In hydraulic system pumps are soure of pressure and flow of oil. Depend of what type and size of pump we will use, we are able to reach parameters needed to work.
Hand pumps are mostly use, when we cannot suport power source by electric motor or engine. They are easy to move and they can work in almost every conditions. Because of thier construction hand pumps can work only with hydraulic cylinders.
Gear pumps are most popular type of pumps in global market. They are efficient, cheap and they can reach high level of pressure and oil flow. Thier weakness are high level of noise and no possibilities of flow regulation.
Vane pumps are very quiet and have very high oil flow. Thier flow can be regulated, but unfortunately their max pressure are lover than gear pumps.
Piston pumps are able to reach very high level of pressure and flow. Thier flow can be also adjust, but piston pumps are expensive and vulnerable to oil contaminations