cameroon gce advanced level 2025 electrical electronics applied mechanics 3

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I. SETTING UP

 

The mechanism in figure 1 represents a tool allowing the clamping of the exhaust pipe of an automobile car.

(Figure 1 is provided, showing a mechanism with labeled points A, B, C, D, and a lever Z.)

 

II. DESCRIPTION AND FUNCTIONING

 

The part is clamp Z is positioned on a V which is used as support and embedded on the frame. The lever S being articulated at A and B, the clamp Z on the V at point K. The rod g articulated at C on ensures the keeping of the lever at B.

The clamping effort is provided by the hydraulic jack 1 and 2 (1 = body, 2 = jack rod) which is articulated at A on the lever S and at D on V via the clevis pin 3 which is liable to describe a segment of line (AAT) thanks to a groove machined in the frame.

 

III. WORK TO BE DONE

 

 

SECTION A: STATICS

 

Aim: To determine the clamping effort at K.

Hypotheses:

• All the mechanical actions are contained in the plan of figure 1
• The connections at A, B and C are pivot linkages which centres bear the same name.
• The weights of the parts are neglected.
• The system is studied in the position of figure 1

Question 1: (10 marks)

1. State the fundamental principle of statics for a material system subjected to two external forces. (2 marks)
2. The characteristics of the jack at the admission are as follows:
   • Pressure: 50 bars
   • Diameter of the piston: D = 42 mm
   • Calculate the section of the jack rod and deduce the jack thrust force. (3 marks)
3. Equilibrium of the set 1+2 and the rod 6.
   • Write the equilibrium equations and draw the line support of the mechanical forces at points A, B, C and D. (5 marks)

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