NEIEP Mechanics Practice Exam

To perform a relief test in hydraulic systems, which switches must be jumped out?

1. The down limit switches

2. The emergency stop switch

3. The up limit switches

4. The manual reset switch

The correct answer is: The up limit switches

In hydraulic systems, performing a relief test typically involves ensuring that the system can operate under conditions that simulate a load or stress on the hydraulic circuit. Jumping out certain switches allows for the system to bypass automatic safety features so that the technician can safely verify the system's pressure and operational behavior. Jumping out the up limit switches is vital because these switches normally prevent upward movement when a limit has been reached. If the up limit switch were active during a relief test, it would inhibit the system from reaching the necessary pressure needed for testing. By bypassing these switches, technicians can ensure that the system can continue to operate through its full range and reach the required conditions to accurately test the hydraulic pressure relief functionality. In contrast, other switches mentioned, such as the down limit switches, emergency stop switch, and manual reset switch, play different roles in system operation and safety. The down limit switch is not necessary to jump out for a relief test of upward motion. The emergency stop switch is meant for immediate system shutdown in case of safety concerns, and bypassing it would not be advisable outside of controlled testing scenarios. The manual reset switch typically can be engaged only after a fault condition has been reset and doesn’t need to be bypassed in this context.