Final answer:
The correct answer is option d) hydraulic pump. In heavy-duty highway truck systems, hydraulic pumps are used to facilitate steering power assist by amplifying the driver's steering input using the pressure of hydraulic fluid.
Step-by-step explanation:
The correct answer is option d) hydraulic pump. Hydraulic systems are commonly used in heavy-duty machinery to provide steering power assist. The use of hydraulic pumps in heavy-duty highway truck systems is prevalent because they can apply a significant force with relatively low input effort, thanks to the incompressibility of hydraulic fluid. The advantage of a hydraulic system is beautifully illustrated by tools like the hydraulic jack, which mechanics use to lift vehicles during repair and maintenance because it can lift heavy loads efficiently. Similar to a hydraulic jack, the hydraulic power assist systems in trucks leverage the pressure of hydraulic fluid to amplify the steering input of the driver, making it easier to control the vehicle.
In the context of heavy machinery like a backhoe, hydraulic systems are critical components. These systems are not only capable of lifting heavy loads, such as with the hydraulic jacks used by auto mechanics, but are also used in the steering systems of large trucks to provide power assistance, ensuring that the steering of such large vehicles remains manageable for the driver.