What are the methods used for diesel engine reversing?
Mainly there are 3 methods used for reversing diesel engine.
- Moving camshaft axially
- where two sets of separate cams are mounted side by side
- correct set of cams are engaged with the follower by axially moving the camshaft with servomotor
- Moving fuel pump guide roller (Used mainly in MAN B&W engines)
- where one set of symmetrical cam is used for reversing
- pneumatic actuators are used for correct positioning of fuel pump
- Lost motion of camshaft (Used mainly in Sulzer engines)
- where one set of symmetrical cam is used for reversing
- lost motion clutch turn the camshaft to the new required position
- rotation of camshaft is independent of rotation of crankshaft
- lost motion or reversing angle is so chosen so that same fuel timing is obtained both in AHD & AST direction
- Consists of a pair of vanes, fitted on the camshaft, which move between another pair of vanes fitted within the gear wheel rim
- By applying lube oil pressure on opposite pairs of vanes, the camshaft is turned relative to the gear wheel & the crankshaft
- Reversing control valve controls the lube oil flow (in & out) of the servomotor
- Relative movement between camshaft & crankshaft, known as Lost Motion, changes the timing of the fuel pump and the starting air distributor for AHD & AST operation
