The twist of a connecting rod is checked by installing push fit arbors in both ends, supported by parallel steel bars on a surface plate. Measurements are taken between the arbor and the parallel bar with a

The twist of a connecting rod is checked by installing push fit arbors in both ends, supported by parallel steel bars on a surface plate. Measurements are taken between the arbor and the parallel bar with a

• A. Dial indicator
• B. Depth gauge
• C. Micrometer
• D. Thickness gauge

Answer: (D)

Measuring twist hinges on detecting the small clearance between the arbors at each end and the parallel reference bars on the surface plate. When the rod is twisted, one end sits slightly higher or lower relative to the other, changing the gap to the bars. A thickness gauge is suited here because it gives a direct reading of those small gaps between parallel surfaces, allowing you to quantify how much twist is present by comparing the readings at the two ends. Other instruments aren’t as well matched to this specific measurement: a dial indicator would track movement or runout of a surface but isn’t as直接 tied to the gap between the arbor and the reference bar in this setup; a depth gauge measures depth of features or recesses rather than a general clearance between two parallel planes; a micrometer measures external size, not the inter-surface clearance; and while a dial indicator could be used to infer twist, the thickness gauge provides the most direct, straightforward measurement of the actual gap that represents twist.

Measuring twist hinges on detecting the small clearance between the arbors at each end and the parallel reference bars on the surface plate. When the rod is twisted, one end sits slightly higher or lower relative to the other, changing the gap to the bars. A thickness gauge is suited here because it gives a direct reading of those small gaps between parallel surfaces, allowing you to quantify how much twist is present by comparing the readings at the two ends.

Other instruments aren’t as well matched to this specific measurement: a dial indicator would track movement or runout of a surface but isn’t as直接 tied to the gap between the arbor and the reference bar in this setup; a depth gauge measures depth of features or recesses rather than a general clearance between two parallel planes; a micrometer measures external size, not the inter-surface clearance; and while a dial indicator could be used to infer twist, the thickness gauge provides the most direct, straightforward measurement of the actual gap that represents twist.