Do We Expect Hub Movement on Key Connection

Keys/keyways themselves won't prevent axial movement. Setscrews may or may not help; they don't have much strength. Clamp-type shaft collars are a better bet.

Thanks,

The design identify the set screws on both Hubs so can we assume the screws are broken and so we are experiencing the hub movement?

They could be broken, loose, or gouging axially along the key surfaces.

Thanks for the detail,

Is there a way to find out if the screw sets are loose or broken? Definitely we have to take a shut and then access it after removing the pans.

I guess the set screw connects the hub with the Shaft collar so prevents the relative movement?

Sounds like this is all new to you.

The Basics Of Roller Chain Sprockets - Maintenance Technology ...

The set screw(s) will tighten on to the top of the key to prevent damage to the shaft. As to checking if they are damaged/broken, take them out.

As to the distance from the shaft shoulder to the sprocket, that can vary due to the drive alignment. Its one of the reasons the sprockets can be moved on the shaft. It's a damn site easier to move the sprocket than the motor and gearbox.

On a heavy drive like what you are describing you sure don't want a standard key/setscrew holding the sprocket in place. Especially since you are a 24/7 operation.

Relative rotation between the key, keyway, and sprocket is definitely not desireable on this kind of drive, since the movement will cause fretting corrosion, wear out the keyways in the sprocket and shaft, and will eventually cause the drive to fail. The slight movement will also make it impossible to keep setscrews tight.

There are many better ways of attaching a sprocket to a shaft that will resist the relative rotation as well as holding the sprocket against sideways motion on the shaft.

The simplest solution is to replace the sprocket with the straight keyed hub with a sprocket using one of the many brands of tapered hub attachments that will close in on the shaft with a clamping action. This clamping will also retain the key in most cases.

Hope this helps,

Jon.

Axial movement on the shaft may be a sign of misalignment in your drive. Check the shaft alignment perpendicular to the rotation as well as the sprocket alignment. If everything is aligned properly, there should be little axial force to move the sprockets. One must make the assumption that the drive was designed properly for the unit you have and there should be some adjustability in it so you can align everything accurately.