rail plate (32) is provided with a horizontal lifting surface (321) which is abutted against the lifting part of the lifting rocker arm (41), one side of the vertical guide rail plate (31) far away from the central lifting bracket (3) is provided with a vertical limiting surface (311) which is vertical to the horizontal lifting surface (321).

2. The central lifting mechanism of mahjong machine according to claim 1, wherein the lifting mount seat (33) is arranged on the outer side of the circumference of the central lifting bracket (3), the vertical guide rail plate (31) is formed on one side of the lifting mount seat (33), the horizontal guide rail plate (32) is perpendicular to the vertical guide rail plate (31) and is formed on one side of the middle part of the lifting mount seat (33), and the central lifting bracket (3), the lifting mount seat (33), the vertical guide rail plate (31) and the horizontal guide rail plate (32) are connected into an integrated structure.

3. The central lifting mechanism of mahjong machine according to claim 2, wherein the lifting mounting base (33) is provided with a plurality of reinforcing ribs (331), and the horizontal lifting surface (321) is connected with the vertical limiting surface (311) through an arc transition part (332).

4. The central lifting mechanism of a mahjong machine according to claim 1, 2 or 3, wherein the positioning structure (6) comprises an arc-shaped limiting part (61) which is arranged at the circumferential inner side of the lower end of the central lifting bracket (3), the lower end of the central lifting rod (2) is abutted against the arc-shaped limiting part (61), the central lifting bracket (3) is circumferentially provided with two positioning holes (62) which are arranged correspondingly to each other, the lower end of the central lifting rod (2) is radially provided with a radial hole (63) corresponding to the positioning hole (62), and a positioning rod (64) is sequentially and fixedly arranged in the positioning holes (62) and the radial hole (63).

5. The central lifting mechanism of mahjong machine according to claim 4, wherein the upper end face of the central lifting seat (1) is provided with a plurality of vertically arranged retaining frame positioning columns (13) located on the circumferential outer side of the central lifting cylinder (11), the lower end of the central lifting seat (1) is provided with a U-shaped sliding shaft retaining frame (14) located on the circumferential outer side of the central lifting bracket (3), the upper end of the sliding shaft retaining frame (14) is arranged in the opening at the lower end of the central lifting seat (1) through a retaining frame detachable mounting structure (7) and is connected with the retaining frame positioning columns (13), and the sliding shaft retaining frame (14) is connected with the central lifting bracket (3) through a guiding limiting component (8) in a sliding manner.

6. The central lifting mechanism of a mahjong machine according to claim 1, wherein the detachable mounting structure of the motor frame (5) comprises a motor mounting hole (51) arranged at the upper end of the motor mounting frame (42), the motor positioning column (12) penetrates through the central lifting base (1), the motor mounting hole (51) corresponds to the motor positioning hole (52) at the circumferential inner side of the motor positioning column (12), the motor mounting hole (51) is connected with the motor positioning hole (52) through a motor positioning bolt, the motor positioning column (12) is circumferentially provided with a first reinforcing rib (53), and the motor positioning column (12) and the first reinforcing rib (53) are integrally formed on the central lifting base (1).

7. The central lifting mechanism of mahjong machine according to claim 6, wherein the motor mounting bracket (42) is a structure with a wide top and a narrow bottom, the lifting driving motor (4) is arranged on one side of the motor mounting bracket (42) and the output shaft of the lifting driving motor (4) passes through the motor mounting bracket (42), and the motor mounting bracket (42) is provided with a reinforcing frame (421) in the circumferential direction.

8. The central lifting mechanism of mahjong machine according to claim 5, wherein the baffle frame detachable mounting structure (7) comprises baffle frame mounting parts (71) which are arranged at two sides of the upper end of the sliding shaft baffle frame (14) and extend towards the outer side of the sliding shaft baffle frame (14), a baffle frame mounting hole (72) is arranged on the baffle frame mounting part (71), the baffle frame positioning column (13) penetrates through the central lifting seat (1), the baffle frame mounting hole (72) corresponds to a baffle frame positioning hole (73) at the circumferential inner side of the baffle frame positioning column (13), the baffle frame mounting hole (72) is connected with the baffle frame positioning hole (73) through a baffle frame positioning bolt, the circumferential direction of the blocking frame positioning column (13) is provided with a second reinforcing rib (74), and the blocking frame positioning column (13), the second reinforcing rib (74), the central lifting cylinder (11) and the central lifting seat (1) are connected into an integral structure.

9. The central lifting mechanism of mahjong machine according to claim 5, wherein the guiding and limiting assembly (8) comprises bar-shaped guiding grooves (81) respectively arranged at two sides of the sliding shaft block frame (14) and axially extending, and guiding bearings (82) slidably arranged in the bar-shaped guiding grooves (81) are respectively arranged at two ends of the positioning rod (64).

10. The central lifting mechanism of a mahjong machine according to claim 1, wherein a lifting seat mounting plate (15) is arranged on the outer side of the opening of the central lifting seat (1) in the circumferential direction, a plurality of lifting seat positioning holes (16) are formed in the lifting seat mounting plate (15), and an annular locking disc (17) is in threaded connection with the upper end of the central lifting cylinder (11).