Your viewer was right and you did the right thing on checking with the manufacturer of the bearings, but at times it is best to check with the machine manufacturer for their specifications, not all bearing preload is set based on its travel once tight only. Some applications require that you torque the nuts to a specific measured tightness and then back the nut out so many flats, and this is the case with many industrial applications. In other cases, you tighten to higher torque, back up the nut and then tighten it to a different reading on the torque wrench, if possible, the equipment manufacturer's procedures should be followed at all times, then go with the bearing manufacturer's instructions only when the equipment data is not available.
End play is not preload. The last thing I want in any timken bearing is ANY looseness. Being loose at all diminishes the ability of the bearing to spread the load evenly among more rollers.
Colin there is 3 of most common ways to check preload. Axial displacement method, Frictional moment method, and Direct force method. Sounds to me like this man read the bearing manufactures installation instructions and this is the way they said to do it. BTW what preloading means is basically reducing the bearings internal clearances.
