Machines used in modern technology. Main types of mechanisms
>>Technology: Concept of mechanism and machine
In the modern world, people are often helped by various mechanisms and machines.
Car- this is a device that performs certain actions in order to facilitate the physical and mental work of a person. For example, a car is a transport machine, a machine for processing any workpiece is a technological machine.
Examples of household machines are a vacuum cleaner, washing machine, and refrigerator. Agricultural machines (tractors, combines, etc.) help people harvest crops. A computer for a person is an information and computing machine.
The design of the machine includes many different mechanisms. Mechanism is a device for converting one type of movement into another. As an example, consider the screw mechanism used in the front and rear clamps of a carpentry workbench (Fig. 52).
In the screw mechanism, the rotational movement of the handle 2 is converted into the rectilinear movement of the lead screw together with the pressure bar 3 (Fig. 52, a). Figure 52, b shows the kinematic diagram of the screw mechanism.
Kinematic diagram- this is a symbol for various gears and parts included in this gear.
Mechanisms and machines consist of many different parts, for example, there are more than 15 thousand of them in a car, and more than a million in an airplane. Some parts are used in almost all machines (bolts, nuts, washers, etc.). They're called general purpose parts. Other parts, such as machine bodies and machine beds, are special-purpose parts. Table 3 shows some typical machine parts.
Mechanism parts are connected to each other in various ways. If they cannot move relative to each other, then such a connection is called motionless. Fixed connections are connections between parts using screws and nuts (threaded connections), welding, etc.
If parts can move relative to each other, then such a connection between parts is called mobile.
A type of mobile connection is a swivel joint (Table 4). 
PRACTICAL WORK
Familiarization with the structure of various mechanisms
1. Inspect the screw mechanism on the front clamp of the woodworking bench. Understand how the rotational movement of the handle is converted into the linear movement of the clamping rod.
2. Examine the gear mechanism of the drill and determine what purpose it serves.
- Machine, mechanism, screw mechanism, kinematic diagram, general and special purpose parts, movable and fixed connections.
1. What is called a car?
2. What is called a mechanism?
3. What cars do you know?
4. Name typical machine parts.
5. Where are screw mechanisms used and how do they work?
A.T. Tishchenko, P.S. Samorodsky, V.D. Simonenko, N.P. Shchipitsyn, Technology 5th grade
Submitted by readers from the website
1.1. Structure of machines and mechanisms
Most modern cars are created according to the following scheme:
Car- a device that carries out mechanical movements necessary to perform the work process in order to replace or facilitate human physical and mental labor.
Mechanism is an integral part of the machine and is a set of interconnected parts and assemblies that ensure the performance of specified functions.
Drive unit consists of a motor and a transmission mechanism. It is designed to provide kinematic and power characteristics of the actuator.
Transmission mechanism designed to transfer energy from the engine to the actuator with transformation of the type and direction of movement, as well as changes in kinematic and power characteristics.
Actuating mechanism designed to perform the direct work process (processing, transportation, mixing, etc.).
1.2. Simple transfers. Main characteristics
and calculated dependencies
The need to introduce a transmission mechanism is due to its ability to perform various functions:
Energy (power) transmission;
Transformation (decrease or increase) of forces or moments of forces;
Conversion (decrease or increase) of the speed of movement of links;
Converting the type of movement (rotational to translational or vice versa) and changing the direction of movement;
Separation of motion flows from the engine to several executive bodies of the working machine.
Among transmission mechanisms, widely used rotational motion transmission , which can be divided into two main groups:
Transmissions based on the use of friction forces (friction, belt);
Transmissions based on the use of gears (gear, worm, screw, chain).
Let's consider simple gear transmissions, each of which contains two moving links (shafts with gears attached to them) performing rotational motion, and one fixed link (shaft supports). In Fig. 1.1 shows the appearance of the gears and the options for depicting them on block diagrams.
| Bevel gear |
| Worm-gear |
Helical gears are characterized parallel arrangement of gear axes A And b and differ in the arrangement of the gearing: with external gearing and with internal gearing. IN conical gear axis transmission A And b intersect . IN worm worm axis transmission A and worm wheel b cross .
The main kinematic characteristic of transmission mechanisms is gear ratio U, which is the ratio of angular velocities w or rotational frequencies n input (leading) A and output (slave) b links In this case, the designation of the gear ratio has two indices indicating the direction of transmission of movement from the link A to the link b:
.
Rotation frequency n is related to the angular velocity w by the relation:
, rpm
Gears that reduce rotation speed are called gearboxes . In them, the gear ratio is realized due to the ratio of diameters d or number of teeth Z slave b and presenter A gears in mesh:
.
Thus, gearboxes reduce the rotation speed by a factor of the gear ratio due to the ratio of the numbers of teeth of the meshed wheels:
.
In this case, the drive gear in cylindrical and bevel gears, which has a smaller number of teeth, is called gear , and the slave – wheel .
The torque in the gearboxes increases by a factor of the gear ratio, taking into account friction losses estimated by the efficiency coefficient η :
.
Efficiency (h) is the ratio of useful power P n on the output link, spent on the implementation of useful work in a production or technological process, to the power on the input link, expended by the engine:
.
Efficiency takes into account power losses to overcome friction forces in kinematic pairs and is an important criterion for assessing the efficiency of energy use and the technical perfection of the mechanism.
When solving problems, you can use the following efficiency values for various gears: cylindrical - η = 0.97; conical – η = 0.96; worm - η = 0.95 (1 – U / 200), where U– gear ratio in the worm gear.
1.3. Multi-stage transmission mechanisms
If it is necessary to implement a gear ratio whose value exceeds the recommended limits for individual gears, use a sequential arrangement of gears (stages) in the transmission mechanism.
In this case, the overall gear ratio ( U total) and the overall efficiency (h total) of a multi-stage transmission mechanism are defined as the product of gear ratios and the efficiency of all its stages (gears):
,
Where m– the number of stages in the mechanism.
Gear ratio of one or group of stages m– a step mechanism is characterized by the ability to change the speed of rotation n and torque T when transferring movement between the leader i and slave k links of the considered part of the mechanism:
.
Net power on the output shaft of the mechanism ( P out, W) are calculated according to the dependence:
,
Where T out, Nm and n out, rpm – respectively the torque and speed of the output shaft of the mechanism.
The required (calculated) engine power () is determined taking into account losses in the friction units of the mechanism:
Based on the design power and rotational speed, a standard electric motor with the nearest higher power value is selected from the catalogue.
1.4. Examples of problem solving
Task 1. Carry out a structural, kinematic and force analysis of what is shown in Fig. 1.2 drive containing an electric motor and gearbox.
Parameters set:
– number of teeth , , , , , ;
– engine shaft rotation speed rpm;
– torque on the output shaft of the gearbox Nm.
Solution
Structural analysis. The three-stage transmission mechanism is formed by connecting three separate gears in series.
The first stage is a cylindrical gear with external gearing; gear axis 1 and wheels 2 parallel.
The second stage is a bevel gear; gear axis 3 and wheels 4 intersect.
The third stage is a worm gear; worm axes 5 and worm wheel 6 cross.
The axes of the input I and output IV shafts intersect.
Kinematic analysis.
– first stage: 
;
– second stage: 
;
– third stage: 
;
– mechanism: .
We determine the rotation frequency of each shaft of the mechanism, taking into account that the gears are fixed to the shafts and have the same speeds with them:
RPM (according to the problem conditions);
rpm;
rpm;
rpm
Force analysis. We determine the torques on each shaft:
Nm (according to the problem conditions);
Nm.
The efficiency of a worm gear is determined by the dependence:
Nm;
Nm.
Thus, the rotational speed of the shafts decreases stepwise by the gear ratio times ( rpm; rpm; rpm; rpm), and the torques increase (taking into account efficiency) by the gear ratio times ( Nm; Nm; Nm; Nm).
We calculate the useful power based on the output shaft of the gearbox:
W = 2.5 kW.
Required (calculated) engine power:
kW,
From the catalog we select a standard 4A100S4 electric motor with a rotation speed of rpm and a power of kW.
Task 2. Carry out a kinematic analysis of the drive (see Fig. 1.2 in task 1), using other initial data.
Parameters set:
– number of teeth: , , , ;
– engine shaft rotation speed: rpm;
– rotation speed of the gearbox III shaft: rpm.
Solution
We determine the gear ratios:
– first stage: 
;
– third stage: 
;
– general gear ratio of the first and second stages:
;
– the gear ratio of the second stage is determined, taking into account that 
:
;
– the entire mechanism: .
We determine the rotation frequency of each shaft of the mechanism:
RPM (according to the problem conditions);
rpm;
rpm (according to the problem conditions);
rpm
Thus, the gearbox reduces the engine shaft rotation speed by 120 times (from 3000 rpm to 25 rpm), changing it stepwise: in the first stage by 3 times (from 3000 rpm to 1000 rpm), in the second stages 2 times (from 1000 rpm to 500 rpm) and in the third stage 20 times (from 500 rpm to 25 rpm).
Control questions
1. What is a drive, transmission mechanism, actuator? What are they for?
2. What functions can the transmission mechanism perform?
3. Name simple gears as gears and draw their structural diagrams. What relative position of the axes of the driving and driven links is typical for each of the gears?
4. What is gear ratio? How does it characterize the transmission mechanism?
5. What is a gearbox? What functions of a transmission mechanism can it perform? How is the required gear ratio implemented in gearboxes? Draw on the diagram: a helical gearbox with a gear ratio; bevel gear with .
6. Make up all possible dependencies from which the gear ratio can be calculated.
7. What is coefficient of performance (COP)? How does it characterize the transmission mechanism? What operational parameters are calculated taking into account efficiency?
8. What are multi-stage transmission mechanisms used for? How to determine the overall gear ratio and overall efficiency?
9. Solve the problem. Carry out a structural, kinematic and force analysis of what is shown in Fig. 1.3 gearbox.
Parameters set:
– number of teeth , , , ;
– shaft rotation speed
- torque
|
Define:
a) the number of stages in the mechanism;
b) type of transmission in each stage;
c) gear ratio of each stage;
d) rotation speed of shafts I and II;
e) torque on shafts I, III, IV;
f) general gear ratio;
g) overall efficiency;
h) useful and expended power;
i) location of the axes of the input I and output IV shafts.
Answers: a) 3; b) 1-Ch, 2-K, 3-C; c) 15, 2, 4; d) 200 and 100; e) 10, 253, 983; e) 120; g) 0.82; h) 2.57 and 3.14; i) cross.
2. BASIC CONCEPTS OF STATICS
2.1. Force and moment of force.
Couple of forces and moment of a couple of forces
Statics is a branch of mechanics that studies the conditions of equilibrium of the links of a mechanism under the action of forces.
Force (F, N) – a measure of the mechanical interaction of solids. Force is represented as a vector, the action of which is characterized by the point of application (for example, point A), direction along the line of action and magnitude F(Fig. 2.1).
Rice. 2.1 Fig. 2.2
Couple of forces(Fig. 2.2) – a system of parallel forces (), equal in magnitude ( F 1 = F 2) and directed in opposite directions ().
Moment of power( , Nm) relative to a point (for example, t. ABOUT) is the product of the numerical magnitude of the force F on the shoulder h– the shortest distance from a point to the line of action of the force (see Fig. 2.1): 
Moment of a couple of forces (concentrated moment)
(m, Hm) is defined as the product of the magnitude of one of the forces by the arm of the pair h – distance between the lines of action of forces (see Fig. 2.2):
.
|
Torque (T, Nm)– moment of force, the action of which is accompanied by rotation of the link (Fig. 2.4, A).
Bending moment (M, Nm)– moment of force, the action of which is accompanied by bending of the link (Fig. 2.4, b).
2.2. Connections and their reactions
Any structural element or link of a mechanism is a non-free body, the movements of which in space are limited by other bodies, called connections . A constraint that prevents the movement of a non-free body acts on it with a force called communication reaction .
The direction of bond reactions is determined based on the following rules:
1. The coupling reaction is applied at the point of contact of the contacting surfaces and is directed in the direction opposite to the direction in which the movement is limited.
2. If the connection limits movement in several directions simultaneously, then the direction of the reaction is unknown and it is represented in the form of components directed along the axes of the selected coordinate system.
Let's consider the direction of reactions for the main types of bonds (Fig. 2.5).
Smooth surface contact(Fig. 2.5, A). The reaction is directed along the common normal to the contacting surfaces.
Contact of smooth surfaces with corner points and cusps(Fig. 2.5, b). The reaction is directed normal to the smooth surface.
Inextensible thread(Fig. 2.5, V). Reactions and are directed along the threads to the points of suspension.
Articulating support(Fig. 2.5, G). The reaction is perpendicular to the supporting surface.
Articulated-fixed support(Fig. 2.5, d). The direction of the reaction is unknown. Presented in the form of unknown components and .
Hard seal(Fig. 2.5, e). In such a support there can be three components of the reaction: , and the support moment.
2.3. Equilibrium conditions for a plane system of forces
A rigid body is in a state of equilibrium if it is motionless relative to the reference frame under consideration.
For the equilibrium of a rigid body under the action of an arbitrary system of forces, it is necessary and sufficient that the main vector and the main moment of this system relative to any point ABOUT bodies were equal to zero:
Main vector system of forces is equal to the geometric sum of all forces of the system:
Main point system of forces is equal to the sum of the moments of all forces relative to the selected center of reduction 0:
.
As a result, the equilibrium conditions take the form:
.
When solving practical problems, the analytical method of solving vector equations is used, according to which the projection of the sum of vectors onto any axis is equal to the sum of the projections of the summands of the vectors onto the same axis .
In this regard, the above equilibrium conditions for a plane system of forces can be written in the form of three independent equilibrium equations of a rigid body relative to a rectangular XY coordinate system:
.
A rigid body is in equilibrium if the algebraic (taking into account the sign) sum of the projections of all forces on each of the coordinate axes is equal to zero and the algebraic sum of the moments of all forces relative to any point O of the XY plane is equal to zero.
To determine the magnitude and direction of the bond reaction, it is necessary to perform the following steps:
1) replace external connections with their reactions, depicting their possible direction on the power diagram;
2) from the equilibrium equations of the system of forces, determine the magnitude of the unknown reactions;
3) if, as a result of calculations, any reaction turns out to be negative, you need to change its direction in the diagram to the opposite;
4) carry out a control check of the correctness of determination of reactions both in magnitude and in direction, using additionally one of the equilibrium equations, for example, the equation of moments about a point on the plane that was not previously considered.
When drawing up equilibrium equations, it is convenient to use the following provisions:
– the projection of the force vector onto the axis is equal to the product of the modulus (magnitude) of the force and the cosine of the angle between the line of action of the force and the axis, taken with a plus sign if the directions of the vector and the axis coincide, or minus if they are opposite:
– the moment of force is taken with a plus sign if it acts in the direction of movement clockwise, and with a minus sign if it acts in the opposite direction.
2.4. Example of problem solving
Task. In Fig. Figure 2.6 shows a beam on two hinged supports A and C, loaded by a flat system of external forces and moments:
N; N; Nm;
Dimensions of beam sections:
It is required to determine the magnitude and direction of the support reaction vectors and .
Solution
Let us depict on the force diagram the estimated direction of the reactions of the supports and - both vectors are directed upward.
Let us determine the magnitude and direction of reactions and using the equilibrium equations of a plane system of forces.
Let's create an equation for the moments of forces relative to the support WITH, considering the effect of the moment in the direction of clockwise movement to be positive (with a plus sign):
Reaction = 400 N,directed downwards.
Let's create an equation for the projections of all forces onto the vertical axis Y, considering the upward direction of the vector to be positive (with a plus sign):
The minus sign indicates the wrong direction. We change the direction of the vector in the diagram to the opposite.
Reaction = 200 N,directed downwards.
We check the correctness of the solution using an additional equation for the moments of forces relative to any non-support point, for example the point IN:
The “zero” obtained as a result of calculations indicates the correctness of the determination of reactions both in magnitude and direction.
Control questions
1. Define force. What characterizes the action of force?
2. How to determine the moment of force about a point?
3. Define a force couple. How to find the moment of a couple of forces? How is it indicated on the diagrams?
4. Define torque and bending moments.
5. What is called a connection, a connection reaction?
6. Formulate rules for determining the direction of bond reactions.
7. What is called the main vector and main moment of a system of forces? How are they determined?
8. Formulate the equilibrium conditions for a plane system of forces; write the equilibrium equations.
9. Solve the problem. In Fig. Figure 2.7 shows a beam on two hinged supports B and D, loaded with forces N, N and a concentrated moment Nm. Size m. Determine the magnitude and direction of the support reactions and check.
Answer: H, directed upward; H, pointing down.
3. BASIC CONCEPTS
RESISTANCE OF MATERIALS
3.1. Strength, rigidity, stability
The performance of a structure depends on the strength, rigidity and stability of its constituent elements.
Strength– the ability of a structure and its elements to bear a load without destruction.
Rigidity– the ability of a structure and its elements to resist deformation, that is, a change in the original shape and size under the influence of loads.
Sustainability– the ability of a structure and its elements to maintain the initial form of elastic equilibrium.
Most mechanical parts are designed for strength, solving three main problems:
Determination of rational sizes;
Determination of safe loads;
Selection of the most suitable materials.
In this case, the real structure is replaced by a design diagram, and the calculation results are verified experimentally.
3.2. Section method. Internal power factors
External forces
, acting on structural elements, are divided into active (loads) and reactive (reactions of connections). They cause the appearance internal forces
resistance. If the internal forces exceed the adhesive forces of individual particles of the material, the destruction of this structural element will occur. Therefore, to assess the strength of the object being studied, it is necessary to know the internal forces and the law of their distribution throughout the object. To solve these problems use section method
. Let us consider a structural element of arbitrary shape in equilibrium (Fig. 3.1), loaded by a system of external forces 
. In any section of this element there will be internal forces that need to be determined. To do this, let’s mentally dissect the object in question with an arbitrarily selected section into two parts: A and B.
Each of these parts will be acted upon by external forces and internal forces in the section, balancing the action of the cut off part:
; 
.
Consequently, the internal forces arising in the section under consideration are equal to the sum of the external forces acting on one of the cut-off parts.
The content of the article
MACHINES AND MECHANISMS, mechanical devices that make work easier and increase productivity. Machines can be of varying degrees of complexity - from a simple one-wheeled wheelbarrow to elevators, cars, printing, textile, and computing machines. Energy machines convert one type of energy into another. For example, hydroelectric generators convert the mechanical energy of falling water into electrical energy. The internal combustion engine converts the chemical energy of gasoline into heat, and then into the mechanical energy of movement of the car. THERMAL ENGINE; TURBINE). The so-called working machines transform the properties or state of materials (metal-cutting machines, transport machines) or information (computers).
Machines consist of mechanisms (motor, transmission and actuator) - multi-link devices that transmit and transform force and movement. A simple mechanism called a chain hoist ( cm. BLOCKS AND CHALLAYS), increases the force applied to the load, and due to this allows you to manually lift heavy objects. Other mechanisms make work easier by increasing speed. Thus, the bicycle chain, which engages with the sprocket, converts the slow rotation of the pedals into fast rotation of the rear wheel. However, mechanisms that increase speed do so by decreasing force, and those that increase force do so by decreasing speed. It is impossible to increase both speed and strength at the same time. Mechanisms can also simply change the direction of force. An example is a block at the end of a flagpole: to raise the flag, pull the cord down. A change in direction may be combined with an increase in strength or speed. Thus, a heavy load can be lifted by pressing the lever down.
BASIC PRINCIPLES OF OPERATION OF MACHINES AND MECHANISMS
The basic Law.
Although mechanisms allow for gains in strength or speed, the possibilities of such gains are limited by the law of conservation of energy. When applied to machines and mechanisms, it says: energy can neither appear nor disappear, it can only be converted into other types of energy or into work. Therefore, the output of a machine or mechanism cannot be more energy than the input. In addition, in real machines, part of the energy is lost due to friction. Since work can be converted into energy and vice versa, the law of conservation of energy for machines and mechanisms can be written as
Work at the input = Work at the output + Friction losses.
This shows, in particular, why a machine like a perpetual motion machine is impossible: due to the inevitable loss of energy due to friction, sooner or later it will stop.
Gain in strength or speed.
Mechanisms, as stated above, can be used to increase force or speed. The ideal, or theoretical, gain in force or speed is the rate of increase in force or speed that would be possible in the absence of energy loss due to friction. The ideal win is unattainable in practice. The real gain, for example in force, is equal to the ratio of the force (called load) that the mechanism develops to the force (called effort) that is applied to the mechanism.
Mechanical efficiency.
The efficiency of a machine is the percentage of work at its output to the work at its input. For a mechanism, the efficiency is equal to the ratio of the real gain to the ideal one. The efficiency of the lever can be very high - up to 90% and even more. At the same time, the efficiency of the pulley system usually does not exceed 50% due to significant friction and the mass of moving parts. The efficiency of the jack can be only 25% due to the large contact area between the screw and its body, and therefore high friction. This is approximately the same efficiency as a car engine. Cm. PASSENGER CAR.
Efficiency can be increased within certain limits by reducing friction through lubrication and the use of rolling bearings.
SIMPLE MECHANISMS
The simplest mechanisms can be found in almost any more complex machines and mechanisms. There are six of them: lever, block, differential gate, inclined plane, wedge and screw. Some authorities argue that in fact we can talk about only two simple mechanisms - the lever and the inclined plane - since it is easy to show that the block and gate are variants of the lever, and the wedge and screw are variants of the inclined plane.
Lever arm.
This is a rigid rod that can be freely rotated relative to a fixed point called the fulcrum. An example of a lever is a crowbar, a hammer with clefts, a wheelbarrow, or a broom.
Levers come in three types, differing in the relative positions of the points of application of load and force and the fulcrum (Fig. 1). The ideal gain in leverage is equal to the distance ratio D E from the point of application of force to the fulcrum to the distance D L from the point of application of the load to the point of support. For a lever of the first kind, the distance D E usually more D L, and therefore the ideal gain in force is greater than 1. For a lever of the second type, the ideal gain in force is also greater than one. As for the third type lever, the value D E less for him D L, and therefore, the gain in speed is greater than one.
Block.
This is a wheel with a groove around its circumference for a rope or chain. Blocks are used in lifting devices. A system of blocks and cables designed to increase load capacity is called a chain hoist. A single block can be either with a fixed axis (leveler) or movable (Fig. 2). A block with a fixed axis acts as a lever of the first kind with a fulcrum on its axis. Since the force arm is equal to the load arm (radius of the block), the ideal gain in force and speed is 1. The movable block acts as a lever of the second kind, since the load is located between the fulcrum and the force. The load arm (block radius) is half the force arm (block diameter). Therefore, for a moving block, the ideal strength gain is 2.
A simpler way to determine the ideal gain in force for a block or system of blocks is by the number of parallel ends of the rope holding the load, as is easy to figure out by looking at Fig. 2.
Leveling and moving blocks can be combined in different ways to increase power gains. Two, three or more blocks can be installed in one holder, and the end of the cable can be attached to either a fixed or movable holder.
Differential gate.
These are essentially two wheels connected together and rotating around the same axis (Fig. 3), for example, a well gate with a handle.
A differential gate can provide gains in both strength and speed. It depends on where the force is applied and where the load is applied, since it acts as a first class lever. The fulcrum is located on a fixed (fixed) axis, and therefore the forces and loads are equal to the radii of the corresponding wheels. An example of such a device for gaining strength is a screwdriver, and for gaining speed is a grinding wheel.
Gears.
The system of two meshed gears sitting on shafts of the same diameter (Fig. 4) is to some extent similar to a differential gate. The speed of rotation of the wheels is inversely proportional to their diameter. If the small drive gear A(to which the force is applied) is half the diameter of a large gear B, then it should rotate twice as fast. Thus, the gain in force of such a gear is equal to 2. But if the points of application of force and load are swapped, so that the wheel B becomes the leader, then the gain in strength will be equal to 1/2, and the gain in speed will be 2.
Inclined plane.
An inclined plane is used to move heavy objects to a higher level without lifting them directly. Such devices include ramps, escalators, regular stairs, and conveyors (with rollers to reduce friction).
The ideal gain in force provided by an inclined plane (Fig. 5) is equal to the ratio of the distance over which the load moves to the distance covered by the point of application of the force. The first is the length of the inclined plane, and the second is the height to which the load rises. Since the hypotenuse is larger than the leg, an inclined plane always gives a gain in strength. The smaller the inclination of the plane, the greater the gain. This explains the fact that mountain roads and railways look like serpentines: the less steep the road, the easier it is to climb along it.
Wedge.
This is, in essence, a double inclined plane (Fig. 6). Its main difference from an inclined plane is that it is usually stationary, and the load moves along it under the influence of force, and the wedge is driven under the load or into the load. The wedge principle is used in tools and implements such as an axe, chisel, knife, nail, and sewing needle.
The ideal gain in force given by a wedge is equal to the ratio of its length to its thickness at the blunt end. The real gain of the wedge, unlike other simple mechanisms, is difficult to determine. The resistance it encounters varies unpredictably for different parts of its “cheeks”. Due to the high friction, its efficiency is so low that the ideal gain does not matter much.
Screw.
The screw thread (Fig. 7) is essentially an inclined plane wrapped repeatedly around a cylinder. Depending on the direction of rise of the inclined plane, the screw thread may be left-handed ( A) or right ( B). The mating part, naturally, must have a thread in the same direction. Examples of simple devices with screw threads are a jack, a bolt with a nut, a micrometer, a vice.
Since the thread is an inclined plane, it always gives a gain in strength. The ideal gain is equal to the ratio of the distance traveled by the point of application of force per revolution of the screw (circumference) to the distance traveled by the load along the axis of the screw. In one revolution, the load moves the distance between two adjacent threads ( a And b or b And c in Fig. 7), which is called the thread pitch. The thread pitch is usually much smaller than its diameter, since otherwise there is too much friction.
COMBINED MECHANISMS
A combined mechanism consists of two or more simple ones. It is not necessarily a complex device; many fairly simple mechanisms can also be considered combined. For example, in a meat grinder there is a gate (handle), a screw (pushing the meat) and a wedge (cutting knife). The hands of a wristwatch are turned by a system of gear wheels of different diameters that mesh with each other. One of the most famous simple combined mechanisms is the jack.
The jack (Fig. 8) is a combination of a screw and a gate. The head of the screw supports the load, and the other end fits into the threaded support. The force is applied to the handle fixed in the screw head. Thus, the force distance is equal to the circumference described by the end of the handle. The circumference of a circle is given by 2 p r, Where p= 3.14159, a r– radius of the circle, i.e. in this case the length of the handle. Obviously, the longer the handle, the greater the ideal strength gain. The distance traveled by the load per revolution of the handle is equal to the thread pitch. Ideally, a very large gain in strength can be obtained if a long handle is combined with a small thread pitch. Therefore, despite the low efficiency of the jack (about 25%), it gives a big real gain in strength.
The gain in force created by the combined mechanism is equal to the product of the gains of the individual mechanisms included in its composition. Thus, the ideal gain in force (IVS) for a jack is equal to the ratio of the circumference described by the handle to the thread pitch. For the gate included in the jack, the IVS is equal to the ratio of the circumference of the handle described by the handle (force distance) to the circumference of the screw (load distance). For a jack screw, the IVS is equal to the ratio of the circumference of the screw (force distance) to the screw thread pitch (load distance). Multiplying the IVS of individual jack mechanisms, we obtain for the combined mechanism
IVS = (Handle circumference/Screw circumference) ґ
(Screw circumference/Thread pitch) = (Handle circumference/Thread pitch).
For more complex combined mechanisms, it is more difficult to calculate the IVS. Therefore, only the real winnings are usually indicated for them.
Lecture 1
Theory of mechanisms and machines - is a science that studies the structure, kinematics and dynamics of machines and mechanisms in connection with their analysis and synthesis.
Analysis– study of structural, kinematic and dynamic properties of mechanisms. There is some ready-made mechanism, the properties of which are being studied.
Synthesis– design of mechanisms with specified structural, kinematic and dynamic properties to carry out the required movements. Thus, when synthesizing a mechanism, we have the opposite task of analysis: to design a mechanism based on given properties.
Theory of mechanisms and machines– the science of the most general methods of studying machines and mechanisms and designing them for given operating conditions.
Let us introduce some basic concepts used in studying the course on the theory of mechanisms and machines.
Car- a device that performs certain movements or operations to perform useful work or convert energy.
A machine is a set of material resources artificially created by man, which reproduces his labor functions. A machine replaces a person not only in his physical, but also in his mental work, facilitates this work and increases labor productivity.
All machines can be divided into the following main types:
energy machines– converting various types of energy (electric motors, generators, pneumatic motors, hydraulic motors, etc.);
technological machines– designed to transform the dimensions, properties, shape or condition of a material (metalworking machines, rolling mills, weaving machines, etc.);
transport vehicles– designed for moving materials (cars, diesel locomotives, airplanes, cranes, lifts);
information machines– designed for receiving and converting information (arithmometers, mechanical integrators, accounting machines). An electronic computer, strictly speaking, is not a machine. The name of the machine was retained in order of historical continuity.
The machine is characterized by three main features:
2) the presence of moving parts;
3) doing useful work.
The kinematic basis of all machines is the mechanism.
Mechanism is a device designed to convert and transmit motion (for example, a gearbox).
Unlike a machine, a mechanism does not directly perform useful work. The mechanism is characterized by two main features:
1) artificial origin;
2) the presence of moving parts.
In all questions of kinematics and calculations of machines, where forces and energy are not taken into account, the concepts of machine and mechanism are identified.
When analyzing a mechanism, they do not use real drawings of the mechanism parts, but its kinematic diagram.
Kinematic diagram of the mechanism– is an abstract (conventional) image of a mechanism, made in the form of interconnected segments of straight lines and other symbols.
Mechanism parts are replaced with their conventional images in accordance with GOST 2770-68. Since the movement of any body can be characterized by the movement of a straight line segment associated with it, the links of the mechanism can be depicted on a kinematic diagram in the form of straight line segments.
EXCAVATORS
The main purpose of excavators is to dig and move soil using a bucket or a continuous mechanism (chain or rotary). Based on this, excavators are divided into single-bucket, intermittent, and continuous excavators.
Single-bucket ones, in turn, are universal construction ones for excavation work and quarry ones for quarrying.
The main parts of construction excavators are the chassis (wheeled or tracked), a rotary platform with a power unit and replaceable working equipment. Single-bucket excavators are classified according to the following criteria:
— by type of working equipment - articulated-lever (Fig. 1) and telescopic (Fig. 2);
— according to the type of chassis - caterpillar (Fig. 3) and pneumatic wheels (Fig. 4);
— according to the design of the suspension of the working equipment - on hydraulic cylinders (rigid suspension - Fig. 5) and rope pulleys (flexible suspension - Fig. 3, 4);
- according to the design of the slewing bearing - into full-rotary (Fig. 3, 4) and part-rotary (Fig. 6);
- by type of drive - single-motor and multi-motor, and these can be either mechanical or electric drives.
Figure 1: 1 - rotary support mechanism; 2 - running device; 3 - outrigger, 4 - rotating platform; 5 - engine; 6, 8, 9 - hydraulic drives; 10 - handle; 11 - bucket (backhoe); 12 - bulldozer blade; 13 - driver's cabin
Figure 2: 1 - rotating support; 2 - chassis; 3 - outrigger; 4 - rotating platform; 5 - telescopic boom; 6 - hydraulic cylinders; 7 - bucket (backhoe); 8 - driver's cabin
Figure 3: 1 - rotating platform; 2 - two-legged stand; 3 - boom lifting cable; 4 - front pillar; 5 - handle; 6 - cabin; 7 - lifting cables; 8 - boom; 9 - tracked undercarriage; 10 - bucket (backhoe); 11 - traction cable; 12 - rotary support device
Figure 4: 1 - rotating support; 2 - bucket (backhoe); 3 - stand; 4 - boom lifting cable; 5 - front pillar; 6 - driver's cabin; 7 - lifting cables; 8 - boom; 9 - handle; 10 - running gear; 11 - traction cable; 12 - rotating platform
Figure 5.: 1 - caterpillar undercarriage; 2 - axis of the turntable; 3 - driver's cabin; 4 - rotating platform; 5 - bucket (straight shovel); 6, 8, 9 - hydraulic drives; 7 - boom; 11 - handle
Figure 6.: 1 - blade; 2 - hydraulic drive of the blade; 3 - engine; 4 - rotary column; 5, 6, 7 - hydraulic cylinders; 8 - traction; 9 - unified bucket; 10 - handle; 11 - boom; 12 - hydraulic cylinders of outriggers; 13 - outriggers; 14 - stars; 15 - bushing-roller chain; 16 - hydraulic cylinders of the rotating mechanism; 17 - frame
Excavators with flexible suspension of working equipment (rope pulleys) are divided into those having working equipment with a forward shovel (Fig. 7) and those having equipment with a backhoe (Fig. 8). The choice of a specific modification of an excavator is dictated by the nature of the work performed, its features, and the correct definition (classification) of the machine needed in this case means a lot.
Figure 7: 1 - boom; 2 - handle; 3 - ladle; 4, 5, 6 - hydraulic drives; h k - digging depth; R k - digging radius; H in - unloading height; R in - bucket lifting radius
Figure 8: 1 - boom; 2, 3, 8 - hydraulic drives; 4 - bucket (backhoe); 5 - handle; 6 - composite boom elbow; 7 - traction; 9 - intermediate insert; Nk - digging depth; R k - digging radius; H in - unloading height; R in - bucket lifting radius
In addition to the classification of excavators, you need to know their indexing well so that there is no error in the operational capabilities of the machine. Fig will help us with this. 9. The first letters will always indicate the classification - in this case: EO (single-bucket excavator). This is followed by four main digits of the index: the size group of the excavator, the running gear (type), the design of the working suspension and the serial number of the specific machine. The figure shows a detailed explanation of the four main digits of the index, but at some points we still need to stop.
Figure 9.
For each size group, several bucket capacities are usually indicated - the main one and replaceable ones with increased capacity, and for the latter, smaller linear parameters and weaker soils are provided than when working with the main bucket. The main one is a bucket, with which an excavator can develop category IV soil at maximum linear operating parameters (digging depth and radius, unloading radius and height, etc.).
The capacity of the main excavator buckets is: for the 2nd size group - 0.25-0.28 m 3; 3rd - 0.40-0.65 m 3; 4th - 0.65-1.00 m3; 5th - 1.00-1.60 m3; 6th - 1.60-2.50 m3; 7th - 2.50-4.00 m3.
The type of undercarriage is indicated by numbers 1 to 9: 1 - tracked (G); 2 - widened tracked (GU); 3 - pneumatic wheel (P); 4 - special automobile-type chassis (SS); 5 - truck chassis (A); 6 - serial tractor chassis (Tr); 7 - trailed running gear (Pr); 8, 9 - reserve. The design of the working equipment is indicated by numbers: 1 (with flexible suspension), 2 (with rigid suspension), 3 (telescopic). The last digit of the index means the serial number of the excavator model. The first of the additional letters after the digital index (A, B, C, etc.) means the serial modernization of this machine, the subsequent ones - the type of special climatic modification (C or HL - northern, T - tropical, TV - for work in the humid tropics) . For example, the EO-5123ХЛ index stands for: universal single-bucket excavator, 5th size group, on a caterpillar undercarriage, with a rigid suspension of working equipment, the third model in the northern version. The excavator is equipped with a main bucket with a capacity of 1.0 m 3, corresponding to the 5th size group, and replaceable buckets with a capacity of 1.25 and 1.6 m 3.
In addition to the listed attachments, excavators with rope pulleys can be equipped with a dragline suspension (Fig. 10, fragment “A”), crane equipment (fragment “B”), and grader equipment (fragment “B”).
Figure 10: A - dragline suspension equipment; B - equipping with crane equipment; B - equipping with grader equipment
Excavators with rigid suspension of working equipment (on hydraulic cylinders) can be equipped with hydraulic hammers (Fig. 11). The hydraulic hammer is mounted instead of the backhoe bucket and is connected to the handle via a quick-release fastener. The hydraulic hammer itself is driven by the excavator's hydraulic pumps, which ensures optimal use of power and reduced costs. Recently, small-sized mini- and microexcavators have become increasingly used (Fig. 12). They can dig pits, trenches, and perform work in hard-to-reach places. They are indispensable in cottage and dacha construction. They have a large selection of quick-release replaceable working equipment.
Figure 11: 1 - boom; 2, 3, 6 - hydraulic cylinders; 4 - handle; 5 - hydraulic hammer
Figure 12: 1 - bucket; 2 - boom; 3 - sectional hydraulic distributors; 4 - driver’s seat; 5 - engine; 6 - hydraulic tank; 7 - back stop; 8 - handle; 9 - middle supports; 10 - driving wheels; 11 - hydraulic motors; 12 - frame; 13 - gear pump; 14 - rear driven wheels
Trench excavators are a separate group. Their main purpose is the preparation of underground communications using an open method. The productivity of trench excavators is higher than that of single-bucket excavators. This is understandable: they are constantly moving in working mode.
Trench excavators consist of three basic parts: a tractor, working equipment and equipment for adjusting the position of all working parts. In Fig. 13 and 14 show a single-chain scraper excavator based on a wheeled tractor and a double-chain trench excavator based on a crawler tractor. Indexing trench excavators is similar to single-bucket excavators, but has its own characteristics. Let's consider this using the example of indexing the most common models: tracked trench excavators with a combined drive (Fig. 15). The first two letters, like those of single-bucket excavators, indicate the type of machine - trench excavator (ET), but the third letter already designates the type of working body (C - chain, R - rotary). The first two digits of the index indicate the greatest depth of the trench being torn off (in dm), the third is the serial number of the model. The first of the additional letters after the digital index (A, B, C, etc.) means the serial modernization of the machine, the subsequent ones - the type of special climatic modification (HL - northern, T - tropical, TV - for work in the humid tropics). For example, the ETC-252A index means: chain trench excavator, digging depth 25 dm, the second model - 2, which has undergone the first modernization - A.
Figure 13: 1 - hydraulic lifting mechanism; 2 - drive shaft; 3 - additional frame; 4 - inclined frame; 5 - replaceable console stripping shoe; 6 - bushing-roller chain; 7 - screw conveyor; 8 - three-stage gearbox; 9 - hydromechanical retarder; 10 - power take-off shaft; 11 - dump
Figure 14: 1 - hydraulic cylinder; 2 - lever; 3 - transverse belt conveyor; 4 - chain drive sprockets; 5 - plate chains; 6 - cutting knives; 7 - inclined frame; 8 - chain tension sprockets; 9 - intermediate rollers
Figure 15.
LOADING AND UNLOADING MACHINES
The main purpose of these machines and mechanisms is to move various loads. Typically these are self-propelled universal vehicles based, as a rule, on wheeled vehicles. They also use quick-release working devices - grippers, buckets, crane attachments, etc.
Loaders are divided into bucket, fork and multi-bucket (continuous) loaders. In urban, country and cottage construction, the most common are the front-end loader (Fig. 16), the bulldozer-loader (Fig. 17), and, of course, the small-sized loader (Fig. 18). Front loaders provide forward unloading of the bucket within a specified height. The main bucket (1 m3) has a straight cutting edge with removable teeth.
Figure 16: 1 - cabin; 2 - engine; 3 - power take-off gearbox; 4 - driving axles; 5 - chassis with an articulated frame; 6 - boom hydraulic cylinder; 7 - boom; 8 - ladle; 9 - rocker arm; 10 - hydraulic cylinder for turning the bucket; 11 - thrust
Figure 17: 1 - bucket; 2 - device for changing working parts; 3 - boom; 4, 5 - hydraulic cylinders; 6 - base tractor; 7 - dump-planner; 8 - thrust; 9 - supporting frame
Figure 18: 1 - caliper; 2 - boom; 3 - hydraulic cylinders for turning the caliper; 4 - levers; 5 - thrust; 6 - lifting hydraulic cylinders; 7 - half-portal
Along with loading and unloading operations, a bulldozer-loader can carry out site leveling, backfilling of holes, and demolition of small hills. The main replaceable equipment is a hydraulically controlled blade and a bucket with a volume of 0.38 m3 or 0.5 m3.
Small-sized loaders are designed to perform work in particularly cramped conditions. They have a large selection of replacement equipment and successfully use a stripping bucket, backhoe, load boom, forks, hydraulic hammer, drill, bulldozer blade, and trencher. The loader can make a 180° turn on the spot with a zone width of up to 4 meters, no more.
MACHINES FOR WORKING WITH CONCRETE AND MORTAR
According to their functional purpose, these machines and mechanisms are of three types: the first prepare concrete and mortar mixtures, the second deliver mortars to the construction site, and the third lay and compact mixtures and mortars.
The first type includes mixers of various modifications: these are continuous mixing machines, cyclic mixers, oar and turbulent type mixers operating on gravitational or forced mixing principles, stationary and mobile mixers. The most modern and mobile representative of this type of machine is shown in rice. 19 concrete mixer truck. He prepares the concrete mixture on the way to the object, directly at the object and, being already loaded with a high-quality mixture, activates (mixes) it along the way. The optimal temperature for operation of these machines is from -30° to +40°.
Figure 19. Concrete mixer truck (ready batch - 4 m3): 1 - KAMAZ chassis; 2 - dosing and washing tank; 3 - drum rotation mechanism; 4 - mixing drum; 5 - loading funnel; 6 - unloading funnel; 7 - folding tray; 8 - rotating device; 9 - mixer frame; 10, 12 - equipment control levers; 11 - instrumentation
The second type includes all machines for transporting prepared mixtures. These are mainly specialized vehicles: mortar trucks, concrete trucks, and the concrete mixer trucks we have already mentioned (since they also combine the function of delivering mortars).
This also includes truck-mounted concrete pumps (Figure 20).
Figure 20: 1 - KAMAZ chassis; 2 - rotating support; 3 - rotary column; 4 - distribution boom; 5, 7, 11 - double-acting hydraulic cylinders; 6 - hydraulic tank; 8 - concrete pump; 9 - concrete pipeline; 10 - water tank; 12 - compressor; 13 - flexible hose; 14 - receiving funnel; 15 - boom frame; 16 - hydraulic outriggers
The concrete pump is designed to supply a mixture with a cone draft within 6-12 cm in both horizontal and vertical directions. These are mobile vehicles with a hydraulic drive of a concrete pump and an articulated boom with a concrete pipeline. The concrete pump device is a piston pump. The mixture supply range horizontally is up to 300 m and vertically up to 70 m.
The third type includes vibrators of various designs and modifications. Their main goal is to displace the air contained in the solution and eliminate all voids between the formwork and the reinforcement. The most widely used in construction are pneumatic and electric vibrators with circular vibrations. According to the method of influencing the mixture, surface, external and deep vibrators are distinguished.
Surface vibrators act on the solution through a trough-shaped rectangular platform (Fig. 21, fragment “A”). External vibrators act through formwork or any other form to which they are attached from the outside (Fig. 21, fragment “B”). Deep vibrators are immersed directly into the solution (Fig. 21, fragment “B”).
Figure 21: A - surface vibrator; B - external vibrator; B - deep vibrator; 1 - vibrator body; 2 - trough-shaped platform; 3 - formwork; 4 - cylindrical vibrating tip; 5 - solution
MACHINES AND EQUIPMENT FOR PILE WORK
While talking about excavators in construction processes, we touched on the possibility of using attachments for using excavators in piling work. But there are also special installations for this.
When installing foundations, two types of piles are used - ready-made (driven) and bored, the installation of which is carried out in wells directly at the construction site. In both cases, pile driver and pile driving installations are used, shown in Fig. 22 and 23. Replaceable equipment is hung on them: pile hammers, vibratory hammers, vibratory hammers. Copier and pile driving installations are mounted on the basis of self-propelled machines (the same excavators).
Figure 22: 1 - lower support; 2 - piles; 3 - auger drill; 4 - drive for drilling; 5 - winch; 6 - hydraulic hammer; 7 - lattice boom; 8 - pile driver mast; 9 - cargo winch; 10 - hook suspension; 11 - head; 12 - hydraulic cylinders; 13 - hydraulic excavator; 14 - hydraulic cylinder for mast installation
Figure 23. 1 - basic machine; 2 - boom; 3 - mast; 4 - working tool; 5 - driven pile
Table 1. Mechanisms for soil development
|
Purpose and types of mechanisms |
Main parameter |
||
|
Name |
Magnitude |
||
|
Single-bucket excavators on a tractor chassis |
Bucket capacity, m 3 |
EO-2621V-2; EO-2621-3 |
|
|
Single-bucket, full-rotary, pneumatic-wheeled excavators |
EO-3322B-2; EO-3322D |
||
|
EO-3323; EO-3532 |
|||
|
Single-bucket full-rotary crawler excavators |
|||
|
EO-3221; EO-3122 |
|||
|
EO-4112; EO-4111G |
|||
|
EO-4125; EO-5111B |
|||
|
Continuous rotary excavators |
Development depth, m |
||
|
Continuous trench excavators |
Development depth, m |
||
|
ETC-252; ETC-252A |
|||
|
Drilling machines |
|||
|
Self-propelled scrapers |
Bucket capacity, m 3 |
||
|
Trailed and semi-trailed scrapers |
|||
|
D3-149-5; D3-77-A-1; D3-172-1-03 |
|||
|
Bulldozers with ripper, bulldozers-loaders, bulldozers with fixed blade |
power, kWt |
||
|
D3-42; D3-42G; |
|||
|
D3-42G-1; D3-110V; D3-171.5-07; D3-116V; D3-177A; D3-117A; DZ-109B; D3-109B-1 |
|||
|
D3-171.1-03; D3-171.5-07 |
|||
|
D3-132-1; D3-126V-2 |
|||
The productivity of earth-moving equipment is distinguished between theoretical, technical and operational.
Theoretical productivity “Po” represents the productivity provided by the design capabilities of the machine during continuous operation (Table 2).
Table 2. Theoretical number of cycles per minute
Note: The number of cycles per minute is based on normal conditions (normal face height, average design hoist rope speed, 90° platform rotation angle and dump dump).
The technical productivity of Pt is the highest productivity in the given soil and face conditions per hour of continuous operation:
where K c is the cycle duration coefficient; K t - soil influence coefficient, taking into account the degree of filling of the bucket and the influence of soil loosening.
Operational productivity depends on the use of the excavator over time, taking into account the inevitable downtime during operation (maintenance, downtime for organizational reasons, moving machines, preparing the face, etc.)
where K in is the coefficient of excavator utilization over time during the shift.
Typically, K in is taken equal to 0.75 when working in transport and 0.9 when working in a dump.
The performance of a multi-bucket excavator can be determined by the formula
where q is the bucket capacity; V - bucket chain speed in m/s; t - bucket pitch; Kn - bucket filling coefficient, equal to an average of 0.8; K p - coefficient taking into account loosening of the soil is taken equal to 0.7-0.9; K in is the coefficient of use of the excavator over time, equal to 0.8–0.9 with good organization of work (Table 3).
Table 3. Mechanisms for piling work
|
Purpose and types of mechanisms |
Main parameter |
||
|
Name |
Magnitude |
||
|
Tubular diesel hammers |
Weight of impact part, kg |
||
|
Diesel rod hammers |
|||
|
Universal pile drivers on rails |
Useful height, m |
||
|
Self-propelled pile drivers |
|||
|
Copier attachments |
|||
|
Devices for cutting pile caps |
Section of cut piles, cm |
||
|
Installation for installation of bored piles |
Drilling depth, casing diameter, m |
||
The productivity of a concrete mixer can be determined by the formula
where N is the number of batches per hour; G - drum loading capacity in l; F - concrete yield coefficient 0.67 (Table 4).
Table 4. Mechanisms for concrete work
|
Purpose and types of mechanisms |
Main parameter |
||
|
Name |
Magnitude |
||
|
Gravity concrete mixers |
Volume of finished batch, l |
||
|
SB-1BG; SB-91B |
|||
|
Forced action concrete mixers |
|||
|
Concrete mixer trucks |
Capacity, m 3 |
SB-159A; SB-82-1A; SB-92V-1 |
|
|
Productivity, m 3 / h |
SB-126B-1; SB-126B; SB-170-1 |
||
|
Concrete mixing plants |
SB-109A (automatic) SB-145-2; SB-145-4 |
||
|
Cyclic concrete mixing plants |
|||
|
Vacuum complexes |
|||
|
General purpose electromechanical vibrators |
Synchronous oscillation frequency, Hz |
IV-10A; IV-106; IV-105; IV-99A; IV-101A; IV-92A |
|
|
Electromechanical deep vibrators |
Case diameter |
IV-117; IV-95; IV-102 |
|
To obtain the performance of lifting equipment in weight units, it is necessary to multiply the number of lifts per hour by the weight of the load being lifted.
As for other auxiliary machines and mechanisms, their data is given for plastering work in table. 6, for roofing work - in table. 7, for painting work - in table. 8, for flooring - in table. 9.
Table 5. Lifting mechanisms
|
Purpose and types of mechanisms |
Main parameter |
||
|
Name |
Magnitude |
||
|
Tower cranes |
Load capacity, t |
KB403A; KB-103B; KB-100.3A-1; KB-100.3B; KB-308A |
|
|
KB-309HL; KB-408; KB-504 |
|||
|
KMB-401P; KB-674A; KB-676A |
|||
|
Self-propelled jib cranes: |
KS-2651K; KS-2561K-1; KS-2571A-1; KS-3575A |
||
|
automotive |
|||
|
KS-3578; KS-4561A; KS-4572; KS-4573 |
|||
|
KS-4574; KS-4562 |
|||
|
automobile type |
KS-6471; KS-6471A |
||
|
pneumatic |
|||
|
tracked |
RDK-250; DEK-252 |
||
|
MKG-40; SKG-401 |
|||
|
SKG-631; DEK-631 |
|||
|
Freight lifts |
PGM-7613; PGM-7623; PGM-7633 |
||
|
Full-rotary portable jib cranes |
Also, kg (persons) |
||
Table 6. Mechanisms for plastering work
|
Purpose and types of mechanisms |
Main parameter |
||
|
Name |
Magnitude |
||
|
Mortar mixers |
Volume of finished batch, l |
SO-133; SO-23V; SO-46B; SO-26B |
|
|
Volume, m3 |
|||
|
Mortar pumps |
Productivity, m 3 / h |
SO-48V; SO-167; SO-49V |
|
|
Plastering units |
|||
|
SO-50A; SO-50B |
|||
|
Plastering stations |
|||
|
Manual plastering and troweling machines |
SO-86B; SO-112B |
||
Table 7. Roofing machines
|
Purpose and types of mechanisms |
Main parameter |
||
|
Name |
Magnitude |
||
|
Units for pumping bitumen mastics |
Productivity, m 3 / h |
||
|
SO-100A; SO-194 |
|||
|
Device for unrolling rolled materials |
Width of rolled material, mm |
||
|
Water removal machines |
Productivity, l/min |
||
Table 8. Mechanisms for painting work
|
Purpose and types of mechanisms |
Main parameter |
||
|
Name |
Magnitude |
||
|
Painting units |
Productivity, l/min |
||
|
Faucets |
The same, l/h |
||
|
Puttying and painting units |
Also, m 3 / h |
||
|
The same, l/h |
|||
|
The same, l/min |
|||
|
Dispersants |
The same, kg/h |
||
|
Installation for applying painting compounds |
Also, kg/h |
||
|
Kraskoterki |
Also, kg/h |
||
|
Meloters |
|||
|
Painting stations |
The same, m 3 / h |
||
|
Putty grinding machines |
|||
Table 9. Flooring machines
|
Purpose and types of mechanisms |
Main parameter |
||
|
Name |
Magnitude |
||
|
Wood Floor Sanding Machines |
Productivity, m 2 / h |
||
|
Parquet sanding machines |
|||
|
Vibrating slats |
|||
|
Machines for smoothing and grinding concrete floors |
|||