Coupling and Clutch: Connections and Differences
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Both are primarily used for linking shafts to each other, enabling them to rotate together and transmit torque. Two shafts connected with a coupling can only be separated after the machine is stopped and disassembled. In contrast, two shafts connected with a clutch can be conveniently engaged or disengaged while the machine is operating.
Features of Fatigue Fracture under Variable Stress
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The maximum stress at fatigue fracture is much lower than the material's strength limit under static stress, and it may even be lower than the yield limit.
Regardless of whether the material is brittle or ductile, the fatigue fracture surface shows a sudden brittle fracture without significant plastic deformation.
Fatigue fracture is the accumulation of damage.
Main Types of Mechanical Wear
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Abrasive wear, adhesive wear, fatigue wear, and corrosive wear.
The Role of Washers
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To increase the support area of the connected parts to reduce the pressure at the contact point and to prevent surface damage when tightening the nut.
Advantages and Disadvantages of Rolling Screws
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Advantages:
There is very little wear, and clearance can be eliminated and a certain amount of preload can be introduced to increase rigidity through adjustment methods, hence its high transmission precision.
It does not have self-locking properties, and can convert linear motion into rotational motion.
Disadvantages:
The structure is complex and difficult to manufacture.
In some mechanisms, additional self-locking devices are required to prevent reversal.
Effects of Errors on Gear Transmission
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It affects the accuracy of transmitted motion.
The instantaneous transmission ratio cannot remain constant, affecting the smoothness of transmission.
It affects the uniformity of load distribution.
Power Losses in Gear Transmission Include
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Friction losses during meshing, oil resistance losses from stirring lubricating oil, and friction losses in bearings.
Advantages and Disadvantages of Single Circular Arc Gears
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Advantages:
High contact strength on the tooth surface.
The tooth profile is favorable for lubrication, resulting in higher efficiency.
The tooth surface is easy to saturate.
There is no root cutting, and the number of teeth can be reduced.
Disadvantages:
High precision requirements for center distance and cutting depth, errors in these two aspects significantly reduce the transmission's load-carrying capacity.
There is more noise, and its application is limited in high-speed transmission.
The bending strength of the teeth is usually low.
Different hob tools are required to cut the same module of convex and concave circular arc tooth profiles.
Properties of Bearing Material for Bushings
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Low coefficient of friction.
Good thermal conductivity and low thermal expansion coefficient.
Wear-resistant, corrosion-resistant, and strong resistance to scuffing.
Sufficient mechanical strength and plasticity are required.
