725C, 725C2, 730C and 730C2 Articulated Truck Systems Caterpillar

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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.

A visual inspection of the hydraulic system is the first step of diagnosing a problem. Perform the following inspections:

1. Park on a level surface. Engage the parking brake. Shut off the engine.

2. Check the oil level in the hydraulic tank.

3. Check for air in the oil for the hydraulic system immediately after the machine has been operated. Keep the engine running and look in the sight gauge. If necessary, use a clear container in order to get a sample of the oil in the hydraulic tank. Check for air bubbles in the oil.

4. Check all oil lines and connections for damage or leaks. Check for oil on the ground under the machine. If oil can leak out of a fitting or a connection, air can leak into the system. Air in the system can be as bad as not enough oil.

5. Remove the filter elements and look for particles that were removed from the oil by the filter element. A magnet will separate ferrous particles from nonferrous particles. Nonferrous components could include the following components: piston rings, O-ring seals, gaskets and dirt. If the filter is plugged, drain the oil for the hydraulic system and replace the oil and the filter.

Independent Suspension Cylinder Checks

A visual inspection of each suspension cylinder is the first step in the analysis of a problem. Make sure that the machine is on level ground. Do the inspection on an empty machine while the engine is stopped.

Check each suspension cylinder for oil leaks around the seals and around the valves.

Check each suspension cylinder for nitrogen leakage. A leakage of nitrogen is difficult to detect. A solution that consists of soap and of water can be used to detect leaks. Make sure that there is no leakage around the valve cores and around the valve bodies. Make sure that the valve caps are in place. Make sure that the valve caps are tightened to 3 to 5 N·m (27 to 44 lb in).

Friction between the rod and the lower wear band may cause a dark stain to appear on the chrome of the suspension cylinder. The stain does not affect the wear life of the suspension cylinder. You can polish the chrome in order to remove the stain. Eventually, the wear band should become soaked by oil and by grease and the blackening should decrease.