Answer EKM Question 2

Q2. A. Sketch and describe the arrangement of a main engine camshaft chain.

B. Describe the repair procedure following fracture of one chain link during operation of the engine.

C. Give possible reasons for the failure and explain how the chain is set initially at the correct degree of tension.

Answer: A. Sketch an describe the arrangement of a main engine camshaft chain.

In order to transmit sufficient power to drive the camshaft a multiple chain is generally required and many larger engines are fitted with double or triple chains. These are all linked together but each have their own sprocket wheels.

For engines with up to six cylinders the chain drive is usually fitted at the after end but for more than six cylinders it is usually placed at the centre of the crankshaft.

Apart from its relative simplicity the chain drive has an advantage in that it is no more complex to have a long chain than a short one thus the camshaft can be placed high in the engine close to the cylinder covers. This means that short hydraulic connections to fuel injectors and exhaust valve actuators can be used thereby minimising timing errors due to the elasticity of the hydraulic pipe systems. Chains are less susceptible to damage by foreign particles than gear wheels but they do suffer from wear at the pins and bushes resulting in