Question 50 QMED05 - Machinist-Pump Technician

The Correct Answer is A. **Why Option A is Correct:** Heavy-duty screwdrivers, particularly those designed for high torque applications (like removing stubborn fasteners), often feature a square section—known as a square shank or bolster—just below the handle. This square shape is specifically designed to allow a user to place an open-end wrench, adjustable wrench, or box-end wrench onto the shaft. Applying a wrench significantly increases the leverage and torque that can be exerted on the screw, which is necessary for breaking loose very tight or corroded fasteners that manual turning cannot overcome. **Why the Other Options are Incorrect:** * **B) prevent the shank from bending:** While the square cross-section might make the shank *slightly* more resistant to bending compared to a standard round shank of the same diameter, the primary reason for the square shape is function (torque application), not structural reinforcement. The material and diameter are the main factors preventing bending. * **C) permit striking with a hammer:** Tools designed for striking are typically labeled as "impact" or "striking" drivers and feature a metal cap or striking surface on the very end of the handle. The square shank itself is not intended for hammering; its function relates solely to increasing turning torque via a wrench. * **D) allow it to be used as a pry bar:** While screwdrivers are sometimes misused as pry bars, the square shank does not facilitate prying. If a screwdriver is designed for heavy-duty leverage, it is usually because the steel composition is robust, but the *square shape* specifically relates to the application of rotational force (torque) using a wrench, not linear force (prying).