Repair, maintenance, and operation of equipment require compliance with certain rules. The more complex the device, the greater the requirements for assembly quality, accuracy of fit of parts and structural elements. Optimal conditions for the functioning of mechanisms and components are determined in the instructions and user manuals. It is impossible to provide the necessary parameters “by eye”; specialized tools are needed, in particular, torque wrenches, to obtain a certain, measurable result. But such devices must be used correctly, because the performance of the equipment, durability and safety of operation depend on it.
Purpose, device and characteristics
Torque wrenches are designed for standardized tightening of screw connections; most often this tool is used in car repairs, for example, for tightening spark plugs, when tightening wheel bolts, fastening the cylinder head and for other objects where it is recommended or required to take into account the tightening torque.
Torque wrenches are also used in the installation of refrigeration equipment, air conditioners, in the assembly of construction equipment, in the construction of railways, bridges, oil and gas pipelines and other structural objects where controlled tightening of screw connections is necessary.
The use of torque wrenches, thanks to their design, prevents the possibility of licking off the edges of bolts and nuts, and also prevents stripping of threads or damage to the fasteners themselves, because tightening is carried out in accordance with established standards.
Thus, using this precise tool, screw connections are tightened with the required force, which eliminates the possibility of overtightening or undertightening.
Attention!
It is unacceptable to use a torque wrench as a wrench.
In other words, you cannot use this tool to unscrew stuck, rusted, or simply overtightened, and especially overtightened, threaded fasteners.
If the “speaker” is not used for its intended purpose, its service life will be very short or even end in an instant.
The body of this tool is made of specialized metal alloys; the device is mainly cylindrical in shape, inside of which there is an adjustment spring.
The spring is adjusted by turning the handle to the right or left to set the required force.
The handle is located at one end of the device, just after the lock nut, if equipped, some models use a special lock to secure the position of the handle.
The handle is movable; it is designed to adjust the tightening torque by rotating it to the right or left.
On the opposite side, an elastic mechanism is built into the core of the torque wrench.
The limit torque coupling is the main mechanism in which the articulated joint is installed; it is the one that is activated when the set tightening torque is reached.
The ultimate torque clutch has a ratchet or ratchet mechanism built into it that allows rotational movements in confined spaces.
The limit coupling can be either an integral part of the torque wrench or a separate attachment installed in the socket end or in the rectangular cavity of the base, depending on the model of the tool.
Almost all modern models of torque wrenches have a flag switch, the so-called reverse, designed to change the direction of tightening clockwise or counterclockwise, so you can tighten in any direction.
Some models of this tool are produced with a double drive square located on two opposite sides.
This modification is also designed to quickly tighten screw connections in two directions.
The tightening torque is determined using an existing scale, on a liquid crystal display, or by a characteristic click that occurs in the limit coupling, depending on the device of the model.
Using the scale of a torque wrench, you can accurately determine how much force was applied to tighten a bolt or nut, which is why some craftsmen call this tool an accurate wrench.
Drive types
The design of the tip (drive) of torque wrenches for attachments comes in two types:
- A convex square tip (outer tetrahedron), designed for installing socket heads and special attachments on it.
- A hollow rectangular tip into which horn heads, split, cap, ratchet and other inserts/attachments are installed.
Nozzles and inserts are mated to the tip of the torque wrenches, and secured in it (on it) using a locking mechanism, if provided by the manufacturer.
The design of older models differs from modern ones; read more about it below in the description of each type of torque wrench.
Dimensions
The dimensions of the drive on which or into which nozzles and inserts are installed depend on the type of seat.
Square shank dimensions for bits in inches:
- Square 1/4
- Square 3/4
- Square 1/2
- Square 3/8
Dimensions of rectangular cavities for inserts:
Rectangle: 9x12mm;
Rectangle: 14x18 mm;
The size range of nozzles and socket heads ranges from 6 to 19 mm, followed by the following sizes:
- 21 mm;
- 22 mm;
- 24 mm;
- 26 mm;
- 27 mm;
- 29 mm;
- 30 mm;
- 32 mm;
- 34 mm;
- 41 mm.
Each size is designed for a certain force applied during operation.
An effort
The unit of force of torque wrenches in the CIS countries is measured in newton meters and is called the moment of force, which is denoted by two Cyrillic letters Nm, at the international level the designation is by Latin letters Nm.
One newton meter is equal to 0.101972 kilogram-force meter.
One kilogram-force meter is equal to 9.80665 newton meters.
Where high accuracy is not required, to simplify the perception of these numbers, for example, in secondary schools and in everyday life, it is generally accepted that one newton meter is equal to one kilogram of meter force.
The force range of different models of this tool can be from 0.1 to 1000 Newton meters.
NOTE:
In car repair instructions for the most important fasteners, as a rule, it is indicated with what exact force it is necessary to tighten a particular bolt, nut, or stud.
General standards for tightening threaded connections are contained in the guidance document RD 37.001.131-89 dated July 1, 1990, which describes the classes of threaded connections and the requirements for them.
There is a solution for every problem
Let's look at an example - inspecting the condition of fasteners. This is necessary if you want the equipment to work smoothly for a long time. What happens if you neglect this responsibility? Loose fasteners lead to a deterioration in the accuracy and speed of operations and, as a consequence, to the production of products of poorer quality. And soon the equipment itself will fail. Let's take a lathe as an example. One of the points in the maintenance rules is to regularly check and tighten the lead screws and ensure clearance between them and the slide. Failure to comply with the prescribed requirements will lead to gradual loosening of the screws. The required gap will disappear completely over time - the slide will rest on the screws. Further consequences of this process are described above. Don't wait - it's better to prevent them with a ratchet wrench.
Another example: a buyer purchased a ratchet wrench to work in a narrow niche, for example, when repairing a car, where it would be impossible to swing a regular wrench. And I encountered a problem: in order to grab the next edge of the nut, the wrench had to be pulled back very far, and there was practically no room for this. Why did this happen? Because the gear that was in the key did not have enough teeth. The solution in this situation is to use a high-quality ratchet wrench with 72 teeth. This is an important decision you need to make: are you willing to invest money twice in purchasing a wrench or are you ready to immediately purchase a quality tool. If you have made the right decision, then we will figure out what kind of ratchet wrenches there are and for what work they are needed.
GOST
GOST 33530-2015 has been developed for installation tools intended for standardized tightening of threaded connections, namely for torque wrenches and screwdrivers.
Verification is carried out in accordance with the State System for Ensuring the Uniformity of Measurements GOST 8.541-86 clause 2.1.2.
Torque wrenches from WERA, NORGAU, KING TONY, Jonnesway (Johnsway) and Tohnichi are certified in Russia and included in the state register of measuring instruments, so they can be used at sites where high demands are placed on torque accuracy and work with the most critical threaded connections, provided that the verification period has not expired.
As a rule, branded “speakers” are of higher quality, they have high performance and small errors, which are stated in the instrument’s data sheet.
Also, the number of documents attached to the measuring instrument must include certificates.
Certificates
Although this tool is called a key, at its core it is a measuring device that must have the appropriate documents: a device passport with a mark from the metrology laboratory about verification, certificates, etc.
A calibration certificate, also known as a verification certificate, indicates that the instrument has been tested in laboratory conditions to determine the accuracy and error of the device.
The test is carried out using different tightening forces, as a result of which the real values are established.
Wrenches suitable for international use, including the EU region, must comply with the calibration procedures of ISO 6789, Type I, Class B.
Error
Manufacturers claim an error of 3-4% for high-quality branded torque wrenches, which indicates a fairly high accuracy of such devices.
The accuracy of some models of this instrument reaches 99%.
Calibration and verification
All measuring instruments included in the Russian Register must be verified within the time limits established by the standards; it is unacceptable to use them without verification.
By average standards, torque wrenches are required to be calibrated once a year or after every thousand operating cycles.
Important!
A tool that requires verification must be calibrated independently, and tampering with its design is prohibited.
At the same time, nothing prevents you from calibrating devices used in conditions where verification is not necessary.
Arrow torque wrenches
The tools are equipped with a dial indicator that shows the amount of force. It operates on the principle of a dynamometer. The device has a durable body, an indicator and an arrow on top. The joining square is also placed at the top. The tightening is limited by an arrow that reaches the “stop” movement when it reaches the optimal force parameters.
Pointer instruments are more often used in repair work than in automotive work. Their main advantages are affordable cost, high level of strength (due to the material - hardened steel) and time-tested reliability, as well as a large range - from 1 to 300 Nm.
The disadvantages of pointer instruments are an error of up to 10%, the need to independently set the level of force required to achieve optimal torque.
Checking torque wrenches
Control over the functional condition and accuracy of torque wrenches must be exercised by the user (individual or organization) and verification must be carried out in accordance with established standards and deadlines.
Attention!
In case of violation of the verification deadlines, the use of measuring devices is prohibited.
If the rules and regulations are violated when working with screw connections, where accuracy of the tightening torque is required, the perpetrators are held accountable in accordance with the law.
To prevent errors, the standards provide for a special procedure called calibration.
Calibration of torque wrenches
Calibration must be carried out at least once per shift before starting work; the results must be recorded in the wrench calibration log.
The log form is given in Appendix “E” to SP 70.13333.2012 “Load-bearing and enclosing structures”, see paragraph 4.6.8.
As a sample, a template key calibration log can be
Key adapters
The design of the adapters is an electronic device with an attached “ratchet” and a mechanical drive. The working square allows you to install any attachment or head. The device is otherwise called an adapter-dynamometer. A set of devices can be equipped with adapters that differ in the size of the intervals.
The adapters are equipped with digital displays and buttons that allow you to configure the device yourself. The operating principle is almost the same as that of an electronic device. On the outside there is a body made of high-quality materials (plastic), on the inside there are batteries with a long service life. The main advantage of such a device is its versatility, as it is suitable for working with various connections.
The cost of the adapter is almost the same as that of a mechanical tool. It is also actively used for the production and repair of cars and their components.
Types and Types of Torque Wrenches
Torque wrenches vary in type of mechanism, which can be torsion, pointer, click or digital.
Pointer (indicator)
Pointer torque wrenches have in their device a pointer indicator dynamometer, from which the name of this type of tool comes from; it is also called indicator.
The inconvenience of this model is that due to the lateral, strongly protruding location of the dynamometer, with such compact dimensions it is sometimes difficult to turn the tool.
In addition, to work with it you need to use some kind of rod as a swing arm.
In other cases, the small size of the device may be an advantage.
Some models of indicator-type precision keys have a function for saving the last measurement, and the dial can be protected with a shock-proof surface; an example of this option is shown in the picture below.
Turns by the pointer “speaker” can be made in both directions without any switching; this is provided for by the device of the instrument, as well as by the scale marked in both directions.
Arrow torque wrenches are often confused with scale wrenches, mistakenly believing that they are the same type of tool.
Despite the fact that both of them have a dial indicator in the device, these are two different types of the same instrument.
The pictures clearly show that they differ from each other, both in appearance and in design, but their operating principle is similar.
Scale (torsion)
Torsion-type scale torque wrenches look like a cylindrical rod, at one end of which there is a handle, and next to it a transverse scale.
At the other end there is a built-in torque mechanism with a fixed pointer and a square for bits and sockets.
The scale is indicated by a long arrow located along the main pin and attached to the base of the mechanism of this instrument.
The measurement is made in kilograms per meter.
When the handle is loaded, upon reaching the tightening torque, the arrow remains stationary, and the pin itself moves further and thereby a divergence occurs between the two lines (arrow and pin), the difference of which is displayed on the scale.
A torque wrench, like pointer models, has the ability to work both clockwise and counterclockwise.
A simple device is reflected by a greater error than that of modern analogues of this instrument, which is about 10% or more.
You can easily get by with such a tool in a private garage when repairing your car, where high tightening accuracy is not required.
For example, the use of a torsion-type torque wrench will be very appropriate for tightening the valve cover head, spark plugs, wheel bearings, wheel bolts and other screw connections where it is desirable to take into account the tightening torque, the standards of which are indicated in the vehicle instructions.
Clicky (ultimate)
A click-type torque wrench has a mechanical device, the connection of the hinges of which, when the set tightening torque is reached, opens, with an accompanying single specific click, which is felt by the hands and is clearly heard.
After such a click, further tightening of the fastener is prohibited, because the required tightening torque has already been reached, and exceeding the set torque may damage the tool mechanism.
Important!
The clicks of the ratchet and the click of reaching a certain tightening torque have characteristic differences, in the sense that they are not the same thing.
Due to the fact that the control click occurs after reaching a given torque (limit), this type of this tool is called a limit or limit type torque wrench.
Rozhkovy
An open-end torque wrench has open-end attachments in its arsenal, hence the name of this tool.
The nozzles are installed in a landing socket in the form of a hollow rectangle.
The principle of operation of open-end torque wrenches fully corresponds to click models, i.e. they are also of the ultimate type.
Electronic (digital)
An electronic torque wrench differs from a mechanical one in that when the specified tightening force is reached, a sound signal is triggered and a light bulb (LED, backlight) lights up.
Setting and control is done by pressing the appropriate buttons, with an indication on the liquid crystal display, where everything is displayed in numbers, hence the name digital or digital type torque wrench.
Digital models are powered by a lithium battery in the form of a CR2354 tablet or its analogues.
Adjustable (universal)
An adjustable torque wrench is called a universal torque wrench because it can be adjusted to fit almost any bolt or nut size.
Digital adjustable torque wrenches allow you to work in places where other models cannot handle or would be difficult to do the necessary work.
The adjustable speakers are equipped with a unique power sensor in the handle that accurately detects and analyzes the load applied to the handle, regardless of hand position.
This is a type of digital model with a wider range of capabilities that affect the cost of the instrument.
Prices for a universal torque wrench start from 27,000 rubles.
Electronic Premium
Premium class torque wrenches are equipped with the latest technology, the results are displayed on the LED status panel, next to which there are setting buttons, the memory can be up to 2000 measurements, there is a built-in mini-USB connector for data transfer.
It is possible to use a previously configured tightening torque, which greatly speeds up and simplifies working with the device.
The achievement of the set value is signaled by visual, audible and sensory vibration signals.
The software displays a graphical assessment on a high-contrast, backlit display.
The cost of such devices amounts to hundreds of thousands of rubles.
Torque adapter
The torque adapter is a compact device with a wide torque range from 2 to 200 Nm.
This device is designed in the form of a small box with an LCD display and control buttons, on one edge there is a square for attachments of different sizes, on the other side there is a socket for installing a ratchet wrench.
The convenience of this gadget lies precisely in its size and the ability to install various attachments, both for bolts, nuts, and for specific slots that have bits for screwdrivers.
Thus, the torque adapter can also be used in applications where a screwdriver is required.
In addition, it is possible to select units of measurement in the settings.
The accuracy of this device is inferior to professional analogues, but at the same time it is quite sufficient for home use.
You can buy this device by clicking on this link, where more detailed characteristics and price are presented.
Hydraulic torque wrench
A hydraulic torque wrench is a highly specialized professional tool used in industrial enterprises, aircraft manufacturing, and the construction of large structural objects where screw fasteners of different sizes are used.
These devices operate on a hydraulic drive, and therefore are distinguished by great power, while operating with high precision, and are designed for a wide range of threaded connection sizes.
This type of tool comes in the following types: end, cassette; with square drive; bolt tensioners, prices for them start from about 200,000 rubles.
Limit (mechanical) torque wrenches
The most used type of tool, equipped with a dynamometer. It has an affordable price and wide functionality. Before you start working with it, you will have to set the necessary indicators for torque.
At the moment of screwing, the mechanism snaps into place. Upon reaching a predetermined parameter, the key does not transmit torque and does not break the thread due to too active tightening. The internal structure of the tool resembles a ratchet, which attaches the attachment and fixes the position using a switch.
The error varies from 3 to 5%. When choosing such a device, pay attention to the intervals and focus on your current data. Before purchasing, study the regulations for threaded connections.
The minimum range is 0.5 to 15 Nm, and the maximum range is from 3 to 100 and above.
The disadvantage of working with such a tool is the lack of experience on the part of the master, which can result in overtightening of the threaded connection. After several uses of the key, it is necessary to constantly check the adjustment parameters.
How to choose a torque wrench?
When choosing a torque wrench, the first thing you should pay attention to is the torque range for which the tool is designed.
It must be selected so that the work is carried out within the capabilities of the wrench, marked on the scale.
Attention!
You cannot use the “dynamic” to tighten threaded connections that require a force greater or less than the working limits of the tool.
When tightening with a lower value (below the minimum permissible on the “dynamic” scale), there is no guarantee that the tightening was carried out to the desired level.
If the maximum force value marked on the torque wrench scale is exceeded, the tool mechanism will not withstand the load and will break.
How to choose a torque wrench for private use?
The choice of a torque wrench for yourself can be made based only on its characteristics, for example, you need to take into account the conditions in which the tool will be used, where its dimensions and design will be important.
The conditions include the surrounding environment; here you should ask questions about how free the space is near the work site, whether it is possible to easily manipulate the torque wrench.
So, in one case it will be convenient to work with end models, and in another with horn, adjustable or switch models.
In addition, it is necessary to take into account the working conditions, for example, to choose a torque wrench for a car or for other similar work, where hands will often be stained with oil, grease, dirt and chemicals, you need to choose a copy that is resistant to chemical influences.
These models include metal tools without plastic, rubber and similar elements.
And vice versa, if, for example, you plan to carry out work with refrigeration equipment, then it is more appropriate to choose items with rubberized or similar handles so that the grip is comfortable and your hands do not freeze.
Before making the final choice, it makes sense to pay attention to the additional functionality and versatility of the tool.
For example, a more convenient torque wrench with a built-in socket ejector, which allows you to immediately remove the installed nozzle, without any effort, by simply pressing the corresponding button.
It makes sense to choose models that have a lock that prevents settings from being lost.
In some cases, it is advisable to purchase two-way “speakers”, or with a reversing switch (flag), so that you can tighten the fasteners both to the right and to the left.
Options with a hinged head allow you to work with the tool in hard-to-reach places at any angle, which makes the work of the master easier.
If necessary, you can consider professional models that are more accurate and premium options, where the additional functionality is fully consistent with the latest developments.
For greater versatility, it is recommended to purchase a torque wrench with a set of different attachments; such a set expands the range of work performed on tightening fasteners of different sizes.
Knowing the features of choosing torque wrenches and the functionality of different models, everyone will be able to choose the most suitable option for themselves.
How to choose a torque wrench for your organization?
Businesses often need to carry out work with high-precision torque control, which only professional tools can handle.
Therefore, there are a number of mandatory requirements for organizations, in accordance with which it is necessary to select torque wrenches.
The tool must be calibrated, verified, and included in the State Register of Measuring Instruments (GRSI) of Russia, for which a corresponding certificate is issued with an appendix that specifies the characteristics of the torque wrench.
Otherwise, the choice is made according to the parameters described above.
Manufacturers of torque wrenches:
- Alca
- FORCE
- GEDORE
- HANS
- Jonnesway
- KING TONY
- Licota
- NORGAU
- OMBRA
- STAYER
- THORVIK
- Tohnichi
- WERA
- Avtodelo
- Arsenal
- Bison
- Eureka
Removing the ratchet from the bike
It is not always possible to correctly see the malfunction when the ratchet mechanism is on the bicycle itself, so the best solution would be to disassemble it.
It will not be possible to simply remove the ratchet mechanism, so we will need a special tool - a puller. With the help of this simple device, the ratchet will quickly be removed from its rightful place.
Tool for removing and securing the ratchet
Second model
This version of the tool is more popular than the previous model.
There are already 24 teeth, and there is a reverse flag, by switching which we get the reverse stroke of the tool.
This model also has a head locking function that does not allow you to remove/put on the head.
Universal Bolt Torque Chart
Thread/pitch mmStrength class4.65.88.810.912.95/0.82,13,55,57,89,36/1.03,65,99,413,416,38/1.258,514,423,031,738,410/1.516,327,845,162,475,812/1.7528,849,077,8109,4130,614/2.046,176,8122,9173,8208,316/2.071,0118,1189,1265,9319,718/2.598,9165,1264,0370,6444,520/2.5138,2230,4369,6519,4623,022/2.5186,2311,0497,3698,9839,024/3.0239,0399,4638,4897,61075,227/3.0345,6576,0922,61296,01555,230/3.5472,3786,21257,61766,42121,633/3.5636,51056,01699,22380,82860,836/4.0820,81363,22188,83081,63696,039/4.01056,01756,8…3955,24742,4The dependence is indicated not only on the diameter and thread pitch. One of the important characteristics is the strength class. This limitation is associated with the so-called fluidity of the metal, when deformation can lead to failure of at least the thread, and at most the bolt head (stud rod).
Important! The values indicated in the table refer only to the strength of the fastening elements.
It is unacceptable to use this guide when installing components and parts of a car, and especially wheel rims! The tightening torques for fasteners set by the manufacturer are not only related to the strength of the bolts.
The geometry of the part and the tightness of the gasket may suffer. The operating conditions of bearings and seals will change.
