The hydraulic fan oil and the brake oil are filtered through the same oil filter. The filter guard is removed for clarity.|
(1) Hydraulic fan oil and brake oil filter
The brake oil filter (1) is mounted on the left rear of the tractor frame under the guard.
(1) Brake oil filter
(2) Oil flow from fan and brake pump
(3) Hydraulic oil filter bypass valve and switch
(4) Oil flow to hydraulic fan motor
(5) Engine ECM
The externally mounted brake oil filter (1) has a bypass valve. If there is a restriction in the oil filter or if the oil viscosity is high, the bypass valve (3) in the filter housing will open. A block of the filter can result in a greater hydraulic oil temperature than the limit programmed into the ECM for each component.
The pressure switch (3) contains a plunger that closes the contacts with an acceptable pressure drop across the filter. The pressure switch grounds the signal circuit during normal operation. The plunger of the pressure switch moves to allow the pressure switch contacts to close. The pressure switch contacts open when pressure across the filter is greater than the specified value. If the filter is restricted the open pressure switch sends a signal to the Engine ECM. The ECM informs the operator that the filter is restricted or dirty. With a maximum PSI is present, the switch will remain closed. When the PSI is at a minimum, the switch is open. The circuit for the switch is normally closed. The bypass valve opens to protect the system if the filter is restricted. The bypass switch provides an input signal to the Engine ECM. The Engine ECM determines if the filter is restricted. The status of the system can be observed by use of the Cat ET program.
If the inlet pressure to the oil filter is greater than the outlet pressure, the bypass valve will open. When the oil does not flow through the filter element, the debris in the oil could damage other components in the hydraulic system.
Correct maintenance recommendations must be followed in order to ensure that the element does not fill with debris. If the element is full of debris, the flow of clean oil to the hydraulic system stops.