Pre load bearings

[bob starkey]

One of the few things that ware on a lathe is bearings. Mostly in the head stock drive spindle. I have a feeling the cost of a lathe means better bearings.
It's not talked about much if any in the specs of most machines for sale. Do preload bearings take more motor power operating on a lathe?
Are they better or same as what ever the standard style is?

[Rich Aldrich]

Preload bearings do take more power, although it isn't that much for a lathe.

The reasons for preload are:
1) maintain running accuracy of the shaft
2) increase stiffness of the bearing assembly
3) reduce vibration and noise
4) prevent rolling elements from skidding in the raceways

The style of bearing is the same, It depends on the application as to how the assembly is designed. Wheel bearings and lathe spindles require preload.

[Dennis Ford]

"Pre-load" is not a type of bearing, it is about how they are installed. Rich covered the reasons for pre-load very well. Done correctly, very little extra power is needed. Done incorrectly, premature bearing failure is certain.

[Rich Aldrich]

Dennis - good point. I didn't point out that it isn't a bearing type. It is all how the assemblies are designed.