GZO Group
INDUSTRY STANDARD
Tested in 1986. To be tested in 1996 (Changed edition, Amendment No. 1, 2). This standard establishes the following types of locking of bolts, screws, studs, and nuts in threaded connections and pins: - 1- locking with lock washers; - 2 - locking with cotter pins; - 3 - locking by metal deformation; - 4 - locking with wire. In threaded connections, other types of locking can be used, for example, locking with self-locking nuts, spring and toothed washers, locknuts. (Changed edition, Amendment No. 1 , 2).1. LOCKING WITH LOCK WASHERS
1.1. Locking type 1 must correspond to that indicated in the drawing. 1, 2 and 3.
Execution 1.1.
Execution 1.2.
(Changed edition, Amendment No. 1).1.2. The bending of the washer petals on the hexagon face of the nut (bolt) is done with the washer turned towards unscrewing along its stop with the toe in the socket of the part (Fig. 4) or with the claw at the end of the part (Fig. 5).
1.5. Adjustment of the coincidence of the washer petals with the edges of the nut (bolt) is done by tightening the nut (bolt) to an angle of no more than 30 ° or replacing the nut (bolt). Adjustment by unscrewing the nut is not allowed. When tightening the nut (bolt), exceeding the maximum permissible tightening torque is not allowed allowed. (Changed edition, Amendment No. 2).1.6. The petals of the washers should be pressed against the edges of the nuts.1.7. The bending of the washer petals can be done on either one or two faces of the nut (bolt). Bend the reinforced petals onto the edge using that part of the bent petal that provides the largest area of contact with the edge of the bolt (nut). 1.8. The following are not allowed: - cutting or shifting of the material, cracks and tears in the place where the washer petals are bent; - nicks and flattening of the washer petals when bending; - bending the petals more than once; - protrusion of the petals above the nut (bolt) by more than 2 mm; - blows with a hammer at the place where the washer petals are bent; - leave the washer petals unbent.1.9. The bending of the washer petals must be done with special pliers according to the technology for assembling the product. In hard-to-reach places, it is allowed to bend the washer petals using special mandrels or drifts made of copper and aluminum alloys. (Changed edition, Amendment No. 1).
2. LOCKING WITH SPLITS
2.1. Locking type 2 must correspond to that indicated in the drawing. 7, 8 and 9.
Execution 2.1.
Execution 2.2.
l = 0.5 d ¸ 0.75 d
d - diameter of bolt, screw, stud
Version 2.3.*
2.2. Aligning the hole for the cotter pin in the bolt, screw and stud with the slot in the nut should be done by tightening the nut to an angle of no more than 30°, by replacing the nut or bolt, screw, stud, or by selecting the thickness of the washers. Adjustment by unscrewing the nut is not permitted. When tightening the nut, exceeding the maximum permissible tightening torque is not allowed. ________ * Use in hard-to-reach places (Changed edition, Amendment No. 2). 2.3. The cotter pin should fit into the hole freely or under a slight shock-free load. 2.4. The cotter pin should fit into the slot of the nut. It is allowed for the cotter pin to protrude above the nut slot by an amount of no more than 0.4 of the nominal diameter of the cotter pin. 2.5. The following are allowed: - loose fit of the ends of the cotter pin to the surface of the nut within 0.1 ¸ 0.3 mm; - contact of the bent ends of the cotter pin with the threads of a bolt, screw, or stud; - biting off cotter pins and then removing burrs. If necessary, a paint coating prescribed by the product developer is applied to the areas disturbed as a result of biting. (Changed edition, Amendment No. 1). 2.6. The following are not allowed: - crushing of the cotter pin head; - tears and cracks at the ends of the cotter pin; - flattening and twisting of the ends of the cotter pin; - rocking of the cotter pin after installation; - using a cotter pin more than once. 2.7. Bending the ends of the cotter pin at the edge of the nut should be done with a drift made of copper or aluminum alloys, and threading the ends of the cotter pin into the slot of the nuts with a blunt screwdriver.
3. STOPPING BY METAL DEFORMATION
3.1. Locking type 3 must correspond to the specified: - to hell. 10, 11 and 12 - for bolts, screws and studs; - to hell. 13 and in table. 1 - for installation screws; - to hell. 14 and in table. 2, damn it. 15 and in table. 3 - for cylindrical pins; - to hell. 16 - for conical and cylindrical pins. (Changed edition, Amendment No. 1).
Execution 3.1.
End punching
(Changed edition, Amendment No. 1).
Execution 3.2.
Punching into thread
(Changed edition, Amendment No. 1). ___________ * Dimensions of supply. instr.
Execution 3.3.
Punching into the slot
Execution 3.4.
Punching set screws
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View A |
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For permanent connections |
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For screws |
For screws |
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with thread M6 or less |
with thread over M8 |
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Table 1
Execution 3.5.
Punching of cylindrical pins
Table 2
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Pin diameter d |
Execution 3.6.
Caulking of cylindrical pins
Table 3
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Pin diameter d |
Housing material |
Aluminum alloy |
Aluminum alloy |
Execution 3.7.
Caulking of conical and cylindrical pins
d 1 = d - 0.2 ¸ 0.8
d 2 = d +0.2 ¸ 0.8
___________ * Provision size. tools (Changed edition, Amendment No. 1). 3.2. When punching a thread, place the center punch at the point where the bolt, screw, or stud exits the nut. 3.3. The size and location of the punching points cannot be controlled.4. STOPPING WITH WIRE
4.1. Locking type 4 must correspond to that indicated in the drawing. 17-22.
Execution 4.1.
(Changed edition, Amendment No. 1).
Execution 4.2.
Execution 4.3.
(Changed edition, Amendment No. 1, 2).
Execution 4.4.
The nuts are shown conventionally. This design can also be used on hexagonal bolt heads
(Changed edition, Amendment No. 1). When locking three or more parts (versions 4.1 and 4.4), the number of bolts or nuts locked with one wire is established by the design documentation or manufacturing technology of the product. (Changed edition, Amendment No. 2). 4.2. The wire must be positioned in such a way that when an arbitrarily oriented load is applied to it, the threaded connection is tightened.4.3. The wire must be intertwined without gaps between the turns. A turn is defined as one full turn of one end of the wire relative to the other. The number of turns must be at least three over a length of 10 mm for wire with a diameter up to 0.8 mm inclusive, and at least two over a length of 10 mm for wire with a diameter over 0.8 mm. By agreement with the customer, it is allowed to reduce the number of turns in the leno to 1.5. (Changed edition, Amendment No. 2). 4.4. In hard-to-reach places with small distances between locking parts, it is permissible not to twist the wire. Note. Hard-to-reach places are installed according to reference samples of products agreed with the customer. (Changed edition, Amendment No. 1). 4.5. The ends of the wire should be twisted (3-4 turns) and pressed. 4.6. When performing locking, tears and twisting of the wire are not allowed. 4.7. The wire must be taut, bending and slack are not allowed. An example of an entry in the design documentation for locking design 2.1:
Stopping 2.1 – OST 1 39502-77
Lead organization for standardization
The text corresponds to the source Author: elremont from 06/26/2015* nut/bolt clamps *
The fixation of the nut is very important in some cases. So I'll list you a few fixation methods and show you exactly how they are used. This is not complete guide, there may be more methods, but these are most of the methods that I am aware of.
*Lock-nut*
The basic way to secure a standard nut is to thread the nut onto the bolt and then tighten it to the specified torque using a torque wrench, but for this demonstration we'll just hand tighten it and you could use a counter nut.
That is, the locknut is designed to secure the nut and stop it from moving. After you tighten the first nut, the second nut, or lock nut, will be placed behind the first one, and then we will tighten it. This will stop the nut from coming loose. In extreme cases, with high vibration, this type of nut can actually become loose. This happens quite often when using two regular nuts, although you can buy a specially designed lock nut like this one made specifically for this purpose.
* thread fixing compound *
You can use a thread locking compound. It is a highly fluid anaerobic fluid. Since it displaces the air around it, it is actually used as an adhesive. You simply apply it to the threads where you want them to be secured. Then you tighten the nut... Tighten it and then wait for it to dry, this will compress the nut and stop it from moving. Thread locking compound is one of the most common ways to secure a nut or bolt. This is very effective way. There are quite a few different brands of compound available, so you need to make sure it's the right one for you. Some are so strong that you may need an impact wrench to remove them. Loctite is a very common brand. I'm sure most people have seen it. So this is a quick and easy way to secure the nut.
*Spring washers*
There are also spring washers, they are made of spring steel, and they are designed so that when you tighten the nut, there is a constant load on it, which can prevent it from unscrewing. Typically a spring washer is used along with a regular washer. First install the regular one, and then the spring one. They don’t always use a regular washer when using a spring washer; it depends on the specific location. After this, attach the nut and tighten it to the specified torque. This is a very common way to secure threads, but in extreme cases, with high vibration, the connection can become loose. I've seen this happen, the spring washer broke into several pieces, which meant the nut could now come loose. But in most cases, such a washer puts pressure on the nut, which makes it difficult to unscrew it. So once everything is tightened, it is difficult to unscrew it. And this will work, but it is not ideal if there is strong vibration, vibration weakens this connection.
*Toothed washers*
Serrated washers can be used to prevent some nuts and bolts from coming loose, but they are not ideal either. The problem is that if you tighten them too much, it can flatten the teeth and they will eventually just turn into regular washers. Once they are flat they are pretty much useless. But you can use them in certain circumstances, they are very popular in washing machines because they are very cheap. So you simply throw on the washer, tighten the nut, and tighten it to the specified torque using a torque wrench. It's important not to overtighten them so as not to flatten the washer, otherwise you'll end up with something like this. Like I said, it's very cheap, so they're used in a lot of washing machines and things like that. They can prevent nuts and bolts from coming loose, but this is a local solution.
*Self-locking nut*
The self-locking nut has a nylon ring at the top that grips the bolt as you tighten it. That is, you can start to tighten quite easily, just like a regular nut, but once you reach nylon, then it becomes difficult to tighten, you will need a tool in order to screw the nut onto the bolt. This can take quite a long time, because you will need to turn the wrench all the way, with a regular nut you can just screw it down quite easily by hand. So self-locking nuts are very useful, they are used in many places, but they take a lot of time to turn. Self-locking nuts are useful and you will find them on all machines, but they are not very suitable for critical machinery as they can be loosened by vibration.
*Deformed node*
Sometimes you won't see a nut with warped threads on the inside, it's actually only slightly warped, so it's pretty easy to get it on initially until you get to the warped spot, and then it grips really tight. Then you will need spanner or a head to be able to tighten the nut. Once tightened, everything holds up very well, but in extreme conditions, again with high vibration, they can become loose.
*Nord washers*
They are unique in that they have cams on the face of the washers. They should be placed in pairs, like this. That is, you put two things together with the cams facing out and tighten the bolt on them. You can put a nut. Tighten to the specified torque. Once the nut is tightened, the two washers will lock onto each other and the joint will be very difficult to remove. They are very good at vibration. It is very unlikely that any of these washers, if positioned correctly, will become loose due to vibration.
* Castle nut *
They are often used in critical machinery such as aircraft. On board the aircraft, after it is tightened, a piece of wire will be threaded through it, and this will prevent the nut from ever unscrewing. So, to use one of these, you thread it onto the bolt, tighten it to the specified torque or as long as it stretches. Now I'll drill through the bolt with a small drill bit. But such a drill would be better suited for larger nuts and bolts than this. It's stainless steel, so I'll work carefully and slowly. I'll put a little more lube on the drill bit. Once you've done that, you can insert the pin and bend it around and it will keep the nut from coming off until you pull the pin out.
I hope this demo was helpful to you. I've outlined some of the methods you can use to stop nuts and bolts from loosening on their own. There are also spacers for washers, which I don't have, but it's a regular washer and tab that bends and prevents the nut or bolt from coming loose.
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The main remedy against self-unscrewing of nuts and studs is primarily right choice type of thread.. Typically, all fastening threads are self-locking. Their helix angle is always less than the friction angle. In practice, despite the correct selection of threads, spontaneous unscrewing of nuts and bolts is observed during operation of the mechanism. Therefore, to ensure reliable and trouble-free operation of connections, all nuts and bolts on the aircraft, engines, components and equipment are locked.
Nuts, bolts and beads of detachable connections can be secured with cotter pins, wire, self-locking nuts, locknuts, various washers, pins, etc. When replacing a unit, pipeline or hoist, the locking mechanism provided for by the design must be used. Replacing one type of lock with another (for example, using single lock washers instead of double lock washers or spring lock washers instead of plate lock washers, etc.) is not permitted. Reuse of safety parts (cotter pins, wire, plate washers, etc.) is also prohibited.
Below we discuss the basic rules for locking nuts, bolts, coupling shafts and other parts of the main types of detachable joints.
Locking with plate washers. For this control, the following rules are observed:
Before final tightening of the nut, select the gap between the stud and the inner diameter of the plate washer on the side opposite to the tendril bent onto the flange or body (Fig. 4.9);
The tendril bent onto the flange or body must have an emphasis in the direction of unscrewing the nut and be bent until it fits tightly (Fig. 4.10);
Both antennae of the washer, which lock the nut, are bent after the final tightening of the nut on one or two edges (Fig. 4.11). .
Bending the washer's antennae onto the corner of the nut is prohibited. A gap between the washer's shoulder and the edge of the nut is not allowed. After bending the antennae, it is necessary to use a magnifying glass
Rice. 4.9. Plate installation diagram
lock washer
check for cracks in the bending areas of the locking washer antennae.
Plate washers come in several varieties.
Lock washers (Fig. 4.12, a and b). Lock washers connect two adjacent nuts in pairs using tendrils bent upward, thereby preventing them from unscrewing themselves. This type of lock is widely used on jet engines.
Locking washers. A locking washer with an outer nose that fits into a hole drilled in the part being fastened is shown in Fig. 4.13. After tightening the nut, the edge of the washer is bent to any edge of the nut and thereby prevents it from self-unscrewing.
tion. Lock washers with an internal toe are also used.
Union lock washers (Fig. 4.14) are put on the nuts and screwed to the parts with screws.
Rice. 4.14. Locking nuts using lock washers
The hole in the part is shaped to allow the nut to be rotated 30° around its axis and locked.
Locking with cotter pins. When locking nuts with cotter pins, the following rules must be observed:
After normal tightening of the nut, the cotter pin should pass through the slots of the castle nut (Fig. 4.15). Unscrewing the nut to align the slots and the hole for the cotter pin is prohibited. If when tightening the nut
The cotter pin is placed with the head facing up only; in this case, when the antenna is broken off, the cotter pin does not fall out;
When bending the antennae of the cotter pin onto the crown of the nut or stud, a smooth transition is maintained with a radius of curvature no less than the thickness of the cotter pin.
After bending, the spread ends of the cotter pin should fit snugly against the nut, and the head should fit into its slot (Fig. 4.16). When securing the responsible connections
For control of the aircraft, engine and units, the antennae of the cotter pins are moved in both directions and tucked into the crowns of the nuts (Fig. 4.15). When locking conventional connections (less critical units), the antennae of the cotter pins are only spread in both directions and pressed tightly against the edges of the nut, bolt or stud. The rollers and fingers are secured with cotter pins with the obligatory installation of a washer (Fig. 4.17).
When locking nuts and shafts, use cotter pins, the dimensions of which are indicated in the table. 4.14 and 4.15.
_____________________________ #
Table 4.14
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Cotter pin sizes for locking standard castle nuts
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Locking with locknuts. The locknut usually matches the size of the main fastening nut. It is screwed onto the bolt (stud) after tightening the main nut (Fig. 4.18) and pressed against it, thereby creating additional friction force in the thread. The locknut is tightened moderately with such force that it does not take the entire load of the tightened connection. The main nut should absorb most of the tightening force. The disadvantage of locknuts is that they increase the dimensions of bolted connections and make the structure heavier, so they are rarely used.
Locking with split spring washers. When locking with spring split washers, the nut is tightened until the ends of the spring washer come together to the same level (Fig. 4.19). The split washer with its antennae cuts into the body of the nut and the part and thereby prevents the nut from self-unscrewing. A washer that has lost its elasticity and is broken is not allowed to be reinstalled.
Wire control. Locking nuts with wire is widely used in threaded pipe connections.
iodines, mainly in immobile ones. To secure with wire, special security holes are drilled in the faces of the nuts. A wire is passed through these holes, then it is twisted and passed through
Locking the nuts and bolts of detachable connections with wire must be carried out in accordance with the requirements of the operating instructions for this type of aircraft. For example, general locking of bolts on a flange is prohibited if the instructions provide for locking the bolts in pairs (Fig. 4.21).
The tether connections of the cables are secured in such a way that the coupling cannot turn away from the tension of the cable (Fig. 4.22). The thunderbolts are countered with soft wire.
In some cases, nuts are counterbalanced by punching, riveting the end of the bolt, or welding the nut to the bolt. Such connections become permanent and are used in
Rice. 4.21. Wire bolt locking diagram
connections where tightening of bolts during operation is not required.
Locking by punching is carried out after tightening the nut and filing the end of the bolt so that it protrudes from
nuts by no more than 1 mm. Then, using a core, three or four cores are made at the end of the bolt near the edge of the nut, due to which the end of the bolt expands and does not allow the nut to unscrew itself.
Please note that in all types of aircraft inspections, the reliability of detachable connections and the locking of their parts must be checked.
The simplest and one of the earliest methods is known as locking a bolted joint with an additional nut called a locknut. Installation of the locknut precedes installation of the main one, as shown in the figure. Locking with locknuts is rarely used due to insufficient reliability. When tightening, the lock nut (see figure), pulling the bolt, takes on the entire load, while the main nut is unloaded. This sometimes makes it necessary to use reverse circuit: The locknut is placed under the main nut, which provides a more favorable distribution of forces.
Lock nuts are indispensable in cases where stepless fixation of the position of the nut on a bolt is required, especially when the nut moves significantly along the bolt
By using tapered locknuts, the adhesion between the locknut and the main nut is increased. To increase the adhesion in the thread, conical locknuts are equipped with slots that increase the compliance of the cone in the radial direction. Excessive compliance of the cone can make full tightening difficult due to the nut jamming on the threads during the final stages of tightening. The disadvantage of conical locknuts is that they complicate the processing of the cone seating surfaces and the occurrence of increased bearing stresses on the supporting surfaces.
Common types of castle nuts:
- DIN 935, 937, 979
- ISO 7035—7038
- GOST 5918-73, 5919-73, 5932-73
Threaded connections are quite reliable and efficient. They are considered one of the most common and cost-effective. However, when exposed to vibration, there is a possibility of weakening them. This can often be seen in the example of nuts that loosen randomly during operation of various devices. Therefore, methods have been developed that can reduce this effect or completely eliminate it.
Ways to avoid loosening the nut
1. Using a washer. This method is one of the most common. It is used in the manufacture household appliances and some types industrial equipment. It does not have a high degree of reliability and is protected from arbitrary unwinding. A soft metal washer is placed on the thread, and then the nut is tightened, squeezing it out.
2. Washer and Grover. A more reliable method practiced by the transport industry. Protects the threaded connection from arbitrary unwinding even in the presence of slight vibration. First, a regular washer is put on the thread, and then a groover. After this, tighten the nut. The Grover here serves as a kind of spring, creating tension that prevents unwinding.
3. Special nut with lock. The method using a special nut cannot be called the most effective. However, it takes place in world practice and is used in some types of production.
4. Using thread locker. The composition is applied to the place where the nut will be located, after which it is put on the thread. This is a fairly effective way to prevent random unscrewing, but its effectiveness is affected by changes in temperature, high humidity and exposure to active substances. Therefore, its scope is limited.
5. Use of two or more nuts. One of the most reliable methods. Two nuts are screwed onto the thread at once. After clamping the first, the second is tightened separately, holding the first in its original position and even trying to unscrew it a little.
6. Fixation with a cotter pin. This is the most reliable method, able to withstand almost any external influence and strong vibration. It is used in particularly critical areas. The nut is fully tightened. Then, using a drill and a thin drill bit, a hole is made that pierces it along with the bolt. A pin is inserted into the resulting hole, the tendrils of which are unbent, preventing it from falling out. Such a nut can be torn off only with a very strong rotational force in the direction of the thread.