A wide range of hydraulic pumps are available, the two most common types which are applicable to the Jacks described in the former chapter are as follows: Hand-Operated Pumps for Spring Return Jack. Widely used as the hydraulic source for the 720 kgf/cm2 hydraulic jack group. The main body is of forged special steel, has long durability, with safety valve recessed. Pumps are classified according to effective oil volumes into 5 categories (0.3, 0.7, 0.9, 1.3, 2.3 litres respectively). Oil volumes are the base for pump selection. Applicable to spring return system jacks.