Always wear your personal protective equipment for the job.

This can include, but is not limited to, steel toed boots, safety glasses, and gloves.

Also, always follow the standard safety practices established by your employer.

Bench setting refers to axial clearance within the unmounted tapered roller bearing, or referred to as TRB.

The different bench settings are bench end play, which is clearance, line-to-line, which is zero clearance, and bench preload, which is negative clearance.

In most cases, a new TDO will come as a matched assembly.

There is no need to do any special measurements.

However, if you need a custom fit or need to machine your own spacer, this measurement process is needed.

Let's also cover the terminology we will be using during the measurement process.

A TDO assembly is made of two cones, a double cup, and a cone spacer.

We need to identify the cone back faces and the front faces.

Take one of the cones and place the back face on your work surface.

Take the double cup and engage it with that cone.

Apply pressure and rotate to seat the rollers.

At this point, we're ready for our first measurement.

Using a depth mic, take measurements from the face of the cup down to the cone front face in four locations.

Three, six, nine, and twelve.

Make sure you don't rotate the cup on the cone so that your readings will be accurate.

Record those and average that number.

Then take the double cup and flip it so that it engages the other cone with the other race.

Again, apply pressure and rotate to seat the rollers.

Then take four additional readings in each of the quadrants, record, and take the average.

The third measurement requires an OD mic.

Measure the width of the cup in four locations around the double cup.

Record that.

With these three values, we can determine the gap that exists between the cone front faces and the bearing assembly.

This gap is known as the B gap.

To calculate the B gap, add the two averages generated from your depth mic reading and then subtract the average from your OD mic reading.

If a spacer is supplied with the assembly, measure the width of the spacer in four locations, calculate the average, and record the value.

The spacer width minus the B gap equals the bench setting of the bearing assembly.

An assembly with a spacer width exactly the same width as the B gap has a setting of zero clearance, also known as line-to-line.

By increasing or decreasing the spacer width, the bearing bench setting can be changed.

For example, an assembly has a measured B gap equal to 500 thousandths of an inch.

By making a spacer with a width of 500 two thousandths of an inch, the assembly setting now becomes two thousandths of an inch bench end play.

If you have any questions, contact your Timken sales or service engineer or your authorized Timken distributor. www.timken.com