An industrial machinery mount is assembled using standard fractional fasteners with bolt h… — Armed Services Vocational Aptitude Battery (ASVAB)

An industrial machinery mount is assembled using standard fractional fasteners with bolt heads measuring $3/4\text{ in}$ . Which tool must be selected to turn these fasteners securely and prevent rounding the bolt heads?

A
A $19\text{ mm}$ box-end wrench
A $3/4\text{ in}$ box-end wrenchAnswer
C
A $20\text{ mm}$ combination wrench
D
An $18\text{ mm}$ open-end wrench

Answer

3/4\text{ in}

box-end wrench

Fasteners must be turned with a wrench of the matching measurement standard and exact size. A

3/4\text{ in}

box-end wrench matches the

3/4\text{ in}

(

0.750\text{ in}

) bolt head perfectly, while the closed box end surrounds the fastener to distribute torque evenly and prevent rounded corners.

Step-by-Step Solution

Identify the fastener measurement system and exact head size specified.

The fastener is standard fractional SAE measuring

3/4\text{ in}

(

0.750\text{ in}

Fasteners must always be paired with wrenches manufactured in the same measurement standard to ensure an exact fit.

Evaluate potential metric substitutes against the exact SAE dimension.

18\text{ mm} \approx 0.709\text{ in}

(too small),

19\text{ mm} \approx 0.748\text{ in}

(undersized by

0.002\text{ in}

), and

20\text{ mm} \approx 0.787\text{ in}

(oversized by

0.037\text{ in}

Metric wrenches do not perfectly match fractional inch sizes, leading to improper seating, slippage, and fastener damage.

Select the proper tool design and size to apply torque without fastener damage.

3/4\text{ in}

box-end wrench provides full perimeter contact and the exact required dimension.

Using the matching SAE size in a box-end configuration distributes torque evenly across all six points of the fastener.

Key Concept

Proper SAE Wrench Sizing and Metric Non-Interchangeability

Estimated Time:1m 0s

Question

Answer

Step-by-Step Solution

Key Concept

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