Apparatus air cushion
The invention relates to vehicles and can be used to create light apparatus on an air cushion. The apparatus of the air cushion includes a housing and an elastic enclosure, forming with the bottom of the chassis lifting the camera, pull the fan and the internal combustion engine to drive it. Traction and lifting the contours of the device, hovercraft split rib, designed to direct airflow from the fan in the specified paths. Traction circuit apparatus has a nozzle and a bucket of reverse thrust, mounted on the nozzle exit. The apparatus of the air cushion includes system management, including the management of reverse thrust bucket and management system rudders. Control surfaces rudders are located at the nozzle exit and in the lifting circuit. Rudders are kinematically connected to each other and with the governing body of the apparatus. The nozzle of the traction circuit can be made flat and cylindrical surface of the bucket reverse - gap. Rudders located on the nozzle, can be installed with the possibility of rotation about the vertical axis, and the rudders are located in the lift to the Oia, located at the nozzle exit, with rudders located in the lifting circuit may be configured to provide a delay deviation rudders located at the nozzle exit, compared with deflection of the rudders is located in the lifting path, in the initial period of exposure to the governing body of the apparatus. The technical result of the invention is to improve the manageability of the device on an air cushion. 4 C.p. f-crystals, 11 ill.
The technical field to which the invention relates
The invention relates to vehicles, in particular for light vehicles, air cushion (LAIT).
The level of technology
Known designs of LAMP with a single propulsion propulsion, in which part of the flow from a single drawing or pushing the fan is directed into the cavity air chamber under the bottom and creates the necessary conditions for bathing apparatus (for example, US patents 3869020, B 60 V 1/14, 1975 (1), US 5007495, B 60 V 1/14, 1991 (2), US 3608663, B 60 V 1/14, 1971 (3)).
Also known apparatuses, in which the entire flow from the blower into the chamber airbag (US patents 3669212, B 60 V 1/14, 1972 (4) and US 3401766, B 60 V 1/00, 1968 (5)). In this part of this thread b is free maneuvering. "Pulling" power of such devices is small, because the pressure in the cushion may not exceed required for steaming pressure and increasing venting on all sides evenly. Given that the fan is always craving, which is formed due to the "suction" of the air, this thrust is neutral only if the horizontal position of the fan. By tilting the fan forward the machine will start moving in the direction of inclination of the fan even with a uniform expiration of air around the perimeter of the airbag.
While the thrust of the fan can not be balanced by the bypass air from the cavity of an air cushion in the direction of providing reverse thrust, i.e., when the reverse (due to the laws of physics), as suggested in (5), although the management direction of movement and reduction of direct thrust almost to zero is possible.
Management direction in (4) due to behind the fan wheel is realized due to the eccentricity of the thrust relative to the longitudinal axis of the apparatus and is characterized by very low efficiency as control, and propulsion system.
Known technical solution (3), in which the control surfaces placed the population at its aft. In General provided good control characteristics on cruise mode and in the mode of acceleration.
Direct pull may be almost zero at full overlap traction channel valves at the outlet of the channel, however, completely lost the ability to control the device.
As well known design LAMP (2), in which the running direction and reverse thrust is a single iterative reverse scoop device. The solution is characterized, as in the previous case, a complete lack of clarity from the management apparatus in the "reverse", in addition to the characteristics of the management of such devices can be so non-linear that the control becomes feasible.
The coefficient of reverse thrust reversing device is a topic well studied in aviation. For classic aircraft engines it does not exceed 0,4 even with careful engineering (engine NK-8-2U aircraft "TU-154" is 0,35). For short devices, such as described in solution (2), it can generally be zero. Also known attempt at a comprehensive solution of the question of control and reversing thrust in solution (1). There remains theoretical possibility is given in figure 13, through the bypass dampers "142 and 146", with the opening of the control valves will reduce reverse thrust and very likely will lead to lateral forces on the casing, the opposite of the desired result because of the effect of aerodynamic "curvature" profile add-in, which is especially dangerous may occur at a considerable speed, while this dependence is nonlinear.
Analysis of the known constructions of apparatus air-cushion-shows the following.
1. None of them provided a good solution to the question of the traction control apparatus (of the maximum possible positive to maximum reverse).
2. No proposal does not address the issue of quality control unit position on the braking mode when driving at high speed.
3. No single solution is suitable for controlling the position and direction of movement of the device at zero and near-zero speeds with simultaneous fulfillment of the requirements for sufficient tagavoranist and propulsive efficiency of the propeller.
Disclosure of the invention
The present invention is the creation of design LAMP, which can eliminate the above disadvantages isoamsa "flat" movement along the support surface with minimal (close to zero) resistance in the desired direction, and in any other.
The only source used to create the control action is thrust propulsion system, LAMP (includes traction and lifting loop). This provision was especially tough at zero and near-zero speeds when the effects of aerodynamic forces on the body and a special aerodynamic surface slightly. On large vessels with an air bag, the management direction and position of the unit (which is in General not the same) are solved by the use of rotary propulsion systems and reverse thrust propellers. This solution is unacceptable, at least for economic reasons for mass-produced consumer and sports LAMP, the source of thrust and lifting forces for which, typically, is a single screw-fan, driven by a single motor. In addition to the tasks associated with controlling the speed and direction of movement, for LAIT are also responsible for obtaining competitive dynamic characteristics of motion, such as velocity, acceleration, motion and slow motion, velocity and acceleration angular motion (movement of rotation around the vertical axis of the apparatus), as well as Martyr the movement of light LIT is necessary to obtain the minimum mass of the apparatus and acceptable characteristics of the propulsion efficiency of the vehicle.
According to the invention the apparatus of the air cushion includes a housing, an elastic enclosure, forming with the bottom of the chassis lifting the camera, pulling the fan, the internal combustion engine for driving the fan, traction and lifting paths, separated by a rib designed to direct airflow from the fan in these circuits, the nozzle of the traction circuit, bucket of reverse thrust, mounted at the exit of the nozzle, the control system of the apparatus, including the control system of reverse thrust bucket and management system rudders, control surfaces which are located at the nozzle exit and in the lifting circuit, and rudders are kinematically connected to each other and the control apparatus.
It is advisable to perform a nozzle traction contour flat.
Cylindrical surface of the bucket of reverse thrust can be made a slit for the separation of solid particles and liquid that helps to protect the crew from the return action of the jet stream.
Mainly rudders located on the nozzle, mounted to rotate about a vertical axis, with rudders located in the lifting circuit, installed with vozmozhnosti, located at the nozzle exit, with rudders located in the lifting path, was made with the possibility of a delay deviation rudders located at the nozzle exit, compared with deflection of the rudders is located in the lifting path, in the initial period of exposure to the governing body of the device.
Brief description of drawings
Advantages and characteristics of the device for air cushion shown in the description of examples of implementation of the invention with reference to the accompanying figures of the drawings:
figure 1 - apparatus for air cushion according to the invention, a side view,
figure 2 slit on the side view of figure 1;
figure 3 - device air cushion according to the invention, a top view;
figure 4 - device air cushion according to the invention, a front view;
figure 5 - unit air cushion according to the invention, rear view;
figure 6 - unit air cushion according to the invention, bottom view;
figure 7 - unit air cushion according to the invention, bottom view with the designation of the shoulders of control points (l1- shoulder front steering, l2- shoulder wheel) relative to the center of gravity of the apparatus; and
figure 8 - combined top view and Alami;
figures 10 and 11, a side view of the nozzle of the traction circuit and a bucket of reverse thrust.
The implementation of the invention
Light apparatus, air cushion (LAIT) chamber scheme (Fig.1-7) consists of a platform - base 1 of a relatively small height (8-20% of the length of the device) fixed on the contour platform elastic barrier 2, forming together with the bottom of the platform lifting the camera LAMP.
In the front (forward) side of the platform has a pull fan 3 driven by the internal combustion engine 4. The plane of rotation of the fan at an angle of 45-60to the horizontal plane. The flow of air behind the fan is divided by a rib section 5 on the air flow of the traction circuit 6 and the airflow lifting circuit 7. Airflow traction circuit passes through the longitudinal channel, the limited U-shaped seat base crew and channel 9 in the body of the platform base. The air flow of the traction circuit is thrown out the rear of LAMP through a flat nozzle with respect to the height of the nozzle "A" and width "B"=0,5-0,25. Thus the axis of the stream exiting the nozzle tilted at 4-10up to the horizon. Above the upper surface of the nozzle has a bucket of reveice air flow traction circuit and turning the air flow of the traction circuit to generate the desired reverse thrust (reverse thrust).
In the channel the air flow of a winding circuit includes rudders (front control surfaces) 13. In the canal towing path on the nozzle as set rudders 14 - nozzle control surfaces. And the front 13 and nozzle 14 control surfaces are set at the maximum design considerations the destruction of axis "X" from the center of gravity 15 of LAIT.
In the fore part of LAMP installed front fairing 17, combining the functions of the input device fan and protective visor crew. In Fig.4 the dashed line shows the contour 18 of the channel of the winding path. In Fig.6 position 19 marked the outlet channel of the winding circuit in lifting the camera.
The crew is placed on the seat cushion 11 longitudinally.
The airflow created by the fan 3, is divided by an edge of the partition 5 into two circuits.
The flow of the traction circuit 6 serves to generate the thrust necessary for the horizontal movement. While the thrust vector flow may deviate in the horizontal plane air rudders 14 to create unwrapping the moment about the vertical axis of the apparatus, passing through the center of gravity of the apparatus 15. Torque is manufacturing the tour can be rotated relative to the transverse axis of the apparatus in a vertical plane through the deflection of the reverse bucket 12 to an angle of 180that allows you to smoothly adjust thrust from full positive to full negative on any mode of engine operation.
Thread lifting circuit 7 is sent from the rib section 5 in the channel of the winding path, and then into the cavity of the chamber airbag, limited elastic enclosure chamber 2 and the lower part of the platform of the base 1. Excess pressure in the cavity of the chamber air cushion due to the braking of the thread winding circuit 7 provides lifting and hovering LAIT.
In the lifting channel circuit installed in the front (bow) of the control surface 13. Efforts that occur on the control surface 13, is directed in the direction specified by the driver of the direction of rotation of the device and opposite in sign to the efforts of the nozzle on the control surfaces. Managing time effort nasal surfaces is equal to the product of the magnitude of these efforts on the shoulder of their application relative to the vertical axis of LAMP passing through the center of gravity of LAMP 15. Joint action control efforts on the surfaces 13 and 14 can be selected so due to changes in the area and angles of deflection of the control surfaces to get a "clean" control point, which causes only turn around-ear, closed the machine to perform the rotation and to produce precise manoeuvring, including small and close to zero speed. Deflection of control surfaces 13 and 14 by the driver synchronously with the steering device 16. Synchronous control is possible, for example, if there are two cable management channels driven from two governors leashes, located on the same shaft of the steering device 16.
As shown in Fig.8, on the shaft of the steering device 16 is fixed to the pulley 20, by providing the cable kinematic relationship with the pulleys 22 rudders 13 of the winding path. The pulley 21 is mounted on the shaft of the steering device 16 for rotation relative to the specified shaft. The pulley 21 is made a slot in the form of an annular sector under the rod 24, which is fixed on the end face of the pulley 20. The pulley 21 is connected with the pulleys 23 rudders 14, installed on the nozzle. Rake pivotally connecting the pulleys 23, biased by springs 26 to hold the rudders 14 in a neutral position in all cases, while the rod 14 moves within the slot on the pulley 21 without touching its edges. This design of the control system provides a delay deviation rudders located at the nozzle exit, compared with deflection of the rudders healthy lifestyles is Rotom.
Managing reverse bucket 12 is provided by cable transmission with two pulleys 27 and 28 (Fig.9), while the pulley 27 mounted on the shaft of the handle 29 of the control bucket reverse, and the pulley 28 on the shaft of the reverse bucket.
Bucket of reverse thrust with slotted cylindrical surface (Fig.10-11) works as follows. The effect of the slit surface is well known in aviation and is that a jet of gas flowing from the slit at an angle to the surface, close to zero, "sticks" to the convex side surface and is deflected with her at a considerable angle. Losing kinetic energy to friction, a jet of gas having gone some way along the surface, breaks away from her. To create a continuous flow to rotate the jet of gas is necessary to replenish the energy of the surface layer of gas, running around the surface of the multislot (in aviation is two and trendeleva flaps of the aircraft).
Designed so the surface of the reverse bucket allows the centrifugal separation of solid particles and liquid droplets in order to avoid them from falling in the area for accommodation of the crew, as well as reduce the dust (snow cover area) in this area when braking the reverse. Legend:
"T" - the path of motion of solid particles and drops gidia the presence of Delta N in the range of 0.5-2% of N, where H is the height of the nozzle on the cut.
Delta R - value of the limb inside the bucket single slotted element is in the same range as the DeltaN.
- pie angle single slotted element bucket reverse (15-30).
When compliance with specified parameters "backdraft" reverse despite the separation, at least, not decreases, and with careful tuning increases.
The driving modes of the device:
1. Start and manoeuvring at zero speed.
The reverse bucket is in an intermediate position when the pull of the air flow is rejected by the reverse bucket will balance forward thrust flow of the traction circuit.
The engine is displayed on the mode in which it is possible to "freeze" of the device.
Simultaneous deviation of the control winding circuit and traction path will lead to forces on them in the opposite direction and to a certain extent approximately equal in magnitude, leading to a net rotation of the apparatus around a vertical axis. The intensity of the spread increases with deflection of the rudders and the increase of the mode of operation of the engine. When assessing the performance of controllability should be remembered that the power line is at a preset speed.
From "freezing" in place of the reverse bucket is deflected forward. Each deviation until it stops will correspond to a certain speed. This speed will also depend on the mode of operation of the engine, which varies from the minimum required to hang up to a maximum corresponding to the maximum acceleration and maximum speed.
The control deviation of the steering device 16 results in the first phase to the deviation of the control winding circuit, located in the front part of the apparatus. The force on the rudder of a winding path leads to a slight movement of the bow and the entire apparatus as a whole in the direction of rotation with its simultaneous rotation around the vertical axis, which causes the rotation of the thrust vector in the direction of rotation with a corresponding reduction in turning radius.
It should be noted that the angular velocity and acceleration of the device will remain in any position of the reverse bucket and their maximum values are at 40-65% higher than that of any of the above apparatus, since the increased characteristics as optional power lifting loop.
At any speed vehicle braking osbome or emergency braking;
b) deviation of the reverse bucket is in position "reverse". When this braking will be the more intense, the higher the mode of operation of the engine.
It should be noted that this effective braking deceleration is higher, the higher the speed. As jet reverse creates on the body the effect of the jet flap", the housing is pressed against the surface movement and braking by the friction forces and more "inductive" resistance.
The movement of "reverse".
The scheme of the reverse (shovel with a clean shockless entry and exit allows you to focus on the high rate of reversal (up to 0.45), which provided the initial tagavoranist 0.2 and above will allow the device not only to move "backwards", but also to climb the slope 3-4but this is a minor mode for small-size apparatus.
Obviously, this detailed description and described specific examples, although they characterize preferred specific embodiment of the invention, are given only for illustrative purposes and should not be considered as limiting the amount of claims of the invention.
1. The apparatus of the air cushion, comprising a housing, a yoke of combustion for driving the fan, traction and lifting paths, separated by a rib designed to direct airflow from the fan in these circuits, the nozzle of the traction circuit, bucket of reverse thrust, mounted at the exit of the nozzle, the control system of the apparatus, including the control system of reverse thrust bucket and management system rudders, control surfaces which are located at the nozzle exit and in the lifting circuit, and rudders are kinematically connected to each other and the control apparatus.
2. The apparatus according to p. 1, characterized in that the nozzle of the traction circuit is made flat.
3. The device under item 1 or 2, characterized in that the cylindrical surface of the reverse bucket is made slit.
4. Apparatus according to any one of paragraphs.1-3, in which the rudders located on the nozzle, mounted to rotate about a vertical axis, and rudders located in the lifting circuit, installed with the possibility of rotation about the longitudinal axis of the device.
5. Apparatus according to any one of paragraphs.1-4, in which the kinematic relationship rudders located on the nozzle, with the rudders located in the lifting circuit, configured to provide a delay spallogenic in the lifting circuit, in the initial period of exposure to the governing body of the apparatus.
FIELD: transport engineering; amphibian vehicles.
SUBSTANCE: proposed vehicle has trimaran water displacement body, wheeled propulsive device and water propulsor. Two pressure chambers with fans are installed in bow of body. Surface of body bottom part is provided with bend having two slot-like holes connected with pressure chambers to let out air jets created by fans and forming air cushion in under-bottom space. Wheeled propulsive device is of rolling type and it has individual drive from geared motors. Wheels of propulsive device are made in form of cylindrical housing with flanges on outer surfaces of which round-shape cross slots are milled in number corresponding to number of support and rest flexible members of rim secured by pins in holes of flanges for turning through angle of roll out to form, together with wheel rim and inner engagement of support-and-drive device of vehicle, mechanism with three degrees of freedom implementing rolling system with negative friction providing translational movement of vehicle owing to upward-forward (backward-up-ward) displacement of center of masses. Support-and-drive device can be furnished with covers interconnected by studs. End of upper stud can be made in form of cylinder fitted into extensible grip installed in upper part of vehicle body on its side to change mode of operation of wheel. Water propulsor can be made in form of paddle wheels installed on vertical posts for vertical displacement and containing cylindrical housing fitted in bearings on axle and paddles of rectangular shape or paddles with bevels to build additional traction force and increase efficiency when moving in water or negotiating bogged terrains.
EFFECT: improved operating characteristics of amphibian vehicle.
3 cl, 6 dwg
FIELD: transport engineering; shipbuilding.
SUBSTANCE: invention relates to propulsion plants of high-speed vehicles (air cushion, hydrofoil ones) and other watercraft, and it can be used in ground and air vehicles. Proposed air-jet propulsion plant contains at least two hermetically interconnected converging nozzles of one axis. Each nozzle is coaxially driven into nozzle following in direction of air flow, being rigidly secured or installed with possibility of axial displacement. These two nozzles form spaces in between. Art least one of spaces communicates with devices delivering and sucking out gas (air). Intake valves are arranged on wall in at least one space, and also gas (air) energy exciting devices. Spaces accommodate also pressure transmitters, and flow velocity pickups at inlet and exit nozzles with delivery of information of plant control unit.
EFFECT: increased efficiency of vehicles, reduced mass, overall dimensions pf plant, store and consumption of fuel, possibility of arrangement of useful load additionally.
SUBSTANCE: proposed aerodynamic craft has hull, propulsors for horizontal motion actuated by cruise engine, propulsors for vertical lift located in through vertical passages of hull and control system for steering the craft in space. Novelty of invention consists in form of each propulsor of vertical lift: propulsor has cylindrical body closed with grates at the top and at the bottom; vertical shaft mounted inside body is used for securing upper and lower pressure wheels; lower wheel is lesser in diameter. Each pressure wheel is made in form of bush secured on vertical shaft and connected with rim by means of spokes. Secured on upper surface of rim are air intakes whose inlet openings are open in way of rotation of pressure wheel; rim body has vertical passages according to number of air intakes; each vertical passage is made in form of Laval nozzle. Radial blades of straightening apparatus are located below each pressure wheel.
EFFECT: improved aerodynamic properties.
FIELD: shipbuilding; dynamically supported vessels.
SUBSTANCE: proposed vessel has hull with navigator and passenger compartments, main engine mounted inside fore part of hull, propulsors for vertical lifting which are kinematically linked with main engine, cruising engine mounted inside aft part of hull and kinematically linked with two horizontal motion propulsors and control mechanisms. Vertical lift propulsors are similar in construction; each disk of these propulsors has lower smooth surface. Upper surface has alternating concentric half-round troughs and concentric half-round ridges. Each concentric half-round ridge is divided into several parts and each part has bevels at the front and at the rear with through vertical passages in between them; longitudinal axis of each of them lies at angle relative to lower surface of disk and in parallel relative to rear bevel of ridge standing in front of it. Height of concentric half-round ridges and depth of concentric half-round troughs are equal to radii of similar circles whose centers lie in one line which is equidistant from lower surface of disk. Two horizontal motion propulsors are similar in construction. Each propulsor is made in form of horizontal hollow cylindrical housing with reduction gear mounted in center; reduction gear has front and rear horizontal shafts on which front and rear groups of variable-pitch propellers is secured. Air propellers are mounted at some distance from one another. Diffuser mounted in rear part of hull is turned away from air propellers by its wide part.
EFFECT: simplified construction of cruising engines; increased lifting force of vertical lift engines.
FIELD: ground-effect vehicles; updating of ground-effect vehicle supercharging plants.
SUBSTANCE: according to the first version, supercharging plant includes two centrifugal superchargers which are mounted tightly relative to each other at opposite location of side outlet ports. Superchargers are provided with spiral casings which have opposite apertures closed by opposite working surfaces of swivel flap mounted in between casings at level of said apertures; during turn, flap enters outlet passages of superchargers. According to the second version, supercharging plant has two centrifugal superchargers mounted tightly relative to each other at opposite located of side outlet ports; they are provided with transversal partitions relative to axis of rotation of impeller; these partitions divide working chambers of superchargers into at least two chambers. Spiral casings of superchargers are provided with open apertures communicating the interiors of one supercharger with similar interior of other supercharger; apertures are closed with opposite working surfaces of swivel flaps. Swivel flaps are mounted between spiral casings of superchargers at level of said apertures at one axis with partitions; during turn, they enter interior of supercharger outlet passages.
EFFECT: enhanced controllability and safety of vehicle at turns.
11 cl, 7 dwg
SUBSTANCE: system comprises propeller pitch indexing mechanism, control signals generator, logical elements, mismatch warning light, converters, actuating unit. System comprises two independent channels for propeller control - for forward and back vessel motion. The channels are hydraulically connected to actuating unit and electrically - to its limit switch. Each control channel contains channel follow-up rate monitoring unit, automatic channel switch and elements to compare actual and preset rates. Automatic switch contains memory devices which are connected to follow-up rate monitoring units, fault signaling units, switch and control channels locking device. Into hydraulic channels between actuating unit and throttling devices of both variable pitch propellers control channels hydraulic capacitances are introduced. Each of these capacitances has volume exceeding volume of actuating unit chamber and is fitted together with throttling devices in thermostable chamber.
EFFECT: reliability and dynamism enhancement of variable pitch propellers control for hoverships; elimination of operator faults in variable pitch propellers control under conditions of ambient air temperature sudden changes.
SUBSTANCE: air-cushioned river rolling stock consists of lead ship with steering gear and ships coupled with it by coupling devices. Lead ship is a motor ship with engine and air duct parallel to coupler capable of blowing-up of rolling stock air cushions. All engines installed in rolling stock are electric engines and are fed from suspended two-contact electric line via sliding poles, like those of trolleybus.
EFFECT: simplification of relocation of heavy passenger traffic, obtaining of routes not crossing with other transport routes with year-round use of ecologically pure air-cushioned river rolling stock, ability to easily circumflex dams by shore and to pass under low bridges by building ashore necessary tunnel parallel to riverbed with rolling stock being able to climb soft slopes.
SUBSTANCE: invention relates to air-cushion ships. In compliance with proposed method, air-cushion ship is provided with two rotary rudders arranged at the thrust air duct outlet. Pilot cab is provided with two handles that can independently rotate about appropriate axis of rotation. Each said handle is connected with said rotary rudder so that turning said handle causes rudder turning. To allow joint displacement of both handles, they are articulated by link element with hinge joints on their ends. Said link element can vary the distance between said handles on applying opposite=direction forces thereto. Turning said handle in one direction turns rudders in one direction, while turning said handle in opposite directions causes turning of rudders in opposite directions.
EFFECT: simplified control of air-cushion ship.
14 cl, 5 dwg
SUBSTANCE: proposed propulsor comprises one or several pairs of side paddle wheels. Said pairs of side paddle wheels have axles with disk fitted thereon with line of plates secured along perimetre. Said plates are arranged regularly along circumference of disks. Elastic vanes with weights-grousers arranged on their free ends are secured to said plates radially with respect to wheel axle.
EFFECT: higher thrust due to increased friction and better adhesion with bearing surface.
SUBSTANCE: invention relates to ship building. Proposed ship comprises hull with lengthwise lateral compartments accommodating vertical lift propulsors. Primary engine is arranged at ship hull fore-part and engaged with said vertical lift propulsors. Sustainer propulsor is arranged at hull stern part and engaged with horizontal motion propulsors. Ship incorporates navigation control system and course-keeping ability control system Vertical lift propulsors feature identical design, each comprises rectangular housing accommodating two identical lifting mechanisms arranged one above the other. Every said mechanism has rectangular box with open part directed upward. Several pairs of cylindrical drums are fitted on bearings in top section horizontally and in parallel. Gear is fitted on shaft of every drum while idle gear are fitted between gears to engage with two gears of two adjacent drums. Distance between drums makes 0.3-0.5 mm. Taper gears and drum vertical shafts on bottom lifting element engage with drums of top lifting element. Drums run in one direction. Porous elastic wear proof insert is fitted inside the box to get in contact with bottom surfaces of drums and box bottom.
EFFECT: higher operating performances.