793D Off-Highway Truck Power Train Testing and Adjusting : General Information

WARNING: Sudden movement of the machine or release of air or oil under pressure can cause possible injury or death to persons on or near the machine.To prevent possible injury or death, do the procedure that follows before testing and adjusting the Hydraulic System.

1. Move the machine to a smooth horizontal location. Move the machine away from any machines. Move the machine away from any personnel.

2. Move the transmission control to the NEUTRAL position. Stop the engine.

3. Permit only one operator on the machine. Either keep other personnel away from the machine, or keep other personnel in the sight of the operator.

4. Activate the parking brakes.

5. Place blocks in front of the wheels and behind the wheels.

Illustration 1	g00280963
Retaining cable that is connected to the dump body



6. If it is necessary to lift the dump body of the truck, connect the retaining cable to the rear of the truck.

7. Make sure that the transmission rotary selector spool is in the NEUTRAL-1 position.

8. Make sure that all air pressure and oil pressure is released before any fittings, hoses or components are worked on.

Visual Checks are the first steps for troubleshooting a problem. The visual checks will determine the problems that can be corrected quickly.

Visual Inspection (Power Train)

SMCS - 3000; 4000

Perform a visual inspection at the beginning of troubleshooting a problem. Perform the inspection while the engine is turned off. Put the transmission control in the NEUTRAL position and put the transmission rotary selector spool in the NEUTRAL-1 position. Engage the parking brake.

• Check the oil level.

Inspect the oil level in the torque converter sump.

Note: Many problems in the power train are caused by low oil levels or by air in the oil. If the engine has not been started for several minutes, this oil level check will ensure that oil is in the transmission and that the engine can be started. If the machine has not been moved overnight or an extended period of time and the engine has not been started, the oil level will be high. An accurate oil level check can be performed after the oil is hot.

• Check for leaks.

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.

Inspect all oil lines, hoses, and connections for damage or for leaks. Look for oil on the ground under the machine.

Note: 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 a low amount of oil.

• Check the electrical system.

Inspect the fuse for the power train electronic control module, the harnesses, and the electrical connectors. Refer to the proper Electrical Schematic.

With the engine start switch and the battery disconnect switch in the OFF position, check the 10 ampere fuse for the power train electronic control module. If the fuse is open, replace the fuse.

Inspect the electrical harnesses for damaged wires or for broken wires. Disconnect each connector and look for pins and sockets that have been bent, broken, or removed. Look for any foreign material inside the connectors. The connectors must be tightened with normal force. The connectors must be disconnected with the same amount of force.

• Check the batteries.

Check the batteries. Turn the battery disconnect switch ON.

• Check the filters and the screens.

Inspect the transmission charging hydraulic filter, the torque converter hydraulic filter, the torque converter screen, the transmission magnetic screen, and the suction screen.

Note: The transmission charging hydraulic filter, the torque converter hydraulic filter and the torque converter screen have a bypass valve. A bypass valve allows oil to bypass the oil filter elements whenever the difference in pressure between the inlet oil and the outlet oil in the oil filter is too high. Any oil that does not go through the filter elements goes directly in the hydraulic circuit. Dirty oil causes restrictions in the valve orifices, the sticking valves, etc.

The pressure setting of the bypass valve in the torque converter hydraulic filter is approximately 127 kPa (18 psi). The pressure setting of the bypass valve in the transmission charging hydraulic filter is approximately 345 kPa (50 psi). The pressure setting of the bypass valve in the torque converter screen is approximately 125 kPa (18 psi).

All of the bypass valves are next to bypass switches. The Vital Information Management System (VIMS) will notify the operator of a restriction.

If any contamination is found in the filter elements or the screens, all the components of the transmission hydraulic system must be cleaned. Do not use any damaged parts. Any damaged parts must be removed and new parts must be installed.

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793D Off-Highway Truck Power Train Testing and Adjusting : General Information 2013-01-06T20:13:00-08:00 Rating: 4.5 Diposkan Oleh: Unknown