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Subjects · Leaving Cert Engineering

Leaving Cert Engineering: Pneumatics & hydraulics

How often Pneumatics & hydraulics comes up on the Engineering papers, every year it was asked, and questions to try.

HL Asked on 6 of the last 9 Higher Level papers, most recently in 2025. most years

OL Asked on 3 of the last 9 Ordinary Level papers, most recently in 2021.

June 2028 is the first exam on the new Engineering course. These come from the 2016–2025 papers, so read them as a guide.

Pneumatics & hydraulics, Higher Level(8 marks)

Quick ones on Pneumatics & hydraulics.

(a)How does a single-acting pneumatic cylinder make its return stroke?
  1. Air is fed to the other side of the piston
  2. A spring pushes the piston back
  3. The valve sucks the piston back
(b)Why is a receiver (reservoir) fitted after an air compressor?
  1. To lubricate the cylinders with oil mist
  2. To heat the air before it reaches the air tools
  3. To store air and smooth out pressure changes
(c)Hydraulic press: 200 N on a master piston of 0.0004 m². Slave piston 0.01 m². Force at the slave?
  1. 5000 N
  2. 2000 N
  3. 8 N
Show the answers

(a) A spring pushes the piston back

(b) To store air and smooth out pressure changes

(c) 5000 N

Your turn: Higher Level questions on Pneumatics & hydraulics.

Higher Level

Asked on 6 of the last 9 Higher Level papers, most recently in 2025. most years

Every paper, year by year

YearWhere it came up
2025Q1(l)
2024Not asked
2023Q1(h)
2022Not asked
2021Q1(f)
2019Q1(c)
2018Not asked
2017Q1(l)
2016Q1(h)

Links open the State Examinations Commission’s paper for that year.

More Pneumatics & hydraulics questions

Pneumatics & hydraulics, 3 marks

Why can a pneumatic cylinder not hold a load steadily part-way along its stroke?

  1. Air is incompressible, so the piston locks
  2. Oil leaks from the seals, so it creeps
  3. Air is compressible, so the piston gives
Show the answer

Air is compressible, so the piston gives

Compressed air acts like a spring, so the piston moves when the load changes. Hydraulic oil is nearly incompressible, so it holds position firmly.

Pneumatics & hydraulics, 3 marks

Why is a double-acting cylinder's instroke force less than its outstroke force?

  1. A spring opposes the piston on the return
  2. The piston rod reduces the area the air acts on
  3. The air pressure falls on the return stroke
Show the answer

The piston rod reduces the area the air acts on

Force = pressure × area. On the rod side, the rod takes up part of the piston area, so the same pressure gives less force on the instroke.

Pneumatics & hydraulics, 3 marks

A shuttle valve lets a cylinder be operated?

  1. From either of two input valves (OR)
  2. Only when both valves are pressed (AND)
  3. After a time delay
Show the answer

From either of two input valves (OR)

A shuttle valve has two inlets and a ball that seals whichever side is not in use, so air from either input reaches the outlet. It gives OR control.

Ordinary Level

Asked on 3 of the last 9 Ordinary Level papers, most recently in 2021.

Every paper, year by year

YearWhere it came up
2025Not asked
2024Not asked
2023Not asked
2022Not asked
2021Q1(i)
2019Not asked
2018Not asked
2017Q1(i)
2016Q3(d)OR

Links open the State Examinations Commission’s paper for that year.

More Pneumatics & hydraulics questions

Pneumatics & hydraulics, 3 marks

A force of 500 N acts on a piston of area 0.002 m². What is the pressure?

  1. 1 kPa
  2. 1 Pa
  3. 250 kPa
Show the answer

250 kPa

P = F ÷ A = 500 ÷ 0.002 = 250 000 Pa = 250 kPa, since 1 kPa = 1000 Pa.

Pneumatics & hydraulics, 2 marks

What does hydraulic mean?

  1. Worked by electricity only, such as a motor
  2. Worked by a liquid, such as oil, under pressure
  3. Worked by compressed air, such as in a nail gun
Show the answer

Worked by a liquid, such as oil, under pressure

Hydraulics uses oil, which cannot be squashed, to give large, steady forces in diggers and car lifts. Pneumatics uses compressed air.

Pneumatics & hydraulics, 2 marks

How does a single-acting pneumatic cylinder return?

  1. A spring pushes the piston back
  2. Air pushes the piston back again
  3. A motor pulls the piston back
Show the answer

A spring pushes the piston back

Air enters one port only and drives the piston out. When the air is released, the spring returns it. A double-acting cylinder uses air for both strokes.

Other Engineering topics

All of Leaving Cert Engineering