1. Mechanical Arrangement
Piston Engines
The main bits and pieces that make up the piston engine

2. Mechanical Arrangement - Basics

3. Mechanical Arrangement - Basics
Leg force in direction ‘B’ gives rotational force on pedal/crank propels bicycle along
Hand force in direction ‘A’ gives rotational force on nut
Mechanical Arrangement - Basics

4. Counter Balance Weight
Gudgeon Pin
Cylinder
Main Bearings
Piston
Connecting Rod
Offset Bearing
‘Big-end’
Counter Balance Weight
Crank Shaft
Mechanical Arrangement - Basics

5. 3 2 4 1 Mechanical Arrangement - Basics
Pistons 1
Timing Belt and Water Pump driving pulley location
Flywheel attachment flange
Rear
Front
Main Bearings
Crankshaft
Mechanical Arrangement - Basics

6. Exploded View of the Engine Mechanical Arrangement – Main Parts
‘Rocker Box’ Cover
Valve Gear
Cylinder Head Assembly
Cylinder Block
Timing Shaft
Flywheel
Crankshaft and Pistons
Sump (Oil Tank)
Mechanical Arrangement – Main Parts

7. Mechanical Arrangement – Valve Gear
Valve Operation
Inlet Valve
Exhaust Valve
The Inlet Valve needs to be open to allow fuel/air mixture in
The Exhaust Valve needs to be open to allow burnt gases out
Mechanical Arrangement – Valve Gear

8. Mechanical Arrangement – Valve Gear
Inlet Valve Closed
Inlet Valve Open
Rocker
Rocker Shaft
Closing spring
Valve Seat
Push Rod Mechanism
Push Rod
Valve Lift
Cam Shaft
Mechanical Arrangement – Valve Gear

9. Overhead Cam and Rocker Overhead Cam -No Rocker
Push Rod Mechanism
Mechanical Arrangement – Valve Gear

10. Modern Engines use a toothed rubber belt to drive the cam shafts
Twin Cam System
Modern Engines use a toothed rubber belt to drive the cam shafts
Chain Tensioners
Crankshaft and Pistons
Cam Drive Mechanism
Mechanical Arrangement – Valve Gear

11. Mechanical Arrangement
Put it all together
How does it work?
Mechanical Arrangement