DIY ratchet mechanism

Structural design

The classic ratchet mechanism is designed to transmit intermittent rotation in one direction. Most often installed for gears. The ratchet mechanism in question is characterized by the following features:

1. When manufacturing the workpiece, casting and forging technology is used. This ensures a high degree of reliability.
2. The most important part of any device can be called gears. They are represented by wheels made of metal, on the surface of which there are teeth.
3. The number of teeth on the surface depends on the intended purpose of the mechanism. As practice shows, the most common version is with 12 teeth for 30-degree rotation.
4. For tensioning belts, a design option is often installed that has only 6 teeth.

Another important design element is the dog. It acts as a locking element. The basic properties of the element and its arrangement, certain functions and dimensions largely depend on the specific model and its field of application.

How does a ratchet mechanism work?

The spread of the ratchet mechanism can be associated with a fairly simple mechanism and operating principle, which ensures a long service life. The ratchet as a part is in many ways reminiscent of a ratchet element, since a corresponding sound occurs during operation. The features of the operating principle include the following points:

1. The main part is represented by a hook, lever or drive. The trigger element activates the entire system.
2. At the beginning of operation, the pawl is engaged with the wheel, but after activating the mechanism, the main element performs axial rotation. In this case, the latch moves a small distance relative to its original location.
3. Traction can be represented by various mechanisms. You can often find a mechanism that provides force adjustment.
4. At the moment of axial rotation, the dog slides along the surface. Due to intermittent movement, in some cases it is not possible to use the mechanism in question, as a strong hum occurs.
5. The pawl, which is necessary to ensure the functionality of the device, at the moment the axial rotation stops, falls into a special groove, due to which the main part is fixed.

The main cycle can be repeated until the desired result is achieved. An example is lifting the device and some other purposes.

Ratchet mechanism

Rice. 1: a - shutdown circuit; b - dog calculation

The circumferential force is determined from the equation:

where D is the outer diameter of the ratchet wheel; z is the number of teeth of the ratchet wheel; m—module of engagement of the ratchet wheel; Mk is the torque acting on the ratchet wheel shaft.

Parameters for calculating a ratchet connection

Table 1: Note. The [q] values ​​correspond to mechanisms for the 1st, 2nd and 3rd groups of operating modes. For more intense modes, these values ​​should be no lower than 25-30%.

Application area

Today, the ratchet as a part is used in the creation of various industrial units with components of engineering structures. At the same time, stable operation of various small elements of tools can be ensured. This point indicates the versatility of using ratchet mechanisms.

From a technical integration point of view, the device outperforms many other designs.

The simplest ratchet part allows you to adjust the position of the head and its fixation.

Very often, manufacturers use a ratchet as an element through which operating parameters are set. An example is fixing the cutting step in a certain range. In addition, installation is carried out during the direct manufacture of machine tools.

Recently, installation has been carried out in cylindrical grinding machines, the device provides radial feed. The mechanism is found in jacks and various winch systems, wind-up cars and other devices.

Application of ratchet mechanisms

Despite the fact that the scope of application of ratchet mechanisms is extremely wide, one of the main industries in which these products are used is mainly the machine tool industry. In particular, planing equipment today cannot do without ratchet mechanisms with end couplings. True, there is equipment that uses ratchet mechanisms of an alternative design.

Grinding equipment also cannot do without ratchet mechanisms with piston drives. They are installed in radial feed systems.

However, machine tool construction is not the only area where ratchet mechanisms are used. They can also be found in instrument making, the automotive industry, aircraft manufacturing and other high-tech industries.

Types of mechanism

There are a wide variety of friction ratchet mechanisms available on the market. They can be used to implement a wide variety of tasks. Among the features of the classification, we note the following points:

1. The profiled surface is often made in the form of a drum or rack.
2. The rack-and-pinion version is extremely rare, since the functionality of the device is significantly reduced. Drum friction ratchets are much more common due to their compactness and other properties.
3. The base profile is also classified according to a large number of characteristics. The most common are radial, rectangular and flat designs. Radial ones are widely used because they are compact and easy to install.

In most cases, the tooth has a classic shape, which ensures reliable operation.

Friction ratchets

In technology, such specific designs as friction ratchet mechanisms are often in demand. These products have their own varieties and are manufactured depending on the needs and technical characteristics. Friction mechanisms are presented in three versions: block, cam and roller.

Friction ratchets are used to engage various moving elements at relatively high speeds. Such technical properties are often required in industrial applications under certain circumstances.

The vector of movement in one given direction in such kinematic devices is achieved due to the fact that predictable jamming of the intermediate links of the friction races occurs and a large friction force arises.

Features of the operation of bidirectional mechanisms

Many ratchet mechanisms are characterized by the fact that the rotation of the wheel or rack is carried out in only one direction. They also began to produce versions that can rotate in both directions. The key points are the following:

1. Rotation is realized left and right. It is this moment that significantly increases the functionality of the device.
2. The shape of the teeth is rectangular. Only this ensures uniform rotation of the wheel in both directions.
3. A key feature is also how the locking pawl works. At the moment of rotation of the main element, it does not jump, but rises. Due to this, the device becomes more functional, but at the same time less reliable.

The scope of application of such an element has become very widespread today. A variety of materials can be used in its manufacture; in most cases, attention is paid to versions with increased corrosion resistance.

Ratchet mechanism for lashing straps

Samson LLC products are delivered to all regions of Russia and neighboring countries. When placing an order with us, you can choose the most convenient way for you to receive the goods.

1. Pickup.
2. Delivery by transport company.
3. Courier delivery service.

Transportation of finished products is carried out by leading Russian forwarding companies, which are ready to offer various delivery methods and convenient terms and transportation schemes.

For small consignments of goods, the most popular service is that of transport companies for the delivery of groupage cargo. Our company delivers goods to the TK terminal free of charge, in this case the buyer is responsible for paying for the service of transporting goods between terminals and delivery to the door (if necessary).

To send large cargo or large consignments of goods, it is possible to charter special vehicles or containers.

The order is dispatched after receipt of payment to the company's bank account within the time period agreed with the recipient. Cargo is delivered to the transport company’s terminal 2 times a week – Tuesday and Thursday.

You can get more detailed information from our managers or on the official websites of TC.

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How to make your own ratchet?

In order to significantly save on creating a mechanism, you can make a ratchet with your own hands. The calculation of the ratchet mechanism is carried out depending on the requirements for the system. You can make a ratchet mechanism with your own hands as follows:

1. A metal pipe can be used as the main element. It is used to create a shaft that will be used to directly transmit rotation. When choosing a pipe, care should be taken to ensure that the wall thickness is of the required size. Otherwise, it will not be able to withstand the required load.
2. A small piece of profile is cut out of a steel sheet, which plays the role of a fixing part. It is recommended to pay attention to alloys with increased strength and wear resistance. In most cases, attention is paid to the design option, which has been hardened to increase the hardness of the surface layer.
3. The most problems arise in the case of fitting the main elements to each other. Only in this case will the device work correctly. This is why you have to use precise measuring instruments when working. An example would be a micrometer or caliper.
4. The supporting base is made of metal sheets, which are connected to each other using welding technology. Such a base is created depending on the features of the future design.
5. The wheel must have teeth on the working surface, which ensure engagement. This element is often connected to the shaft using a key, which is highly reliable. It is quite difficult to make a wheel yourself, since the surface layer must be characterized by high reliability and strength. Most often, the ratchet wheel is removed from other mechanisms or ordered from a specialist who provides the appropriate services.
6. The shaft is attached by welding. This type of connection is characterized by increased strength and long service life. It is necessary to pay quite a lot of attention to the quality of the weld, since even minor defects can cause significant problems. The pawl is made using a spring and a running element. The spring can be removed from other mechanisms; the running part is responsible for the displacement of the pawl relative to the tooth.

In general, we can say that the manufacturing process of the structure in question is characterized by a fairly large number of difficulties. Only if you have the required skills and tools can you achieve your goals. The ratchet mechanism drawing can be downloaded on the Internet. When using a properly designed project, you can be sure that all the parts will fit together perfectly.

Calculation of the ratchet mechanism

When considering how the ratchet mechanism works, attention should be paid to the fact that the most dangerous position is when the top of the pawl rests on the top of the tooth. This phenomenon causes a strong impact, due to which the mechanism wears out quite quickly. Among the features of the calculations carried out, we note the following:

1. The strength of the edges is calculated.
2. The circumferential force is determined.

When designing, a variety of formulas can be used, and some information is taken from tables.

Calculating the ratchet mechanism creates quite a lot of difficulties, since in some cases the required parameter is selected depending on the operating conditions.

Toothed ratchets

From the very name of the ratchet wheel it is clear that it is part of the mechanism of the same name. The classic ratchet mechanism consists of a supporting body, a ratchet wheel and a spring-loaded movable locking stop, which is popularly called a “pawl”.

Depending on the design of ratchet wheels, external teeth are used for the simplest products, internal teeth, which are more complex to manufacture, and end teeth.

In some cases, instead of a round gear, straight racks are made, which also have their place. However, this solution is not as widespread as traditional ratchet wheels.

Based on technical requirements, it is possible to design a mechanism that is capable of ensuring ratchet movement in both directions. For these purposes, a cylindrical gear with teeth of rectangular section is made, and the dog is made reversible. By changing the working position of the pawl, the direction of movement of the ratchet changes accordingly.

Ratchet wheel calculation

You can calculate the ratchet wheel yourself. Among the features of the procedure, we note the following points:

1. In all cases, a coefficient is calculated, which is the ratio of the tooth width to the modulus indicator. Larger values ​​are used for devices that may experience significant shock loads during operation. The width of the dog is 2-4 mm, which compensates for the possibility of inaccuracy in installation work.
2. A variety of formulas can be used in calculations, it all depends on what data is known at the beginning of the calculations.
3. The bending resistance is calculated when considering the tooth as a beam, since it will be subject to a high load.

You can find just a huge number of different formulas that can be used when carrying out calculations.

Calculation of the ratchet pawl

The installed ratchet pawl acts as an important design element. Among the features of its manufacture, we note the following points:

1. When creating the movable pawl of the mechanism, 40X steel is used, which is additionally thermally processed to increase hardness. After heat treatment, the material in question becomes more protected from environmental influences.
2. To ensure reliable fixation, a special spring or weight is used.
3. When installing the dog, care is taken to ensure that its axis of rotation is positioned so that its contact surface contacts the tooth at an angle of 90 degrees or close to it. This ensures higher reliability of fixation.

The operation of the device in question determines that periodic maintenance does not have to be performed. With prolonged use there is a possibility of rapid wear of the surface. In addition, over time, the spring may lose its basic properties.