Parallel Keys – How to Use It?

Stainless steel parallel key is a mechanical transmission connection between a shaft and a hub, with a wheel. (e.g. a gear wheel or a bullwheel)

Stainless steel parallel keys: What are them?

Parallel key is essentially a stainless steel parallelepiped. According to UNI 6604 standard, it shall be constructed of stainless steel with a breaking load Rm more than 590 MPa. Also, the parallel key dimentions must comply the standards:

as the base and the height of the rectangular section depends mainly to the shaft diameter. Then we can deduce that a big shaft it will be associated an equally great power to be transmitted. So, the size of the connecting element it will subside accordingly.
maximum and minimum values are indicated for the length, within which there is the actual size. The latter is obtained from calculations on the strength of the material. (in this specific case, on the shear strength)

Parallel key: what’s that for?

The parallel keys are mounted within two locations (also called slots). These slots are carved into the objects to assemble and they are carved in such a way that to do join sides those same parallel keys.

This is very important because parallel key works on them for obstruction and it is subject to a cutting effort which limits the force transmitted. Considering that there is any kind of radial force (along the radius of the shaft), the parallel key ensures proper centering of shaft and hub. The latter once in rotation are coaxial and they produce limited vibrations. Then the parallel keys are especially indicated for applications that provide for medium loads and high rotation speeds.

Indeed, if the load to be transferred is very high, we can use a grooved shape (considered as a series of more parallel keys working simultaneously).