TUBE AS 3450328 - Caterpillar

1. Move the machine to a smooth horizontal location. Move away from working machines and personnel and lower implements to the ground.2. Permit only one operator on the machine. Keep all other personnel either away from the machine or in view of the operator.3. Engage the parking brake.4. Stop the engine.5. Move the hydraulic control levers to all positions to release the pressure in the hydraulic system.6. Carefully loosen the filler cap on the hydraulic tank to release the pressure in the tank.7. Make sure all hydraulic pressure is released before any fitting, hose or component is loosened, tightened, removed or adjusted.8. Tighten the filler cap on the hydraulic tank.9. The pressure in the system has now been released and lines or components can be removed.During a diagnosis of the hydraulic system, remember that correct oil flow and pressure are necessary for correct operation. The output of the pump (oil flow) increases with an increase in engine speed (rpm) and decreases when engine speed (rpm) is decreased. Oil pressure is caused by resistance to the flow of oil.When troubleshooting a possible problem in the steer system, perform the Visual Checks first. If a problem is still indicated, perform the other tests and adjustments as necessary to identify and solve the problem.
Some of the following tests and adjustments are performed with the machine engine operating. When these tests are done away from the operator's station, two people must be working. One person performs the tests and adjustments, and the other should be at the controls. This will help prevent accidental movement of machine.
Do not check for leaks with your hands. Pin hole (very small) leaks can result in a high velocity oil stream that will be invisible close to the hose. This oil can penetrate the skin and cause personal injury. Use cardboard or paper to locate pin hole leaks.
Reference: Be sure to follow correct safety practices when performing procedures covered in this module. See Safety Page, Form No. SENR7733.Visual Checks
A visual inspection of the hydraulic system and its components is the first step when a diagnosis of a problem is made. Stop the engine, lower the blade to the ground. To remove the tank filler cap, slowly turn the filler cap until it is loose. If oil comes out the bleed hole, let the tank pressure lower before the filler cap is removed. Make the following inspections:1. Measure the oil level.2. Look for air in the oil that is in the tank. Do this immediately after the machine is stopped. Use a clear bottle or container to get a sample of the oil. Look for air bubbles in the oil that is in the bottle.3. Remove the filter elements and look for particles removed from the oil by the filter element. A magnet will separat ferrous particles from nonferrous particles (piston rings, o-ring seals, etc.).4. Inspect all oil lines and connections for damage or leaks.5. Inspect control linkage for bent, broken or damaged components.Pump Efficiency Test
Hand Metering Unit