Selection of equipment for a steering diagnostic station. Steering Diagnostics

The steering as a whole is checked with a model K-187 device. The K-187 device is portable, includes a dynamometer with a scale and a play meter, which is mounted on the steering wheel; The playmeter arrow is mounted on the steering column. It allows you to determine the total play (by the angle of rotation of the steering wheel), as well as the total force of friction, for which the front wheels are suspended to eliminate friction of the tires in the contact patch, and the force of turning the steering wheel is measured with a special dynamometer.

When servicing steering systems equipped with a hydraulic booster, the K465M model is additionally used, which allows you to determine oil leakage, hydraulic pump pressure, and pump performance. The wear of the kingpin assembly of the front axle of a truck is checked using a model T-1 device.

There are also more accurate and easy-to-use instruments for measuring total play in the steering, developed by domestic scientists. For example, a dynamometer with a hydraulic playmeter on a disk for diagnosing steering.

The measuring element of this device is a sealed transparent ampoule containing liquid and an air bubble left in it. The prototype is shown in Fig. 3.4.

The device is made of three structural parts connected into one block: a dynamometer, a backlash meter and a connecting device.

The double-acting dynamometer is equipped with two torque handles 1 with scales 2 and locking rings 7. Its springs are housed in a cylindrical body closed with covers 12.

The play meter is arranged on disk 6 and is a sealed transparent ampoule 5 filled with a low-freezing liquid (alcohol) with an air bubble 4 left. This ampoule is graduated and combined with the play meter scale 3, consisting of two parts - respectively, with the starting point from left to right and from right to left. Disk 6 is installed in sleeve 8 with the ability to rotate both left and right. The axial movement of disk 6 is limited by two setscrews 11.

Rice. 3.4

1 - torque handle; 2 - dynamometer scale; 3 - backlash meter scale; 4 - air bubble; 5 - ampoule; 6 - backlash meter disk; 7 - retaining ring; 8 - disk bushing; 9 - bracket; 10 - pressure screw; 11 - set screw; 12 - dynamometer cover.

The connecting device consists of an L-shaped bracket 9 with a nut pressed into it, into which a pressure screw 10 is screwed. To assemble the device into one unit, sleeve 8 is rigidly attached to the dynamometer cylinder from above, and bracket 9 is also connected to this body, but from below.

The operating principle of a dynamometer-backlash meter. The device is secured with screw 10 to the lower or upper point of the steering wheel rim. In this case, it is desirable that the plane of the disk 6 be parallel to the plane of rotation of the specified rim. The locking rings 7 are pressed against the covers 12. The device is ready for use.

The force on the steering wheel rim (friction force) is checked by turning the rim by the torque handles 1 from one extreme position to another. The springs are deformed and, as a result, the handles move, as well as the locking rings shift along the specified handles. When the handles are released, they return to their original position, and the rings are held on them by friction. Based on the position of the hairline on ring 7 relative to the strokes of scale 2 on handle 1, the measurement result is found - the maximum force on the steering wheel rim.

To measure the total play, turn the steering wheel first, for example, clockwise, applying a given (normalized) force to the handle 1 and in this position set zero on the play meter by rotating disk 6. In this case, the left edge of the air bubble 4 is aligned with the zero mark of the play meter scale - extreme mark on ampoule 5. Then turn the steering wheel in the opposite direction, applying the same force to the other handle. When the steering wheel rotates, the ampoule makes a portable movement, and the air bubble moves in its cavity under the action of a lifting force. Therefore, the measurement results do not depend on both the angle of inclination of the steering wheel rim to the horizontal plane and the diameter of the specified rim. By the movement of bubble 4 relative to the corresponding scale of the play meter - the mark on ampoule 5, the play of the steering wheel is determined.

If necessary, repeat the measurement by starting to turn the steering wheel rim in the opposite direction. Diagnosis is complete. Loosen screw 10 and remove the device from the rim.

Checking the steering play

To check the angular free play of the steering wheel, it is necessary to rock the steering wheel while the engine is idling before the steering wheels begin to turn.

The test can be carried out using a spring dynamometer model K-402.

Free play should be checked by first setting the front wheels straight. The amount of free play of the steering wheel when the engine is running should not exceed 25°.

If the free play of the steering wheel is more than permissible, you need to check the air pressure in the tires, the presence of lubrication in the steering units and wheel hubs, the adjustment of the wheel bearings, steering rods and the correctness of their position, the normal adjustment of the steering mechanism, the clearances in the joints and splines of the propeller shaft, tightening the driveshaft mounting wedges, tightening the thrust bearing nuts in the steering mechanism, as all this affects the operation of the steering.

In addition, you should check the oil level in the power steering pump reservoir, the lack of air in the system, and oil leaks in the pipeline connections.

If the steering mechanism or rods are not adjusted correctly, the unit must be repaired.

If there are increased gaps of more than 2 ° in the cardan joints, the cardan shaft must be replaced. After making sure that the listed components are in satisfactory condition, you should check the tightness of the steering gear thrust bearing nuts.

Axial movement of the steering wheel is not permitted. If there is axial movement of the steering wheel, it is necessary to tighten the nut at the lower end of the shaft, having first straightened the antennae of the lock washer. After adjustment, bend one of the antennae into the groove of the nut. The rotation moment of the steering shaft, disconnected from the propeller shaft, should be 0.3-0.8 N*m.

Excessive tightening of the nut and then unscrewing it to obtain the specified shaft rotation torque is unacceptable, as it may cause damage to the bearing.

The operation of the steering mechanism can be checked without removing it from the vehicle with the steering linkage disconnected, by measuring the force in the following three positions using a spring dynamometer attached to the steering wheel rim.

First, the steering wheel is turned more than 2 turns from the middle position, the force on the steering wheel rim should be 5.5-13.5 N.

Second, the steering wheel is turned 3/4 -1 turn from the middle position, the force should not exceed 23 N.

The third steering wheel has passed the middle position, the force on the steering wheel rim should be 8.0-12.5 N greater than the force obtained when measured in the second position, but should not exceed 28 N.

If the force does not correspond to the specified values, then the steering mechanism must be adjusted.

When checking the torque of the steering wheel, it is recommended to simultaneously check the torque of the bipod shaft (with the longitudinal steering rod disconnected), which should not exceed 120 N*m.

When checking the torque of the bipod shaft on a car, you must perform the following operations:

• -start the engine and warm up the oil to approximately 50°C, stop the engine and set the steering wheel to the middle position;
• - hook the dynamometer in the center of the bipod ball pin hole and pull in any direction, maintaining the angle between the dynamometer and the bipod at approximately 90 °. The dynamometer should show no more than 510N, corresponding to a torque of 120 N*m.

If these indicators exceed the specified values, then you should adjust the force on the steering wheel rim in the third position by rotating the adjusting screw of the bipod shaft, since this does not require disassembling the steering mechanism. When you rotate the adjusting screw clockwise, the force will increase, and when you rotate it counterclockwise, it will decrease.

The discrepancy between the force on the wheel rim in the second position and the value indicated above can be caused by damage to the parts of the ball nut assembly, and in the first position, by the same reason and incorrect adjustment of the preload of the thrust ball bearings.

To adjust the thrust bearings (without removing the steering gear from the vehicle), you must do the following;

• - drain the oil from the power steering system;
• - disconnect the driveshaft;
• -unscrew the bolts securing the top cover and remove it. To avoid damaging the cuff and o-ring, use a safety mandrel placed on the end of the screw;
• - using a special wrench, unscrew the tail screw together with the control valve body by 10-15 mm so that the valve body rotates freely on thrust bearings without touching the intermediate cover;
• -check the axial movement of the tail rotor in the ball nut while holding the bipod.

If it exceeds 0.2 mm, disassemble the steering mechanism and replace the screw pair (the factory supplies a screw-nut kit as spare parts); if it does not exceed 0.2 mm, it is necessary to unlock the thrust bearing nut and tighten it so that the moment of rotation of the valve body relative to the tail rotor is 0.6-0.85 N*m.

You can measure the turning torque with a spring dynamometer, which is hooked onto one of the bolt holes of the control valve housing. In this case, a torque of 0.6-0.85 N*m corresponds to dynamometer readings of 11-15 N.

Checking the hydraulic booster pump on a car

On a car, checking the pressure developed by the pump and the serviceability of the steering mechanism is carried out by installing a device between the pump and the high-pressure hose, which includes a pressure gauge with a scale of up to 1500 mPa and a valve that shuts off the oil supply to the steering mechanism. To check you need to do the following:

• - open the valve in the device;
• - start the engine and at a crankshaft rotation speed of 1000 rpm, slowly close the valve (if the pump is working, the pressure should be at least 9.0 MPa);
• - open the valve;
• - turn the wheels to the right all the way and record the pressure on the pressure gauge, then turn the wheels to the left all the way and also record the pressure.

If the mechanism is working properly, in each of these checks the pressure should not decrease by more than 0.5 mPa compared to the pressure measured during the operation specified in paragraph 2.

The check must be carried out at an oil temperature in the pump reservoir of 65-75°C. If necessary, the oil can be heated by turning the wheels from lock to lock and holding them in their extreme positions for no more than 3 s.

When checking the pump, in order to avoid damage due to overheating, do not leave the valve in the closed position or the wheels turned all the way for more than 3 seconds.

The operation of a vehicle with faulty steering is not without reason prohibited by the current legislation of the Russian Federation. It's no secret that on our roads the chance of getting into a traffic accident is relatively high, even with ideal driving. When the number of registered cars crosses the fifty million mark, the busyness of the traffic itself becomes a serious risk factor. Failure of any important component of the car in such conditions can end extremely badly. To ensure proper and safe driving, it is important to carry out diagnostic measures in a timely manner. A procedure such as steering diagnostics deserves special attention. Therefore, today we will try to consider it in a little more detail.

One of the most common in this case will be the occurrence of gaps between steering parts. In a professional environment, such gaps are most often called backlash.

They appear as a result of various unfavorable external influences, the occurrence of which is simply inevitable in traffic conditions. In addition, active use of a vehicle is associated with deterioration of the condition of parts even without external influences, since no one has canceled the friction between various components. The more play, the more intensively the steering column wears out. As a result, the chance of getting into a traffic accident gradually increases.

Since the occurrence of play is one of the most common problems with the steering mechanism, steering diagnostics are largely aimed at identifying this particular defect. To conduct a competent inspection of the mechanism elements, a specialist may need an overpass or an equipped pit. In some cases, it is possible to use suitable equipment, but often the attentive eye of a specialist is quite sufficient.

Steering diagnostics is a relatively simple procedure, which, however, has several important nuances. This operation will not require the involvement of a large number of specialists or serious resources, however, the quality of its implementation is directly related to the qualifications and experience of the performer. Therefore, steering diagnostics should be carried out only in trusted auto repair shops and only by competent specialists. Otherwise, the reliability of the results obtained may be extremely doubtful.

If you need steering diagnostics, contact our expert organization. We will carry out all necessary activities quickly, efficiently and inexpensively

In what cases is steering diagnostics necessary?

It is advisable that steering diagnostics be carried out regularly. Moreover, not separately, but as part of the general diagnostics of the main vehicle systems. This approach will ensure proper controllability and safety of the car over a long period of time. It is no secret, however, that most car owners prefer to ignore the benefits of regular diagnostics, carrying out the latter only when problems arise. Therefore, let's look at this issue in a little more detail.

Steering diagnostics will be necessary in the following situations:

• the occurrence of unfamiliar noises during the rotation of the steering wheel;
• the occurrence of strong knocking in the steering wheel when the car moves on a bad road;
• tight, difficult rotation of the steering wheel.

All the circumstances mentioned are a serious reason to seek help from specialists. If the driver is not concerned about the safety (of his own and those of others), then he should also remember that over time, minor defects can become much more significant. In other words, fixing a problem after a few months can cost much more than if the problem were solved immediately after the fact. occurrence. Therefore, prompt diagnostics of the steering and its subsequent repair is also an excellent way to protect yourself from potential costs.

Steering diagnostics is also a preliminary step for all procedures involving the replacement of steering gear components.

Any questions? Contact us by phone, email, or through comments on this post. Our specialist will clarify in detail all the ambiguities that have arisen and advise on the cost of the service in your specific case.

Steering diagnostics. Main malfunctions of the mechanism

Difficult rotation of the steering wheel, mentioned just above, is usually the result of insufficient oil in the crankcase of the mechanism. Common causes of malfunction include:

• insufficient tire pressure;
• wheel imbalance;
• damage to suspension components;
• deformation of steering drive elements.

If we are talking about a worm-type system, then most often the main cause of problems is a violation of the gap in the engagement of the elements.

What is the procedure for diagnosing steering?

Like many other diagnostic measures, steering diagnostics begin with a visual inspection. All the main components of the mechanism, as well as the elements associated with it, are studied. In particular, the specialist evaluates the geometry of all those parts of the suspension that are connected to the steering.

Checking backlashes is the main stage of diagnosis, which is a complex of visual and instrumental examinations. As noted earlier, in some cases the experienced eye of a specialist may be quite sufficient. However, to increase the accuracy and reliability of the results, professionals usually use special equipment. In particular, a dynamometer-play meter is a precise device that allows you to determine the angular movement (play) of the steering wheel of a vehicle.

If we are talking about power steering, then the hydraulic system can be checked separately.

In some cases, initial steering diagnostics do not lead to the results that experts initially expected. If a malfunction is present, but its main cause cannot be determined, the wheel angles can be checked. The wheel alignment procedure can help with this.

Repair

As a rule, steering diagnostics reveals the need for urgent repairs to system faults. The nature of the measures taken directly depends on the specifics of the detected problems.

Often, a specialist discovers parts that are so worn out that the question of how they continued to function properly for so long becomes very interesting. In this case, the only possible way to return the mechanism to its previous condition is to replace those elements whose wear is too high with suitable spare parts.

If the steering diagnostics revealed only minor defects, be it cracks or minor deformations, it will be quite possible to get by with cosmetic repairs: fix something, fix something. In this case, the cost of the work will be quite low. However, those car owners who turn to us for help immediately after a problem arises most often have a chance to get by with such low costs. Otherwise, cosmetic repairs will hardly be possible.

It is noteworthy that repair work in this case almost always requires preliminary dismantling of the steering wheel. Unlike diagnosing the steering, which compared to many other procedures can be considered a relatively simple procedure, repairing the same mechanism is a rather delicate process, very sensitive to the experience and qualifications of the specialist. The list of necessary equipment to fix the problem will also be somewhat wider than the list of equipment for diagnosing it.

The steering system must keep the vehicle moving in a straight line, ensure that the steered wheels roll without slipping during turns, and automatically return them to the straight-ahead position.

In accordance with the requirements of GOST 25478-82, steering diagnostics is carried out based on the total play and total friction force (the force required to turn the steering wheel). Checking the condition of the steering control of cars at service stations and service stations is carried out, for example, with K- 187 and K-405. The K-187 portable device includes a dynamometer with a scale and a play meter, which is mounted on the steering wheel. The playmeter arrow is mounted on the steering column. The device provides force measurement in the range of 0...80 N and total backlash in the range of 0...15°.

To check the hydraulic booster and steering pump (for ZIL vehicles), a portable device K-405 is used. The device includes a hydraulic unit and an electric pulse tachometer. The hydraulic unit includes a pressure gauge, a remote thermometer, a volumetric flow meter, a load valve, a reversing spool and a damper to dampen pressure fluctuations in the fluid. An electronic pulse tachometer is used to measure the rotation speed of the power steering pump shaft (a signal proportional to the rotation speed of the power steering pump shaft is removed from the breaker contacts of the vehicle being diagnosed). The device provides measurement of pressure in the range O...10 MPa, temperature 0...120°C, volume of working fluid 0...10 l, angular displacement -45...0...45°.

The installation of steered wheels of trucks is checked mainly by their toe-in parameter. At ATP, the 2182 and K.463 model lines are used for these purposes.

To check the technical condition of the front suspension (front axle) of ZIL and GAZ trucks, the KI-4872 stand (designed by GosNITI) with running drums is widely used. At the stand, lateral forces in contact of the wheel with the stand drum are measured. To check the technical condition of the front axle of cars with an axle load of no more than 10,000 N, a similar stand model KI-8945 is used.

Checking the wheel alignment angles of passenger cars is carried out on site stands and mainly on optical and electro-optical stands. The first includes domestic stands K-112, Testos-1 and BEM-682 from Boehm-Muller (France). The second includes domestic stands K-111, 1119M, as well as Polish-made stands RKO-1, RKO-4, RK -1, etc.

The design of the RK-1 stand is characteristic, which provides measurement of wheel camber angles, longitudinal and transverse inclination of king pins, and wheel rotation of cars, trucks and buses. The stand (Fig. 5.69) includes two rotary disks 1 under the front wheels of the car; two stands for the rear wheels for leveling the car, measuring device 2. The measuring device consists of a round rod on which two support arms and a body are mounted. The upper movable single arm sets the size corresponding to the wheel rim of the car being diagnosed. This arm attaches the device to the car wheel. The lower double support arm is motionless. The device body is mounted on a rod between the supporting arms and has two angular scales and an arrow with a level. One of the scales and the pointer are attached in such a way that they can be deflected at a certain angle relative to the axis of the instrument rod. The housing can be rotated around the rod and fixed in two positions, in which the scale is perpendicular or parallel to the plane of the wheel.

The stand allows checking the alignment angles of wheels with a rim diameter of 12"... 22". Ranges for measuring camber angles: -5°...+5° angles of longitudinal and transverse inclination of the king pins; -15°...+15° wheel rotation angles -40...+40°. The stand can only be used on a carefully verified horizontal platform.

In general, the development of car diagnostics occurs in two main directions: stationary and built-in (on-board monitoring). A combined diagnostic method using a system of built-in sensors of control points and secondary measuring devices built into the design of cars is being used.

In general, a wide range of different analysis methods mentioned in Table 1 can be used to diagnose wear (tribodiagnostics). 5.30.

Most of those listed in table. 5.30 methods are laboratory. In recent years, there has been a tendency to carry out diagnostics continuously, for which transport vehicles are equipped with built-in monitoring means, for example, using sensors that monitor the number and size of wear particles released from the oil flow.

In Fig. 5.70. shows a diagram and general view of such a sensor, developed at Samara Aerospace University under the leadership of prof. Logvinova L.M.

As can be seen from the figure, particles, depending on their size, cause pulses generated by the piezoelectric element. In the instrumentation part, these pulses are analyzed, taken into account and classified into size groups.

On-board tribodiagnostic systems are recommended as one of the components of the implementation of a comprehensive system for diagnosing complex units (gas pumping units, diesel engines and electric units of diesel locomotives of railway transport, equipment of thermal and hydraulic stations, passenger buses, etc.), which allows the use of a progressive system for operating equipment based on its actual condition.

The instrumental part of the tribodiagnostics system was developed at Samara Aerospace University and is a set of devices that allows, based on the results of dispersion analysis of wear particles in the oil flow, to evaluate all stages of the life of friction units, starting from the initiation and development of defects to the occurrence of emergency situations.

The PHOTON system allows you to:

control the level of contamination of working fluids;

maintain the purity of working fluids at a given level;

diagnose the wear condition of friction units;

control the level of hydration and diagnose the state of heat exchange;

automatically turn off additional cleaning units;

automatically turn off the pumping station, block the supply of liquids, etc.

The system devices are protected by Russian Federation Patents and represent a new step in the technology of operation, maintenance and repair of transport vehicles.

The technical condition of the steering has a significant impact on road safety and the technical and economic performance of the vehicle. The steering system includes a steering gear and a steering gear.

Steering is classified into mechanical and hydraulic, with or without power steering. The most common types are mechanical steering, with or without power steering. vehicle technical diagnostic tool

Diagrams of various steering controls represent a mechanical (hydromechanical) or other system consisting of interconnected friction pairs, springs, rods and other parts. The deterioration of the technical condition of the steering is determined by wear, loosening of fastenings and deformation of parts.

The main parameters for assessing the technical condition of the steering include the total play (free play) in the steering, the force of turning the steering wheel, as well as play in individual connections for fault localization.

The determined total play is significantly influenced by the measurement mode, for example, the position of the front wheels of the car (Table 2.15).

Table 2.15. Values ​​of total play in the steering

From the table 2.15 it can be seen that the total play is greater for cars with the left wheel hanging out. Therefore, it is advisable to carry out tests with the left wheel suspended or when the wheels are installed on turntables.

For diagnosing the steering of cars, the K-187 device was previously recommended (Fig. 2.48). It is a dynamometer-play meter. A dynamometer (mechanical type) is mounted on the rim of the steering wheel, and the play meter needle is mounted on the steering column. The backlash meter scale is made on the dynamometer body. The dynamometer consists of a base (bracket) with an axis, drums 3 and 7 with annular collars freely sliding along the axis, and a connecting sleeve, two springs and two spring grips with a gear sector and rods.

Rice. 2.48. Device K-187 for diagnosing car steering: 1-backlash gauge scale, 2-connecting plug, 3-arrow, 4-bracket, 5-capture

The dynamometer scale is printed on the cylindrical surface of the drum. It consists of two zones with different division values: for measuring small forces up to 0.02 kN and for measuring large forces - more than 0.02 kN,

To protect springs (especially for measuring small forces) from overloads that can cause residual deformation and violation of the calibration of the dynamometer, the compression of the springs is limited.

The play meter consists of a scale pivotally connected to the dynamometer brackets and a pointer mounted on the steering column.

The device provides force measurement in the ranges of 0-0.2 and 0.2-0.8 kN and backlash measurement in the range of 10-0-10 degrees. Device weight 0.6 kg.

Of great interest electronic device to control the forces and play of the vehicle steering (Fig. 2.49).

Rice. 2.49. Block diagram of an electronic device for monitoring steering force and play

The output of the micro-displacement sensor 2 is connected to the input of the threshold amplifier 6, the output of which is connected to the input of the control key 10. One of the outputs of the key 10 is connected to the “Measurement” indicator 16, the other to the reset input of the pulse counter 12, the third to one of the inputs of the digital indicator 15, the fourth - to the control input of logical element AND 8, the information input of which is connected through a normalizing amplifier 4 to the angular displacement sensor 1. The fifth output of the control key 10 is connected to the control input of logic element AND 9, the information input of which is connected to the output of the analog-frequency converter 7. The input of the analog-frequency converter is connected to the output of the normalizing amplifier 5, the input of which is connected to the force sensor 3.

The outputs of logic elements AND 8 and 9 are connected to the inputs of logic element OR 11, the output of which is connected to the counting input of the pulse counter 12. The information input of the digital indicator 15 and one of the inputs of the comparator 13 are connected to the output of the pulse counter. The reference sensor 14 is connected to the other input of the comparator signals, and the “Excess” indicator 17 is connected to the comparator output.

As a force sensor 3, you can use a strain gauge or piezo microdisplacement sensor having an electrical signal at the output. This sensor is installed on housing 2 (Fig. 2.50), fixed to the steering wheel using a self-centering grip 1. The housing 2 is hinged to a rod 7 that is rotated relative to it around the axis of the steering wheel and interacts with the force sensor 8. From above, housing 2 is closed by a transparent disk 3 , having radial reflective strokes 4.

Rice. 2.50. Diagram of a self-centering device for installation on a car steering wheel

Sensor 1 (see Fig. 2.49) of the angular movement of the steering wheel is made of light-optical. It is installed parallel to disk 3 on a flexible rod 5 (see Fig. 2.50), which, for example, is attached to the windshield or instrument panel using a suction cup.

Sensor 2 (see Fig. 2.49) is micro-moved

It is connected to the steered wheel of the car. It can be attached, for example, to the outside of the wheel.

Angular displacement sensor 1, normalizing amplifier 4, micro-displacement sensor 2, threshold amplifier 6, control key 10, logical AND element 8, logical OR element 11, pulse counter 12, digital indicator 15 and “Measurement” indicator 16 form the backlash measurement circuit. Force sensor 3, normalizing amplifier 5, analog-frequency converter 7, micro-displacement sensor 2, threshold amplifier b, control key 10, logic element OR 11, pulse counter 12, digital indicator 15 form a force measurement circuit. The reference signal sensor 14, the pulse counter 12, the comparator 13 and the “Excess” indicator form a circuit for setting and comparing standards for diagnostic parameters.

Key 10 generates pulses that control logical elements AND 8 and 9, turning the measuring circuits on and off depending on the parameter being diagnosed (backlash or force). In addition, the control key 10 generates control signals for the "Measurement" indicator 16, the pulse counter 12 and the digital indicator 15. The supply of signals from the key 10 is controlled using its switch, which has three positions: the first two correspond to the mode of measuring the force on the steering wheel at choice of backlash; third - the mode for measuring the force on the steering wheel when turning the steered wheels.

The preferred steering wheel position during control corresponds to the vehicle moving in a straight line. The steering wheel is rotated by the force-measuring rod of the device, applying force in the direction perpendicular to the axis of the rod in the plane of the steering wheel.

When the control unit switch is in the first position, counter 12 and digital indicator 15 are reset to zero and the “Measurement” indicator 16 is turned off. In this mode, as soon as the steering wheel begins to turn from its original position in any direction, backlash begins to be selected, while the control key 10 gives an enabling signal to enter logical element AND 9, and the signal from the force sensor 3 through the normalizing amplifier 5, the analogue-frequency converter 7, the logical element AND 9 and the logical element OR 11 is sent to the pulse counter 12. After processing this signal, the control key 10 supplies an enabling signal to digital indicator 15, which displays the force value on the steering wheel when selecting play.

The measured force value from the output of the pulse counter 12 is supplied (simultaneously with the input to the digital indicator 15) to the input of the comparator 13, in which it is compared with the standard (limit or permissible) value coming from the output of the reference signal sensor 14. If the specified value is exceeded from the output comparator 13 sends a corresponding signal to the “Excess” indicator 17.

When the backlash in this measurement mode is completely selected, the steered wheels begin to turn, influencing the micro-displacement sensor 2, the signal from which is sent to the threshold amplifier 6.

When the threshold displacement value, determined by the threshold amplifier, is reached, the prohibiting output signal from the latter, through the control key 10, is supplied to the control input of the logical element AND 9, after which the backlash measurement circuit is turned on.

At the same time, the pulse counter 12 is reset and, after a specified period of time, the digital indicator 15 is reset.

Resetting the indicator to zero indicates full play in the direction of rotation of the steering wheel.

After this, the control key switch is moved to the second position and the steering wheel begins to rotate in the opposite direction. When the steering wheel returns to the initial state of backlash measurement, the influence of the wheels on the micro-displacement sensor 2 stops. The latter, through the threshold amplifier 6, sends a signal to the control key 10, which generates an enabling signal for the logical element AND 8. As a result, pulses from the angular displacement sensor 1 through the normalizing amplifier 4, open logical element AND 8 and logical element OR 11 are supplied to the pulse counter 12, where the pulses reflecting the backlash are counted. After selecting the backlash, the micro-displacement sensor 2 is triggered again and at the output of the threshold amplifier 6 and, accordingly, at the output of the control key 10, a prohibiting signal appears for the AND 8 logical element, turning off the “Measurement” indicator 16, and an enabling signal on the digital indicator 15. The latter then produces a value measured backlash.

The measured value of the backlash from the output of the pulse counter 12 is simultaneously sent to the digital indicator 15 and to the input of the comparator 13, in which it is compared with the standard value coming from the output of the reference signal sensor 14. If the specified value is exceeded, the output of the comparator 13 to the "Excess" indicator 17 a corresponding signal is given.

To measure the force on the steering wheel when turning the steering wheels, the control key switch is set to the third position.

When, at the end of the backlash selection, the micro-displacement sensor 2 is triggered, then, based on its signal through the threshold amplifier 6, the control key 10 gives an enabling signal to the input of the AND logic element 9. In this case, the signal from the force sensor 3 through the normalizing amplifier 5, the analog-frequency converter 7 , logical element AND 9 and logical element OR 11 are supplied to the pulse counter 12 and then, according to the enabling signal of the control unit, to the digital indicator 15.

As in the case of force measurement, when choosing backlash, the obtained value is compared with the corresponding standard value.