The diagram in figure shows a device which makes use of the principle of transmission of pressure.

(i) Name the parts labelled by the letters X and Y.

(ii) Describe what happens to the valves A and B and to the quantity of water in the two cylinders when the lever arm is moved down.

(iii) Give reasons for what happens to the valves A and B in part (ii).

(iv) What happens when the release valve is opened ?

(v) What happens to the valve B in cylinder P when the lever arm is moved up ?

(vi) Give a reason for your answer in part (v)

(vii) State one use of the above device.

(i) The parts are —

X → Press plunger

Y → Pump plunger

(ii) When the lever arm is moved down, the valve B closes and the valve A opens, so water from cylinder P is forced into the cylinder Q.

(iii) When the lever arm is moved down, the valve B closes due to an increase in pressure in cylinder P. Now pressure from cylinder P is transmitted to the connecting pipe. As the pressure in connecting pipe becomes greater than the cylinder Q, the valve A opens, so water from cylinder P is forced into the cylinder Q.

(iv) When the release valve is opened the ram (or press) plunger Q gets lowered and water of the cylinder Q runs out into the reservoir.

(v) When the lever arm is moved up the valve B opens upwards.

(vi) When the lever arm is moved up the valve B opens upward because the pressure in cylinder P decreases.

(vii) An hydraulic press is used for pressing cotton bales and goods like quilts, books, etc.