- Articulated Truck:
- 740 (S/N: AXM1-UP; B1P1-UP)
- 740 EJECTOR (S/N: B1R1-UP; AZZ1-UP)
Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, the solution that is identified below may be used if necessary.
Do not perform any procedure that is outlined in this Technical information Bulletin until you have read all the information that is contained in this Technical information Bulletin. The information must also be understood before you perform any procedure that is described in this Technical information Bulletin.
Problem
Erratic shifting of the transmission on the listed machines may be due to inconsistent measurements of the transmission output speed. This erratic shifting is noticeable only when the transmission is at the transmission's normal operating temperature.
The erratic shifts are a result of fluctuations in the measurements from the speed sensors at the transmission output yoke. There is no fault in the speed sensors. The fault is improper preload of the bearing race for the output yoke that allows the rotor for the sensors to slip. This causes the erratic signals from the speed sensors to the transmission ECM.
Solution
Check the rotor for the sensors. If the rotor is loose then the rotor is the cause of the problem. If the rotor for the sensors is loose then the preload of the bearing race must be reset. If the rotor for the sensors is not loose then the cause of the erratic shifting of the transmission must be investigated for other causes.
Procedure to Check the Rotor for the Sensors
ReferenceDisassembly and Assembly, RENR5139, "740 and 740 EJECTOR Articulated Trucks Power Train", "Speed Sensor (Transmission) - Remove and Install"
- Remove one of the speed sensors.
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| Illustration 1 | g01284983 |
- Use a suitable small screwdriver in order to contact the visible surface of the rotor. Attempt to use the screwdriver to move the rotor. If the rotor slips on the output yoke, then the preload of the bearing race needs to be reset. Refer to ""Procedure to Set the Preload for the Bearing Race" ".
- Reinstall the speed sensor that was removed in Step 1.
Procedure to Set the Preload for the Bearing Race
ReferenceDisassembly and Assembly, RENR5139, "740 and 740 EJECTOR Articulated Trucks Power Train", "Main Drive Shaft - Remove and Install"
ReferenceDisassembly and Assembly, RENR5139, "740 and 740 EJECTOR Articulated Trucks Power Train", "Speed Sensor (Transmission) - Remove and Install"
- Disconnect the main drive shaft from the transmission.
- Remove speed sensors (1) from retainer (3) .
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| Illustration 2 | g01285221 |
- Remove bolts (2) and the washers that secure retainer (3) to the transmission.
- Remove retainer (3) with yoke (4) from the transmission.
- Place retainer (3) with yoke (4) on a suitable work bench.
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| Illustration 3 | g01285220 |
- Remove bolts (6) that secure plate (7) to yoke (4). Remove the plate and shims (5) .
- Reinstall plate (7) and bolts (6). Do not tighten the bolts. Measure the gap between the plate and yoke (4) and record the measurement.
- Remove bolts (6) and plate (7) .
- Subtract 0.03 to 0.08 mm (0.0012 to 0.0031 inch) from the measurement that was recorded in Step 7. This will give the thickness of shims (5) that is required to set the preload of the bearing race.
Note: Additional shims (5) from 7G-1158 Shim Pack might be required if the existing shims are not adequately thick enough.
- Install shims (5), plate (7), and bolts (6) .
- Reinstall retainer (3) with yoke (4) into the transmission.
| | |
| Illustration 4 | g01285221 |
- Reinstall bolts (2) and the washers that secure retainer (3) to the transmission.
- Reinstall speed sensors (1) to retainer (3) .
- Reconnect the main drive shaft to the transmission.