Atlas Copco PowerMACS 4000, User Manual

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Introduction
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1.2.2.1 Torque To Turn Gauging Application
An example of a Torque To Turn application is when an engine manufacturer wants to rotate the crank or
cam shaft under controlled conditions for the first time. Metal chips, burrs, sharp edges (spot distortions)
may cause excessive drag and eventually lead to early bearing shell failure and warranty repairs.
With PM4000 Gauging it is easy to create a program that rotates the shaft 360 or 720 degrees and
continuously monitor the torque and angle.
1
2
The curve present torque vs. time. There are two critical points.
1. Break-Away
2. Low Torque Rotation Test
To check break-away the torque is gently increased without rotation. If the torque reaches a preset limit
before any rotation starts the test stops immediately, preventing any damage.
If the break-away torque is within limits the rotation starts and the torque is monitored for the full rotation at
slow speed. Any friction out of limit indicates mechanical problems that should be corrected.
The combination of the two tests will show up any mechanical problems at a very early stage, before the
motor has been built into e.g. a vehicle. This eliminates the risk that the motor later experience expensive
service warranties.