QUESTION $4($HYDRAULICS$)$

$[13]$

$4\mathrm{.}1$ Briefly discuss the main purposes of a hydraulic fluid reservoir

$(3)$

$4\mathrm{.}2$ Briefly discuss the advantages of hydraulics.

$(5)$

$4\mathrm{.}3$ Examine the figure below which represents a simple hydraulic circuit diagram. Interpret what is happening on the circle represented by the letter A$.$

$(5)$