Case MX215, MX245, MX275, MX305 Magnum Tractor Service Manual

Description

Table of Contents

General
Engine
Electrical
Steering
Power Train
Brakes
Hydraulics
Chassis
Air Conditioning
Controller Fault Codes
Electrical Schematic
Hydraulic Schematic

Manual Extract: PFC AXIAL PISTON PUMP

NOTE: The principles of operation for the standard flow pump apply to both the optional high flow pump and Twin Flow pump systems. The artwork supporting the PFC pump operation depicts only the standard flow pump.

Principle of Control
All remote valves, the hitch control valve and the trailer brake option each contain a signal port. If a Power Beyond circuit has been installed, it also contains a signal port to the pump. Each signal port directs a signal pressure, which is equal to the working pressure in that particular circuit along signal lines through check valves to the pump compensator spool. The compensator will place the pump swash plate at the correct angle to meet system demands.

A single check valve is located in each signal line connection from the control valves to the compensator spool. If several control valves are operated at the same time, the signal line at the higher pressure will cause the check valve(s) to seat against the signal at the lower pressure. This prevents signal bleed off through other control valves and ensures that the highest signal line pressure will act on the compensator spool.

Operating Modes
The pump is designed to operate in two different modes according to the demand for flow and pressure placed upon it. These modes are as follows:

Low Pressure Standby
When there is no demand for flow or pressure, the pump provides just enough flow to make up for internal leakage in the hydraulic system at low pressure. In this mode the pump requires very little power to drive it.

Pressure and Flow Delivery and Compensation
When there is a demand for flow and pressure from the hydraulic system, the pump responds to provide only the flow that is required. This limits the power consumption of the system.