Case Cx130 cx160 cx210 cx240 Service Manual
Filters
Case cx130, cx160, cx240 service manual, The oil returning from the main control valve flows through the oil cooler. There is a cooler bypass valve in the circuit to protect the system during cold start conditions. As the oil returns from the oil cooler, it passes through a full-flow 10-micron filter.
Some of the return oil is routed through a 1-micron ultra-fine filter. Drain oil from the pilot control circuits and the case drain oil from the swing and travel motors is returned through the main return filter.
A cartridge type filter is installed in the outlet of the pilot pump to protect all pilot valves from contamination. All of these filters have filter bypass valves for cold start-up protection.
Reservoir
The reservoir is pressurized on all models. The air charge is provided by thermal expansion and the differential area of the cylinders as they are stroked the first time.
There is a breather/pressure regulator/fill cap installed in the top cover of the units. A rubber-covered button on top of the breather is provided to release the air pressure in the reservoir. A sight gauge mounted to the side of the reservoir indicates the oil level. There is a 150-mesh screen at the outlet of the reservoir to the hydraulic pump.
Case Cx130 cx160 cx210 cx240 Service Manual
CX SERIES EXCAVATORS
Service Training Manual
Table of Contents
Section 1 ……General Introduction
Section 2 ……Component Locations – Hydraulics / Electrical
Section 3 ……Controller
Section 4 ……Electrical – “How it Works”
Section 5 ……Hydraulic – CX130/CX160 “How it Works”
Section 6 ……Hydraulic – CX210/CX240 “How it Works”
Section 7 ……Pressure Data
Section 8 ……Engine Electronic Fuel System
Section 9 ……Schematics
TABLE OF CONTENTS
Section 1 – General Introduction
PAGE NO.
Engines ..2
Reservoir3
Filters …..3
Pumps….4
Pilot System .6
Hydraulic Systems ..6-7
Cushion Control ………7
Swing …..7
Travel …..8
Cylinders 9
Electrical System.10-11
Manufacture
model number
Case
model number
SHO120 CX130
SHO150 CX160
SHO200 CX210
SHO220 CX240
Variable Pumps
All of the CX Series Excavators uses an open center hydraulic system, in that there is always an output flow from the hydraulic pump flowing through the system.
The CX Series Excavators use a variable volume piston pump system to be able to fully use the engine horsepower available. As the system operating pressure increases, the flow gradually reduces, to maintain a constant horsepower load on the engine. The theory is that when very high pressures are required, speed isn’t so important.
The CX Series Excavators use a two-section variable displacement piston pump, to provide the flow required to operate the functions. Variable pumps are used to allow the delivery of a higher flow rate at lower
working pressures, and then allow the pump to reduce flow at higher pressures to keep from stalling the engine. The increased flow at lower pressures makes the machine cycle faster, to increase the overall efficiency of the machine.
The engine horsepower required to drive a hydraulic pump depends on the flow delivered by the pump, as well as the pressure at which system is operating.
There is a mathematical formula to calculate the pump drive horsepower, but a rule of thumb to visualize this is that it requires approximately 1 engine horsepower to deliver 1 gallon per minute of oil at 1500 psi. Therefore, it would require 25 HP to deliver 25 GPM at 1500 psi. If the pressure increases to 3000 psi, the requirement would be 50 HP.
The CX Series Excavators have an automatic pump de-stroke feature that reduces pump flow to a minimum delivery when all control levers are in the neutral position. This is accomplished with a hydraulic pilot signal from the control valve.
This system saves fuel and eliminates wasted engine and hydraulic power. The minimum flow delivery of the pumps increases with machine size and engine horsepower. Although the pump configuration and manufacturer varies, in principle, all of the pump control systems operate the same.
Case Cx130 cx160 cx210 cx240 Service Manual
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