CONTACT 2I6474 - Caterpillar

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids.Refer to Special Publication, NENG2500, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat products.Dispose of all fluids according to local regulations and mandates.
Introduction
The following procedure is used to adjust the maximum clamping pressure of the upper knives. The upper knives must put enough pressure on the tree in order to remove the bark cleanly. The correct pressure is required to prevent the tree from falling out of the head. If the pressure is too low, during the feeding process the knives will open and drop the tree. Excessive pressure will cause excessive wear on the harvester head. Excessive pressure will slow down the processing speed and in some cases damage the smaller diameter wood. The computer aided bucking system will automatically adjust the clamping pressure as the diameter of the tree gets smaller according to the values input in the machine variables section. Also, adjust the minimum pressure setting and the maximum pressure setting in the computer aided bucking system.The movement of the upper knives is controlled by the upper knives cylinders. The maximum pressure of the oil flow to the cylinders is controlled by a pressure reducing valve in the main control valve.Note: The computer aided bucking system is used to vary the clamping pressure of the upper knives. The computer aided bucking system controls the current that is sent to the solenoid of the variable pressure reducing valve for the upper knives. The variable pressure reducing valve varies the oil pressure to the upper knives cylinders. The variable pressure reducing valve drains oil to the tank in order to reduce oil pressure. As the current to the solenoid increases, less oil is drained to the tank. This action will cause the oil pressure to the upper knives cylinders to increase. Thus, the clamping pressure of the upper knives increases.ReferenceRefer to Systems Operation, UENR0357, "Dasa4 Control System", "Machine Variables" for setting the minimum clamping pressure and the maximum clamping pressure of the upper knives. The following procedure is used to set the pressure reducing valve of the upper knives.Required Tools
Table 1
Required Tools    
Part     Description     Quantity    
8T-5320     Hydraulic Test Group     1    
198-4240     Digital Pressure Indicator Gp     1    
177-7861     Hose As     1    Test Procedure
Prepare the machine for test and adjust procedures. Refer to Testing and Adjusting, "Preparation for Troubleshooting".
Illustration 1 g02549477
Harvester head in the HORIZONTAL position.
Harvester head in the HORIZONTAL position.
Open the valve cover on the harvester head. Disconnect the wire connectors from the tilt valve and the rotator valve if equipped.
Illustration 2 g02392758
Main Control Valve
Attach a 0 to 40000 kPa (0 to 5800 psi) pressure gauge to pressure tap (1) (M8).
Start the engine. Lower