Tractor accessories abstract. Auxiliary equipment. Working equipment of cars
WORKING AND AUXILIARY EQUIPMENT OF TRACTORS AND CARS
Goal of the work: to study the purpose, principle of operation and components of the working and auxiliary equipment of tractors and cars. Equipment: working auxiliary equipment as part of units, in a collapsible state, posters. Work order- To study the design and principle of operation of the working equipment of tractors. To study the design and principle of operation of the working equipment of automobiles. To study the auxiliary equipment of tractors and cars. Familiarize yourself with the maintenance of the tractor linkage mechanism. Answer the control questions and write a report on the work done.
Rice. 33 Towing device:
1 - bracket; 2 - cap; 3 - hook nut; 4 - shock absorber; 5 – shock absorber body; 6 - lid; 7 - the axis of the control handle;
8 - bottom catcher; 9 – locking lever; 10 - hook;
11 - clamp mouth of the hook; 12 - visor; 13 - control handle;
14 - locking pin; 15 - stop of the latch; 16 - spring;
17 – retainer spring; 18 – the case of automatic hitch;
19 – a spring of the handle of management; 20 - finger; 21 - finger check
The towing device is a traction hook 10 with rubber damper 4 , bottom catcher 8 , visor 12 and fixative 11 . The latch is controlled by a handle 13 . For attaching a trailer to a hook 10 turn the handle 13 back. In this case, the mouth of the hook is open, and the lower catcher 8 is placed in a horizontal position. When the tractor is moving in reverse, the drawbar loop of the trailer slides over the catcher, presses the lock 11 , moving it inside the body, and enters the mouth of the hook. In this case, the latch under the action of the spring 17 comes out of the body 18 and automatically locks the mouth of the hook. Lever 13 under the action of a spring 19 returns to its original position. A hydraulic hook is used when tractors are used with single-axle trailers, manure spreaders and other machines that create not only longitudinal and lateral, but also normal loads. The hydroficated hook, in comparison with the previously considered towing devices, is able to withstand a large normal load. PTO(PTO) is the driven (output) shaft of the power take-off (PTO) of rotary motion. According to the location on the tractor, rear, side and front PTOs are distinguished. The rear PTO is usually located in the rear axle housing of the tractor, and the PTO is located together with the transmission mechanisms. The side PTO is placed in a special housing mounted on the gearbox housing. There are PTOs with constant and variable speed. The working bodies of harvesting, tillage and some other machines must have a constant speed, and such machines as seeders, planters, spreaders - a speed proportional or synchronous to the forward speed of the tractor. The following two values of the rated PTO speed are set: 540 and 1000 min-1 at the rated speed crankshaft diesel. According to the drive method, PTO and their PTO are divided into dependent, independent, semi-independent, synchronous and combined. Dependent PTO (Fig. 34, A) is characterized by the fact that its PTO stops rotating when the main clutch is turned off. Turn the PTO on and off with the lever 1 with gear coupling 3 with the clutch disengaged. With a dependent shaft, the acceleration of the unit and the working bodies of the machine occurs simultaneously, which requires increased engine power and additional fuel consumption. Semi-independent PTO (Fig. 34, b) rotates from the crankshaft of the diesel engine, regardless of whether the clutch is on or off. PTO is turned on and off by a gear clutch 3 with diesel not running.
An independent PTO differs from a semi-independent one in that an additional friction clutch or a planetary gearbox is installed to control the PTO when the tractor is moving and stopping. Synchronous PTO (Fig. 34, V) changes the PTO speed when changing from one gear to another and rotates from the gear wheel of the gearbox output shaft or from one of the transmission output shafts. The PTO of a synchronous PTO is usually dependent. Turn it on and off with a gear clutch 3
with the clutch disengaged. Combined PTO (Fig. 34, G) consists of independent and synchronous PTO. To engage independent PTO lever 1
put into position II and gear clutch 3
connects to the drive shaft 7
gear wheels 2
. When moving the lever 1
into position I
gear clutch 3
connects to the shaft 7
gear wheels 4
and includes a synchronous PTO. All PTO shafts have splined output ends (tails) with standard dimensions for attaching the universal joint of the drive of the working parts of the coupled machines. Working equipment of cars towing device. At the front ends of the longitudinal beams of the frame of trucks, hooks are installed for towing a faulty vehicle. To connect the car with the trailer, a towing device is located in the rear cross member of the frame, reinforced with braces. The towing device of the KamAZ-5320 car is a hook, the rod of which passes through a hole in the rear cross member of the frame. The rod is inserted into a cylindrical body, closed with a lid and casing. To mitigate impacts, a rubber elastic element is inserted into the housing between the washers with a slight preload. A latch is installed on the axis passing through the hook, which is locked by a pawl and a cotter pin with a chain. Winch, installed on all-wheel drive trucks, is designed for self-pulling and pulling up cars and trailers in difficult areas. The winch of the Ural-4320 car consists of a worm gear, a drum with a cable, a band brake, a drive and
cable layer. The working length of the rope is 65 m, the maximum pulling force on the rope is 70 ... 90 kN. The winch is driven from the transfer case through an additional power take-off and three cardan shafts with intermediate supports. car bodies designed to accommodate various cargoes, passengers or special equipment. According to the type of body, trucks are of general purpose (with bodies in the form of a cargo onboard platform) and specialized (dump trucks, tanks, vans, etc.). Car bodies can be of the following types: sedan - a four-door body with two or three rows of seats; limousine - a sedan body with a partition separating passengers from the driver; coupe - a two-door body with one or two rows of seats; phaeton - a body with a soft folding top and removable sidewalls; convertible - a body with a reclining rear wall and part of the roof; station wagon - the body of a utility vehicle with two or four doors and a rear hatch; sport - a double body with a closed or open top. The buses have a closed frame car body. The body of a general purpose truck is designed to accommodate and transport a variety of goods and is a wooden or metal platform. To facilitate the loading and unloading of cargo, the rear 9
(Fig. 35) and side 5
And 10
retractable sides. Front board 11
platforms are immovable. The flaps are fastened with slats 6
, turning on hinges 7
. All boards are interconnected by gates 3
, and the floor boards 1
- cross bars 4
who are stepladders 8
tied with longitudinal bars 12
and frame beams. Longitudinal bars are additionally fastened to the frame with ladders 2
. The platform of the KAMAZ-5320 car is metal, onboard, consisting of a base, six sides and a frame with an awning. Side (two on each side) and tailgate folding. The floor of the platform is wooden. The platform with longitudinal bars is attached to the frame longitudinal beams by ten ladders. The body of the dump truck is a welded metal platform of a rectangular or bucket type. The platform of the KamAZ-55102 dump truck is of rectangular type, metal, with overturning on three sides. In the rear part, to the base of the platform between two transverse beams, brackets are welded with sockets for the tipping axle bushings and holes for locking.
Rice. 35 Loading platform:
1 – body floor; 2 , 8 - ladders; 3 - shutter; 4 - crossbar;
5 , 10 - side boards; 6 - plank; 7 - a loop; 9 - tailgate;
11 - front board; 12 - longitudinal bar
In the middle part of the first cross member of the subframe, four bolts are welded for fastening the lower support of the hydraulic cylinder. Attached to the front side of the platform is a mounting bracket for the upper support of the hydraulic cylinder. The platform has a shock absorber (rubberized plate) that serves as a support in the transport position, as well as a trap with a catcher-shock absorber to give the platform the necessary position in the longitudinal direction and hold it in this position when the vehicle is moving. fifth wheel coupling tractors is intended for articulated connection of the tractor with the semi-trailer, transfer of part of the mass of the semi-trailer to the frame of the tractor and traction to the semi-trailer. Auxiliary equipment General information about auxiliary equipment. To create convenience in driving and improve the working conditions of drivers, tractors and cars are equipped with auxiliary equipment. It includes a cab, controls and controls, devices for creating a microclimate in the cab and reducing the level of vibration, noise, etc. In order to improve the working conditions of the driver, first of all, the efforts on the controls are reduced through the use of hydraulic and pneumatic actuators, spring servomechanisms. The force on the tractor controls that require constant action (steering wheel, control levers, injection pump regulator lever, etc.) should not exceed 30 ... 50 N, on the bodies of periodic, intermittent action (gear shift levers, PTO engagement , hydraulic systems, etc.) - no more than 150 ... 200 N. The driver's performance decreases when exposed to vibration loads, especially in the frequency range of 3 ... 5 Hz. To reduce vibration, the design of suspensions is improved, and tractors are also equipped with more comfortable sprung seats. Noise has a negative effect on a person. It arises primarily due to the operation of the engine, transmission mechanisms, and for caterpillar tractors - additionally during the operation of the caterpillar mover and agricultural machines. The noise level in the tractor cab should not exceed 85 dB. To reduce it, tractors install noise-insulating cabins and hoods, exhaust gas silencers, etc. To create comfortable conditions, the cabins of modern tractors are equipped with air conditioners, fans, heaters, devices for maintaining a certain air humidity, etc. Cabin- this is the workplace of a driver or tractor driver, where they spend most of their working time. The following requirements are imposed on the cab design: rational placement of controls and seats; reliable protection against precipitation, sun, wind, dust, exhaust gases, negative temperatures, vibration and noise; good visibility; large margin of safety. The cabin is usually made of all-metal with two hermetically sealed glazed doors. On tractors, it is installed on four shock absorber supports, which reduce the vibration of the tractor operator's workplace. On trucks, cabs can be with a separate hood in which the engine is located (GAZ-53-12, ZIL-130 cars), and cabover with the engine located directly under the cab (GAZ-66, KamAZ-5320 cars). On fig. 36 shows the cab of a truck (Fig. 36, A) and tractor T-150K (Fig. 36, b). For thermal and noise insulation, vibration reduction, the floor, roof and front panel of the cabins are torn with insulating and sound-absorbing materials. The doors also have soundproofing gaskets and hermetically close the doorway thanks to rubber seals. The door windows are opened with power windows. Full opening of doors is limited by stops. Each door has a lock. Wide cab windows provide good visibility. Windshield wipers are installed on the rear and front windows. Cabins are equipped with a sun visor, rear and side view mirrors, a thermos for drinking water, a fire extinguisher, a tool box, a clothes hanger.
Rice. 36 cabins:
A– double truck; b- tractor T-150K;
1 - a layer of mastic; 2 - cardboard; 3 - screen; 4 – the handle of a window regulator;
5 - lock; 6 - handrail; 7 - shock absorber; 8 - buffer
The cabs of general purpose tractors and cars of the second and third classes are equipped with seats for the driver and passenger with seat belts. On universal row-crop tractors, the cabs are single (the seat is only for the tractor driver), and on cars of the fourth to sixth classes, they are three-seater with two seats for passengers. The seat of the tractor driver (Fig. 37, a) is mounted on a suspension 4
parallelogram type and spring sprung 2
or torsion bar. To dampen vibrations, it is equipped with a hydraulic shock absorber. 5
. spring tightening force 2
adjust by screw 1
directly proportional to the mass of the driver. On the MTZ-80 tractor, the seat (Fig. 37, b) are bolted to the cab floor. The seat is single, with a torsion bar suspension and a hydraulic shock absorber. The design of the seat provides for its adjustment in height, length, backrest tilt and suspension stiffness. handle 2
change the position of the seat in height within 0 ... 80 mm. When moving the lever 1
to the left 
Rice. 37 Tractor seat:
A- device diagram: 1 - adjusting screw; 2 - spring; 3 - bracket;
4 - suspension; 5 - shock absorber; b– MTZ-tractor seat 80 : 1 – length adjustment lever; 2 – the handle of fixing of a seat on height;
3 – the lower lever; 4 - rubber stop; 5 – the top lever; 6 – hardness adjustment screw; 7 - backrest adjustment bracket
You can move the seat forward or backward by 150 mm every 25 mm. With bracket 7 the backrest is set in three positions at different angles to the seat. screw 6 adjust the stiffness of the suspension. Levers in the free state 3 hangers must touch the rubber stop 4 , and in the loaded state (with a tractor driver), the seat should lower by 60 mm, i.e. halfway through its full length. With a larger stroke of the seat screw 6 increase the stiffness of the suspension (rotate the screw 6 counterclockwise), and with less deflection, they reduce stiffness. Devices for maintaining the microclimate in the cabins. The microclimate in the cabin must meet the following requirements: the air temperature during the warm season must not exceed the ambient air temperature by more than 2 ... 3 °С and must not be lower than 14 and not higher than 28 °С; air speed during ventilation - no more than 1.5 m / s; dust content in the air - no more than 2 mg / m 3, carbon monoxide - no more than 20 mg / m 3. The ventilation system can be natural (through the cabin windows) and forced (air supply by a fan). Most tractors and cars use both ventilation systems. On vehicles, forced ventilation is combined with the cabin heating system in cold weather.
Control questions
- What is included in the working equipment of tractors? Tell us how the tractor linkage mechanism is arranged? Purpose and principle of operation of the automatic hitch. Purpose and principle of operation of the trailer shackle. Why use a towing device on tractors, its design and operation. Application of a hydroficated hook on a tractor. The purpose of the power take-off shaft (PTO) and where is it located on the tractor? The work of the power take-off shaft. The purpose of the drive pulley. What is included in the working equipment of cars? Tell us about the winch device. Appointment of the car body and body types. Purpose and device of the fifth wheel coupling. Tell us about the auxiliary equipment of tractors and cars. Literature: .
Lab #6
HYDRAULIC LINKAGE SYSTEMS, PUMPS AND
DISTRIBUTORS, HYDRO CYLINDERS, TANKS,
PIPELINES AND FITTINGS
Goal of the work: to study the purpose, design and principle of operation of the hydraulic hinged system, pumps and distributors, hydraulic cylinders, tanks, pipelines and fittings. Equipment: hydraulic hinged system, pumps and distributors, hydraulic cylinders, tanks, pipelines and fittings as part of units, disassembled, posters. Work order- Familiarize yourself with the diagram of the hydraulic mounted system of tractors. To study the purpose, design and principle of operation of the pump. To study the purpose, design and principle of operation of the distributor. To study the operation of cylinders, tanks, pipelines and fittings. Answer the control questions and write a report on the work done.
Rice. 38 Scheme of the hydraulic system of the tractor(A) And
hydraulic oil path(b):
1 - pump; 2 - oil tank; 3 - distributor; 4 - distributor spool;
5 - spool handle; 6 - hydraulic cylinder; 7 – oil pipelines (hydraulic lines);
8 - suspension mechanism; 9 - mounted machine; 10 - support wheel of the machine;
P, O, N, Pl - position of the spool handle
When the handle is set to the H position, the distributor will direct the working fluid from the pump into the tank 2
and close the channels through which it enters and exits the cylinder. Therefore, the liquid-locked piston will hold the mounted machine motionless (P). When the handle 5
is set to position O, the working fluid will be pumped by the pump through the distributor into cavity A and displaced by the piston from cavity B into the tank. The machine will be forcibly lowered (W). When the handle is set to the Pl position, the pump will distill the working fluid through the distributor into the tank, and that which is in one cavity of the cylinder will be able to flow under the action of the piston through the distributor into its other cavity. Therefore, the attached machine will be freely lowered by its own weight or lifted by the support wheel. 10
Ministry of Agrarian Policy and Food of Ukraine Lugansk National Agrarian University Library
Document
В 93 Vysotskaya, Natalya Dmitrievna Tasks and guidelines for performing settlement and graphic work in the discipline: "Building structures" and the section of the diploma project "Foundations and foundations": for
The educational program of primary general education of the gymnasium No. 10 in Voronezh
Educational programThe main educational program of primary general education (EPE) for schools working on the textbooks of the Harmony system has been developed in accordance with the requirements of the Federal State Educational Standard for Primary
Various tractor implements
As you know, a modern tractor is a universal mobile (mobile) machine that can perform a wide variety of jobs. For example, tractors MTZ-80, MTZ-82 can be aggregated with 273 different machines - implements. In addition to working with agricultural machines, tractors can be used for other jobs: picking up stones from the surface of the field and loading them into trailers; loading aircraft and helicopters with fertilizers, herbicides, etc.; cutting packed stacks of straw and hay, etc. And in emergency cases, tractors can play the role of a mobile power plant of low power, a vacuum pump necessary for milking cows, a fire pump, etc.
A tractor driver sitting in the cab of a modern tractor can not only control its movement along the desired trajectory, but also act on the working bodies of the machine (implement) attached to the tractor, transfer it to a working or transport position, start it up and stop it.
To perform these actions, working equipment is installed on the tractor: a hydraulic hitch system (Fig. 114, a), which allows you to hang a machine or implement 7 on the tractor from behind using the hitch mechanism 6, and hitches in front. In some cases, it is possible to simultaneously hang the machines both from the rear and from the front. The hydraulic system makes it possible to control the working bodies of machines mounted or hitched to the tractor. Trailers (see Fig. 114, d) are used to connect the tractor to the trailer or trailers. Drive pulleys 8, placed on the side of the tractor or behind (see Fig. 114, b, c), are designed to transmit the torque of the tractor engine to a stationary machine.
Rice. 114. Tractor working equipment:
a - hydraulic system; b - drive pulleys; in-shafts of selection of power; g-trailing devices; 1, 6 - hinge mechanisms; 2, 5-power cylinders; 3 - pump; 4 - distributor; 7 - mounted tool; 8 - side pulley; 9 - rear pulley; 10- side PTO; 11-rear BOM .
In addition to the devices shown in Figure 114, the tractor can be equipped with drive wheel loaders that reduce their slippage, a hydraulic power take-off system, etc.
Mineral oils (motor MG-8 or MG-10), transmission (AKp-10) or industrial 20 (spindle 3) are used as a working fluid in the tractor hydraulic system. The type of oil used for a given tractor is usually indicated in the factory instructions.
The device of separate parts of the hydraulic system. The tank is equipped with a filling hole closed with a lid with a breather (Fig. 115), a level gauge, a drain plug and a filter for systematic cleaning of the working fluid from impurities.
Rice. 115. Oil tank:
1 - filter; 2-indicator; 3- breather; 4 - level gauge; 5 - filter element; 6 - bypass valve; 7 - drain plug; 8 - throttle; I - the filter is clean; II - the filter is dirty.
The filter elements of the filter consist of separate sections made of fine mesh, through which the working fluid is passed during the operation of the hydraulic system (position /).
If the filter elements are clogged, the passage of liquid will be difficult and the pressure in front of the filter will increase. To prevent an accident (rupture of pipes, nets, etc.), a bypass valve 6 is provided in the hydraulic system, which, when the pressure of the working fluid rises to 0.2 ... tank, bypassing the filter element (position //).
To control the degree of contamination of the filter on some tractors, a filter status indicator is placed in the drain line between the distributor and the tank.
When oil enters from the line, a throttle is installed into the indicator, which protects the indicator from sudden splashes of oil that contaminate the upper part of the internal cavity of the transparent cap with oil.
Oil pipelines and fittings. To connect hydraulic system devices fixed to the tractor, seamless steel tubes designed for pressure up to 32 MPa are used, which are connected with union nuts to the fittings of the corresponding parts of the hydraulic system: to the power cylinders, main and remote, the liquid is supplied through flexible hoses, which are rubber tubes , covered with two cotton braids and one or two steel braids (depending on the pressure for which they are designed), having a layer of rubberized fabric on the outside. In the manufacture of hoses, oil-resistant rubber is used. Non-separable tips are fixed at the ends of the hose.
The oil pipelines are interconnected by means of couplings equipped with self-closing ball valves (Fig. 116, a).
When both coupling bodies are connected with a nut, the balls, resting one against the other, move away from the sockets and open a passage for the liquid (position /).
After disconnecting the coupling, the balls are pressed by springs to their sockets and do not allow the liquid in the hoses to flow out (position //).
Rice. 116. Couplings: a - with a union nut; b-discontinuous; 1 - ball valve; 2-nut; 3,4 - coupling halves; 5 - ball; 6 - spring; / - connected position; II - disconnected position.
The oil pipelines leading to the power cylinders installed on the machines and implements attached to the tractor are connected by burst couplings with ball locks (see Fig. 116, b).
If the machine is accidentally disengaged and the tensile force increases above 150 N, the spring (position I) is compressed, the balls of the locking device come out of the cage and release both halves of the coupling, which are separated, and the ball valves close the outlet holes of the hoses (position II), as a result of which liquid leakage will be excluded.
Pump. In the hydraulic systems of tractors, pumps are installed to supply the working fluid to the power cylinders under high pressure (up to 12.5 MPa) and in such quantity as to ensure the transfer of the mounted machine or implement from the working position to the transport position within 2 ... 3 s.
Consider the design of pumps using the example of NSh-32U and NSh-32-2 (H-pump, Sh-gear, 32-theoretical supply of working fluid (in cubic centimeters) per shaft revolution, U-unified).
The NSh-32U pump consists of a housing (Fig. 117, a), inside of which two gears are installed that engage with each other - driving and driven. Pinion gears are made in one piece with them and installed in massive support bushings. The pump housing is closed with a cover. Between the body and the cover there is a sealing rubber plate (cuff). To prevent the flow of working fluid from the high-pressure cavity into the intake, a metal insert and a rubber seal are placed in the housing.
Rice. 117. Oil pumps:
a - NSh-32U; b - NSh-32-2; 1 - cover; 2 - body; 3 - drive gear; 4- driven gear; 5 - support bushings; 6 - cuff; 7 - liners; I am the seal; 9 - scheme of action; 10- plastic; 11 - clamping clip; 12- centering sleeve; 13 - bearing race; / - suction cavity; 11 - injection cavity.
The pump operates as follows. When the engine is running, the rotation from the crankshaft or from the transmission mechanisms (depending on the design of the tractor) is transmitted through the gear transmission to the pump gears, which at the same time begin to rotate in opposite directions.
The tooth cavities of the rotating gears capture the working fluid, then throw it against the walls of the housing and transfer it without compression from the suction cavity / to the discharge cavity II. At that moment, when the teeth in the injection cavity engage with each other, forming a tight contact, the transition of the liquid back into the cavity is impossible.
With further rotation of the gears, the teeth disengage, forming a vacuum in the cavity. Due to this rarefaction, liquid enters the suction cavity from the tank, which fills the vacated gear cavities. In the future, this process is repeated.
In order to prevent leakage of fluid along the ends of the gears, bushings are constantly pressed against them under the pressure of the working fluid.
The NSh-32-2 pump consists of a housing (see Fig. 117, b) with a cover, driving and driven gears, bearing and clamping cages of a centering sleeve that prevents the cages from turning after they are installed in the casing, sealing plastics and fasteners.
The gears, made as one piece with the trunnions, are placed in a bearing cage. A clamping clip is installed on top of them, which is pressed by the cuff of the radial seal.
On the sides of the gears in the clamping cage, bronze plastics with rubber cuffs are installed. Plastics, pressing against the side surfaces of the gears, prevent the flow of the working fluid from the discharge cavity to the receiving one.
The inner surfaces of the cages are very carefully machined and fit snugly to the outer surfaces of the gear teeth.
The pressure force of the working fluid in the injection cavity through the rubber cuff 6 ensures a constant tight fit of the inner surfaces of the cages to the tops of the teeth, while maintaining the necessary clearance.
The operation of this pump is similar to that of the NSh-32U pump.
NSh pumps consume a lot of power. So, for example, to create a pressure of 10 MPa, the pump NSh-32U requires a power of up to 12.1 kW.
The drive of pumps for different tractors is carried out in different ways, for some the pump receives rotation from the transmission mechanisms, for others, less often, from the engine distribution gears. The pumps are turned on and off with special couplings or by moving a gear sitting on the splines of the pump shaft.
Rice. 118. Distributor: a device; b - schemes of action; 1 - holding device; 2 - spool; 3 - safety valve; 4 - handle; 5 - lever; 6 - body; 7 - a plate mounted on a tractor; I- rise; II- neutral position; III - lowering; IV - floating position.
The distributor (Fig. 118, a) serves to control the action of the power cylinders installed on the tractor and on the machines - implements towed by it.
Device. The distributor consists of a housing 6, closed at the ends with covers. Inside the case there are spools, the number of which can be from one to three. Spools are cylindrical rollers with grooves for the passage of the working fluid. The rollers are very carefully processed and adjusted to the cylindrical holes in the housing and serve to direct the flow of the working fluid supplied by the pump in the right direction.
In the lower part of each spool (in the figure on the left) there is a device that holds it in the required positions and returns it to the neutral position after lifting or lowering the machine (implement) mounted on the tractor.
In the upper cover of the distributor (in the figure on the right) there are levers connected to the spools. Control handles are fixed on these levers. A safety valve 3 is located on the side of the body.
Action. If you put the distributor handle in the "Lift" position (as shown on the plate mounted on the tractor), then the working fluid supplied by the pump will go into the cavity above the piston (see Fig. 118) of the power cylinder and the piston together with the rod will move to the right and lift the car*. After the piston reaches the end of the cylinder and rests against the bottom cover, the fluid pressure will begin to rise. How. as soon as the pressure reaches 12.5 ... 13.5 MPa, device 1 (see Fig. 118, a) will automatically move the spool to the right and put the handle in the "Neutral" position (see Fig. 118, b). In this case, the liquid supplied by the pump will begin to be pumped under low pressure from the tank and back into the same tank. The cavities of the power cylinder will be locked, and the piston together with the rod will be motionless.
If for some reason the retaining device does not move the spool to the "Neutral" position, the pressure of the working fluid in the distributor will increase. As soon as the liquid pressure reaches 14.5 ... 16.0 MPa, the safety valve will come into action, which will open the passage of the liquid to the drain into the tank and thereby stop further pressure increase.
Having discovered such a phenomenon, the tractor operator must immediately manually put the handle in the “Neutral” position.
When the handle is set to the “Lower” position, the piston of the power cylinder will be pushed out of the cylinder, and at the end of the stroke, the handle will also automatically return to the “Neutral” position *.
If the lever is put in the “Floating” position, the spool will direct the liquid supplied by the pump back to the tank and at the same time connect both cavities of the power cylinder to each other. This will allow the piston to move freely in the cylinder - "float".
The power cylinder is a hydraulic motor that converts the energy of the working fluid flow created by the pump into the mechanical energy of the piston.
Power cylinders are designed to raise, lower or hold in a certain position agricultural machines and implements attached to the tractor or their working bodies. Cylinders installed at the rear of the tractor are called the main ones, and those placed on hitch attachments or on hydraulic machines or implements are called remote. In their design, the main and remote cylinders differ only in the design of the connecting places and dimensions.
Device. The power cylinder is a steel case (Fig. 119, a), inside which a piston with a rod is installed. At the ends, the cylinder is closed with caps connected to each other by pins.
Rice. 119. Power cylinder:
a - device; b- rise; in - locked; g - lowering; d-mechanism of fixation; 1, 7-forks; 2 - piece ^ k; 3 - piston; 4 - body; 5 - tube; 6, 10 - valves; 8 - emphasis; 9 - studs; 11, 15 - levers; 12 - capture; 13 - tooth; 14 - thrust; 16-bracket; A, B - cavities; V, G - fitting.
In the front cover there is a valve for hydromechanical control of the stroke of the rod. There is a stop on the stem, the position of which can be changed by moving it along the stem.
The power cylinder is connected with a pin to the fixed bracket of the attachment using the fork of the rear cover, and with the fork of the rod - to the lifting lever of the attachment.
Action. When the distributor lever is moved from the “Neutral” position to the “Lift” position, the working fluid supplied by the pump under high pressure begins to flow into cavity B through fitting C, in which a slowdown valve is installed with a small hole in the center and with cutouts along the edges. In this case, the valve moves along the flow of the liquid, abuts against the pressed pins and passes the liquid into the cylinder both through the central hole and between the walls of the fitting and the cutouts in the valve, i.e. without resistance.
The piston, under the action of fluid pressure, moves to the left and turns the lift lever of the linkage mechanism, as a result of which the mounted machine or implement rises. At this time, the liquid from cavity A is pushed out by the piston through pipe 5, fitting D and the hose back to the distributor, which directs it to drain into the tank.
This movement of the piston will occur until the stop presses the hydromechanical control valve, which at the same time moves inside the cover and closes the liquid outlet. At the moment of closing the valve, its movement is accelerated by the outflowing liquid, it is ahead of the stroke of the stem and therefore a gap of 5 ... 10 mm is formed between its shank and stop.
After the valve is closed, under the action of the liquid pressure increased in the cylinder, the distributor spool will move to the “Neutral” position and close the inlet and outlet openings of the power cylinder. In this case, the power cylinder will be locked, the piston will not be able to move, and the mounted machine will be rigidly connected to the tractor.
If it is necessary to lower the raised machine into the working position, the distributor lever should be set to the "Floating" position (see Fig. 118.6, position IV), while the machine, lowering under the action of its mass, will move the piston of the working cylinder and push out of the cavity B (see Fig. 119, d) the working fluid, which, when moving through the fitting C, will press the retarder valve 10 to the shoulder of the fitting. Only the throttle (located in the center) valve hole will remain for the fluid to exit, passing through which it encounters increased resistance, which will significantly slow down the speed of lowering the machine. If there is no such valve, then when the distributor lever is set to the “Floating” position, the mounted machine will lower quickly, with a blow.
In cases where the mounted machine must be lowered forcibly (for example, when working with a hole digger), the distributor lever should be set to the “Lower” position. Then the working fluid under high pressure will flow through the fitting D into the cavity A of the cylinder and push the piston with the rod to the right.
The described power cylinder performs work both with the piston stroke to the right and to the left and therefore is called a double-acting cylinder, in contrast to single-acting cylinders, in which fluid is supplied only to one cavity - under the piston, and the opposite cavity communicates with the atmosphere through a breather.
The greatest force on the rod of power cylinders is in the range from 2000 to 110,000 N, depending on the diameter of the cylinder and the pressure of the supplied working fluid.
The hitch locking mechanism is designed to hold the machine (implement) mounted on the tractor in the extreme upper position during long transport journeys. Such a mechanism is installed on some universal row-cultivator tractors.
Device. The mechanism consists of a grip connected to rods pivotally mounted on a bracket, and a control handle, which is connected by a rod to a lever system.
Goal of the work: to study the purpose, principle of operation and components of the working and auxiliary equipment of tractors and cars.
Equipment: working auxiliary equipment as part of units, in a collapsible state, posters.
Work order
1 To study the design and principle of operation of the working equipment of tractors.
2 To study the design and principle of operation of the working equipment of vehicles.
3 Study the auxiliary equipment of tractors and cars.
4 Familiarize yourself with the maintenance of the tractor linkage mechanism.
5 Answer control questions and write a progress report.
Tractors as mobile power tools for agricultural production are designed to transmit rotational and translational motion and hydraulic flow to aggregated machines. The transfer of these forms of movement determines the design of the power take-off mechanisms that form the basis of the working equipment.
To transmit rotational motion on tractors, power take-off shafts (PTO) with their drive mechanisms and drive pulleys are used. Translational motion is communicated through towing devices (towing hook, shackle with eyelet), linkage mechanisms or tractor frame, and hydraulic flow through the hydraulic power take-off system (GPS).
The linkage mechanisms of all tractors are controlled by a separate-aggregate hydraulic system, which simultaneously performs the functions of a GPS (except for the MTZ-100 tractor). The control of the PTO drive mechanisms of the T-150 and K-701 tractors is also hydraulically controlled.
The purpose, design and principle of operation of the hydraulic drives of the power take-off mechanisms and the GPS of tractors are discussed in Ch. 3.
Hinge mechanism. The method of connecting agricultural and other machines with a tractor depends on their design. Some machines are hung on a tractor, others are attached to it, and still others are rigidly attached to its frame.
The design of devices for hitching machines depends on the location of the machine relative to the tractor. If the machine is hung on the side or in front of the tractor, then its frame is provided with seats with holes for mounting bolts or special brackets. On self-propelled chassis, the machines are hung to the longitudinal tubes of the frame.
The rear linkage mechanism consists of two lower longitudinal rods 6 And 10 (Fig. 31, a) and the upper central adjustable rod 4 . The front ends of all the rods are pivotally connected to the frame of the tractor, and the rear ends - to the mounted machine. Lower links 6 And 10 braces 3 And 11 articulated with lifting arms 2 And 12 , and through them - with a lifting shaft 1 .
Raise and lower the mounted machine using a hydraulic cylinder 14 , whose stem through the lever 13 connected to the lifting shaft 1 .
By changing the length of the right brace 3, the position of the mounted machine is adjusted in the horizontal plane, and by changing the length of the upper central rod 4 equalize the depth of travel of the front and rear working bodies of the machine.
Depending on the design of the mounted agricultural machines and the technological operations performed, they are attached to the tractor according to three- and two-point schemes.
Three-point hitch scheme (Fig. 31, A) are used when the tractor is working with wide-cut machines (cultivators, seeders, etc.). To do this, the front ends of the lower longitudinal rods 6 And 10 they are fixed separately at points B and C, and the upper one at point A. This suspension scheme ensures a stable rectilinear movement of the machine.
Rice. 33 Towing device:
1 - bracket; 2 - cap; 3 - hook nut; 4 - shock absorber; 5 – shock absorber body; 6 - lid; 7 - the axis of the control handle;
8 - bottom catcher; 9 – locking lever; 10 - hook;
11 - clamp mouth of the hook; 12 - visor; 13 - control handle;
14 - locking pin; 15 - stop of the latch; 16 - spring;
17 – retainer spring; 18 – the case of automatic hitch;
19 – a spring of the handle of management; 20 - finger; 21 - finger check
The towing device is a traction hook 10 with rubber damper 4 , bottom catcher 8 , visor 12 and fixative 11 . The latch is controlled by a handle 13 .
For attaching a trailer to a hook 10 turn the handle 13 back. In this case, the mouth of the hook is open, and the lower catcher 8 is placed in a horizontal position. When the tractor is moving in reverse, the drawbar loop of the trailer slides over the catcher, presses the lock 11 , moving it inside the body, and enters the mouth of the hook. In this case, the latch under the action of the spring 17 comes out of the body 18 and automatically locks the mouth of the hook. Lever 13 under the action of a spring 19 returns to its original position.
A hydraulic hook is used when tractors are used with single-axle trailers, manure spreaders and other machines that create not only longitudinal and lateral, but also normal loads. The hydroficated hook, in comparison with the previously considered towing devices, is able to withstand a large normal load.
PTO(PTO) is the driven (output) shaft of the power take-off (PTO) of rotary motion.
According to the location on the tractor, rear, side and front PTOs are distinguished. The rear PTO is usually located in the rear axle housing of the tractor, and the PTO is located together with the transmission mechanisms. The side PTO is placed in a special housing mounted on the gearbox housing.
There are PTOs with constant and variable speed. The working bodies of harvesting, tillage and some other machines must have a constant speed, and such machines as seeders, planters, spreaders - a speed proportional or synchronous to the forward speed of the tractor.
The following two values of the rated PTO speed are set: 540 and 1000 min-1 at the rated speed of the diesel crankshaft.
According to the drive method, PTO and their PTO are divided into dependent, independent, semi-independent, synchronous and combined.
Dependent PTO (Fig. 34, A) is characterized by the fact that its PTO stops rotating when the main clutch is turned off. Turn the PTO on and off with the lever 1 with gear coupling 3 with the clutch disengaged. With a dependent shaft, the acceleration of the unit and the working bodies of the machine occurs simultaneously, which requires increased engine power and additional fuel consumption.
Semi-independent PTO (Fig. 34, b) rotates from the crankshaft of the diesel engine, regardless of whether the clutch is on or off. PTO is turned on and off by a gear clutch 3 with diesel not running.
An independent PTO differs from a semi-independent one in that an additional friction clutch or a planetary gearbox is installed to control the PTO when the tractor is moving and stopping.
Synchronous PTO (Fig. 34, V) changes the PTO speed when changing from one gear to another and rotates from the gear wheel of the gearbox output shaft or from one of the transmission output shafts. The PTO of a synchronous PTO is usually dependent. Turn it on and off with a gear clutch 3 with the clutch disengaged.
Combined PTO (Fig. 34, G) consists of independent and synchronous PTO. To engage independent PTO lever 1 put into position II and gear clutch 3 connects to the drive shaft 7 gear wheels 2 . When moving the lever 1 into position I gear clutch 3 connects to the shaft 7 gear wheels 4 and includes a synchronous PTO.
All PTO shafts have splined output ends (tails) with standard dimensions for attaching the universal joint of the drive of the working parts of the coupled machines.
Auxiliary equipment is used to create convenience in various operating conditions of machines.
Means that improve traction and coupling qualities and controllability of tractors
Improving the traction and coupling qualities of wheeled tractors can be achieved, for example, by installing ballast weights, using a half-track, pouring liquid into the wheel chambers, etc. Ballast weights are used to load both the front and rear wheels. On caterpillar modifications, the installation of ballast weights is provided only in front.
When working with heavy machines mounted from the rear, the front of the tractor is unloaded, which leads to a deterioration in the stability and controllability of the tractor. Additional loading of the front part of the tractor restores the normal controllability of the tractor, and on tractors with a front drive axle, it also improves the traction qualities of the front wheels. On tractors with a reversible control post, to work with wide-cut harvesters, it is provided to install 18 weights in front on a special bracket.
Rear ballasting is used when working with front loaders, which cause significant unloading of the rear wheels.
The half-track consists of two rubber-metal tracks and idler wheels. Bolts with lugs are attached to the caterpillars with lugs, which, on the one hand, do not allow the drive wheel to slip along the caterpillar, and on the other hand, reduce the slipping of the tractor when moving across the field.
Rice. 1 Tractor with half-track: 1 - caterpillar; 2 - tension wheel; 3 - star hook
Means that increase the cross-country ability of cars
These include a winch, chains, bracelets and various other special devices.
The winch is mounted on the front of the frame of some off-road trucks. It is used to lift a load or self-extract a stuck car.
The winch consists of a gearbox, a drum and a drive.
Fine-linked chains are used to drive a car on soft soils, virgin steppe, slippery and icy roads and in mountainous areas.
Caterpillar chains are effective when driving on very soft soils, wetlands and virgin steppe. Chains are used on three-axle vehicles and are attached to the wheels of the intermediate and rear drive axles.
Snow chains are put on the wheels on the way to a difficult section of the road. To do this, the chains are laid out in front or behind the car along the wheel track and slowly run into the middle of the chains. Then the chains are stretched and their ends are connected with locks. Driving with snow chains on paved roads is unacceptable, as this leads to increased tire wear.
Chain bracelets and traction control shoes can be put on the wheels in case of easy towing of the car.
Track chains are used for driving on soft, soggy soils, broken dirt roads and in muddy roads. They are also applicable for driving in wetlands and virgin snow.
Means to create ease of machine control and comfort
To create control conveniences, modern tractors and combines are equipped with automobile-type cabins, and their interior does not actually differ from the interior of car interiors. Cabins are equipped with a fan; air conditioning; protective frame; seat belts; a seat adjustable according to the weight of the tractor driver, height, forward - backward and according to the inclination of the back; convenient control panel; adjustable steering column; tinted panoramic front and side windows; radio receivers, etc.
Auxiliary equipment includes a cabin, controls and controls, devices for creating a microclimate in the cabin and reducing the level of vibration, noise, etc.
In order to improve the working conditions of the driver, first of all, the efforts on the controls are reduced through the use of hydraulic and pneumatic drives, spring servomechanisms. The force on the tractor controls should be no more than 30...50N.
To provide the necessary comfortable conditions for drivers, tractors and cars are equipped with pressurized cabins. The cabins of modern tractors and cars are subject to a number of ergonomic requirements. All controls of the tractor and the vehicle must be placed in the cab in the so-called zones of ergonomic accessibility, i.e., they must be accessible to the driver with minimal energy consumption.
An important characteristic of the cab is visibility, so the cab has front, rear and side panoramic windows with rubber seals. The side windows are made opening, for which the cab doors are equipped with power windows. The front and rear windows can also be opened to improve visibility.
To ensure the safety of the driver in a collision, rollover and in traffic accidents, the cab must be sufficiently strong. Therefore, it is made all-metal, welding from a cold-rolled profile.
Driver performance is significantly affected by noise and vibration in the cab. To reduce them, noise-absorbing pads are used between the outer and inner walls of the cabin, floor mats. The cabins themselves are attached to the frame on rubber-metal, spring or hydraulic shock absorbers. The driver's seat is equipped with an anti-vibration device and can be adjusted according to the driver's weight, seat height and proximity to the controls (back and forth)
The cabs of many modern trucks are located above the engines. For ease of access to the engine during its maintenance, they are made reclining and equipped with reliable locking devices that prevent spontaneous tipping of the cab.
To protect the driver from being affected environment, cabins are made with sealed doors and windows that provide a slight excess air pressure. It is possible to use an air conditioning system. Excess pressure is maintained by a fan, which is often combined with a heating system.
For the safety of the driver's work, seat belts are installed, and for work in difficult weather conditions - windshield wipers, anti-icing and defogging devices.
The microclimate in the cabin must meet the following requirements: the air temperature must not be lower than 14 and not higher than 28 ° C, and in the warm period of the year no more than 2 ... more than 1.5 m/s, dust content in the air - no more than 2 mg/m 3 , carbon monoxide - no more than 20 mg/m 3 .
The ventilation system can be natural (through the cabin windows) and forced (air supply by a fan). Most tractors and cars use both ventilation systems. On vehicles, forced ventilation is combined with the cabin heating system in cold weather. For forced ventilation of tractor cabs, a fan-dust separator is used, installing it on the roof of the cab. This fan consists of a housing, a cap, a branch pipe, a shield and an electric motor with an impeller.
To ensure normal temperature conditions in the summer, the cabs of some tractors are equipped with forced ventilation with an air cooler, usually of the water evaporative type. Such a ventilation unit supplies dust-free, humidified and cooled air to the cabin. In the cold season, tractor cabs are blown with air heated in the core of the radiator of the diesel cooling system. Air enters the core of the radiator through the intake through a metal sleeve. Warm air is directed into the cab first through nozzles with slots to blow windshields, and then directly into the cab
Control questions
1. What tractor equipment is called working?
2. What components does the mounted hydraulic system consist of?
3. What is the difference between a two-point linkage mechanism and a three-point one?
4. What is the brake mechanism used for?
5. Tell the device and the operation of the parking brake of the car.
6. Explain according to the diagram (see Fig. 1.6.4) the operation of the pneumatic drive of the car brakes.
7. List tractor and vehicle accessories.