Usage:
773B (63W1221-Up),
777 (84A1284-Up),
777B ( 4YC),
785 (8GB),
789 (9ZC),
768C (2X350-Up),
772B (64W186-Up),
776B (14H206-Up),
621E ( 6AB, 6BB),
623E (6CB, 6DB),
627E (6EB, 6GB, 6FB, 6HB),
631E (1AB, 1BB),
637E (1FB, 1JB, 1HB, 1LB, 7CB),
651E (89Z),
657E (6MB, 86Z, 87Z, 90Z, 91Z)
Introduction
Field experience with ICM transmission hydraulic controls in haul units has dictated that clean-up of power train systems following a component failure is critical. Eliminating and keeping residual debris from the controls is critical to transmission reliability.
This instruction gives the procedure to clean the power train oil system on the above machines after they have been contaminated with foreign material.
Follow this procedure after all causes for the contamination have been identified and corrected.
NOTE: It is important to follow these instructions, because a system that has not been cleaned correctly can cause repetitive failures. Perform all work in a clean area so that foreign material will not enter a cleaned part or system.
Reference: Service Manual, Parts Book, Operation & Maintenance Guide and Service Magazine
Off-Highway Truck, Tractor-Scraper and Scraper Power Train Oil Systems
The off-highway truck transmission has a separate oil reservoir. The torque converter, brakes and hoist system have a common oil reservoir. Oil from one reservoir will not contaminate the other reservoir. However, because transmission operation is dependent upon torque converter lockup a malfunction of one system can cause the other to fail.
The tractor-scraper transmission shares an oil reservoir with the torque converter
The scraper transmission shares a hydraulic tank with the torque converter
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Hot oil and components can cause personal injury. Do not allow hot oil or components to contact skin. |
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Before any component is removed see the information that follows for assistance to find how much of the system needs to be cleaned.
Inspection Procedure
NOTE: Inspect and clean the components in the sequence listed. If debris is not found in a particular component, proceed to the remaining components.
1. On trucks remove the torque converter filter and screens. Cut the filter element open and inspect the filter media.
- * If a quantity of particles are found in the screen or filter, remove the torque converter for repair.
- * If the torque converter must be repaired, removed disassemble and inspect all torque converter valves. Clean the valve bodies and spools. It is important that the spools move freely in their bodies.
- * Make sure all orifices are clean and open. Inspect the charge and scavenge pumps for damage.
- * If the torque converter must be repaired, removed disassemble and inspect all torque converter valves. Clean the valve bodies and spools. It is important that the spools move freely in their bodies.
Transmission Tank (1), Converter, Hoist, and Brake Hydraulic Tank (2).
The off-highway truck has a split hydraulic tank. The transmission has a section and the torque converter shares a section with the brake and hoist system. If there should be a torque converter failure, the torque converter section of the tank should be cleaned similar to the transmission section. Also the brake and hoist system must be cleaned of all debris.
2. On off-highway trucks, tractor-scrapers and scrapers; remove the transmission filter, transmission scavenge screen and magnetic strainer assembly. Cut the filter element open and inspect the filter media.
- * If a quantity of particles is found in the screen and filter, remove the transmission for repair.
3. Remove the transmission hydraulic manifold and controls. Disassemble the control valves keeping each spool assembly separated. Clean the valve bodies and spools, making sure each spool moves freely in its body. Remove and clean the filter in the selector spool. Inspect the charge and scavenge pumps for damage.
4. On trucks that have return oil filters, remove the return oil filter cover and inspect the transmission oil filter element and screen.
- * If a quantity of particles is found in the element or screen, drain the transmission hydraulic tank.
NOTE: There can be contamination in the tank because the filters bypass the oil during a cold start and when the filters become clogged.
5. Drain the transmission hydraulic tank oil through a fine mesh screen, such as 4T2694 Screen. If there are particles in the screen, the screens on the inside of the tank must also be checked. See the procedure that follows.
NOTE: There is a possibility that the tank contains particles even if none appeared in the drained oil.
Cleaning Procedure
NOTE: The following guidelines are for the complete power train oil system.
1. Remove the major component, that is to be repaired, from the machine. Drain the oil from the hoses and tubes as they are removed. Check the oil cooler screen on machines so equipped.
2. Before reinstalling the repaired component, remove the other end of the tubes or hoses that were disconnected. Wash the inside of the lines with clean, filtered solvent. Air dry the lines, plug both ends and set aside until needed for assembly.
3. Remove all filter elements from the power train side of the hydraulic tank. Clean the hydraulic tank, filter bypass valve and screens with clean filtered solvent. Install new filter elements. The correct element number is given in Step 11.
4. Remove, disassemble and clean all of the valves in the tank. Make sure all the passages are clean and all spools and puppets are free to move. Wash and wipe clean the walls of the tank.
5. Remove all screens, magnets and filter elements from the filter housings. Clean the screens, bypass valves and magnets. Wash and wipe clean the filter housing. Install new filter elements. The correct element number is given in Step 11.
6. Remove each tube or hose connected to the hydraulic tank. Remove the seals, clean the seals, ring grooves and the inside of the tube or hose with filtered solvent and air dry.
7. Locate all remote mounted filters or screens in the power train hydraulic system. Drain and clean all housings and screens. Install new filter elements and inspect all bypass valves for contamination.
8. Remove the power train pump and all lines fastened to it not previously removed. Disassemble the pump and inspect for any damage. Clean the pump and make any repairs. Clean all tubes and hoses.
9. If the power train oil cooler has contamination, remove it and all cooler lines. The oil cooler cannot be cleaned. Therefore, a replacement cooler must be installed. Clean all the tubes and hoses connected to the cooler.
10. Thoroughly clean all housings, parts, and valves to remove the debris. See the July 14, 1986 Service Magazine article on cleaning non-metallic friction material.
11. After all repairs have been made and all components installed, connect all tubes and hoses. Install new 6-Micron power train oil pressure filter elements in place of the standard elements.
12. Fill the power train hydraulic tank or reservoir with clean hydraulic oil. Fill the pump, if possible.
13. Check the Operation and Maintenance Guide for oil recommendations.
14. Start the engine and run it at low idle. Do Not run engine at high idle, as this will increase the possibility of opening the filter bypass valve. Run the engine at low idle for one hour. Stop the engine and remove the power train filters and screens.
| NOTICE |
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The 6-Micron filters can not be changed at the intervals given in the Operation and Maintenance Guide. They have a much lower sediment capacity and will bypass foreign material back into the system. |
15. Install clean 6-Micron filters and clean the screens. If no foreign material is found in the filter or screens return the vehicle to service. If any foreign material is found repeat Step 14.
16. Stop the vehicle on level ground and check the power train hydraulic tank oil level. Add oil if needed.
Follow Up Procedure
After a repair or cleaning operation, some foreign material can still be in the system. To keep the effect of this contamination at a minimum, check the filters and screens at shorter than normal intervals.
1. Clean all screens and install all new 6-Micron filters at one-half shift time and at the end of the first shift.
| NOTICE |
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The 6-Micron filters can not be changed at the intervals given in the Operation and Maintenance Guide. They have a much lower sediment capacity and will bypass foreign material back into the system. |
2. When no foreign material is found and there are no operation problems, install the regular service filter.
3. If any foreign material is found, locate the cause of contamination and perform additional cleaning, if necessary. Check the screens and filters at shorter intervals than given above.