(4)       The figure below is a sketch diagram of a diesel engine.

1. Identify the:
2. type of diesel engine;
3. number of its cylinders.

 

1. Name the parts labelled U, V and W.

1. (i)        State one function of the part labelled U.

(ii)       State two functions of the part labelled V.

1. State two merits of the engine.

A high percentage of the candidates who attempted this question did not perform well.   The required responses to the various parts of the question are:

(a) (i)  it is a two-stroke diesel engine or a horizontally-opposed engine.
     (ii)        it has one cylinder.
(b)  U    -   injector
      V    -  piston
      W   -   cylinder

(c)   (i)  One function of the part labelled U is to introduce fuel
           under pressure into the highly compressed, heated and
            turbulent charge of air in the combustion chamber.

      (ii)    The functions of the part labelled V are

        -   accommodates the rings;
        -   form a moveable gas light plunger in the cylinder;
        -    forms a guide and a bearing for the small end of the connecting rod;
        -    takes the side thrust caused by the angularity of the crankpin and connecting rod assembly;
        -   transmits the force caused by the expansion of gases in the cylinder through the connecting rod
             to the crankshaft during the power stroke.

(iii)       Merits of the engine are:

     -  it is very compact;
     -  it has very little vibration;
     -  it has better power-to-weight ratio.