Hydraulic system of the E-153 A excavator consists of two control boxes (hydraulic distributors), power hydraulic cylinders, an oil tank with a capacity of 200 l with filters and hydraulic lines with safety valves.
The hydraulic system is powered by the working fluid from the pumping group.
The pumping group consists of two NPA-64 axial-plunger pumps and a step-up cylindrical reducer, providing a nominal speed of rotation of the pump shaft - 1530 rpm. This speed of rotation at a specific pumping capacity of 64 cm3/min ensures that 96 l/min of oil of the left pump and 42.5 l/min of the right pump are supplied to the hydraulic system to the actuating elements (power cylinders). The power take-off to drive the pumps is carried out from the tractor gearbox using a step-up gearbox.
The gearbox is assembled in a cast iron housing, which is flanged to the front of the tractor transmission housing, on the left along the latter.
A spur gear sits on the primary spline shaft, which engages with the tractor drive pulley gear and the reduction gear shaft.
The following three gearbox settings are possible.
- If the input roller and pinion shaft rotate, both pumps work.
- If the roller is rotating and the pinion shaft is off, only one pump is running.
- If the main gear of the gearbox is disengaged from the gear of the tractor drive pulley, both pumps will not work.
The gearbox is turned on and off by turning the lever connected to the control roller.
The pumps are mounted on a cast iron gearbox housing. The pumps are driven by the tractor gearbox and supply the working fluid from the oil tank (capacity 200 l) at a pressure of 75 kg/cm2 through the steam distributors to the power cylinders. From the power cylinders, the used oil flows through the drain lilies through the filters back to the tank.
Below is a hydraulic pump device ( rice. 45). A flange 7 is bolted to the casing 1 of the pump, covered with a cover 11. A drive shaft 3 with seven pistons is installed in the casing on bearings.
The connecting rods 17 of the pistons are rolled with their ball heads in the flange part of the drive shaft 3.
On the second ball end of the connecting rods, the pistons 16 themselves are attached in the amount of seven pieces.
The pistons enter the cylinder block 10, which is mounted on a bearing support 9 and, by the action of the spring 12, is in close contact with the distributor 15. The latter, in turn, is firmly pressed against the cover 11 by the force of the same spring. To prevent the distributor from turning, it is locked with a pin.
The rotation from the drive shaft to the cylinder block is driven by cardan 6.
The lip seal 4, placed in the front cover 2 of the housing 1, serves as an obstacle to the leakage of the working fluid from the non-working cavity of the pump into the drive gear.
The drive shaft 3, with its polished part, is connected to the gearbox and receives rotation from the latter. Cylinder block 10 receives rotation from the drive shaft through cardan 6.
Due to the inclination of the axis of the cylinder block to the axis of the drive shaft, the pistons 16 reciprocate during the rotation of the block. The stroke length of the piston and, consequently, its performance depends on the angle of inclination.
In this pump, the angle of inclination is constant and equal to 30°.
To understand the principle of operation of the pump, consider the operation of only one piston.
Piston 16 completes one double stroke per revolution of the cylinder block.
The extreme left and right positions correspond to the beginning of suction and discharge. When the piston moves to the left (when the block rotates clockwise), suction occurs, when moving to the right, it is pumped.
The suction and discharge positions are coordinated with the location of the hole 14 relative to the suction and discharge grooves (the grooves are oval, they are not visible in the figure) of the distributor 15.
In the process of suction, the hole 14 of the block takes up a position against the suction slots of the distributor connected to the suction channel. When pumping, hole 14 occupies a position opposite the injection slots connected to the injection channel.
At the same time, the remaining six pistons work in the same way.
Oil from the working cavity of the pump to the non-working cavity is discharged into the working fluid tank through the drain hole 5.
An increase in pressure beyond the allowable limit is limited by two safety valves installed on each pump.
Hydraulic cylinders are designed to carry out all movements of the working bodies of the excavator. On excavator E-153A nine cylinders installed ( rice. 47) piston type with rectilinear reciprocating movement of the rod.
During the movement of the rod, one cavity of the cylinder is connected to the discharge line, and the other to the drain line. The direction of movement of the rod is set by the lever of the hydraulic system control box. The power cylinders are the executive bodies of the hydraulic line of the machine.
All cylinders have an internal diameter of 80 mm, except for the boom cylinder, which has a diameter of 120 mm. The rod diameter of all cylinders is 55 mm.
All cylinders (except the swing cylinder) are double acting cylinders.
Double acting hydraulic cylinder ( rice. 46) consists of the following main parts: pipe 1, rod 29 with piston 9, front cover 27 and rear cover 5, angle fittings 7 and seals.
Pipe 1, which creates the main working volume of the cylinder, has a carefully machined inner surface. At the ends of the pipe there is an external thread for attaching covers 27 and 5 to it.
The bulldozer cylinder additionally has a thread in the middle of the pipe. An additional thread is required for fastening the traverse with trunnions (Fig. 76).
Rods for 29 boom, stick, bucket and swing cylinders ( rice. 46) are hollow and consist of a pipe 28, a shank 13 and an ear 21, welded together.
The rods of the remaining cylinders are made of solid metal.
The cylinder rod moves in the bronze bushing 24 of the front cover.
For better wear resistance and anti-corrosion, the working surface of the rod is chrome-plated.
A piston 9 with two cuffs 10 supported by stops 11 and a cone 12 is mounted on the free shank of the rod.
The cone, together with the ring, forms a damper, which serves to soften the blow at the end of the stroke when the rod is extended to its extreme position.
The piston, stops and cone are fastened with a nut 4 and a lock washer 3.
Piston 9 has ledges on both sides for placing cuffs 16 in them. Inside the piston there is an annular groove with a sealing ring 2, which serves to prevent fluid from flowing from one cavity of the cylinder to another along the rod. There is a body on the stem shank, which, in the extreme left position, enters the hole in the rear cover and forms a damper that softens the blow at the end of the stroke.
The piston serves as a support for the rod, and, together with the seals, reliably divides the cylinder into two cavities, into which oil enters one or the other.
The rear covers of all cylinders, with the exception of the bulldozer cylinder, are deaf and in their tail section have an ear with a pressed hardened bushing 6 for the hinged connection of the cylinder.
The threaded part of the cover has an annular groove with a sealing ring 8, which serves to prevent fluid leakage from the cylinder.
The back cover of the bulldozer cylinder has a central through connection for supplying fluid through a fitting bolted to the cover.
The rear cylinder covers of the boom, stick, bucket and support shoes have central and side drillings that connect with each other and form a working fluid channel.
The rear swing cylinder covers have channels similar to those in the boom, stick and skid cylinder covers.
Through these channels, the non-working cavities of the cylinders are connected to each other with the help of fittings 7, a steel pipe and a breather.
The front cover 27 is screwed onto the pipes. For the passage of the stem in the cover there is a hole with a bronze bushing 24 pressed into it. Inside the cover has two ledges: the cuff 16 rests against the first one, supported from axial displacement by the collar ring 25 and the retaining spring ring 26; in the second, the ring 14 rests, which together with the cone 12 on the rod forms a damper and limits the piston stroke. On the other hand, a cover 18 is screwed onto the front cover, which secures the washer 19 and the wiper 20.
On the side of the cover there is a hole for transferring liquid through the fitting.
All caps have key slots and are secured with locknuts.
The angle fitting is attached to the cylinder with bolts and sealed with a rubber ring 15.
For smooth operation of hydraulic cylinders, worn seals and wipers should be replaced in a timely manner. Make sure that the cylinder rods do not have nicks or scratches. Tighten the connections of the fittings periodically, since if there is a gap between the fitting and the roof, the seals are quickly destroyed.
Hydraulic distributors, or control boxes, are the main components of the excavator control mechanisms. They are designed to distribute the working fluid coming from the supply hydraulic pumps to the power cylinders, of which there are nine pieces on the excavator ( rice. 47). All of them have their purpose:
- a) the boom cylinder is designed to raise and lower it;
- b) two cylinders of the handle - to communicate the movement of the handle along the radius in one direction or another;
- c) bucket cylinder - for turning the bucket (when working with a backhoe) and for opening the bottom (when working with a front shovel);
- d) bulldozer cylinder - for lowering or raising the blade;
- e) two rotation cylinders - to communicate the rotational movement of the rotary column;
- f) two cylinders of support shoes - for raising and lowering the latter during excavation.
left box ( rice. 47), distributing the working fluid over the cylinders of the boom, the support shoes and the rotary column, consists of three pairs of rigidly interconnected chokes and spools 1. The shunt spool 2 serves to connect the working cavities of the boom power cylinder to each other and to the hydraulic drive drain line. Four spring zero-setters 4 return the hydraulic controls to the neutral (zero) position. The speed controller 3 automatically equalizes the pressure on the feed pump and the actuators.
The right box, connected to the right rear pump, distributes fluid to the stick, bucket, and dozer cylinders. There is no shunt spool in this box; there is one shut-off valve 6 and two safety valves 7 and 8. Otherwise, the design of the boxes is the same.
To operate one of the mechanisms of the excavator, it is necessary to move the corresponding pair of throttle - spool up or down, depending on the direction in which the mechanism should move. The left component of this pair is a throttle that changes the oil flow in magnitude, and the right component is a spool that changes the oil flow in direction.
Oil tank 17 ( rice. 47) is a stamped-welded structure made of 1.5 mm thick sheet steel. It consists of a rectangular body, inside which four baffles are welded, designed to calm the working fluid and separate the emulsion.
The top of the tank is closed with a stamped lid with a gasket made of oil-resistant rubber. In the center of the cover there is a rectangular hole where the filter tank 12 is inserted, which serves for partial oil purification.
At the bottom of the tank, two fittings are welded through which oil enters the pumps, and there is a hole closed with a stopper through which oil is drained from the tank as needed.
Three cylindrical wire filters are inserted into the tank from the sides. The tank has a viewing window 10, which allows you to monitor the level of the working fluid in the tank. Conical funnels 11 give direction to the flow of the working fluid and increase its speed. The safety valve 8 in the filter tank is adjusted to a pressure of 1.5 kg/cm2. At higher pressure, oil flows out through the drain hole of the valve.
All tank connections are hermetically sealed, and only through the air filter is the inner cavity of the tank connected to the atmosphere to avoid pressure buildup in the tank.
The supply of the working fluid from the pumps to the hydraulic distribution boxes, hydraulic cylinders and discharge into the tank is carried out by means of seamless steel pipes, rubber hoses and fittings.
Pipes with a diameter of 28 X 3 are installed on the discharge and power lines, a pipe 35 X 2 is installed on the power common line from the distributors to the working fluid tank. The remaining hydraulic lines are made of pipes with a diameter of 22 X 2 mm. The supply of working fluid from the tank to the pumps is carried out by two durite hoses with a diameter of 25 X 39.5.
In places where the working fluid is supplied to the moving mechanisms of the excavator, high-pressure hoses are used. 20 X 38 hoses are installed on boom and stick cylinders only, 12 X 25 hoses on all other cylinders.
All elements of the hydropyropod - pipes, hoses - are connected to each other using fittings 7 ( rice. 46).
62 63 64 65 66 67 68 69 ..Piston pumps and hydraulic motors for excavators
Piston pumps and hydraulic motors are widely used in the hydraulic drives of a number of excavators, both on mounted and on many full-turn machines. The most widely used rotary piston pumps are of two types: axial piston and radial piston. -
Axial piston pumps and hydraulic motors for excavators - part 1
Their kinematic basis is a crank mechanism, in which the cylinder moves parallel to its axis, and the piston moves together with the cylinder and, at the same time, due to the rotation of the crank shaft, moves relative to the cylinder. When the crank shaft is rotated through an angle y (Fig. 105, a), the piston moves along with the cylinder by a value a and relative to the cylinder by a value c. The rotation of the plane of rotation of the crank shaft around the y-axis (Fig. 105, b) at an angle of 13 also leads to the displacement of point A, in which the crank pin is pivotally connected to the piston rod.
If, instead of one, we take several cylinders and arrange them around the circumference of the block or drum, and replace the crank with a disk, the axis of which is rotated relative to the axis of the cylinders by an angle of 7, and 0 4 y \u003d 90 °, then the plane of rotation of the disk will coincide with the plane of rotation of the crank shaft. Then a schematic diagram of an axial pump will be obtained (Fig. 105, c), in which the pistons move when there is an angle y between the axis of the cylinder block and the axis of the drive shaft.
The pump consists of a fixed distribution disk 7, a rotating block 2, pistons 3, rods 4 and an inclined disk 5, pivotally connected to the rod 4. Arc windows 7 are made in the distribution disk 7 (Fig. 105, d), through which the liquid is sucked in and pumped pistons. Between the windows 7 there are bridges with a width bt separating the suction cavity from the discharge cavity. When the block rotates, the holes of 8 cylinders are connected to either the suction cavity or the discharge cavity. When the direction of rotation of the block 2 is changed, the functions of the cavities change. To reduce fluid leakage, the end surface of the block 2 is carefully rubbed against the distribution disk 5. The disk 5 rotates from the shaft b, and the block 2 of the cylinders rotates with the disk.
The angle y is usually taken equal to 12-15°, and sometimes it reaches 30°. If the angle 7 is constant, then the volumetric flow of the pump is constant. When the value of the angle 7 of the inclination of the disk 5 changes in operation, the stroke of the pistons 3 changes for one revolution of the rotor and the pump flow changes accordingly.
The diagram of an automatically controlled axial piston pump is shown in fig. 106. In this pump, the feed regulator is a washer 7 connected to the shaft 3 and connected to the piston 4. On the one hand, the spring 5 acts on the piston, and on the other hand, the pressure in the pressure line. When the shaft 3 rotates, the washer 7 moves the plungers 2, which suck in the working fluid and pump it into the hydraulic line. The pump flow depends on the inclination of the washer 7, i.e., on the pressure in the pressure hydraulic line, which in turn varies from external resistance. For pumps of small power, the pump flow can also be adjusted manually by changing the inclination of the washer; for more powerful pumps, a special amplifying device is used.
Axial piston motors are designed in the same way as pumps.
Many mounted excavators use an unregulated axial-piston hydraulic motor pump with an inclined block NPA-64 (Fig. 107). Block 3 of the cylinders receives rotation from the shaft / through the universal joint 2. Shaft 1, driven by the engine, rests on three ball bearings. The pistons 8 are connected to the shaft 1 by rods 10> the ball heads of which are rolled in the flange part of the shaft. Cylinder block 3 ”rotating on a ball bearing 9, located relative to the shaft 1 at an angle of 30 ° and pressed by a spring 7 to the distribution disk b, which is pressed against the cover 5 with the same force. The liquid is supplied and discharged through the windows 4 in the cover 5. Shaft seal 11 in the front cover of the pump prevents leakage of oil from the non-working cavity of the pump.
Pump delivery per shaft revolution - 64 cm3. At 1500 rpm of the shaft and an operating pressure of 70 kgf/cm2, the pump flow is 96 l/min, and the volumetric efficiency is 0.98.
At the NPA-64 pump, the axis of the cylinder block is located at an angle to the axis of the drive shaft, which determines its name - with an inclined block. In contrast, in axial pumps with an inclined disk, the axis of the cylinder block coincides with the axis of the drive shaft, and the axis of the disk is located at an angle to it, with which the piston rods are pivotally connected. Consider the design of an adjustable axial piston pump with an inclined disk (Fig. 108), The peculiarity of the pump is that the shaft 2 and the inclined disk b are connected to each other using a single or double cardan mechanism 7. The working volume and flow of the pump are regulated by changing the slope disk b relative to the block of 8 cylinders 3.
105 Axial piston pump diagrams:
A - piston action,
B - pump operation, c - constructive, d - actions of a fixed distribution disk;
1 - fixed distribution disc,
2 - rotating block.
3 - piston,
5 - inclined disk,
7 - arc window,
8 - cylindrical hole;
A - the length of the full section of the arc window
106 Diagram of a variable displacement axial piston pump:
1 - washer,
2 - plunger,
3 - shaft,
4 - piston,
5 - spring
In the spherical supports of the inclined disk 6 and pistons 4, the ends of the connecting rods 5 are fixed. During operation, the connecting rod 5 deviates by a small angle relative to the axis of the cylinder J, so the lateral component of the force acting on the bottom of the piston 4 is insignificant. The torque on the cylinder block is determined only by the friction of the end of the block 8 on the distribution disk 9. The magnitude of the moment depends on the pressure in the cylinders 3. Almost all the torque from the shaft 2 is transferred to the inclined disk 6, since during its rotation the pistons 4 move, displacing the working liquid from cylinders 3. Therefore, a heavily loaded element in such pumps is the cardan mechanism 7, which transmits all the torque from the shaft 2 to the disk 6. The cardan mechanism limits the angle of inclination of the disk 6 and increases the dimensions of the pump.
Cylinder block 8 is connected to shaft 2 through mechanism 7, which allows the block to self-align on the surface of the distribution disk 9 and transfer the moment of friction between the ends of the disk and the block to shaft 2.
One of the positive features of variable pumps of this type is the convenient and simple supply and removal of the working fluid.
The car frame is reinforced with two additional frames. In addition, to improve the maneuverability of the gangway and reduce its length, the rear chassis springs were replaced with shorter ones, the transfer case for connecting a gear pump was improved, and the transmission to the front axle was removed.
The ladder ladder consists of two parts: stationary and retractable.
The power frame of the stairs is a truss welded from rolled steel profiles. The stationary part of the ladder has eleven fixed steps and one folding one. The flooring of the steps is made of steel sheets and covered with corrugated rubber. The lower part of the stairs is covered with removable panels. The stationary part is attached to the chassis frame.
The retractable part of the ladder has an exit platform to the aircraft, which is edged with elastic buffers at the points of contact with the aircraft. It is driven by a special mechanism consisting of a hydraulic pump, a bevel gear and a lead screw with a nut. The stop of the sliding part of the ladder is made automatically.
A certain position of the ladder in height corresponds to its emphasis on the retractable ladder. For unloading the wheels and springs, as well as for the stability of the ladder during boarding and disembarking of passengers, four hydraulic supports are installed on the vehicle chassis. The hydraulic system of the ladder serves the hydraulic supports and the mechanism for raising and lowering the stairs. The pressure in the hydraulic system is created by the NSh-46U gear pump driven by the engine of the UAZ-452D car through the transfer case. In addition, there is an emergency hand pump.
The ladder is controlled from the driver's cab. Control lamps of the control panel signal the lifting of the hydraulic supports and the fixation of the ladder at a given height. The steps of the stairs are illuminated by ceiling lamps at night. To improve illumination at the entrance of the gangway to the aircraft, the roof of the front part of the cabin is glazed. A headlight is installed on the roof to illuminate the point of contact of the retractable ladder with the aircraft.
The hydraulic system of the SPT-21 ladder (Fig. 96) serves the hydraulic supports and the ladder lifting mechanism. The left-hand gear pump NSh-46U is designed to supply hydraulic units with liquid. The pump is driven by an automobile engine through a transfer case and a front propeller shaft.
hydraulic tank is a tank of welded structure, in the upper part of which there is a locking neck with a filter and a measuring ruler. The tank has fittings: inlet, return line and drain. In case of failure of the main pump or its drive, the system provides an emergency hand pump mounted on the rear chassis frame near the right fairing. There are four hydraulic supports on the chassis frame, two at the rear and two at the front. They serve as a rigid support for the ladder at the entrance and exit of passengers, as well as for unloading wheels and springs. A hydraulic lock is used to fill the fluid in the outlet line of the supports.
Pump NPA-64 operates as a hydraulic motor to rotate the lead screw of the lifting mechanism.
To limit overloads that may occur in case of malfunction of the mechanisms, the hydraulic system is equipped with a safety valve adjusted to a pressure of 7 MPa. The hydraulic system is controlled by a hydraulic panel installed in the gangway cabin on the right side of the driver. A pressure gauge, hydraulic support and ladder control valves are mounted on the panel.
In addition to the electrical system of the car, the electrical equipment of the gangway SPT-21 includes systems: automatic stop stairs; ladder lighting; light and sound signaling and the readiness of the ladder for boarding passengers.
The ladder automatic stop system consists of: a limit switch 6 of an electromagnetic valve 10, a signal light 8, a button for forced activation of the electromagnetic valve 7 (Fig. 97) A stop mounted on a retractable ladder corresponds to a certain position of the ladder at a height. the circuit and turns on the electromagnetic valve, the spool of which connects the working line with the drain, and the ladder stops. At this time, the control lamp on the control panel lights up. When moving the ladder to another height, it is necessary to press the button for the forced activation of the electromagnetic crane.
IN ladder lighting system includes step lamps and a flight indicator lamp.
The light signaling system consists of two light boards and a relay-breaker. A car signal is used to give a sound signal, and a relay breaker is used to give an intermittent sound signal. A light panel with inscriptions is attached to the railing of the retractable ladder. Lighting, alarm control and a button for forced activation of the electromagnetic valve are installed on the control panel in the gangway cabin.
Passenger ladder TPS-22 (SPT-20)
Developed on the chassis of the UAZ-452D truck. Produced at the airport mechanization facility.
TPS-22 is designed for boarding and disembarking passengers from the aircraft, the threshold level of the entrance doors of which is in the range of 2.3-4.1 m.
Management is carried out by one driver-operator. The earlier SPT-20 model was intended for servicing aircraft at airports located in the northern regions, where the operation of airstairs with battery power sources is difficult.
As power equipment, a carbureted four-cylinder internal combustion engine of the UAZ-451D type is used here. The ladder of the SPT-20 ladder has a constant angle of inclination and consists of a stationary part mounted on the ladder chassis, a retractable section with a landing platform and an additional retractable landing platform intended for servicing aircraft with a passenger door threshold height of about 2 m. The extension of the upper telescopic section is carried out with using a cable-block system driven by a NPA-64 hydraulic motor.
The extension of the additional platform to the front position is carried out by a hydraulic cylinder.
Operation features. The procedure for the operation of the ladder at the aircraft is as follows: stop the ladder at a distance of 10 ... 12 m from the aircraft and set the ladder in height to the required type of aircraft. To do this, turn off the rear axle, turn on the hydraulic pump, put the ladder control valve in the “Lift” position, press the forced on button and hold it until the light goes out, and then, slowly lowering the clutch pedal, start lifting;
when the jumper connecting the sidewalls of the retractable ladder approaches, at a distance of 100 ... 150 mm to the required height indicator, applied with paint on the bottom skin of the stationary ladder, release the button;
after the automatic stop system has been activated, the ladder will stop, and the signal lamp will light up;
the rise of the stairs is carried out at the second speed, the descent at the third; after stopping the ladder, turn off the clutch, put the ladder control valve in the neutral position, turn off the hydraulic pump and prepare the ladder for movement;
when approaching the aircraft, all safety precautions must be observed; after approaching the aircraft, turn off the rear axle, turn on the second speed, turn the pump, turn the handle of the outrigger control valve to the “Release” position, put the gangway on the outriggers. Turn off the speed, put the crane handle in the neutral position.
Give a lingering signal (3 ... 5 s) by pressing the car signal button and set the switch located on the control panel to the side "Disembarkation in progress";
when the gangway leaves the aircraft, perform all operations in the reverse order, and set the signaling switch to the “No landing” position.
The ladder allows you to adjust the height of the ladder in the range of 2400...3900 mm at an angle of inclination of not more than 43°. The step pitch is 220 mm, the width is 280 mm. The operating speed of the ladder is 3...30 km/h.
Maintenance.
For maintenance it is necessary:
carefully check the serviceability of components, mechanisms and systems, carry out preventive maintenance in a timely manner;
monthly check the condition of the helical frame of the ladder lifting mechanism and lubricate it with graphite grease;
upon detection of a leak in the hydraulic system, immediately find out the cause of the malfunction and eliminate it;
pour AMG-10 oil into the hydraulic system. During operation, it is necessary to periodically add fresh oil to the hydraulic tank;
in the hydraulic system once a year it is necessary to do the following maintenance work: completely drain the oil from the hydraulic system; flush the hydraulic tank; remove and wash the filter element; fill in fresh oil and bleed the system to remove air;
bleed the lines by repeatedly raising and lowering the ladder, as well as releasing and retracting the supports.
change the oil in the gearbox of the lifting mechanism should be at least 2 times a year. Automobile transmission oil TAp-15V should be used, and at temperatures below -20 ° C - TS 10;
lubricate the guide carriages of the retractable ladder with USSA graphite grease at least once a month;
lubricate the bearings of the upper assembly of the lead screw and the pump mounting bracket NSh 46 U with universal grease at least once every 3 months;
carry out preventive work on the car chassis of the gangway in accordance with the instructions for operation of the car UAZ-452D.
A ladder based on the UAZ, which was attached to the "Buran" in the Central Park in Moscow (2009): 
TPS-22 at the airport in Yaroslavl 
TPS-22 in Yakutia 
Airport in Kuibyshev 
TPS-22 as a holiday car 
TPS-22 company KVM 
Description of TPS-22 
The process of docking the ladder TPS-22 with the aircraft 
The first hydraulic excavators appeared at the end of the 40s in the USA as mounted on tractors, and then in England. In Germany, in the mid-1950s, a hydraulic drive began to be used both on semi-rotary (mounted) and full-rotation excavators. In the 60s, hydraulic excavators began to be produced in all developed countries, displacing rope excavators. This is due to the significant advantage of the hydraulic drive over the mechanical one.
The main advantages of hydraulic machines over cable machines are:
- significantly smaller masses of excavators of the same size and their dimensions;
- significantly greater digging forces, which allows you to increase the filling of the backhoe bucket at great depths, because soil resistance to digging is perceived by the mass of the entire excavator through the boom lifting hydraulic cylinders;
- the ability to carry out earthworks in cramped conditions, especially in urban areas, when using equipment with a shifting digging axis;
- an increase in the number of replaceable equipment, which allows expanding the technological capabilities of the excavator and reducing the amount of manual labor.
A significant advantage of hydraulic excavators is the design and technological properties:
- the hydraulic drive can be used as an individual one for each actuator, which allows these mechanisms to be assembled without reference to the power plant, which simplifies the design of the excavator;
- in a simple way to convert the rotational movement of mechanisms into translational, simplifying the kinematics of the working equipment;
- stepless speed control;
- the ability to implement large gear ratios from an energy source to working mechanisms without the use of bulky and kinematically complex devices, and much more that cannot be done with mechanical energy transfers.
The use of a hydraulic drive makes it possible to maximally unify and normalize the components and assemblies of a hydraulic drive for machines of different sizes, limiting their range and increasing the serial production. This also results in a reduction in spare parts stock at the operating warehouse, reducing the cost of acquiring and storing them. In addition, the use of a hydraulic drive allows the use of an aggregate method of repairing excavators, reducing downtime and increasing the useful life of the machine.
In the USSR, the first hydraulic excavators began to be produced in 1955, the production of which was immediately organized in large volumes.
Rice. 1 Excavator-bulldozer E-153
This is a mounted hydraulic excavator E-151 based on the MTZ tractor with a bucket with a capacity of 0.15 m 3. NSh gear pumps and R-75 hydraulic distributors were used as a hydraulic drive. Then, to replace the E-151, the E-153 excavators began to be produced, (Fig. 1), and later the EO-2621 with a bucket of 0.25 m 3. The following factories were specialized in the production of these excavators: Kiev "Krasny Excavator", Zlatoust Machine-Building Plant, Saransky Excavator Plant, Borodyansky Excavator Plant. However, the lack of hydraulic equipment with high parameters, both in terms of productivity and working pressure, hindered the creation of domestic full-circle excavators.
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Rice. 2 Excavator E-5015
In 1962, an international exhibition of building and road machinery was held in Moscow. At this exhibition, an English company demonstrated a caterpillar excavator with a bucket of 0.5 m3. This machine impressed with its performance, maneuverability, ease of control. This machine was purchased, and it was decided to reproduce it at the Kiev plant "Red Excavator", which began to produce it under the symbol E-5015, having mastered the production of hydraulic equipment. (Fig. 2)
In the early 60s of the last century, a group of enthusiastic supporters of hydraulic excavators was organized in VNIIstroydormash: Berkman I.L., Bulanov A.A., Morgachev I.I. and others. A technical proposal was developed for the creation of excavators and cranes with a hydraulic drive, for a total of 16 machines on a caterpillar and special pneumatic wheel chassis. Rebrov A.S. acted as an opponent, arguing that it is impossible to experiment on consumers. The technical proposal is being considered by the Deputy Minister of Construction and Road Engineering Grechin N.K. The speaker is Morgachev I.I., as the leading designer of this range of machines. Grechin N.K. approves the technical proposal and the department of single-bucket excavators and boom mobile cranes (OEK) of VNIIstroydormash starts developing technical specifications for design and technical projects. TsNIIOMTP Gosstroy of the USSR, as the main representative of the customer, coordinates the technical specifications for the design of these machines.
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Rice. 3 NSh series pump-motor
In the industry at that time there was absolutely no base for hydraulic machines. What could designers expect? These are gear pumps NSh-10, NSh-32 and NSh-46 (Fig. 3) with a working volume of 10, 32 and 46 cm 3 /rev, respectively, and a working pressure of up to 100 MPa, axial-plunger pump-motors NPA-64 (Fig. 4) working volume 64 cm 3 /rev and working pressure 70 MPa and IIM-5 working volume 71 cm 3 / rev and working pressure up to 150 kgf / cm2, high-torque axial-piston hydraulic motors VGD-420 and VGD-630 with a torque of 420 and 630 kgm, respectively.
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Rice. 4 Pump-motor NPA-64
In the mid-60s Grechin N.K. seeks to purchase from the company "K. Rauch" (Germany) a license for the production in the USSR of hydraulic equipment: axial-plunger adjustable pumps of the type 207.20, 207.25 and 207.32 with a maximum displacement of 54.8, 107, and 225 cm 3 /rev and a short-term pressure of up to 250 kgf/cm2, double axial piston variable pumps type 223.20 and 223.25 with a maximum working volume of 54.8+54.8 and 107+107 cm3/rev and short-term pressure up to 250 kgf/cm2, respectively, axial piston unregulated pumps and hydraulic motors types 210.12, 210.16, 210.20, 210.25 and 210.32 with a working volume of 11.6, 28.1, 54.8, 107 and 225 cm 3 / rev and short-term pressure up to 250 kgf / cm power, regulators, etc.). Machine-tool equipment for the production of this hydraulic equipment is also purchased, though not in the full required volume and range.
Photo source: tehnoniki.ru
At the same time, the Minneftekhimprom of the USSR is coordinating the development and production of hydraulic oils of the VMGZ type with the required viscosity at various ambient temperatures. In Japan, a metal mesh with 25 micron cells for filters is purchased. Then Rosneftesnab organizes the production of paper filters "Regotmas" with a cleaning fineness of up to 10 microns.
In the construction, road and municipal engineering industries, factories are specialized in the production of hydraulic equipment. This required the reconstruction and technical re-equipment of workshops and sections of factories, partly their expansion, the creation of a new production of mechanical processing, casting of malleable and anti-friction cast iron, steel, chill casting, electroplating, etc. In the shortest possible time it was necessary to train tens of thousands of workers and engineering and technical workers of new specialties. And most importantly, it was necessary to break the old psychology of people. And this is all with a residual funding principle.
An exceptional role in the re-equipment of factories and their specialization was played by the First Deputy Minister of Construction, Road and Municipal Engineering Rostotsky V.K., who supported Grechin N.K. with his authority. in the introduction of hydraulic machines into production. But the opponents of Grechin N.K. there was a serious trump card: where to get machinists and mechanics-operators of hydraulic machines?
Groups of new specialties were organized in vocational schools, machine manufacturers are training excavator workers, repairmen, etc. The publishing house "Vysshaya Shkola" ordered manuals for these machines. The employees of VNIIstroydormash, who wrote a large number of textbooks on this topic, were of great help in this. Thus, the excavator plants Kovrov, Tver (Kalininsky), Voronezh are switching to the production of more advanced machines with a hydraulic drive, instead of mechanical ones with a cable control.
