Question

The diagram below in Fig. 4.12 shows a device which makes the use of the principle of transmission of pressure.

1. Name the parts labelled by the letters X and Y.
2. Describe what happens to valves A and B and to the quantity of water in the two cylinders when the lever arm is moved down.
3. Give reasons for what happens to valves A and B in part (ii).
4. What happens when the release valve is opened?
5. What happens to valve B in cylinder P when the lever arm is moved up?
6. Give a reason for your answer in part (v).
7. State one use of the above device.

Answer 1

1. X : Press Plunger; Y: Pump Plunger
2. When the lever is moved down, valve B closes and valve A opens, so the water from cylinder P is forced into cylinder Q.
3. Valve B closes due to an increase in pressure in cylinder P. This pressure is transmitted to the connecting pipe and when the pressure in connecting pipe becomes greater than the pressure in cylinder Q, valve A opens up.
4. When the release valve is opened, the ram (or press) plunger Q gets lowered and water of cylinder Q runs out in the reservoir.
5. When the lever arm is moved up valve B opens upwards.
6. When the lever arm is moved up valve B opens upward because the pressure in cylinder P decreases.
7. An hydraulic press is used for pressing cotton bales and goods like quilts, books, etc.