363 results about "Trunnion" patented technology

Apparatuses, systems, and methods are disclosed for use in or with firearms. A firearm receiver includes an elongated channel machined or 3D printed from a metallic material, and has a front end and a rear end. The firearm also includes a front trunnion having a rear portion coupled to the front end of the elongated channel and having a front portion configured to couple to a handguard. Also includes is a rear trunnion coupled to the rear end and configured to receive an accessory adapter.

The invention discloses a welding slag ladle for containing copper slag and a design method. The welding slag ladle is suitable for containing, cooling and inverted placing procedures of high-temperature copper slag. The cinder ladle comprises a cylinder body, a ladle bottom, rib plates, trunnions and supporting legs, the cylinder body and the ladle bottom are formed by welding high-temperature-resistant and high-strength rolled plates, the thickness of the cylinder body is 70-100 mm, and the thickness of the ladle bottom is 80-120 mm; setting an inclination angle beta of 11.5-21 degrees relative to the center line of the bus of the cylinder body, and controlling the roughness of the inner wall to be less than or equal to 12.5 microns so as to reduce the separation resistance after the copper slag is cooled; thickness combination, stress distribution, deformation and rib plate arrangement are optimized through structural mechanical simulation, and it is ensured that the structural strength meets the requirements under high temperature and thermal cycle loads; full penetration weld joints are adopted, nondestructive testing is carried out, and the welding reliability is guaranteed; compared with a traditional casting cinder ladle, the mass of the cinder ladle is reduced by 10%-15%, the deslagging efficiency is improved, the service life is prolonged to more than two times of the original service life, and the cinder ladle has the advantages of being light in structure, high in bearing capacity, high in deformation resistance and good in maintainability.

The present application is directed a Joint Revision Surgery Apparatus which includes a surgical knife blade guide block which has a plurality of rearward blade guide slots, a central cavity and a large forward slot having an adjustable knife blade guide pressure plate. The surgical knife blade guide block central cavity houses a stem trunnion securing member and is positioned over the trunnion end of the existing prosthesis to be removed and secured to the prothesis. The guide blade block is secured to the trunnion of the prosthesis to be extracted using a stem trunnion securing member housed within the guide block. Straight, curved and compound curved knife blades are guided by the blade guide slots to cut the prothesis free. The Joint Revision Surgery Apparatus facilitates rapid, efficient and complete removal of an existing prosthesis during joint revision surgery, and significantly increases positive medical outcomes for joint revision procedures.

The invention provides a crown block operation monitoring method and system, relates to the technical field of remote monitoring of crown blocks, is applied to ground monitoring equipment, and specifically comprises the following steps: acquiring crown block position information of a target crown block from crown block control equipment; target information of target operation executed by the target crown block is determined according to the crown block position information, the target operation comprises ladle hanging operation and / or ladle removing operation, the ladle hanging operation is operation of hanging a plate hook of the target crown block into a trunnion of a target steel ladle, and the ladle removing operation is operation of removing the plate hook from the trunnion; the target information is sent to the crown block control equipment, so that the crown block control equipment controls the target crown block to enter a target range to execute the target operation; when it is determined that the target crown block enters the target range, first identification information and second identification information are obtained, the first identification information is obtained by monitoring the target crown block through a two-dimensional identification technology, and the second identification information is obtained by monitoring the target crown block through a three-dimensional identification technology; and monitoring whether the target crown block successfully executes the target operation or not according to the first identification information and the second identification information.

A trunnion bar locker assembly for a rear load refuse vehicle for use when dumping a refuse container having a trunnion bar, includes a pair of spaced apart locking assemblies, each locking assembly further including a base frame to be connected to the refuse vehicle, a trunnion bar receiver connected to the base frame, a locker door connected to the base frame and having an open position wherein the trunnion bar receiver removably receives an end of the trunnion bar of the refuse container, and a closed position wherein the pivotable locker door confines the end of the trunnion bar in the receiver, an electrically powered actuator coupled to the base frame and to the pivotable locker door, and a controller connected to each respective locking assembly to control the actuator to move the pivotable locker door between the open and closed positions.

A blancher includes a tank and auger. The tank has a wall defining an interior space at least partially cylindrical with end walls. The auger is in the interior space and has flights Each flight has a circumferential edge in close proximity to the wall. The flights move food product from one end to the other as the augur is turned. The auger is preferably supported by a trunnion ring extending through the end wall and as the trunnion ring turns the augur and of flights are turned. An inlet is preferably located at one end wall and located along a center line of the augur. An outlet is preferably a discharge chute extending through the other end wall. The auger preferably includes at least one lifting flight between the plurality of flights and the end, such that the lifting flight lifts the food product to the discharge chute.

The utility model discloses a locking type hydraulic cylinder for a supporting platform of an under-pressure operation machine, which comprises a cylinder body and a Tr tooth piston rod slidably connected in the cylinder body, one end of the Tr tooth piston rod is connected with a ball head and a locking trunnion assembly, the ball head is connected with a supporting assembly, and the Tr tooth piston rod is connected with a locking trunnion assembly. The inner wall of the end, arranged in the cylinder body, of the Tr tooth piston rod is connected with an inner guide sleeve, the inner guide sleeve is fixed to the end of the Tr tooth piston rod through an inner gland, the inner guide sleeve and the inner gland are both arranged on the inner piston rod in a sliding and sleeving mode, one end of the inner piston rod is fixed to the cylinder body, and the other end of the inner piston rod is connected with an inner piston. The inner piston is connected to the inner wall of the Tr tooth piston rod in a sliding mode, two oil ports are formed in the cylinder body, a lower platform supporting block is installed on the outer wall of the cylinder body, and the cylinder body is connected with the supporting platform through the lower platform supporting block. The hydraulic locking device is simple in structure, can be mechanically locked after being lifted to a proper position, does not need to maintain hydraulic pressure, is high in reliability, and has simple requirements on a hydraulic system.

The present application is directed a Joint Revision Surgery Apparatus which includes a surgical knife blade guide block which has a plurality of rearward blade guide slots, a central cavity and a plurality of guide slots having a two-way adjustable L-shaped guide plate. The surgical knife blade guide block central cavity houses a stem trunnion securing member and is positioned over the trunnion end of the existing prosthesis to be removed and secured to the prothesis. The guide blade block is secured to the trunnion of the prosthesis to be extracted using a stem trunnion securing member housed within the guide block. Straight, curved and compound curved knife blades are guided by the blade guide slots to cut the prothesis free. The Joint Revision Surgery Apparatus facilitates rapid, efficient and complete removal of an existing prosthesis during joint revision surgery, and significantly increases positive medical outcomes for joint revision procedures.

A swirl recovery vane (SRV) includes a trunnion configured to pivotally connect to an exterior surface of an inner platform of an SRV structure system. The SRV includes a body extending radially from the trunnion to an unshrouded distal vane tip of the vane. The SRV includes a heat exchanger that includes a gas inlet configured to couple a bleed air valve of a compressor section of a gas generator to a gas channel. The heat exchanger includes the gas channel adapted to: enable gas to flow into the gas inlet as cool gas and out through a gas outlet as warm gas; and extend into the body of the vane to enable heat transfer from a heat source within the vane to the cool gas. The heat exchanger includes the gas outlet configured to output the warm gas from the channel to an ambient environment outside of the vane.

A multipod joint having an outer joint part with a first longitudinal axis and a cavity which runs parallel to the first longitudinal axis and which has an open end. At least two recesses running parallel to the first longitudinal axis are distributed along a circumferential direction, which extends around the first longitudinal axis. The joint has a joint inner part with a second longitudinal axis, comprising at least one central body on which at least two trunnions are formed with trunnion axes extending radially from the second longitudinal axis. A roller body rotatable at least about the trunnion axis is arranged on each trunnion.

The application discloses a double-safety-redundant tilting actuator of a tilt-rotor unmanned aerial vehicle, which comprises a ball screw mechanism and lug connections and trunnion connections installed on the ball screw mechanism; the lug connections are fixed on the wing ribs of a wing, and the trunnion connections are fixed on a nacelle; the ball screw mechanism is configured to drive the nacelle to rotate correspondingly synchronously with extension and retraction actions of the ball screw mechanism; wherein the ball screw mechanism comprises two-stage serial ball screws and two independent driving mechanisms; the two driving mechanisms are configured to independently control the two-stage serial ball screws to complete all extension and retraction actions, so that the operation of the aircraft is safer and more reliable; when any one-stage ball screw is damaged or stuck at a certain angle to cause the ball screw to be unable to retract, the other one-stage ball screw can still normally operate, the nacelle can still rotate within a certain angle, the function of aircraft landing and taxiing can be realized, and the aircraft can be safely landed.

The invention discloses a crown block safety monitoring system based on YOLO V5 and Wincc, belongs to the field of monitoring systems, and aims to solve the problems that a crown block monitoring system mainly depends on manual judgment and is easily influenced by experience and judgment of an operator, and the operation risk is increased. The system comprises a data acquisition module, an image vision module, a hoisting state judgment module and an abnormity alarm module, the data acquisition module is used for acquiring variable point locations of the crown block PLC in real time; the method comprises the following steps: reading a variable point location in a PLC (Programmable Logic Controller) through KepServerEX software; the image vision module is used for recording a steel ladle trunnion position working image in real time from the front angle through n high-definition network cameras mounted on the two sides of a crown block working area and transmitting the steel ladle trunnion position working image to the hoisting state judgment module; the hoisting state judgment module is used for receiving the steel ladle trunnion position working image transmitted from the image vision module; and performing visual image identification on the steel ladle trunnion position working image based on a YOLO V5 algorithm, and identifying whether a lifting lug of the steel ladle and a lifting hook of the crown block are in safe positions or not.

A universal joint bearing includes a trunnion, a cup, rolling elements rotatably supporting the cup relative to the trunnion, and at least one seal for sealing a space between the trunnion and the cup. The cup has a substantially cylindrical surface, which is a part of a radially outer surface of the universal joint bearing. All of the rolling elements of the universal joint bearing are arranged in a certain number of rows of rolling elements. A sum of the maximum axial lengths of all the rows of rolling element divided by the sum of the maximum axial length of the substantially cylindrical surface and the maximum axial length of a radially outer surface of the at least one seal, which is another part of the radially outer surface of the universal joint bearing, is between 0.6 and 0.75.

The invention provides a rotor turnover device, and relates to the technical field of gas turbine equipment. The rotor overturning device comprises a supporting platform which comprises a first support, a second support and a third support; the two rotating shaft limiting assemblies are respectively fixed on the first bracket and the second bracket; two trunnions are arranged on the switching disc and are respectively embedded into the two rotating shaft limiting assemblies; the transfer hanging ring is fixedly connected with a front journal of the rotor; the limiting rotary supporting plate is fixedly arranged on the third bracket; and a front journal of the rotor is embedded into the limiting rotary supporting plate. The rotor turnover device can perform multi-degree-of-freedom turnover on the gas compressor rotor, one lifting point is reduced compared with a traditional turnover mode, the requirement for the operation ability of operators is weakened, the possibility of risk generation in the rotor turnover process is reduced, and reliable and safe multi-degree-of-freedom turnover work of the gas compressor rotor is achieved. And therefore, the overturning efficiency and safety are improved, and the stability of multi-degree-of-freedom and multi-angle overturning of the gas compressor rotor is improved.

A customizable firearm system includes a chassis. A barrel assembly is disposed in the chassis. The barrel assembly including a trunnion and a barrel nut assembly. The barrel nut assembly includes an outer barrel nut sleeve and an inner barrel nut sleeve receiving a barrel. The barrel nut assembly is removably disposed in the trunnion. A bolt carrier assembly is disposed in the chassis. The bolt carrier assembly includes a backplate assembly and a pair of guide rods. Each of the guide rods have a first end disposed in the backplate assembly, and a second end disposed in the trunnion. A bolt carrier slidably disposed on the guide rod.

The invention discloses a gear transmission type electric cylinder trunnion supporting device, and relates to the technical field of electrotechnic.The gear transmission type electric cylinder trunnion supporting device comprises a device base, a groove is formed in the device base, and a swing adjusting structure is arranged in the groove of the device base; a rotary clamping structure is arranged on the upper surface of the side, away from the swing adjusting structure, of the device base, and a maintaining and cleaning structure is arranged on the side, close to the swing adjusting structure, of the device base. According to the electric cylinder trunnion supporting device, through cooperation of the first servo motor and the second servo motor, precise positioning and clamping are achieved, and the machining precision and efficiency are improved; a third servo motor is used for driving swing adjustment, the swing amplitude and angle are accurately controlled, stability and reliability are improved, an electric telescopic rod is used for starting and driving a maintenance and cleaning structure, cleaning and maintenance of the interior of the device are achieved, the service life of the device is prolonged, stable operation under various working conditions is ensured, and powerful guarantee is provided for production.

An actuating mechanism for a fluid displacement and pressuring device where the actuating mechanism comprises a pivotable component which has two pivot points - an upper pivot point provided by trunnions integral with a unitary link lever, and a lower pivot point provided by stub pins which are integral with either the housing of the device or a carrier component thereof. Preferably, the number of parts is reduced, assembly is easier, and the overall reliability of the device is increased.

The application discloses a vertical kneader facilitating discharging, which is applied to the technical field of vertical kneaders and comprises a cross beam, a lower barrel body, a base, a stand and a material containing barrel, wherein the bottom surface of the cross beam is provided with a camera at the front part, one side of the stand is fixedly provided with a control center, the front surface of the stand is fixedly provided with a mechanical arm at the middle part, the top structure of the mechanical arm is in the shape of a hammer, support frames are threadedly connected to the two sides of the stand, a turnover assembly is arranged on the support frame, and a groove is formed in the front end of the support frame. The application drives the turnover assembly, so that the turnover output rod drives the trunnion, the trunnion drives the lower barrel body to turn over, the slurry is conveniently poured out, the reinforcing ring provided with a vibrator is arranged, the vibration makes the residual slurry on the inner wall of the lower barrel body flow down, the mechanical arm is arranged to knock the bottom of the lower barrel body, and the residual slurry on the inner bottom of the lower barrel body flows down. The device solves the problem that the kneader is inconvenient to discharge.

The invention provides a hydraulic servo oil cylinder trunnion positioning and repairing method and a positioning device, which are used for carrying out in-situ welding and repairing on a fractured oil cylinder trunnion, and the method comprises the following control conditions: (1) heating an oil cylinder barrel before welding and carrying out heat preservation on the oil cylinder barrel after welding; (2) the tensile strength of the selected welding rod is higher than that of an oil cylinder barrel matrix; and (3) the welding rod is baked and heated before welding.

The utility model provides a cradle structure for a machine gun weapon station. The cradle adopts a double-trunnion-hole groove-shaped structure, a trunnion hole is formed in the side wall of one end, and a guide rail is fixedly connected to the other end in a groove. The sliding base is installed on the guide rail and can slide along the guide rail, weapon installation structures are arranged at the first end and the second end of the sliding base respectively, the first end is closer to the trunnion hole of the cradle than the second end, and the protruding block in the middle of the guide rail is located between the first end and the second end. One end of the buffer rod is connected to the bump of the guide rail, and the other end is connected to the second end of the sliding seat. The buffer spring can buffer forward impact and recoil force generated when a weapon is shot, and the buffer rod is sleeved with the portion, between the protruding block and the second end, of the buffer spring. The buffering device is compact in structure, the buffering device can be provided for a small-caliber weapon without an external buffering device, so that the weapon rushes forwards and sits backwards in the shooting process, meanwhile, the spring buffers the impact load, and the stress of the trunnion and the bracket can be reduced to protect the trunnion and the bracket.

The invention discloses a cutting device for refractory material processing, and relates to the technical field of building block manufacturing, and the cutting device comprises an adjustable cutting assembly. According to the cutting device for refractory material machining, the cutting head only makes contact with materials in the advancing process and is automatically lifted and separated in the return stroke, scraping damage to a notch in the returning process can be eliminated, the ineffective stroke can be effectively shortened, the service life of a cutter can be effectively prolonged, and when a user needs to adjust the cutting angle to achieve oblique cutting, the cutting head can be automatically lifted and separated. The movable plate can be driven to adjust the cutting angle within the arc range of the angle adjusting plate only by pulling out the plug pin, driving the movable plate to rotate with the trunnion as the axis and re-inserting the plug pin into the partition gap of the corresponding angle, so that the cutting angle can be adjusted within a certain range, and the cutting efficiency is improved. Angle deviation of the movable plate is achieved through simple and convenient operation, switching between vertical cutting and oblique cutting is achieved, and the machining requirements of different notch angles of refractory materials are met.

The utility model relates to the related technical field of high-temperature and high-pressure dyeing machines, in particular to a hole cover structure of a high-temperature and high-pressure dyeing machine, which comprises a dyeing machine main barrel and a combined mechanism arranged on one side of the surface of the dyeing machine main barrel. According to the hole cover structure of the high-temperature and high-pressure dyeing machine, through the arrangement of the combined mechanism, the manhole base is fixedly connected with the main barrel of the dyeing machine to form a fixed sealing base, and the manhole sealing piece is located at the bottom of the manhole cover and installed on the inner side of the manhole cover, so that airtightness and liquid tightness are achieved after the manhole sealing piece is attached to the manhole base, and dyeing liquid is prevented from leaking; when the manhole cover needs to be opened, the handle is operated, the hand-screwing nut is loosened, the movable fastening bolt is separated from the fixed clamping jaw, then the manhole cover is pulled through the manhole cover handle, the manhole cover is rotated to the opening position through the manhole cover opening and closing trunnion, and rapid inspection and operation are facilitated.

The utility model provides a vacuum induction furnace steel pouring tundish which comprises a bearing bottom box, the bearing bottom box comprises a bottom plate, two short edge surrounding plates and two long edge surrounding plates, and the bottom plate is provided with a molten steel inlet and a molten steel outlet; the two long-edge coamings and the two short-edge coamings are vertically fixed to the edge of the bottom plate and define a cuboid structure with an opening in the top with the bottom plate; hollow heat insulation cavities are formed in the two long-edge surrounding plates, trunnion assemblies are arranged on the two long-edge surrounding plates, each trunnion assembly comprises at least two trunnions arranged in the length direction of the cuboid structure, and blocking mechanisms are arranged at the second ends of the trunnions. The blocking mechanism is matched with the trunnion to form a limiting mechanism used for limiting the chain type lifting appliance in the direction perpendicular to the long side coaming; the cover plate is used for covering the top opening of the bearing bottom box, and the cover plate is matched with the top opening of the bearing bottom box in shape.

The application discloses a special tool for adjusting and fixing a single-point mooring chain stopper, and relates to the technical field of ocean engineering.The special tool for adjusting and fixing a single-point mooring chain stopper comprises a chain stopper trunnion shell and two chain stopper X-axis joint cylinders, the chain stopper X-axis joint cylinders are located on the two sides of the chain stopper trunnion shell, the chain stopper X-axis joint cylinders can rotate around the chain stopper trunnion shell through internal pin shafts, the chain stopper trunnion shell is provided with a fixing tool on the side facing the chain stopper X-axis joint cylinders, and the fixing tool comprises a support fixed on the chain stopper trunnion shell and an eye ring fixed on the top end of the chain stopper X-axis joint cylinder.The first rotating shaft, the second rotating shaft and the fixing rod are arranged, the relative position of the first rotating shaft and the second rotating shaft is changed by adjusting the rotary motion of the left threaded rod and the right threaded rod at the two ends of the fixing rod, and the relative angle between the chain stopper trunnion shell and the chain stopper X-axis joint cylinder is adjusted and fixed.

The gas-liquid linkage lower ejection device comprises a cylinder base fixed to a machine body and a lower ejection shaft rotationally connected to the machine body, an air cylinder and a hydraulic cylinder are arranged in the cylinder base in series, a cylinder shaft sleeve is installed in the cylinder base, trunnions are arranged on the two sides of the air cylinder, and the trunnions are rotationally connected with the cylinder shaft sleeve. The lower end of a piston rod of the hydraulic cylinder is inserted above a piston of the air cylinder, a displacement sensor is installed at the upper end of the piston rod of the hydraulic cylinder, the lower end of the piston rod of the air cylinder is connected with a cylinder connector, and the cylinder connector is rotationally connected with a rocker arm which is fixedly connected with a lower ejecting shaft. The ejection stroke of an original hydraulic cylinder is shortened, especially for the hydraulic cylinder with the maintaining function, the workpiece is separated from the mold through ejection of the hydraulic cylinder, the subsequent ejection stroke and the workpiece maintaining action are independently completed by the lower air cylinder, the ejection stroke requirement is met, meanwhile, the stroke of the hydraulic cylinder is shortened, a hydraulic station system is reduced, and the cost is reduced. And the response speed is improved.

A shiplift transfer system for moving a ship between a shiplift platform and a shipyard is disclosed. The system includes transition rails coupled with the shipyard that are pivotable about trunnion pins between a position that bridges a gap between the shipyard and the shiplift platform and a position that is clear of the gap and of the shiplift platform. The pins are positioned such that the load is not transferred to the pins. Load on the transition rails is reacted at curved surfaces of the transition rails that are engaged with curved surfaces on the yard. The transition rails are accessible for maintenance and replacement via removable plates. The rails include beveling to accommodate misalignment between the yard and platform.

The invention belongs to the technical field of oil and gas drilling and completion, and particularly relates to a self-grouting float collar and a using method. A self-grouting float collar comprises a float collar float shoe body, a metal ball valve and a mushroom valve, the metal ball valve comprises a metal ball valve seat, a ball valve body and a valve element trunnion, gears are arranged at the two ends of the valve element trunnion respectively, the gears are connected with valve rods, and the valve rods are provided with fixing teeth meshed with the gears. A hydraulic piston and a check valve are sequentially arranged in a gap between the float collar float shoe body on the upper portion of the valve rod and the metal ball valve seat, the mushroom valve comprises a mushroom valve seat and a mushroom valve body, and a mushroom valve spring seat, a mushroom valve spring and a mushroom valve limiting pin are arranged on the lower portion of the mushroom valve body. Through the double-valve structure of the metal ball valve and the rubber mushroom valve, the metal ball valve is resistant to high temperature and corrosion, the performance requirements of complex working conditions for the float collar and the float shoe are met, in the well descending process, a channel of the double-valve structure is opened, self-grouting is achieved, after bumping pressure is completed, the channel of the double-valve structure is closed, and backflow of well cementation cement is avoided.

The invention discloses a cooperative control method for blanking lumpiness of a semi-autogenous grinding vibrating ore feeder, and belongs to the technical field of ore grinding control. The method comprises the following steps: training an improved YOLOv11 algorithm model by using a collected raw ore image, and judging whether ore of a currently running / standby ore feeder is lump ore or fine ore through the trained model; then dividing the mill sound value, the power value and the feed end trunnion pressure into three levels of threshold values, and constructing 27 mill internal ore lumpiness rules according to the threshold value ranges of the current mill sound value, the power value and the feed end trunnion pressure value of the mill according to expert rules; the method comprises the following steps: inputting data of a running mill into an ore lumpiness rule in the mill, then giving an ore powder matching scheme by referring to an expert rule, judging whether lumpiness matching of the currently running ore feeder is reasonable or not, and adjusting the vibrating ore feeder to complete control and adjustment of the ore feeding amount of the system. Real-time feeding quantity control feedback adjustment can be carried out on the ore grinding system, optimization control over the ore grinding process of the semi-autogenous mill is achieved, and the process control effect of the semi-autogenous mill is improved.

A shipboard platform is provided for azimuth and elevation pivoting of a targeting payload. The platform is coupled to a ship and includes a pedestal, an azimuth drive trunnion, a yoke having first and second struts, an elevation drive trunnion and an elevation support trunnion. The pedestal is disposed on the ship. The azimuth drive trunnion is disposed in the pedestal. The yoke is rotatably disposed on the azimuth drive trunnion. The elevation drive and support trunnions are rotatably disposed in their respective first and second struts. The payload is mountable to the elevation drive and support trunnions. Further, a gimbal trunnion is provided for pivoting a payload along an axis. The trunnion includes an annular shaft, an interface mounting plate, an annular rotor, an annular stator, and inner and outer annular housings. The shaft turns the payload along the axis. The interface mounting plate is axially disposed between the payload and the shaft. The annular rotor extends radially outward from the shaft for turning the mounting plate. The annular stator extends radially outward from the rotor to laterally constrain the rotor. The inner and outer annular housings extending radially outward from the stator for encasing the axially tandem bearings.

The present invention relates to an agricultural machine comprising at least one working tool and a hitch frame by which it is connected to a tractor and which includes a crossbar and two levers, each lever carrying a respective trunnion intended to be attached to a respective lower arm of the tractor and capable of moving vertically relative to the crossbar, each lever being associated with a return device capable of exerting a force on the associated lever when the respective trunnion moves vertically relative to the crossbar, the machine being able to occupy a working configuration in which the tool or tools are close to the surface and at least one transport configuration, in which the tool or tools are further from the surface than in the working configuration, each return device comprising a hydraulic return cylinder fixed to the respective lever on one side and to the crossbar on the other side.Each return cylinder is hydraulically connected to a hydraulic reservoir in the working configuration. Figure to be published with the abbreviation: Fig. 1,