Ratchet is defined as a kind of gear wheel with rigid tooth shaped surface or friction surface on the outer or inner edgegear, is a componentcrank shaft ratchetImportant components of.[1]frompawlThe ratchet can only rotate in one direction instead of reverse.
Ratchet is the main component of ratchet mechanism.The spring forces the pawl and ratchet to remain in contact.The rocker is sleeved on the ratchet shaft, the pawl is installed on the rocker, and the ratchet is fixed on the driven shaft with a key.[1]
working principle
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When the rocker of the driving part swings counterclockwise, the drive pawl is inserted into the tooth slot of the ratchet, pushing the ratchet to rotate an angle, and at this time, the stop pawl slides on the tooth back of the ratchet.When the rocker of the driving part swings clockwise, the detent pawl prevents the ratchet from rotating in the clockwise direction, while the drive pawl can slip over the tooth back of the ratchet, so the ratchet is stationary.In this way, when the rocker makes continuous reciprocating swing, the ratchet wheel will make one-way intermittent movement.Wherein, the reciprocating oscillation of the driving part can be realized by oscillating the driven partCam mechanism, crank rocker mechanism or hydraulic transmission and electromagnetic device.[1]
Main types
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The gear ratchet mechanism is simple in structure, convenient in manufacturing and reliable in operation. The ratchet angle can be adjusted step by step. However, because the pawl slides on the back of the ratchet tooth during the return trip, it is easy to wear and produce noise.In addition, in order to make the pawl mesh smoothly between the teeth of the ratchet wheel, the displacement of the pawl must be greater than the corresponding displacement of the movement angle of the ratchet wheel, which will lead to idle travel and impact.The friction ratchet mechanism has no above shortcomings, and the angle of the driven wheel can be adjusted steplessly. However, due to the sliding between the contact surfaces, its movement accuracy and reliability are worse than that of the gear ratchet mechanism.In general, ratchet mechanism is not suitable for occasions with high speed or high motion accuracy requirements.[2]
Ratchet mechanism is commonly used to realize the movement of feeding, indexing or indexing, braking and overrunning clutch.The types, characteristics and applications of ratchet mechanism are shown in the table below:
Ratchet type
characteristic
application
Toothed ratchet (mechanism)
Single acting ratchet mechanism
The outer edge or the inner edge is provided with rigid gear teeth;Ratchet angle can only be a multiple of the center angle between two adjacent teeth, and can only be adjusted step by step.Simple structure, convenient manufacturing and reliable movement, but it is easy to cause noise and tooth tip wear, and the transmission stability is poor.
It is commonly used as the cross feed device of the worktable in the shaper.
Double acting ratchet mechanism
Variable direction ratchet mechanism
Friction ratchet
The movement is transmitted through the friction between the pawl and the ratchet wheel to realize the stepless intermittent movement of the ratchet wheel.
The feed mechanism of machine tools and automata is also commonly used as a stop or brake.
Overrunning ratchet
In addition to being commonly used to realize intermittent movement, it can also realize overtaking movement, that is, the driven member can rotate beyond the driving member.
2. Industrial ratchet products.The utility model relates to a manual screw tightening tool, a single head, a double head and a multi specification movable handle ratchet box wrench (for fixing holes).It is connected by the main and secondary quincunx sleeves with different specifications and sizes through the way of engaging the female key and the male key of the hinge key.Because a quincunx sleeve has two specifications of quincunx shaped through holes, it can be used to tighten two specifications of screws, thus expanding the scope of use and saving raw materials and labor costs.The flexible wrench handle can conveniently adjust the angle of use of the wrench.The wrench is used for the tightening operation of screws and has the characteristics of strong applicability, convenient use and low cost.
3. Ratchet (musical instrument) is a percussion instrument.The principle is the same as that of industrial ratchet, which is equipped with a gear that can only rotate in one direction, and several thin pieces of wood are mounted on the tooth edge.When the gear rotates, the tooth touches the thin wood chip to make it bend, and the rear wood chip bounces back to its original position and contacts the next tooth, during which the friction and collision between the two produce a sound of "snap, snap".
Ratchet effect, also known as wheel control, refers to the irreversibility of people's consumption habits after they are formed, that is, it is easy to adjust upward, but difficult to adjust downward.
