The System Circuit; The Basic Closed Circuit; Case Drain And Heat Exchanger - Danfoss T90 Series Service Manual

Service Manual
Series T90 Axial Piston Pumps
Introduction

The system circuit

© Danfoss | March 2020

The basic closed circuit

Hydraulic lines connect the main ports of the pump to the main ports of the motor. Fluid flows in either
direction from the pump to the motor then back to the pump in this closed circuit. Either of the hydraulic
lines can be under high pressure. In pumping mode the position of the pump swashplate determines
which line is high pressure as well as the direction of fluid flow.
Basic closed circuit diagram
Reservoir
Input
MF
PV
Flow (Bi-directional)
Case drain line

Case drain and heat exchanger

The pump and motor require case drain lines to remove hot fluid from the system. The topmost port
drains the motor to ensure the case remains full of fluid. Fluid routes through the lower drain port on the
pump and out the topmost port to the reservoir. A heat exchanger, with a bypass valve, cools the case
drain fluid before it returns to the reservoir.
Output
P104 120E
AX216086485386en-000101 | 9