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Question

Difficulty: MediumMeasuring and Layout Tools

A technician is inspecting an engine block to check for cylinder bore wear, taper, and out-of-roundness. Because the cylinder bore is too deep for standard micrometer anvils to reach directly, which T-shaped tool is inserted and locked inside the bore to transfer the dimension to an outside micrometer?

  1. A
    Feeler gauge
  2. Telescoping gaugeAnswer
  3. C
    Thread pitch gauge
  4. D
    Bevel protractor

Answer

A telescoping gauge is the correct tool used for indirect internal measurement of cylinder bores.
A telescoping gauge (also known as a telescoping bore gauge) is specifically designed for indirect internal measurement. Its spring-loaded arms expand to contact the inner walls of the cylinder, are locked in place with a knurled knob on the handle, and the resulting span is measured with an outside micrometer.

Step-by-Step Solution

1
Identify the type of measurement required by the task.
The task requires measuring the internal diameter (bore) deep inside an engine cylinder where direct measuring tools cannot easily fit.
Direct reading instruments like standard outside micrometers cannot access internal recessed surfaces.
2
Select the appropriate transfer (indirect) measuring instrument.
A telescoping gauge (snap gauge) is inserted with compressed arms, allowed to expand against the cylinder walls, and locked.
Spring-loaded telescoping plungers conform accurately to the internal diameter and can be locked via the knurled handle screw.
3
Read the dimension using an external precision tool.
The locked telescoping gauge is extracted and measured across its contact points using an outside micrometer.
Telescoping gauges lack a built-in scale and function strictly as transfer standards.

Key Concept

Indirect precision measurement of internal diameters using transfer tools and micrometers
Estimated Time:1m 0s
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Topics

Measuring and Layout Tools

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