- An engine indicator consists of a small bore cylinder containing a short stroke piston which is subjected to the same varying pressure that takes place inside the engine cylinder during one cycle of operations.
- This is done by connecting the indicator cylinder to the top of the engine cylinder in the case of single-acting engines, or through change over cocks and pipes leading to the top and bottom ends of the engine cylinder in the case of double-acting engines.
- The gas pressure pushes the indicator piston up against the resistance of a spring, a choice of specially scaled springs of different stiffness being available to suit the operating pressures within the cylinder and a reasonable height of diagram.
- A spindle connects the indicator piston to a system of small levers designed to produce a vertical straight-line motion at the pencil on the end of the pencil lever, parallel (but magnified about six times) to the motion of the indicator piston.
- The “pencil” is often a brass point, or stylus, this is brought to press lightly on specially prepared indicator paper which is scrapped around a cylindrical drum and clipped to it.
- The drum, which has a built-in recoil spring, is actuated in a semi-rotary manner by a cord wrapped around a groove in the bottom of it; a hook at its lower end to a reduction lever system from the engine crosshead attaches the cord, passing over a guide pulley.
- Instead of the lever system from the crosshead, many engines are fitted with a special cam and tappet gear to reproduce the stroke of the engine piston to a small scale.
- The drum therefore turns part of a revolution when the engine piston moves down, and turns back again when the engine piston moves up, thus the pencil or stylus on the end of the indicator lever draws a diagram which is a record of the pressure in the engine cylinder during one complete cycle.
The electrohydraulic control mechanisms of the ME engine replace the following components of the conventional MC engine: Chain drive for camshaft Camshaft with fuel cams, exhaust cams and indicator cams Fuel pump actuating gear, including roller guides and reversing mechanism Conventional fuel pressure booster and VIT system Exhaust valve actuating gear and roller guides Engine driven starting air distributor Electronic governor with actuator Regulating shaft Engine side control console Mechanical cylinder lubricators. The Engine Control System of the ME engine comprises: Control units Hydraulic power supply unit Hydraulic cylinder units, including: Electronically controlled fuel injection, and Electronically controlled exhaust valve activation Electronically controlled starting air valves Electronically controlled auxiliary blowers Integrated electronic governor functions Tacho system Electronically controlled Alpha lubricators
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