Torque Transfer 3

[ape2010]

The 50' thickener consists of a centrally mounted drive head and the rake. The rake, shaft and the drive head are supported by the 51' bridge spanning across the thickener. My question is, does the torque generated by the rake transfer to the supporting bridge structure? When I apply the torque to the supporting frame the main beams of the frame fails but not other members of the bridge. I have a feeling that the torque does not transfer to the bridge structure as a torque because of the ball bearing but only the vertical load of the rake, shaft and the drive head. I highly appreciate your clarification.

Thank you,

 

[Ron]

You need to look only at the mounting condition at the drive head and it start-up torque on the connection. It is not likely the rake-induced torque has any effect on your structure since the shaft is able to turn at the top.

I've designed clarifiers with similar conditions and the rake torque is typically not transferred to the structure. As a safety precaution to make sure that does not happen, a shear key is usually used at the shaft so that in the event of a high torque event that would be transferred to the structure, the shear key would fail and prevent that.

 

[dhengr]

Ape2010:
You say... “The rake, shaft and the drive head are supported by the 51' bridge spanning across the thickener.” And, there may well be a shear key on the shaft to limit some excessive torque loading to the bridge, or entire system. Part of the weight of the shaft and rake could be carried by some sort of a thrust bearing at the bottom of the shaft, but I don’t know this for a fact. You have to study the details of the system to determine these things. The bridge may also be treated as some fort of a 51' long box truss structure, carrying both vert. loads and running torque, plus. But what, other than the bridge would provide the running torque or prevent the top mounted motor from just spinning. Take a look at the max. cap’y. of the bridge vs. the shear key strength, don’t use some hypothetical max. torque.

 

[XR250]

not that I have a completely clear picture of this, but how is the torque reacted otherwise?