CPM Bearings, Seals, and Shaft Couplings 3

Question 1

Parallel (offset) misalignment between two coupled shafts is best described as a condition where:

Accepted Answer

The shaft centerlines are parallel but displaced laterally from each other

Answer

The shafts meet at an angle but share the same centerline intersection point

Answer

The coupling gap varies in width as the shaft is rotated 360°

Answer

There is excessive axial distance between the two shaft ends

Question 2

Why is a cold alignment offset (intentional misalignment) sometimes introduced when aligning a pump-motor set at ambient temperature?

Accepted Answer

To account for thermal growth that shifts shaft centerlines once equipment reaches operating temperature

Answer

To compensate for manufacturing tolerances built into the coupling

Answer

To reduce vibration levels during the initial startup transient

Answer

To extend the service life of the flexible coupling element

Question 3

A rigid coupling is the appropriate coupling choice when:

Accepted Answer

Both shafts are precisely aligned and must act as a single continuous shaft

Answer

Significant angular misalignment between the shafts is anticipated

Answer

High shock and impact loads must be absorbed between driver and driven machine

Answer

A reduction in rotational speed between two machines is required

Question 4

In the reverse dial indicator alignment method, dial indicators are positioned:

Accepted Answer

On brackets spanning the coupling with each indicator reading the opposite shaft

Answer

On the coupling hub of only the driven machine

Answer

On the machine anchor bolts to detect soft foot

Answer

On the bearing housings to measure radial vibration

Question 5

A torque limiter (slip coupling) is used primarily to:

Accepted Answer

Protect machinery by slipping or disengaging when torque exceeds a preset limit

Answer

Increase the torque available at the driven machine output

Answer

Compensate for angular misalignment between driver and driven shafts

Answer

Reduce rotational speed between the driver and the driven machine

Question 6

Maintaining the correct axial gap (end float) between coupled shaft ends is important primarily because:

Accepted Answer

It prevents axial thrust loads from being transferred between the two coupled machines

Answer

It determines the maximum torque the coupling can continuously transmit

Answer

It controls the maximum allowable operating speed of the coupled system

Answer

It sets the degree of angular misalignment the coupling can accommodate

Question 7

Bracket sag in dial indicator shaft alignment refers to:

Accepted Answer

The downward deflection of the indicator bracket under its own weight, which introduces measurement error

Answer

Thermal elongation of the indicator bracket during hot alignment checks

Answer

Oscillation of the dial needle caused by shaft vibration during readings

Answer

Angular error introduced when the mounting bracket is not parallel to the shaft centerline