Page 245 - Mechanic Diesel - TT

MECHANIC DIESEL - CITS

On the contrary, sometimes a small gear is located on the shaft of the oil pump and the end of the shaft of the
distributor, which is in the shape of a screwdriver, fits into the groove made in the shaft of the oil pump and gives
drive to the distributor shaft through the pump.
2 Contact breaker point
The important part of the distributor assembly which is made up of two pieces is called the contact breaker circuit.
One piece of it remains fixed with the base plate and the other piece, to which the spring leaf is attached, is
movable.
A piece of fiber or Bakelite is attached to it. The distance between the two points is kept minimal but sufficient in
open condition. When the distributor shaft rotates and rotates the cam, pressure of the cam lobe is applied on the
moving part, due to which this point is pressed against the tension of the spring and the primary circuit is broken.
On the contrary, when the pressure is removed due to rotation of the cam lobe, the points come back together
due to the spring.
As long as the engine runs, this process continues and the primary circuit keeps creating high tension current by
making and breaking.

A = Closed contact
B = Large Point Gap-Small Well Angle

C = Small Point Gap-Large Well Angle
C.B. Point gap is usually kept as per the vehicle manufacturing instructions. This gap should be from 0.35 to
0.51 mm, which should be measured by filler gauge. If this gap is less, then C.B. The points will burn out and get
damaged quickly and the engine will miss. On the contrary, if the gap is large, then high tension current will be
formed for a very short time and proper spark will not be obtained and it may happen that high tension current is
not formed at all.
3 Rotor
This rotor, made of Bakelite or ebonite, is fitted in the grooves made in the distributor cap. The brass leaf on
the edge of the rotor is connected to the carbon rod in the distributor. The rotor rotates with the rotation of the
distributor shaft and transmits the high tension current coming to the distributor cap to the spark plug with the help
of segments and leads respectively.

4 Condenser
CB on the base plate of the condenser and distributor. The points are fitted parallel. CB in the ignition circuit of
petrol engine. Two condensers are connected with the points, which are C.B. Protects the points from getting

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CITS : Automotive - Mechanic Diesel - Lesson 71 - 75