3 - Hydraulic pumps

Abstract

This chapter explains the differences between positive and non-positive displacement pump; the principle of operation of gear, vane and piston pumps; fixed and variable displacement pumps; external and internal gear pumps as well as axial and radial piston pumps. the chapter explains how pressure-compensated pumps work and identifies the various types of pumps used in hydraulics. The sole purpose of a pump in a hydraulic system is to provide flow. A pump, which is the heart of a hydraulic system, converts mechanical energy, which is primarily rotational power from an electric motor or engine, into hydraulic energy. While mechanical rotational power is the product of torque and speed, hydraulic power is pressure times flow. The pump can be designed in such a way that either flow or pressure is fixed, while the other parameter is allowed to swing with the load. The chapter also explains the two categories of pumps:- non-positive displacement pumps and positive displacement pumps. The chapter explains the design, function, and operating principle of axial piston pumps and radial piston pumps in detail.