 | |
| Illustration 1 | g02333073 |
Schematic for the hydraulic fan system (1) Axle oil cooler (2) Control manifold (3) Filter (4) Pressure and flow compensator valve (5) Piston pump (6) Hydraulic tank (7) Engine ECM (8) Sensor for the charge air temperature (9) Sensor for the engine coolant (10) Sensor for the hydraulic sump (11) Sensor for the transmission oil (12) Radiator (13) Hydraulic fan motor (14) Hydraulic oil cooler (15) Hydraulic oil cooler bypass valve | |
 | |
| Illustration 2 | g02333076 |
Hydraulic fan system (Left side view) (2) Control manifold (3) Filter (4) Pressure and flow compensator valve (5) Piston pump (6) Hydraulic tank (12) Radiator (13) Hydraulic fan motor (14) Hydraulic oil cooler (15) Hydraulic oil cooler bypass valve | |
Piston pump (5) is mounted to the front housing of the engine on the left side of the machine. Piston pump (5) draws oil from hydraulic oil tank (6) through the inlet of the pump. High-pressure oil then flows through filter (3) and then to control manifold (2). Control manifold (2) directs oil to the braking system, pilot system, or to the hydraulic fan motor (13). The braking system has priority. When oil is not required by the braking system, the oil is directed to hydraulic fan motor (13). Hydraulic fan motor (13) is located at the rear of the machine between radiator (12) and the engine. Pressurized oil from control manifold (2) flows into the inlet of hydraulic fan motor (13). The flow of the hydraulic oil causes hydraulic fan motor (13) to rotate the fan blades. The rotation of the fan forces cool air to flow through the cooling package.
After the hydraulic oil exits hydraulic fan motor (13), the oil flows through a hydraulic oil line to hydraulic oil cooler (14). When the engine is first started, the hydraulic oil may be cold. This cold oil from the piston motor cannot easily flow through the hydraulic oil cooler. The oil pressure will increase in the hydraulic oil cooler. The hydraulic oil cooler bypass valve (15) will open. The valve (15) limits the maximum oil pressure in hydraulic oil cooler (14) to 450 kPa (65 psi). Case drain oil from piston pump (5) and the case drain from piston motor (13) flow to hydraulic oil tank (6). The oil from the case drain is filtered through a screen in hydraulic tank (6) .
When the temperature of the oil increases, the pressure of the oil decreases. The force of the spring in hydraulic oil cooler bypass valve (15) is greater than the force of the oil pressure acting on the spring. The spring will close hydraulic oil cooler bypass valve (15). The hydraulic oil flows through hydraulic oil cooler (14). The oil flows through axle oil cooler (1) and into hydraulic tank (6) .
The hydraulic fan system controls the speed of the fan. The hydraulic fan system allows the speed of the fan to decrease in cool ambient temperature or in a light work application. The fan speed is controlled by four temperature sensors (8, 9, 10, 11). The sensors send data to engine ECM (7). Engine ECM (7) will interpret the data from the four sensors. Engine ECM (7) will send a change in current to control manifold (2). The change in current will change the flow of oil from control manifold (2) to the spools in pressure and flow compensator valve (4). The movement of the spool in the pressure and flow compensator valve will decrease the angle of the swashplate in the hydraulic fan pump. By changing the angle of the swashplate, the volume of oil from hydraulic pump (5) will decrease. The decrease in the angle of the swashplate will slow the flow of oil to hydraulic fan motor (13) .
Pressure and flow compensator valve (4) which controls the pump flow is mounted on top of hydraulic fan pump (5). Pressure and flow compensator valve (4) contains a flow control spool and a pressure cutoff spool. The settings of both spools can be adjusted.
Reference For information about the hydraulic fan pump, refer to the Service Manual module Systems Operation, "Piston Pump (Brake, Pilot, Fan)" for the machine that is being serviced.
ReferenceFor information about the hydraulic fan motor, refer to the Service Manual module Systems Operation, "Piston Motor (Hydraulic Fan)" for the machine that is being serviced.
ReferenceFor information about adjusting the speed of the hydraulic fan system, refer to the Service Manual module Testing and Adjusting, "Hydraulic Fan Speed - Test and Adjust" for the machine that is being serviced.