Question 191General Subjects - Assistant Engineer

The correct answer is B) Sequence valve. A sequence valve is used in hydraulic systems to permit the completion of one action before a second action is allowed to occur. It does this by maintaining a predetermined pressure in the system, which must be overcome before the next function can be initiated. This ensures that the first action is completed before the second action is permitted. The other options are incorrect because: A) Unloading valves are used to divert flow when the system pressure reaches a set level, C) Counterbalance valves are used to control the speed of lowering a load, and D) Pressure-reducing valves are used to reduce the system pressure to a lower, specified level.