276 Machine Drawing
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d:\N-Design\Des18-1.pm5
The two gaskets 4 are placed; one on the end cover 3 and the other on the mounting bracket
1 in position. Two each of bushes 8 are placed on the end cover and mounting bracket to provide
bearing surfaces for the gear shafts. End cover is connected to the pump body 2 after placing the
dowel pins in the body. The shaft with gear 6 is placed in the bottom recess, whereas the shaft
with gear 5 is located in the top recess of the end cover and pump body assembly. Finally, the
mounting bracket is connected to the pump body after locating the dowels in the pump body. The
gland 7 is placed on the mounting bracket, after locating the packing 9 between the mounting
bracket and the shaft with gear 5.
The end cover, pump body and the mounting bracket are connected or fastened, using bolts
and nuts (not shown). Similarly, the gland is fastened to the mounting bracket by using two studs
and nuts (not shown). At the end, oil inlet and outlet connections are made through the mounting
bracket.
Exercise
Assemble the parts of the rotary gear pump, shown in Fig. 18.9 and draw, (i) sectional view from
the front and (ii) view from the right.
18.2.10 Air Valve
Air valve is used with a diesel engine to let-in air into the cylinder. Normally, the valve is in
closed position under spring pressure. It is opened by means of a cam, actuating the rocker arm
through a lever.
Figure 18.10 shows the details of an air valve. The valve 2 is introduced through the valve
box 1 so that it fits into the valve seat. The spring 3 is slipped through the stem of the valve and
made to sit at S-S in the box. The spring seat 4 is then placed on the valve and fixed in position by
means of a hexagonal nut 5 with pin. The rocker arm 6 is fitted to the valve box at M by means of
the pin 7. The lever 8 is placed in the rocker arm at N and positioned by pin 9.
Exercise
Figure 18.10 shows the complete details of air valve of a diesel engine. Assemble the parts and
draw, (i) sectional view from the front and (ii) view from above. Use suitable scale.
18.2.11 Fuel Injector
The fuel injector is used on a diesel engine. It injects highly pressurised diesel, supplied by a fuel
pump, into the combustion chamber of the engine cylinder.
The details of the fuel injector are shown in Fig. 18.11. The spring 7 is located in the body 1
above the distance piece 6. The nozzle pin 5 is placed inside the nozzle 2 and attached to the body by
means of nozzle holder 3. The screw adjuster 8 is placed over the spring from the other side (top) of
the body. The adjusting screw 9 is located in the cap 4 and it is held in position by the lock-nut 10.
The body has a narrow hole of 2 mm diameter, through which the pressurised diesel from
the fuel pump enters the nozzle. When it exceeds the set pressure of the spring, the diesel is
sprayed through the nozzle into the cylinder and as soon as the pressure falls back, the injection
ceases. The excess oil left-over in the injector, flows back through the clearance around the distance
piece into the over-flow exit, provided at location M6.
Exercise
Figure 18.11 shows the details of a fuel injector. Assemble the parts and draw, (i) half sectional
view from the front and (ii) the view from above.
18.2.12 Single Plate Clutch
A clutch is a device through which power is transmitted from the engine or driving shaft to the
driven shaft. Facility for disengaging the connection and stopping the power transmission as and
when required is incorporated in all designs of clutches.
