OPERATING TABLE EXTENSION

Abstract

 The present invention relates to the operating table extension, especially for endoprosthetic replacement procedures of the knee joint, comprising five subassemblies that work together to allow changing the position of the lower limb in the space of the operating table according to the needs of the operating surgeon during the surgery, wherein the extension includes Subassembly I providing a rigid connection to the operating table and a bracket integrating the entire structure, Subassembly II, whose components allow lower limb positioning in the direction of the vertical axis of the operating table, Subassembly III, whose components fasten and set the position of the limb support, Subassembly IV, whose components enable the positioning of the lower limb in the horizontal plane, perpendicular to the longitudinal axis of the patient, Subassembly V-a cart.

Description

[0001] The present invention relates to an operating table extension, especially for endoprosthetic replacement procedures of the knee joint.

[0002] A number of devices are known in the field for assisting in lower limb surgical procedures.

[0003] Thus, the description of the Chinese utility model CN214318493U discloses an orthopedic leg clinical support auxiliary frame, which is characterized in that it comprises a frame body which is fixedly connected at the lower rear part to a fixing device for the operating table. The support frame is connected to the side face of the frame body; this connection ensures that the leg support frame slides in the horizontal axis. By sliding in the horizontal axis, the leg support frame has the function of lifting the legs. The operation table is arranged above the leg support frame and is connected to the top of the frame body. Below the leg support frame is the waste liquid collector, which is fixedly connected to the bottom part of the front surface of the frame body. The side wall of the frame body is connected to two electric pushers that allow it to move vertically. The side of the leg auxiliary frame is fixedly connected to a strap for securing the patient's leg.

[0004] US patent application US3753557A discloses a device which constitutes a support for leg during knee surgery. The device includes a base, adapted to be adjustably and removably secured on a horizontally disposed operating table. An upwardly inclined support will support the leg bent at an angle, preferably less than 45 degrees at the knee, with the knee elevated and both the upper and lower legs in vertical plane. The leg support is free from obstruction to clear visibility, and access to the lateral sides of the knee, and also free from obstruction to lateral movement of the leg. The support is also adjustable as to height and to the angle at which the leg may be bent and supported, and to position in which the leg is supported with the foot elevated to operating level for foot and ankle surgery.

[0005] On the other hand, Chinese patent application CN113101109A discloses an operation platform for leg fracture surgery, comprising a platform body and a leg positioning device positioned on the platform body. The leg positioning device comprises two positioning slide rails, enabling positioning of two legs simultaneously. Each rail includes: thigh supporting plate, connecting roller, shank supporting plate, positioning slide rail. The thigh supporting plate and the shank supporting plate intersect in a V-shape, and the connecting shaft, the thigh supporting plate and the shank supporting plate are arranged between the ends of the thigh supporting plate and the shank supporting plate. The supporting plates are hinged with the connecting shaft around the axis of the connecting shaft, respectively. The lower ends of the thigh supporting plate and the shank supporting plate can slide along the length direction of the positioning slide rail. The thigh supporting plate and shank supporting plate are provided with a plurality of positioning assemblies along the length direction. The positioning assembly comprises an arc-shaped positioning frame, a positioning screw rod and a pressing plate, the positioning screw rod is arranged along the radial direction of the arc-shaped positioning frame and the positioning screw rod axially penetrates through the arc-shaped positioning frame and is in threaded connection with the arc-shaped positioning frame.

[0006] The following Chinese patent application CN113558919A discloses a knee bending auxiliary device for knee joint replacement operation. The knee bending auxiliary device comprises an operating table and further comprises a stopping mechanism arranged on the operating table. The stopping mechanism comprises a stop block assembly arranged on the operating table, and the stop block assembly is rotatably connected to a transmission assembly arranged at one end of the operating table. Adjustment mechanisms are arranged on two sides of the operating table. The sliding of both feet during surgery is limited by the arranged stop block assembly, thus ensuring patient stability when bending the knees during surgery. The sliding assembly drives the adjusting assembly to move, the position supporting legs by the support assembly is changed, the knee bending state of the patient can be conveniently changed by a doctor during an operation, the supporting assembly limits the movement of the legs, and in the meantime, elastic supporting force is provided. The adjusting assembly can also be rotated and adjusted timely, the knee bending angle of the patient is changed in the leg axis in the vertical plane.

[0007] The extension according to the present invention greatly aids the surgeon in performing surgical procedures. The attending physician can practically control the positioning of the lower limb by himself. The assistance of an assistant supporting the entire limb is limited to supporting the leg in the tibial region. The extension is to support the lower limb in the middle of the thigh length and, through the use of electric actuators, a vertical and a horizontal one, makes it possible to reposition the limb in the space of the operating table, depending on the needs in a given stage of the surgery.

[0008] The object of the present invention was to develop such a design of an operating table extension that will enable the surgeon to position the lower limb during surgical procedures of the knee joint (mainly in an endoprosthetic replacement procedure), as well as to limit the function of the physician assisting during surgery only to support the leg in the tibial region.

[0009] This object has been achieved by the operating table extension according to the present invention.

[0010] Thus, the subject matter of the present invention is an operating table extension, especially for endoprosthetic replacement procedures of the knee joint, comprising five subassemblies that work together to allow changing the position of the lower limb in the space of the operating table according to the needs of the operating surgeon during the surgery, wherein the extension includes:

Subassembly I providing a rigid connection to the operating table and a bracket integrating the entire structure, including the following components:

• Fastening clamp (1) that places the extension on the side rail of the table;
• Bracket (2) fastened to the clamp (1) with bolts (3);
• Adjustment lever (4) adjusting the location of the extension on the table guide;
• At least two bolts (3) connecting clamp to the bracket, preferably four bolts (3),

Subassembly II, whose components allow lower limb positioning in the direction of the vertical axis of the operating table, including the following components:

• LA28 actuator (5) positioning the limb, preferably with a stroke of 300 mm;
• Actuator holder (6);
• Two holders (7) and (8) fastening the bracket (2);
• Components that allow movement and fastening of the subassembly II:
• Two bushings, the bushing (9) of the actuator holder (6) and the bushing (10) of the bracket (2) forming a slide bearing with the stop screws (11);
• Stop screws (11) forming a slide bearing, preferably two stop screws (11);
• Nuts (12) preventing the screws (11) from loosening;
• Washers (13) for the screws (11) and nuts (12);
• LA28 actuator (5) fastening components forming a rigid connection:
• Stop screw fastening the bracket (2) to the LA28 actuator (5);
• Nut preventing the screw from loosening;
• Washer adjusting the location of the bracket (2) in the LA28 actuator (5),
• Washer for the nut,

Subassembly III, whose components fasten and set the position of the limb support, which includes the following components:

• Square tube (14) measuring 45x45 mm with a mounting hole, preferably a bean-shaped hole, which is a guide for a tube (15) of 40x40 mm;
• Square tube (15) measuring 40x40 mm with a hole for a butterfly screw (17);
• Butterfly screw (17) locking the hollow sections relative to each other in the desired position;
• Nut (18) extending the threaded hole for the butterfly screw (17), welded concentrically with respect to the hole in the tube (15) of 40x40 mm;
• Cotter pin (19) to prevent the butterfly screw (17) from complete loosening;
• Short section (16) with bolt holes connecting subassembly II to subassembly IV;
• Cap (21) for short section (16) of 40x40 mm and cap (20) for square tube (14) of 45x45 mm,

Subassembly IV, whose components enable the positioning of the lower limb in the horizontal plane, perpendicular to the longitudinal axis of the patient, including the following components:

• ELZ actuator (22) moving the thigh support;
• ELZ actuator (22) holder, with holes for bolts connecting subassembly IV to subassembly II;
• Plate with holes (23) connected to the ELZ actuator (22) carriage by six bolts (24);
• Bolts (24) connecting the plate (23) to the ELZ actuator carriage, preferably six bolts (24);
• Metal thigh support (25) protected with soft material, preferably covered with polyurethane foam covered with artificial leather, for patient comfort and easy disinfection;
• Clamping knob (26) fastening the ELZ actuator handle to the ELZ actuator (22) section;
• Flat-head bolts fastening the short section (16) of 40x40 mm of the subassembly II with ELZ support, preferably two flat-head bolts fastening the short section (16) secured with nuts;
• Actuator motor (27),

Subassembly V-a cart including the following components:

• Cart handle (28);
• Perforated plate (29) with holes in which hooks (30) can be placed to support the extension and servo inverter (31);
• Cart base (32) on which the CB8-A control box (33) of the LA28 actuator (5), remote controls (37), cables, etc., can be placed;
• Pedal base (34) for placing remote controls;
• Four wheels (35), including at least one with a brake (36);
• Hooks (30) of various lengths to support the extension;
• Nuts, washers, welding screws securing the wheels (35) in the base of the cart (32).

[0011] Preferably, the operating table extension includes control components for LA28 (5) and ELZ (22) actuators selected from such as:

• Servo inverter (31) controlling the ELZ actuator (22),
• CB8-A control box (33) controlling the LA28 actuator (5);
• Two remote controls (37) operating LA28 (5) and ELZ (22) actuators.

[0012] The subject matter of the present invention is shown in the drawing, where

Fig. 1 shows the construction of the operating table extension: subassemblies I-IV in front view a), from both sides b) and c), and in top view d);

Fig. 2 shows the construction of the operating table extension: subassemblies I-IV in front view a), rear view b), right side view c) and left side view d);

Fig. 3 shows the construction of subassembly V: cart for the extension, in front view a), side view b) and top view c);

Fig. 4 shows the construction of the subassembly I;

Fig. 5 shows the construction of the subassembly II;

Fig. 6 shows the construction of the subassembly III;

Fig. 7 shows the construction of the subassembly IV;

Fig. 8 shows fastening the extension to the operating table guide using fastening clamp and adjustment lever;

Fig. 9 shows positioning of the thigh support site, where: a) minimal position, b) maximal position;

Fig. 10 shows the limb angle adjustment, where: a) starting position of 0°, b) maximal position of 68°;

Fig. 11 shows the ELZ actuator (22) with marked directions of movement,

Fig. 12 shows the connection of subassemblies I and II, a), b) cross-section, c) left side view,

Fig. 13 shows the connection of subassemblies II and III.

[0013] The operating table extension, especially for endoprosthetic replacement procedure of the knee joint, consists of five co-operating subassemblies, which, due to the appropriate configuration, arrangement and functionality, allow changing the position of the lower limb in the space of the operating table according to the needs of the operating surgeon during surgery. The extension includes:

Subassembly I: A rigid connection to the operating table and a bracket that integrates the entire structure;

Subassembly II: Its components allow lower limb positioning in the direction of the vertical axis of the operating table;

Subassembly III: Components that fasten and set the position of the limb support (components that adjust the limb support site);

Subassembly IV: Components that enable the positioning of the lower limb in the horizontal plane (perpendicular to the patient's longitudinal axis);

Subassembly V: Cart, on which actuator control boxes will be placed during surgery, and then the extension, remote controls, cables, etc., after the surgery.

[0014] Basic features of the device include:

• Movement of the lower limb along the vertical axis and the transverse axis of the patient's body;
• Maximum patient weight: 200 kg;
• Maximum patient height: 200 cm;
• Electrical control;
• Foot remote control;
• Made of materials that can be easily and safely disinfected;
• Fastening to the side rail of a functioning and used operating table;
• The working space of the device reduced to minimum;
• Support at approximately ½ of the thigh length;
• Ability to adjust the height of the lower limb position;
• Versatility-can be mounted to most operating tables.

Description of individual subassemblies

Subassembly I

[0015] The components of subassembly I are designed to fasten the extension to the operating table guide (non-movable connection). The location of the extension is adjusted manually before the surgery. In addition to this function, these parts form the basis of the entire structure, as they support the other subassemblies. This extension segment includes (Fig. 4):

• Fastening clamp (1) that places the extension on the side rail of the table;
• Bracket (2) fastened to the clamp (1) with bolts (3);
• Adjustment lever (4) adjusting the location of the extension on the table guide;
• Four bolts (3) connecting clamp to the bracket.

Subassembly II

[0016] The group of subassembly II components allows the limb to be moved in the vertical direction ("up-down," "down-up"). It includes (Fig. 5):

• LA28 actuator (5) positioning the limb, with a stroke of 300 mm;
• Actuator holder (6);
• Two holders (7) and (8) fastening the bracket (2);
• Components that allow movement and fastening of the subassembly II:
• Two bushings, the bushing (9) of the actuator holder (6) and the bushing (10) of the bracket (2) forming a slide bearing with the stop screws (11);
• Two stop screws (11) forming a bearing;
• Two nuts (12) preventing the screws (11) from loosening;
• Washers (13) for the screws (11) and nuts (12);
• LA28 actuator (5) fastening components (rigid connection):
• One stop screw fastening the bracket (2) to the LA28 actuator (5);
• Nut preventing the screw from loosening;
• One washer adjusting the location of the bracket (2) in the LA28 actuator (5);
• One washer for the nut.

Subassembly III

[0017] With the components of this subassembly, the limb support site can be adjusted according to the length of the patient's thigh, thanks to components such as (Fig. 6):

• Square tube (14) measuring 45x45 mm (with a (bean-shaped) mounting hole), which is a guide for tube (15) of 40x40 mm;
• Square tube (15) measuring 40x40 mm with a hole for the butterfly screw (17);
• Butterfly screw (17) locking the hollow sections relative to each other in the desired position;
• Nut (18) extending the threaded hole for the butterfly screw (17) welded concentrically with respect to the hole in the tube (15) of 40x40 mm;
• Cotter pin (19) to prevent the butterfly screw (17) from complete loosening;
• Short section (16) with bolt holes connecting subassembly II to subassembly IV;
• Cap (21) for short section (16) of 40x40 mm and cap (20) for square tube (14) of 45x45 mm.

Subassembly IV

[0018] The components of subassembly IV allow positioning of the lower limb perpendicular to the horizontal axis of the patient's body ("left-right," "right-left"). In this group of components one could distinguish (Fig. 7):

• ELZ actuator (22) moving the thigh support;
• ELZ actuator (22) holder, with holes for bolts connecting subassembly IV to subassembly II;
• Plate with holes (23) connected to the ELZ actuator (22) carriage by six bolts (24);
• Six bolts (24) connecting the plate (23) to the ELZ actuator carriage;
• Metal thigh support (25) covered with polyurethane foam covered with artificial leather, for patient comfort and easy disinfection;
• Clamping knob (26) fastening the ELZ actuator handle to the ELZ actuator (22) section;
• Two flat-head bolts fastening the short section (16) of 40x40 mm of the subassembly II with ELZ support, secured with nuts;
• Actuator motor (27).

Subassembly V

[0019] Subassembly V consists of components forming the cart and the control system. These are (Fig. 3):

• Components forming the cart:
• Cart handle (28);
• Perforated plate (29) with holes in which hooks (30) can be placed to support the extension and servo inverter (31);
• Cart base (32) on which the CB8-A control box (33) of the LA28 actuator (5), remote controls (37), cables, etc., can be placed;
• Pedal base (34) for placing remote controls;
• Four wheels (35), including at least one with a brake (36);
• Hooks (30) of various lengths to support the extension;
• Nuts, washers, weld screws securing the wheels (35) in the base of the cart (32).

[0020] Examples of LA28 (5) and ELZ (22) actuator controlling components:

• Servo inverter (31) controlling the ELZ actuator (22);
• CB8-A control box (33) controlling the LA28 actuator (5);
• Two remote controls (37) operating LA28 (5) and ELZ (22) actuators.

Capabilities and operation of the device

[0021] The operating table extension according to the present invention is a device that allows the surgeon:

• Fastening to the operating table guide at any location;
• Positioning of the thigh support site;
• Adjusting the angle of the lower limb from the starting position of -5° to the maximal position of 60°;
• Positioning the limb relative to the horizontal plane of the operating table.

[0022] The surgeon can fasten the operating table extension with a fastening clamp (1), which is applied anywhere on the side rail of the table trunk segment. This clamp is secured by an adjustment lever (4) that serves as clamp holdfast (Fig. 4 and Fig. 8).

[0023] Positioning of the thigh support site ±150 mm (Fig. 9, a) minimal position, b) maximal position) is made possible by the use of two square tubes (14) and (15) with dimensions of 45x45 mm and 40x40 mm, respectively, forming the so-called telescope joint (where the first tube (14) with a larger cross-section provides a guide for the second one (15)). On one of the walls of each tube there are holes (the 45x45 section has a oblong hole, and the 40x40 section has a threaded hole) positioned relative to each other by means of a butterfly screw (17). This screw, passing through the oblong hole in the 45x45 section, is screwed into the threaded hole of the 40x40 tube. When the screw is tightened to the maximum, a non-movable connection is formed. The threaded hole has an extended thread, thanks to a concentrically welded nut. A cotter pin (19) placed in the butterfly screw hole (17) prevents the butterfly screw (17) from loosening completely.

[0024] Movement in the vertical plane of the operating table ("up-down"), and thus adjustment of the limb angle (from -23° to 45°, Fig. 10), is made possible by the movable arm of the LA28 actuator (5). Due to two movable connections formed by slide bearings, composed of a bracket bushing (10) and a handle bushing (9) of the LA28 actuator (5) and stop screws (11) a free movement of the entire assembly (the screws rotate in the bushings, Fig. 12) is allowed.

[0025] Movement of the lower limb in the horizontal ("left-right") plane of the operating table is provided by the belt-driven ELZ actuator (22). A thigh support is attached to the actuator carriage, on which the limb is supported (Fig. 11). Fig. 11 shows the ELZ actuator (22) with the directions of movement marked.

Operation of the operating table extension

[0026] The structure of the operating table extension consists of five subassemblies, which are connected to each other and operate interdependently. Subassemblies I and II are connected by three threaded temporary fastenings-stop screws placed in the holes of LA28 mandrels (38), bracket (2) and bracket holders (7) and (8), secured by nuts (12) (Fig. 12).

[0027] Subassemblies II and III connect to each other in a non-separable manner (bracket holders (7) and (8) and actuator LA28 (5) holder are connected to the 45x45 square tube (14) with a weld using a fillet weld and a 1/2 V weld at the respective locations of the 45x45 square tube (14), Fig. 13).

[0028] During the surgery, control components, which have no direct use during the procedure, e.g. control boxes (33), servo inverters (31), etc., can be placed on the operation table extension cart (subassembly 5). After the surgery, the operation table extension can be fixed on the same cart with hooks (30) and other items can be placed upon it, e.g. remote controls, etc..

Material characteristics

1.4401 acid-resistant steel

[0029] ANSI 1.4401 steel is an austenitic chrome-nickel stainless steel that is resistant to high temperatures and has exceptional corrosion resistance. It is widely used in environments where it is subjected to chemical agents, salts, acids and high temperatures. It contains molybdenum additive for higher corrosion resistance in environment containing chloride ions (a component of disinfectants). 1.4401 steel was used to make the largest number of operation table extension components, such as the bracket (2), ELZ holder (39), screws, bolts, nuts and washers.

S235JR structural steel

[0030] S235JR steel (according to PN-EN 10025) is a general-purpose structural steel, used for welded, load-bearing structures subjected to dynamic loads. This steel is characterized by very good machinability. It is used to make square tubes 45x45 (14), 40x40 (15), short section 40x40 (16), handle (28), perforated plate (29), cart base (32), and pedal base (34).

EN AW-6082 aluminum alloy

[0031] EN AW-6082 aluminum alloy is characterized by high mechanical strength, impact strength, and good corrosion resistance. It is poorly suitable for decorative anodizing and is susceptible to polishing. It has medium fatigue strength and can be machined. The following are made of it: plate with holes (23), mounting bracket (1).

UF-1 composite

[0032] UF-1 is a composite based on polytetrafuoroethylene (PTFE) or Teflon. It is composed of three layers of materials: an inner layer of steel, thermally bonded to a porous bronze layer, saturated and interlaced with polymer material. The surface of the polymer layer smoothed to the depth of the bronze cavities is a mixture of PTFE and lead with a thickness of about 0.01-0.03 mm.

[0033] This composite is used for the LA28 handle bushing (9) and bracket bushing (10) due to its very good lubricating properties.

Conclusions

[0034] The present invention relating to an extension allows the surgeon to properly position the lower limb during knee surgery, and allows the assistant's involvement during surgery to be limited to holding the leg at the tibial portion.

Advantages of the solution:

[0035] 

• The extension allows movement of the lower limb along the vertical axis and the transverse axis of the patient's body;
• Is approved for a patient with a maximum weight of 200 kg and a maximum height of 200 cm;
• The device is electrically controlled by a foot remote control;
• The extension is made of materials that can be easily and safely disinfected (1.4401, S235JR steels);
• The device is fastened to the side rail of a functioning operating table with a fastening clamp;
• The device occupies small working space;
• Positioning of the thigh support position in about ½ of its length is made possible by components of subassembly III;
• The height of the lower limb position can be adjusted by components of subassembly I;
• The device is universal, it can be mounted to all operating tables having a side rail;
• The construction of the extension gives the possibility to position the thigh support site, adjust the angle of the lower limb from the initial position of -5° to the maximal position of 60°, and position the limb relative to the horizontal plane of the operating table.

Claims

1. An operating table extension, especially for endoprosthetic replacement procedures of the knee joint, comprising five subassemblies that work together to allow changing the position of the lower limb in the space of the operating table according to the needs of the operating surgeon during the surgery, wherein the extension includes:

Subassembly I providing a rigid connection to the operating table and a bracket integrating the entire structure, including the following components:

• Fastening clamp (1) that places the extension on the side rail of the table;

• Bracket (2) fastened to the clamp (1) with bolts (3);

• Adjustment lever (4) adjusting the location of the extension on the table guide;

• At least two bolts (3) connecting clamp to the bracket, preferably four bolts (3),

Subassembly II, whose components allow lower limb positioning in the direction of the vertical axis of the operating table, including the following components:

• LA28 actuator (5) positioning the limb, preferably with a stroke of 300 mm;

• Actuator holder (6);

• Two holders (7) and (8) fastening the bracket (2);

• Components that allow movement and fastening of the subassembly II:

• Two bushings, the bushing (9) of the actuator holder (6) and the bushing (10) of the bracket (2) forming a slide bearing with the stop screws (11);

• Stop screws (11) forming a slide bearing, preferably two stop screws (11);

• Nuts (12) preventing the screws (11) from loosening;

• Washers (13) for the screws (11) and nuts (12);

• LA28 actuator (5) fastening components forming a rigid connection:

• Stop screw fastening the bracket (2) to the LA28 actuator (5);

• Nut preventing the screw from loosening;

• Washer adjusting the location of the bracket (2) in the LA28 actuator (5),

• Washer for the nut,

Subassembly III, whose components fasten and set the position of the limb support, which includes the following components:

• Square tube (14) measuring 45x45 mm with a mounting hole, preferably a bean-shaped hole, which is a guide for a tube (15) of 40x40 mm;

• Square tube (15) measuring 40x40 mm with a hole for a butterfly screw (17);

• Butterfly screw (17) locking the hollow sections relative to each other in the desired position;

• Nut (18) extending the threaded hole for the butterfly screw (17), welded concentrically with respect to the hole in the tube (15) of 40x40 mm;

• Cotter pin (19) to prevent the butterfly screw (17) from complete loosening;

• Short section (16) with bolt holes connecting subassembly II to subassembly IV;

• Cap (21) for short section (16) of 40x40 mm and cap (20) for square tube (14) of 45x45 mm,

Subassembly IV, whose components enable the positioning of the lower limb in the horizontal plane, perpendicular to the longitudinal axis of the patient, including the following components:

• ELZ actuator (22) moving the thigh support;

• ELZ actuator (22) holder, with holes for bolts connecting subassembly IV to subassembly II;

• Plate with holes (23) connected to the ELZ actuator (22) carriage by six bolts (24);

• Bolts (24) connecting the plate (23) to the ELZ actuator carriage, preferably six bolts (24);

• Metal thigh support (25) protected with soft material, preferably covered with polyurethane foam covered with artificial leather, for patient comfort and easy disinfection;

• Clamping knob (26) fastening the ELZ actuator handle to the ELZ actuator (22) section;

• Flat-head bolts fastening the short section (16) of 40x40 mm of the subassembly II with ELZ support, preferably two flat-head bolts fastening the short section (16) secured with nuts;

• Actuator motor (27),

Subassembly V-a cart including the following components:

• Cart handle (28);

• Perforated plate (29) with holes in which hooks (30) can be placed to support the extension and servo inverter (31);

• Cart base (32) on which the CB8-A control box (33) of the LA28 actuator (5), remote controls (37), cables, etc., can be placed;

• Pedal base (34) for placing remote controls;

• Four wheels (35), including at least one with a brake (36);

• Hooks (30) of various lengths to support the extension;

• Nuts, washers, welding screws securing the wheels (35) in the base of the cart (32).

2. The operating table extension according to claim 1, which includes control components for LA28 (5) and ELZ (22) actuators selected from such as:

• Servo inverter (31) controlling the ELZ actuator (22),

• CB8-A control box (33) controlling the LA28 actuator (5);

• Two remote controls (37) operating LA28 (5) and ELZ (22) actuators.

Drawing