Today I will share several intermittent motion mechanisms, mainly including: ratchet mechanism, sheave mechanism, cam intermittent motion mechanism, and incomplete gear mechanism.
1. Ratchet mechanism
A one-way intermittent motion mechanism composed of a ratchet and a pawl. It mainly consists of a rocker, a pawl and an outer ratchet. The rocker is a motion input component, and the ratchet is a motion output component.
Advantages: The ratchet mechanism has a simple structure, easy manufacturing and reliable movement, and the angle of the ratchet can be adjusted as needed.
Disadvantages: The ratchet mechanism has small force transmission and produces impact and noise during operation. Therefore, the ratchet mechanism is only suitable for situations where the rotation speed is not high, the rotation angle is not large, and the power is low.
2. Sheave mechanism
The sheave mechanism is a one-way intermittent motion mechanism composed of a sheave and a cylindrical pin, also known as the Maltese mechanism. It is often used to convert the continuous rotation of the driving part into the unidirectional periodic rotation of the driven part with pauses.
Sheave mechanisms include external meshing, internal meshing, and spherical sheaves. The characteristics of the sheave mechanism are simple structure, reliable operation and high mechanical efficiency. However, the manufacturing and assembly accuracy requirements are high, and the angle size cannot be adjusted.
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Typical structure of wheel mechanism↓
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Engaging sheave mechanism↓
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Internal meshing sheave mechanism↓
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Face groove wheel mechanism↓
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3. Incomplete gear mechanism
The incomplete gear mechanism is an intermittent mechanism evolved from the gear mechanism. Only one tooth or a few teeth are made on the driving wheel of this mechanism, and according to the requirements of the movement time and intermittent time, teeth are made on the driven wheel. The number of gear teeth that mesh with the drive gear teeth.
The incomplete gear mechanism has a simple structure, is easy to manufacture, and works reliably. The movement time and rest time of the driven wheel can be changed within a wide range. However, the driven wheel has a large impact when it starts to enter and disengage, so it is generally only used in low speed and light load situations.
Incomplete gear mechanism↓
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Incomplete rack and pinion mechanism↓
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4. Non-circular gears
Non-circular gears are also called special-shaped gears. They are gears with an indexed curved surface rather than a rotating curved surface. After it forms a gear pair with another gear, during the meshing process, its instantaneous angular velocity ratio changes according to a certain established motion law.
Non-circular gears are widely used in various special machinery such as automated instruments, solving devices, printing machinery, and textile machinery to achieve certain motion requirements or improve motion performance and dynamic characteristics.
