2010 Section B HL Question 8 (Mechanisms)

Question 1

Explain any three of the following:

(i) The use of bevel gears;
(ii) Double-acting cylinder;
(iii) Clutch;
(iv) The function of an idler gear;
(v) Capacitor.

Answer 1

Explain any three of the following:

(i) The use of bevel gears;
Allows a mechanism to transfer motion at right angles

(ii) Double-acting cylinder;

A pneumatic cylinder which needs compressed air to move the piston but will stay in position if the air is turned off

(iii) Clutch;
It is used in a transmission system to break and make the drive between the engine and wheels

(iv) The function of an idler gear;

A gear that is inserted between two other gears to change the direction of gear rotation

(v) Capacitor.
Is used to store charge and discharges through a circuit so the stored energy can be used

Question 2

Describe
a mechanism to control the vertical movement
of a dental chair

Answer 2

The hydraulic ram is positioned under the chair and is fixedto the base of the chair to raise the seat.

The hydraulic mechanism has been chosen
as it provides a strong, smooth, accurate and reasonably silent movement

Question 3

Describe two functions of a relay in a circuit

Answer 3

The relay acts as a switch when the transistor is on.

It allows the higher voltage circuit to activate from a lower voltage sensing circuit.