Product in focus – advantages
- In combustion engines, the cylinder head sits above the pistons in the combustion chamber.
- The cylinder head accommodates the key components for mechanical control of the gas exchange, including:
- intake and exhaust ducts for charge exchange process
- valves and accessories
- rocker arms or finger type rockers
- The cylinder head is one of the more complex components of a motor, requiring complex manufacturing processes. In addition to holding the described components, the cylinder
head also has to fulfil the following tasks:
- sealing the combustion chamber
- absorbing the combustion power
- supplying the moving components of the valve train
- heat dissipation through coolant channels and cooling liquid with watercooled motors, or via large-scale cooling fins (blower) with air-cooled motors.
- The combustion process that takes place in the cylinder exerts a high amount of force on the cylinder head, so it is vital that the tightening torques of cylinder head bolts always match those specified by the manufacturer.
- The tightening sequence of the cylinder head bolts is important for preventing deformations. If the manufacturer’s instructions are not observed, harmful deformations may occur on the cylinder
head, on the cylinder of the cylinder head gasket or on the valve seat inserts.
Passenger car cylinder heads
- are available in grey cast iron or aluminium, depending on the engine type.
- are available in user and repair-friendly versions either as a bare head (equipped with seat inserts and valve guides), as a cylinder head with fitted valves and valve-springs, or as a complete cylinder head with valves and camshafts.
Single cylinder heads
- Individual cylinder heads are used in many utility vehicles.
- There are various types, e.g. watercooled cylinder heads from grey cast iron (see picture left) and air-cooled cylinder heads from aluminium (see picture right).
- The advantage is that they can be replaced individually in case of damage.
Multiple cylinder heads
Multiple heads are mainly used in passenger car engines, but are also used in utility vehicle engines. V engines with multiple cylinder heads have one cylinder head for each cylinder line. In engines with multiple cylinder heads, camshafts are often accommodated in the cylinder head. Engines with multiple cylinder heads are always water-cooled by design.
Water-cooled cylinder heads
Modern engines are almost exclusively water-cooled with a coolant mixture of water and anti-freeze/anti-corrosion agent.
- Water can absorb and dissipate larger quantities of heat.
- Cooling ducts between the cylinders and cylinder head can achieve more effective cooling within the engine.
Air-cooled cylinder heads
The air is blown directly onto the engine. To increase the size of heat-dissipating surfaces, cylinders and cylinder heads in air-cooled engines have large cooling ribs.
- more straightforward, cost-effective construction method
- more reliable operation
- reduced weight
- coolant does not freeze in low ambient temperatures
All buses over 5.5 tonnes and trucks over 9 tonnes must be fitted with a continuous braking mechanism. With constant throttle or decompression brake, an additional valve is opened at the end of the compression cycle. The gases for compression are drawn into a separate chamber and then fed back into the combustion chamber or directly into the exhaust pipe. This ensures that no new pressure is exerted on the crankshaft during the combustion cycle, preventing new drive force from being generated. The valve is controlled pneumatically or hydraulically. The constant throttle helps to achieve a braking power of 14–20 W per litre displacement.