Hydraulic transmission - A combination of hydraulic devices that allow you to connect the source of mechanical energy (engine) with the actuators of the machine (car wheels, the spindle of the machine, etc.). The hydrotransmission is also called hydraulic transmission. As a rule, in hydraulic transmission, energy is transmitted by fluid from the pump to hydromotor (turbine).

In the presented video, a hydraulic motion was used as a output level. In the hydrostatic transmission, the hydraulic motor of the rotational motion is used, but the principle of operation is still based on the law. In the hydrostatic drive of rotational action, the working fluid is supplied from the pump to the motor. At the same time, depending on the working volumes of hydromachins, the moment of rotation of the shafts may change. Hydraulic transmission It has all the advantages of the hydraulic drive: high power transmitted, the possibility of implementing large gear ratios, implementation of stepless regulation, the ability to transmit power to movable, moving machine elements.

Methods for regulation in hydrostatic transmission

Adjusting the speed of the output shaft in the hydraulic transmission can be carried out by changing the volume of the working pump (volumetric control), or by setting the choke or the flow controller (parallel and consistent throttle). The figure shows a hydrotransmission with a volumetric control with a closed circuit.

Hydrotransmission with closed contour

Hydraulic transmission can be implemented by closed type (closed loop), in this case there is no hydraulic tank in the hydraulic system connected to the atmosphere.

In the hydraulic systems of a closed type, the regulation of the rotational speed of the shaft can be carried out by changing the pump working volume. As a pump-motors in the hydrostatic transmission most often used.

Open contour hydrotransmission

Open Called the hydraulic system connected to the tank, which is reported to the atmosphere, i.e. The pressure over the free surface of the working fluid in the tank is equal to the atmospheric. In the hydrotransissions of the open type it is possible to implement volumetric, parallel and consistent throttle. The following figure shows a hydrostatic transmission with an open circuit.

Where hydrostatic transmissions are used

Hydrostatic transmissions are used in machines and mechanisms where it is necessary to implement the transfer of large capacities, create a high moment on the output shaft, to carry out stepless speed control.

Hydrostatic transmissions are widely used. In mobile, road construction equipment, excavators of bulldozers, on railway transport - in locomotives and traveling machines.

Hydrodynamic transmission

In hydrodynamic transmissions for power transmission, turbines are used. The working fluid in hydraulic transmissions is supplied from the dynamic pump to the turbine. Most often in the hydrodynamic transmission, blade pumping and turbine wheel are used, located directly opposite each other, in such a way that the fluid comes from the pumping wheel immediately to the turbine percentage of pipelines. Such devices combining the pump and turbine wheel are called hydromefts and torque converters, which, despite some similar elements in the design, have a number of differences.

Hydromefta

Hydrodynamic transmission consisting of pumping and turbine wheelinstalled in the general crankcase called hydromuft. The moment on the outlet shaft of the hydraulic clutch is equal to the moment on the input shaft, that is, the hydromefta does not allow you to change the torque. In the hydraulic transmission, power transmission can be carried out through a hydraulic coupling, which will ensure the smoothness of the stroke, the smooth increase in the torque, reduced shock loads.

Hydrotransformer

Hydrodynamic transmission, which includes pumping, turbine and reactor wheels, placed in a single housing is called a torque converter. Thanks to the reactor, hydrotector Allows you to change the torque on the output shaft.

Hydrodynamic transmission in a tetatic gearbox

The most famous example of the use of hydraulic transmission is automatic car gearboxin which hydromefta or hydrotransformer can be installed. Due to the higher efficiency of the hydrotransformer (compared to hydromefta), it is installed on most modern cars with an automatic transmission.

Pump Adjustable Motor Unregulated

1 – valve Safety Safety Pump;2 – check Valve;3 - Pump fuel; 4 - servoscillide; five - hydraulic pump;
6 - cradle; 7 - servoclap; eight - servolapan lever;9 - filter; 10 - tank; 11 - heat exchanger; 12 - hydromotor shaft;13 - emphasis;
14 – valve box shovel;15 – valve overflow;16 – high pressure safety valve.

GST hydrostatic transmission

The GST hydrostatic transmission is designed to transmit rotational motion from the drive motor to the executive bodies, for example, to the chassis of self-propelled machines, with stepless regulation of the frequency and direction of rotation, with the efficiency close to one. The main set of GST consists of an adjustable axial-piston hydraulic pump and an unregulated axial-piston hydromotor. The pump shaft is mechanically associated with the output shaft of the drive motor, the motor shaft is with the actuator. The frequency of rotation of the output shaft of the motor is proportional to the corner of the lever of the control mechanism (servolapan).

The control of the hydrotransmission is carried out by changing the turnover of the drive motor and the change in the position of the handle or the joystick associated with the lever of the pump servolap (mechanically, hydraulically or electrically).

With the operating drive motor and the neutral position of the control handle, the motor shaft is fixed. When the position of the handle changes, the motor shaft begins to rotate, reaching maximum revolutions at maximum handle deviation. For the reverse it is necessary to deviate the lever in the opposite direction from neutral.

Functional scheme GST.

In the general case, the GTS-based bulb includes the following elements: adjustable axial-piston hydraulic pump assembly with a proportional pump and a proportional control mechanism, an unregulated axial-piston motor assembled with a valve box, a thin cleaning filter with a vacuum, oil tank for working Liquids, heat exchanger, pipelines and high pressure hoses (RVD).

Elements and guards of the GST can be divided into4 functional groups:

1. The main circuit of the hydraulic circuit of the GST. Purpose of the main contour of the hydraulic circuit of the GST - transmission of power flow from the pump shaft to the motor shaft. The main circuit includes the cavity of the pumping chambers of the pump and motor and high and low pressure lines with the working fluid flowing along it. The flow of the working fluid, its direction is determined by the turnover of the pump shaft and the angle of deviation of the lever of the proportional control of the pump from neutral. When the lever is deviated from the neutral position in one direction or another, under the action of servo-cylinders, the angle of inclination of the inclined washer (cradle) changes, which determines the direction of the stream and causes the corresponding change in the working volume of the pump from zero to the current value, with a maximum deviation of the lever, the operating volume of the pump reaches the maximum values. The working volume of the motor is constant and is equal to the maximum volume of the pump.

2. Suction line (feeding). Appointment of the suction line (feeding):

· - supply of the control fluid;

· - replenishment of the working fluid of the main circuit to compensate for leaks;

· - cooling the working fluid of the main contour by replenishing the liquid from the oil tank, which passed through the heat exchanger;

· - ensuring minimal pressure in the main circuit in different modes;

· - cleaning and index of the pollution of the working fluid;

· - Compensation of oscillations of the volume of working fluid caused by temperature changes.

3. Purpose of control lines:

· - Transfer of pressure on the actuator servo rotation of the cradle.

4. Drainage assignment:

· - removal of leaks into the oil tank;

· - removal of excessive fluid;

· - heat removal, removal of wear products and lubrication of rubbing surfaces of hydromachine parts;

· - cooling of the working fluid in the heat exchanger.

The operation of the volume hydraulic drive is provided by automatically valves and spools located in the pump, feed pump, the valve motor box.

GST-90 hydraulic drive (Figure 1.4) includes axial-plunger units: adjustable hydraulic pump with a gear pump of feeding and a hydraulic distributor; Unregulated hydraulic motor assembly with a valve box, a thin cleaning filter with a vacuummeter, pipelines and hoses, as well as a tank for the working fluid.

Shaft 2 The hydraulic pump rotates in two roller bearings. A block of cylinders planted on the shaft slot 25 , in the holes of which plungers move. Each plunger with a spherical hinge is connected to the fifth, which rests on the support located on the inclined washer 1 . The washer is connected to the hydraulic pump housing using two roller bearings, and due to this can be changed the tilt of the washer relative to the pump shaft. Changing the angle of inclination of the washer occurs under the action of the effort of one of two servo-cylinders 11 whose pistons are connected to the puck 1 With the help of thrust.

Inside the servo-cylinders there are springs acting on pistons and installing the washer so that the support located in it has been perpendicular to the shaft. Along with the cylinder block rotates an appropriate bottom, moving along the distributor, fixed on the rear lid. The holes in the distributor and the appropriate day periodically connect the operating chambers of the cylinder block with highways that bind hydraulic pump with hydraulic motor.

Figure 1.4 - GST-90 hydraulic diagram: 1 - washer; 2 - the output shaft of the pump; 3 - reversible adjustable pump; 4 - hydrolynia management; 5 - control lever; 6 - spool control of the lulley position; 7 8 - Pump fuel; 9 - check valve; 10 - safety valve feeding system; 11 - servoscillide; 12 - filter; 13 - vacuummeter; 14 - Hydrobac; 15 - heat exchanger; 16 - spool; 17 - overflow valve; 18 - the main safety valve of high pressure; 19 - low pressure hydrolynium; 20 - High pressure hydrolynium; 21 - drainage hydrolynium; 22 - unregulated motor; 23 - the output shaft of the hydraulic motor; 24 - inclined hydraulic washer; 25 - cylinder block; 26 - link link; 27 - end seal

Spherical plunger hinges and sliding stains are lubricated under the pressure of the working fluid.

The inner plane of each unit is filled with the working fluid and is an oil bath for mechanisms running in it. The leakage of the hydraulic aggregate are also coming into this cavity.

The pump fasteners are attached to the rear end surface of the hydraulic pump 8 Six-type, the shaft of which is connected to the hydraulic pump shaft.

Pump feeding sucks the working fluid from the tank 14 And gives it:

- in hydraulic pump through one of the check valves;

- into the control system through the hydrodistributor in quantities limited by the bib.

On the casing pump 8 Safety valve is located 10 which opens with the increase in pressure developed by the pump.

Hydraulic distributor 6 It serves to distribute fluid flow in the control system, that is, to direct it to one of two servo-cylinders, depending on the change of the lever position 5 or locking the liquid in the servoscilliter.

The hydraulic distributor consists of a housing, a spool with a return spring, located in a glass, a control lever with a spring forces, and a lever 5 and two crashes 26 which bind a spool with control lever and inclined washer.

Hydromotor device 22 Similar to the pump device. The main differences are as follows: the plunger spits when rotating the shaft slide on the inclined washer 24 having a permanent angle of inclination, and therefore the mechanism of its turn with the hydraulic distributor is absent; Instead of a pump feeding to the rear end surface of the hydromotor, the valve box is attached. Hydromotor hydraulic pump connected with two pipelines (Hydron pumps-Gitzromotor highways). According to one of the mains, the flow of working fluid under high pressure moves from hydraulic pump to the hydraulic pressure, on the other - under low pressure is returned back.

In the valve box case there are two high pressure valves, overflow valve 17 And Spool 16 .

The feeding system includes a feed pump 8 as well as reverse 9 , Safety 10 and overflow valves.

The feeding system is designed to supply the working fluid of the control system, providing minimum pressure in the hydraulic pump highways, compensating for leaks in hydraulic pump and hydromotor, constant mixing of the working fluid circulating in the hydraulic pump and hydromotor, with a liquid in the tank, removal from heat parts.

High pressure valves 18 Hydraulic drive: from overload, cross-country working fluid from high-pressure highway in low pressure housing. Since highways are two and each of them in the process of work can be a high-pressure high pressure, then high pressure valves are also two too. Overflow valve 17 Must be released excess the working fluid from the low pressure highway, where it is constantly fed to the pump.

Shovel 16 In the valve box connects the overflow valve to the "hydraulic pump hydraulic motor" highway, in which the pressure will be less.

When the valves are triggered by the supply system (safety and overflow), the resulting working fluid falls into the inner cavity of the units, where, mixing with leaks, the drainage pipes enters the heat exchanger 15 and further to the tank 14 . Due to the drainage device, the working fluid takes the heat from the driving parts of the hydraulic units. A special end sealing of the shaft prevents the leakage of the working fluid from the inner cavity of the aggregate. The tank serves as a reservoir for the working fluid, has an inside partition separating it to the drain and suction cavity, is equipped with a level pointer.

Filter of fine cleaning 12 The extraneous particles is delayed with a vacuum. The filter element is made of nonwoven material. The degree of contamination of the filter is judged by the testimony of a vacuum.

The engine rotates the hydraulic pump shaft, and, consequently, the associated cylinder block and the pump shaft feed. The feed pump sucks the working fluid from the tank through the filter and serves it in the hydraulic pump.

In the absence of pressure in the servo-cylinder springs, located in them, set the washer so that the plane of the support in it (washers) is perpendicular to the shaft axis. In this case, when rotating the cylinder block, the plunger fifth will slide along the support, without causing the axial movement of the plungers, and the hydraulic pump will not send the working fluid into the hydraulic motor.

From the adjustable hydraulic pump in the process of operation, you can get a different amount of fluid (feed) supplied in one turn. To change the hydraulic pump feed, you must turn the hydraulic distributor lever, which is kinematically connected to the washer and spool. The latter, moving, will send a working fluid that comes from the pump to the control system into one of the servo-cylinders, and the second servoscillide is connected to the cavity of the drain. The first servo-cylinder piston rendered under the action of the production fluid will begin moving, turning the washer, moving the piston in the second servoscilliter and squeezing the spring. The washer turning into the position given by the hydrodistrator lever will move the spool until it returns it to the neutral position (with this position, the output of the working fluid from the servo-cylinders is closed with spool belts).

When the cylinder block rotates, the fifth sliding along the inclined support will cause the movement of plungers in the axial direction, and as a result, there will be a change in the volume of chambers formed by holes in the cylinder block and plungers. Moreover, half cameras will increase its volume, another half is reduced. Thanks to the holes in the appropriate day and the distributor, these cameras are alternately connected to the "Hydraulic Hydromotor" highways.

In the chamber that increases its volume, the working fluid comes from the low pressure highway, where the feed pump is supplied through one of the check valves. The rotating cylinder block, the working fluid, located in the chambers, is transferred to another highway and is supplanted with plungers, creating high pressure. According to this highway, the liquid falls into the working chambers of the hydraulic driver, where its pressure is transmitted to the end surfaces of the plungers, causing them to move them in the axial direction and, thanks to the interaction of Plungers with an inclined washer, causes the block of cylinders to rotate. Having passed the working chambers of the hydraulic motor, the working fluid will be released into the low pressure highway, at which part of it will return to the hydraulic pump, and the excess via the spool and the overflow valve will flow into the inner cavity of the hydraulic motor. In the overload of the hydraulic pressure, the high pressure in the hydraulic pump highway may increase until the high-pressure valve opens, which is moving the working fluid from high pressure high pressure line to the low pressure highway, bypassing the hydraulic engine.

The GST-90 volume hydraulic guide allows simpler to change the transfer ratio: for each turnover of the shaft, the hydraulic motor consumes 89 cm 3 of the working fluid (excluding leaks). Such a number of working fluid hydraulic pump can be given over one or more, the revolutions of its drive shaft depending on the angle of the washer tilt. Consequently, changing the flow of hydraulic pump, you can change the speed of the movement of the machines.

To change the direction of movement of the machine, it is enough to tilt the washer in the opposite direction. The reversing hydraulic pump with the same rotation of its shaft will change the direction of flow of the working fluid in the high-pressure hydraulic pump triggers on the opposite (that is, the low pressure high pressure will become a high pressure trunk, and the high pressure high pressure line is low). Consequently, to change the direction of movement of the machine, a lever of the hydraulic distributor is necessary to rotate in the opposite direction (from the neutral position). If you remove the effort from the hydraulic distributor lever, then the puck under the action of the springs will return to the neutral position, in which the plane of the support in it will become perpendicular to the shaft axis. Plungers will not move in the axial direction. The supply of working fluid will stop. Self-propelled machine will stop. In the highways "Hydroonasos-hydromotor" pressure will become the same.

A spool in the valve box under the action of centering springs will take a neutral position in which the overflow valve will not be connected to any of the highways. The entire liquid supplied to the feed pump, through the safety valve will be drained into the inner cavity of the hydraulic pump. With the uniform movement of the self-propelled machine in the hydraulic pump and the hydraulic engine, it is only necessary to compensate for leakage, therefore a significant part of the working fluid supplied to the feed pump will be superfluous, and it will have to be produced through the valves. In order for the excess of this fluid to use to remove heat, through the valves produced heated, the hydraulic motor, and the cooled - from the tank. To this end, the overflow valve of the feed system, located in the valve box on the hydraulic engine, is configured to a slightly smaller pressure than the fused on the casing case. Due to this, when the pressure is exceeded in the feeding system, the overfit valve will open and will release the heated fluid released from the hydromotor. Next, the fluid from the valve falls into the inner cavity of the unit, from where the drainage pipelines through the heat exchanger is sent to the tank.

The hydrostatic transmission is a hydraulic drive with a closed (closed) circuit, which includes one or more hydraulic pumps and hydrometers. Designed to transfer the mechanical energy of rotation from the engine shaft to the actuator of the machine, by means of a steplessly adjustable largest and direction of the flow of the working fluid.

The main advantage of the hydrostatic transmission is the possibility of smooth change in the transfer ratio in a wide range of rotational frequency, which makes it much better to use the torque of the engine of the machine compared to the stepped drive. Since the output frequency of rotation can be brought to zero, smooth dispersal of the machine from the place without the use of clutch is possible. Small movement speeds are especially needed for various construction and agricultural machinery. Even a significant change in the load does not affect the output frequency of rotation, since there is no slip-insulation of this type of transmission.

The high advantage of the hydrostatic transmission is simplicity of reversing, which is provided by a simple change in the tilt of the plate or hydraulically, changes in the flow of the working fluid. This allows us to provide exceptional maneuverability of the vehicle.

The following serious advantage is a simplification of mechanical wiring by car. This allows you to gain a gain in reliability, because often with a large load on the car, drive shafts do not stand and have to repair the car. In the northern conditions, this occurs even more often at low temperatures. Due to the simplification of the mechanical layout, it is possible to free the place for the auxiliary equipment. The use of hydrostatic transmission may allow to completely remove shafts and bridges, replacing them with pumping installation and hydraulic models with gearboxes embedded directly into the wheels. Either, in a simpler embodiment, hydraulic motors can be built into the bridge. Usually it is possible to reduce the center of gravity of the machine and more rationally place the engine cooling system.

The hydrostatic transmission allows smoothly and ultra-adjust the movement of the machine or smoothly adjust the frequency of rotation of the working bodies. The use of electriportion management and special electronic systems makes it possible to achieve the most optimal power distribution between the drive and the actuating mechanisms, limit the engine load, reduce fuel consumption. The engine power is used as much as possible at the smallest velocity speeds of the machine.

The disadvantage of the hydrostatic transmission can be considered a lower efficiency compared to mechanical transmission. However, compared with mechanical transmissions, including gearboxes, the hydrostatic transmission turns out to be more economical and faster. This is due to the fact that at the time of manual gear shift, it is necessary to let and press the gas pedal. It is at that moment that the engine spends a lot of power, and the speed of the car is changing jerks. All this negatively affects both at speed and fuel consumption. In the hydrostatic transmission, this process is seamlessly and the engine works in more economical mode, which increases the durability of the entire system.

The most frequent use of the hydrostatic transmission is the drive of the machining of machines on a tracked run, where the hydraulic drive is designed to transmit mechanical energy from the drive motor to the drive star of the caterpillar, by adjusting the pump feed and the output traction power due to the control of the hydraulic motor.

Hydrostatic transmission in passenger cars has not yet been applied, since it is the road and its efficiency relatively low. It is often used in special machines and vehicles. At the same time, the hydrostatic drive has many opportunities for use; It is particularly suitable for transmissions with electronic control.

The principle of hydrostatic transmission is that a source of mechanical energy, such as an internal combustion engine, leads hydraulic pump that feeds oil into a traction hydraulic engine. Both of these groups are interconnected by a high-pressure pipeline, in particular, flexible. It simplifies the design of the machine, there is no need to use many gears, hinges, axes, since both groups of aggregates can be located independently of each other. The drive power is determined by the volumes of hydraulic pump and hydraulic motor. Changing the gear ratio in the hydrostatic drive stepless, its reversing and hydraulic lock is very simple.

In contrast to the hydromechanical transmission, where the connection of the traction group with the torque converter is rigid, in the hydrostatic drive, the transfer of force is performed only through the liquid.

As an example of the work of both transmissions, consider moving the car with them through the folds of the area (Damb). At the entrance to the dam in a car with a hydromechanical transmission arises, as a result of which, with a constant frequency of rotation, the vehicle speed is reduced. When descending from the vertex of the dam, the engine begins to act as a brake, but the direction of the bucking of the torque converter is changing and since the torque converter has low brake properties with this direction of the bucking, the car accelerates.

At the hydrostatic transmission during the descent from the vertex of the dam, the hydraulic motor performs the function of the pump and the oil remains in the pipeline connecting the hydraulic motor with the pump. The compound of both drive groups occurs through a pressure under pressure, which possesses the same degree of rigidity as the elasticity of shafts, clips and gears in a conventional mechanical transmission. The acceleration of the car, so it will not happen during the descent from the dam. Hydrostatic gear is particularly suitable for high-pass vehicles.

The principle of the hydrostatic drive is shown in Fig. 1. The hydraulic pump drive 3 from the internal combustion engine is performed through the shaft 1 and the inclined washer, and the regulator 2 control the angle of inclination of this washer, which changes the fluid supply by hydraulic pump. In the case shown in Fig. 1, the washer is installed rigidly and perpendicular to the axis of the shaft 1 and instead of it, the housing of the pump 3 in the casing 4 is tilted. The oil is supplied from hydraulic pump through the pipeline 6 to the hydraulic motor 5, having a constant volume, and from it - again returns to the pipeline 7 into the pump.

If the hydraulic pump 3 is located coaxially shaft 1, then the supply of oil is zero and the hydraulic motor in this case is blocked. If the pump is tilted down, it serves oil in the pipeline 7 and it returns to the pump on the pipeline 6. With a constant frequency of rotation of the shaft 1, provided, for example, a diesel regulator, the speed control and the direction of the vehicle movement is made by only one knob of the regulator.

In the hydrostatic drive, you can use several regulatory schemes:

• the pump and the engine have unregulated volumes. In this case, we are talking about "hydraulic shaft", the gear ratio is constant and depends on the ratio of the volume of the pump and the engine. Such a transmission for use in the car is unacceptable;
• the pump has an adjustable, and the engine is unregulated volume. This method is most commonly applied in vehicles, as it provides a large range of regulation with a relatively simple design;
• the pump has an unregulated, and the engine is adjustable. This scheme is unacceptable for car drive, because it cannot be braked by car through transmission;
• the pump and the engine have adjustable volumes. This scheme provides the best possibility of regulation, but very complex.

The use of hydrostatic transmission allows you to adjust the output power up to the output shaft stop. At the same time, even on a steep descent, you can stop the car by moving the knob of the regulator to zero. In this case, the transmission is hydraulically blocked and the need to apply brakes disappears. To move the car, it is enough to move the handle forward or backward. If several hydraulic motigaves are used in the transmission, then their regulation can be achieved by the operation of the differential or blocking it.

In the hydrostatic transmission there is no whole range of units, for example, gearbox, clutch, drive shafts with hinges, main gear, etc. This is beneficial from the position of the mass and cost of the car and compensates for a sufficiently high cost of hydraulic equipment. All of the above, first of all, refers to special transport and technological means. At the same time, from the point of view of energy savings, the hydrostatic transmission has great advantages, for example, for use in buses.

Above mentioned the feasibility of accumulating energy and the energy gain received when the engine operates with a constant rotational speed in the optimal zone of its characteristic and its rotational speed does not change when switching gear or change the vehicle. It also noted that the rotating masses connected to the leading wheels should be as small as possible. It was also said, in addition, the advantages of a hybrid drive, when the highest engine power is used during acceleration, as well as the power accumulated in the battery. All these advantages can be easily implemented in a hydrostatic drive, if high pressure hydroaccumulator is located in its system.

The scheme of such a system is presented in Fig. 2. Motor-driven 1 pump 2 with a constant volume supplies oil into battery 3. If the battery is filled, the pressure regulator 4 gives the pulse to the electronic regulator 5 of the engine stop. From the battery, the pressure oil is fed through the central control device 6 to the hydraulic motor 7 and is reset from it to the oil tank 8, from which the pump is again closed. The battery has a branch 9, designed to power the additional equipment of the car.

In the hydrostatic drive, the opposite direction of movement of the fluid can be used to brake the car. In this case, the hydraulic motor takes oil from the tank and serves it under pressure in the battery. In this way, you can accumulate braking energy for further use. The disadvantage of all batteries is that any of them (liquid, inertial or electric) has limited capacity, and if the battery is charged, it can no longer accumulate energy, and its excess must be reset (for example, transformed into warmth) As in the car without accumulating energy. In the case of a hydrostatic drive, this problem is solved by the use of a reduction valve 10, which, with a filled battery, is bypassing the oil into the tank.

Urban bus buses due to the accumulation of braking energy and the possibility of charging the liquid battery during stops, the engine could be adjusted to less power and at the same time ensure compliance with the necessary accelerations when overclocking the bus. Such a drive scheme allows economically to realize traffic in the urban cycle, previously described and depicted in Fig. 6 in the article.

The hydrostatic drive can be conveniently combined with conventional gear. As an example, we give a combined vehicle transmission. In fig. 3 Dana scheme of such a transmission from engine flywheel 1 to gearbox 2 of the main transmission. Torque through cylindrical gear 3 and 4 is supplied to the piston pump 6 with a constant volume. The transfer ratio of the cylindrical transmission corresponds to IV-V transmissions of a conventional manual transmission. When rotating the pump begins to feed the oil into the traction hydraulic motor 9 with an adjustable volume. The inclined hydraulic motor controller 7 is connected to the lid 8 of the transmission housing, and the hydraulic motor body 9 is connected to the main transmission shaft 5.

When the car is accelerated, the hydrodial washer has the highest angle of inclination and oil injected by the pump, creates a large moment on the shaft. In addition, the pump is also valid for the shaft. As the car is accelerated, the tilt of the washer decreases, therefore, the torque of the hydraulic motor body is reduced, but the oil pressure supplied by the pump increases and, consequently, the jet momentum of this pump will increase.

With a decrease in the angle of inclination of the washer to 0 °, the pump is hydraulically blocked and the transmission of torque from the flywheel to the main program will be carried out only by a pair of gears; The hydrostatic drive will be turned off. This improves the efficiency of the entire transmission, as the hydraulic motor and the pump are disabled and rotate in a locked position along with the shaft, with an efficiency equal to one. In addition, wear and noise of hydraulic units disappear. This example is one of many showing the possibilities of using a hydrostatic drive. The mass and dimensions of the hydrostatic transmission are determined by the magnitude of the maximum fluid pressure, which currently reached 50 MPa.