HARNESS AS-DASH 1636204 - Caterpillar

Hydraulic System
Problem Solving
When analyzing the hydraulic system, remember that proper oil flow and correct oil pressure are necessary for proper operation. Oil flow is dependent on the pump output which is a function of engine speed. Oil pressure is a result of restriction to the oil flow.
When testing and adjusting the hydraulic system, move the machine to a suitable location, away from job traffic pattern and away from personnel. Allow only one man on the machine. Keep all other personnel off to one side and within view of the operator.
In all instances, visual checks and measurements should be made first. Then proceed to operational checks and finally to instrumentation checks.Visual Checks
1. Check the oil level in the hydraulic oil supply tank. Slowly loosen the tank filler cap. Allow tank pressure to bleed off before removing the cap.2. Remove the filter elements and check for presence of foreign material. A magnet will separate ferrous metal material from non-ferrous metal and non-metallic sealing material (piston rings, O-ring seals, etc.).3. Inspect all external oil lines, connections and the cylinders for leaks or damage.4. Inspect the implement control linkage for damage.Operational Checks
The oil must be at normal operating temperature. Start the engine and operate the implement circuit. Observe if slow, erratic, or improper raising (closing) or lowering (opening) operation exists. PROBLEM: Pump not delivering sufficient oil. PROBABLE CAUSE:1 Low oil level.2 Oil viscosity too high.3 Incorrectly assembled pump.4 Worn pump.5 Low pressure relief valve settings.6 Ruptured diaphragm seal in pump. PROBLEM: Noisy pump, erratic cylinder movement and/or excessive oil foaming. PROBABLE CAUSE:1 Air leak on inlet side of pump.2 Worn pump.3 Incorrect oil viscosity.4 Low pressure relief valve settings.5 Fluid level either too low or too high. PROBLEM: Overheating. PROBABLE CAUSE:1 Incorrect oil viscosity.2 Overloaded system.3 Worn pump.4 Line restriction.5 Incorrect pressure relief valve setting.6 Excessive operation of brakes and retarder.7 Brake oil cooler malfunction. PROBLEM: Low oil pressure. PROBABLE CAUSE:1 Pressure relief valves. a. Low pressure relief valve setting.b. Groove worn on contact surface of pilot valve.c. Pilot valve seat loose in body allowing oil to bypass pilot valve.d. Foreign matter preventing pilot valve from seating.e. Dump valve stuck open.f. Orifice in dump valve clogged.2 Pump not delivering sufficient oil.3 Faulty control valve.4 O-ring seal failure in circuit. PROBLEM: Slow cylinder movement. PROBABLE CAUSE:1 Pump not delivering sufficient oil.2 Low pressure relief valve setting.3 Cylinder piston seal failure.4 O-ring seal failure in circuit.5 Incorrectly adjusted or damaged linkage.6 Faulty control valve.Checking Hoist Time
With the hydraulic system oil at normal operating temperature, body empty and the engine operating at 1900 RPM, time the body as it hoists from carry (down) to full dump position (up). The hoist time (to full dump) is between 13 and 14 seconds.If the hoist time is within the tolerance, the shaft end section (pump) of the two-section hoist and brake systems pump is probably within specifications.Pump Efficiency Tests
These tests are to determine the efficiency of the hydraulic pump used on this machine. These tests may be performed