RAIL 4T1274 - Caterpillar

Purging of the Radiator
Illustration 1 g00897116
This fan is shown in the PUSH position.The ability to purge debris from the radiator by reversing air flow is the objective of every Flexxaire fan system. In many environments, debris may build up on the radiator and the engine enclosures. This can cause the radiator to become plugged and the engine can overheat. Purging the radiator removes the debris so normal cooling of the engine can occur.Principles of Basic Operation
Mechanical Systems
Operation of a Mechanically Actuated Fan
The electronic controller sends power to the actuator motor. The actuator rod extends or the actuator rod retracts. The pitch of the blades is then changed through the mechanical linkages in the system.Operation of a Hydraulically Actuated Fan
The control system sends power to the solenoid valve. The solenoid valve sends hydraulic fluid to the hydraulic connector on the fan. The hydraulic pressure against the double acting cylinder in the main shaft allows the pitch of the blades to be changed through mechanical linkages in the system.Control Systems
The control systems are designed to minimize the effects of the following conditions:
overcooling due to low ambient temperatures
overheating due to plugged radiators, screens or guardsThe above conditions can directly affect engine life and component life.The system changes the pitch of the blades in order to control the air flow. The system does NOT change the speed of the fan. Electronics and hydraulics are used in order to control the pitch of the fan blades. This is accomplished by monitoring the engine temperature via a temperature sensor that is located in the coolant jacket.There are four different systems of control. The following information describes the four systems:Mark I Control System - This system was used on all fans that were made before January, 1996. As an upgrade, the Mark I control system has been replaced by the Mark III control system.Mark III Control System - This control system has been used on some machines since January, 1996. This system is fully automatic with several features that can be used in order to improve the fan's ability to increase the efficiency of the cooling system.ECM Controlled System - This control system has been used on some D6R Series II, D7R Series II, D8R Series II, D9R (ACLABKJJB), and D10R (AKT) Track-Type Tractors since January, 2001.. This system utilizes the ECM on the machine to control the operation of the fan. This control system is fully automatic and this system can be manually overridden by the operator with the manual purge switch.Timer Controlled System - This control system has been used on various machines since January, 2001. This system is controlled only by a timer. This control system is fully automatic and this system can be manually overridden by the operator with the manual purge switch.Note: The Mark I Control System and the Mark III Control System are used with mechanically actuated fans. The ECM Controlled System and the Timer Controlled System are used with hydraulically actuated fans.Bypassing the Control Systems
Bypassing the control system will