Ratchet - one of the oldest mechanical inventions of man. Structural simplicity and functional efficiency allowed it to remain relevant even in the digital age. Of course, the target systems in which the ratchet mechanism is used can hardly be called technically highly developed, but this does not negate the operational advantages of their device.
Scope of application
Industrial units with components of engineering structures and the work of small fitting elements for tools are based on ratchets. This indicates the universality of the device and its flexibility in terms of technical integration. For example, the simplest ratchet mechanism for helmets allows adjustment of the headband through a wheel that transmits movement to the locking system.
In instruments, this device serves as a means of setting certain operating parameters. In the construction of the pruner, in particular the ratchet allows you to clearly record the cutting step within the specified range.If we talk about more critical areas, then on the foreground machine equipment production equipment. Cross-planing units are equipped with outer wheels of ratchets, which can withstand heavy physical loads. In circular grinding machines, this device is used in order to ensure radial feed rates - installation is carried out in combination with piston drives. In addition, ratchets are used in winch systems, jacks, starter and winding mechanisms.
The functional parts of the mechanism work to provide intermittent movement required for one-way displacement of the gear. The latter is the most significant part of the system and is a metal disk with teeth. To ensure reliability, the wheel is initially made using forging or injection molding techniques.
The number of teeth can be different - it depends on the working range of the target structure. In typical models the possibility of a 30-degree rotation provide 12 teeth. The minimum number of transition grooves reaches 6 - for example, this configuration is used in ratchet mechanisms for tightening straps-rechetov.In addition to the impeller, the design also includes a mounting "dog", a locking mechanism, a shaft and a lever. The physical properties of the elements, the layout, the presence of individual functional components and dimensions may vary depending on the model and design features.
How does the ratchet mechanism work?
Each device has a kind of trigger element (lever, drive, hook), which activates the system. Initially, the “dog” is in contact with the wheel, but after the mechanism is activated, axial rotation begins, leading to the movement of the lock.
Traction can be provided by different sources of thrust. In the same secator, manual pressure contributes to start-up, and an electric motor in machine tools. Anyway, in the process of movement of the wheel, the “dog” begins to slide and then move along the external surfaces of the teeth. It is important to emphasize that at this moment it has no effect on the wheel. But after stopping the movement, the ratchet mechanism is locked by means of an abutment of the “dog” in one of the slots. This cycle can be repeated until the desired result is obtained when adjusting, lifting or adjusting according to certain parameters of the target system.
Varieties of the mechanism
There are many classifications that determine the variety of ratchets. For example, the profiled surface can be rack or drum. The first option is used in special cases, since the linear placement of teeth is less functional and ergonomic than around the circumference. Drum systems are just devices with impellers. There is also a classification of the base profile on which the grooves are located. It can be rectangular, radial and flat. Radial systems are most often used as the most convenient to use, reliable and compact. With a rectangular profile, a ratchet clamping mechanism is usually performed, since the small dimensions of the adjusting tool in this case do not allow the use of teeth with sharp and inclined edges.
Features of work of bidirectional mechanisms
One of the key features of the classic ratchet is the rotation of the wheel or rail only in one direction. But there is also a separate class of mechanisms that retain the same operational effect, but act differently. Rotation in bidirectional systems is realized both to the left and to the right.Moreover, the teeth must be rectangular - only in this configuration can the wheel be evenly displaced. The main feature of the ratchet mechanism of the bidirectional type is in the “dog” movement system. It does not pass and does not slip on the surface of the wheel, but spreads. This expands the possibilities of managing the system, but also complicates it, making it less reliable.
How to make a ratchet yourself?
The technique of construction will depend on the requirements for the system in which it will be used. It is possible to take a shaft in the form of a piece of metal pipe, a cutting from a steel sheet and a piece of a profile that will fulfill the role of a “dog”. The main difficulty will be to fit the sizes of these components, because only with optimal convergence it is possible to ensure stable performance of the ratchet mechanism. You should also make a carrier base with your own hands - they use a metal frame assembled from the same steel sheets. Through welding, a shaft is fastened to it from both sides, on which a pre-machined disc with cut-out slots sits. To install the "dog" should provide a running clamp with a spring system.Installation is carried out by hardware or welding.
Ratchets have many advantages, but there are also weak points that need to be considered when buying devices with such a mechanism. First of all, high responsibility is placed on the system, which also leads to increased maintenance requirements.
In the same machines and lifting units, it is imperative to regularly lubricate the wheel and stains of contact with the “dog”. The use of a ratchet in small tools and accessories also has its drawbacks, due to the jamming of small parts. But in each case, the quality of the system will depend on the characteristics of the product. Large manufacturers use durable components in the construction of ratchets with an optimal combination of performance properties. Another thing is that the presence of such a mechanism can significantly increase the price tag of the device.