Ramsay Test Ramsay Hydraulics & Pneumatics 5

Question 1

In a hydraulic system operating at 3,000 psi, a cylinder with a 4-inch bore and a 2-inch diameter rod is retracting. What is the approximate annular area acting on the rod side of the piston?

Accepted Answer

9.42 in²

Answer

The annular area on the rod side equals the full bore area minus the rod cross-sectional area. Bore area = π(2)² = 12.57 in². Rod area = π(1)² = 3.14 in². Annular area = 12.57 − 3.14 = 9.42 in². This is why a cylinder retracts faster than it extends at the same flow rate — less area means less volume to fill.

Question 2

A technician notices that a double-acting hydraulic cylinder extends at full speed but creeps extremely slowly during retraction, even though flow from the pump is normal. The most likely cause is:

Accepted Answer

A partially blocked rod-side port fitting or check valve oriented backwards

Answer

When extension is normal but retraction is severely restricted, the issue is specific to the rod-side circuit path. A partially blocked rod-side port or a check valve installed backwards would restrict flow entering the rod side during retraction while leaving the cap-side circuit unaffected. A bypassing piston seal would cause slow, weak extension AND retraction. A counterbalance valve set too high affects the exhaust side, typically causing jerky motion rather than creep. Air entrainment affects the cap side.

Question 3

In a pneumatic system using an FRL (Filter-Regulator-Lubricator) assembly, the lubricator bowl is observed to be flooding (filling with oil rather than misting it). What is the MOST likely root cause?

Accepted Answer

Supply air pressure is too low to create sufficient venturi effect in the lubricator

Answer

Lubricators use a venturi (pressure-differential) principle: high-velocity airflow creates a slight vacuum that lifts oil from the bowl as a fine mist. If supply pressure is too low, the venturi effect is insufficient to atomize oil — instead, condensation and gravity return oil to the bowl faster than it can be misted, causing flooding. While an open needle valve adds too much oil, it results in wet downstream components, not bowl flooding. High flow usually improves misting. A relief valve venting upstream would drop pressure — reinforcing the low-pressure diagnosis.

Question 4

A hydraulic system uses a pressure-compensated variable-displacement pump. At no-load idle, the system pressure reads 200 psi and pump displacement is near zero. When a heavy load is applied, pressure climbs to 2,800 psi and the pump destrokes again. A technician suspects the compensator is faulty. Which symptom would BEST confirm the compensator is NOT functioning correctly?

Accepted Answer

The pump maintains maximum displacement regardless of system pressure

Answer

A pressure-compensated pump's compensator destrokes the pump when system pressure reaches the set point, reducing displacement to match demand. If the compensator fails, the pump remains at maximum displacement even when system pressure meets or exceeds the set point — causing the relief valve to open continuously and dumping all flow over relief. This is the definitive symptom of compensator failure. Pressure overshoot can occur with a functioning but aggressive compensator. High-pitched whine suggests cavitation. Elevated case drain flow indicates internal wear/bypass, not compensator failure specifically.

Question 5

Two pneumatic cylinders are connected in a tandem series circuit (exhaust of cylinder A feeds the cap end of cylinder B). Cylinder A has a 3-inch bore and cylinder B has a 2-inch bore. If cylinder A is supplied at 100 psi, what is the maximum pressure available to extend cylinder B, assuming no friction losses?

Accepted Answer

225 psi — force from A is concentrated into B's smaller area

Answer

In a tandem series arrangement where cylinder A's exhaust drives cylinder B, you must think in terms of force, not pressure. Cylinder A produces: F = P × A = 100 psi × π(1.5)² = 100 × 7.07 = 707 lbs. That 707 lbs of force is then applied to cylinder B's cap area: P = F/A = 707 / π(1)² = 707 / 3.14 ≈ 225 psi. The smaller bore of cylinder B concentrates the force into a higher pressure — the same principle as a hydraulic intensifier. This is why tandem/booster circuits can amplify pressure.

Ramsay Test Practice Test

Ramsay Test Practice Test

Ramsay Test Ramsay Hydraulics & Pneumatics 5