Man B&W draw and explain
- The pump is basically a jerk type with a plunger moving in a matched barrel
- Helical grooves machined in the plunger to control the end of injection by uncovering spill ports and causing the discharge pressure to drop rapidly, thus causing the needle valve in the injector to close.
- Oil is supplied to the barrel via the spill ports and a suction valve.
- The suction valve, situated at the top of the barrel opens during downward stroke of plunger, while spill ports are covered by plunger.
- Replaceable erosion plugs are fitted in the pump housing opposite the spill ports.
- The high pressure oil, spilling back, as the edge of the helix uncovers the spill ports at the end of injection, hit the plugs, which prevent damage to the pump casing
- A puncture valve is fitted in the top cover of the pump. It is opened when compressed air from the control air system acts on top of a piston fitted in the top cover. Fuel oil from the discharge side is then returned to the suction side of the pump and no injection takes place.
How to check timing
.fuel pump timing .fp timing .fo pp .fo pump .fpt
Optical method
- Set fuel rack to maximum
- Open spills plug of pump and clean thoroughly
- Turn engine 20 degree before TDC
- Ensure no oil, put light on suction
- Wear goggle, look through spill port
- Turn until TDC
- When light disappear, indicate start of injection
- Check the crank angle marked on fly wheel. This value is the injection timing of that pump.
Oil overflow method
- Stop fuel pump,
- Fuel rack to max
- Take out delivery pipe, puncture suction valve,
- Turn to BDC, put DO, oil will flow out,
- Turn towards TDC, flow will stop, record start of injection
- Continue until overflow again, indicate end of injection
Checking of fuel pump lead,
.fuel pump lead .pump lead .fpl
Pump lead-number of mm , top of plunger lifted above the upper edge of spill ports when piston is at TDC
Cam lead -number of mm plunger is lifted from bottom position when piston at TDC
Planning and preparation
- Inform master about the job and instruct to person get ready and arrange tools.
- Go through instruction Manual
- Check measuring tools
- Risk assessment carried out, prepare work permit
- obtain Immobilization
- Stop engine. Shut starting air valve and drain the system
- Open indicating cocks, get propeller clearance and engage T/G
- Turn engine with lubrication on for 20 minutes
- Stop LO pump, FO supply pump and FO circuiting pump
- Shut FO inlet and outlet vlv.
- Shut FO heater valve,
- Drain off fuel carefully
- Ensure personal safety
- Disconnect puncture valve
- Disconnect suction valve
Procedure
- Set FO rack max, VIT rack “zero”
- Put Reverse mechanism in ahead position
- Take out erosion plug both side
- Set the measuring tool
- Turn the engine in ahead direction until plunger cover spill port, take measurement “K”
- Compare reading with maker data
- If not correct, may be tool not seated properly. Clean top of plunger and set again
- When K match, turn unit to TDC and note value. This is “A” value, pump lead!
- Turn the engine in ahead direction until fuel pump roller is at lowest part of cam
- Push down the gauge, take reading. This is “b” value ! A-b= C, is the cam lead!
- Then Confirm pump lead and cam lead with maker data
Cutting off the fuel for B&W
The steps are:
- Operating the Puncture Valve
- Lift the Fuel Pump Roller.
- Shut Fuel Oil Inlet Valve (Only for Maintenance purpose – Not During Running).
Manual actuation of Fuel Pump Lifting Device (148) activates Cylinder 149, which lifts & locks the Fuel Pump Roller, so that there is a gap (approx. 2 mm) between the roller and cam.
Cutting of fuel for Sulzer
- Lift fuel pump plunger by manual handle, !
- Close the inlet and outlet fuel valve.