||It has one power stroke for each revolution of the crankshaft.
||It has one power stroke for every two revolutions of the crankshaft.
||Lighter flywheel is required and engine runs balanced because turning moment is more even due to one power stroke for each revolution of the crankshaft.
||Heavy flywheel is required and engine runs unbalanced because turning moment on the crankshaft is not even due to one power stroke for every two revolutions of the crankshaft.
||It is of crosshead type i.e. piston rod connected to the crosshead bearing both reciprocate along the axis of the piston.
||It is of trunk type i.e. the skirt is connected to connecting rod by means of a gudgeon pin and bearing.
||The crosshead slippers transmit the connecting rod angularity thrust to the crosshead guides.
||Trunk or extension piece or extended skirt takes the connecting rod angularity thrust and transmits it to the side of the cylinder liner.
||More height for same power and speed.
||Less height for same power and speed.
||More head room.
||Headroom is limited.
||Power/ weight ratio is high.
||Power/ weight ratio is low.
||These are used mostly in slow speed engine.
||These are mostly used in medium/ high speed engine.
||They have long stroke.
||They have short stroke. (1-1.5)
||These are used for propulsion purpose.
||These are used mainly for power generation.
||It has compression type piston rings.
||It has compression as well as oil scrapper rings.
||Directly engine shaft coupled to propeller giving good efficiency as propeller is larger at a very slow speed
||Gear box is used for coupling to propeller (Reason: if directly coupled, prop@ 800 rpm, cavitation occurs, efficiency drops)
||Can burn low Grade fuel
||Requires better grade fuel (Low Ignition lack fuel)
||Low Compression Ratio
||High Compression Ratio (1:16)
||Requires warming of engine
||Doesnot require warming of Engine “Life Boat ratio 1:18/20”
||Thermal efficiency is not better
||Thermal efficiency is better