The cross-sectional dimension b×h of the flat key is selected from the standard according to the diameter d of the shaft. The length L of the key is generally determined according to the width of the wheel hub. The key length is required to be slightly shorter than the wheel hub by 5 to 10 mm and comply with the length series value.

The type should be selected according to the structure, usage characteristics and working conditions of the key joint. The following should be considered when selecting: the size of the switch to be converted; whether the part connected to the shaft needs to slide along the axis and the length of the sliding distance; the alignment requirements of the connection; whether the key needs to be fixed front to back; and the position of the key on the shaft ( in the middle or end of the shaft) etc.

Extended information:

Ordinary flat keys, semicircular keys, hook wedge keys functions:

1. Ordinary flat keys are the lightest to use, because Its structure is simple, easy to disassemble, neutral, and suitable for high speed, variable load and impact situations.

2. The semicircular key is shaped like a semicircle and can swing in the keyway to adapt to the shape of the bottom surface of the hub keyway. Usually used for the connection of tapered shaft ends, the connection workload is not large. Such as the tapered shaft head, which drives the ordinary A-type pulley to rotate by connecting a semicircular key.

3. After assembly, the shaft and parts on the shaft are deflected and eccentric due to the influence of tilt, so they are not suitable for high-precision connections.

Baidu Encyclopedia-Ping Key