The gears of the reducer can be made according to two different technological methods (with two or five undercuts). Gears with two undercuts are marked with a circular groove along the ends of the teeth at the driven gear and a circular groove along the body of the drive gear shaft. The tooth contact patch configuration for both types of gears is slightly different: with an inclination from the top to the root of the tooth (two undercuts) and without this slope (five undercuts). Regardless of the type of gears, the contact patch must be located symmetrically with respect to the midline of the tooth. The position of the contact patch is affected by the gap in the engagement and the position of the drive gear of the gearbox.
Verification procedure
1. Wash the differential cup and gear rims of both reduction gears. There should be no traces of oil on these parts.
2. Tighten bolts of covers of lateral bearings of differential the regulated moment.
3. Apply the parking brake so that the gearbox rotates when a torque of 14 Nm is applied.
Warning: Testing with no load on the gearbox will not give a correct result.
4. For economical application of marking paint, use a medium hard brush. Apply paint to all teeth of the driven gear.
5. Rotate the drive gear until the driven gear has completed three complete turns.
6. Rotate the drive gear in the reverse direction so that the driven gear has completed three complete turns.
7. Compare the contact patch configuration with the examples shown in the figures.
Correct Configuration
Condition: Pinion position and mesh clearance are correct.
Correction: Not required.
Maintenance Recommendations: Loose seating of the pinion bearings or differential cup can cause the contact patch to change shape from tooth to tooth, which is still in its normal position. If so, check the preload of all bearings. If the preload is correct, there may be damage to parts and/or incorrect assembly.
Outward displacement on the working side of the tooth - inward displacement on the non-working side of the tooth
Condition: Incorrect mesh clearance. The driven gear is moved away from the drive gear.
Correction: Reduce the clearance in the engagement. Move the driven gear towards the drive gear by replacing the differential side bearing shim.
Inward displacement on the working side of the tooth - outward displacement on the non-working side of the tooth
Condition: Incorrect mesh clearance. The driven gear is moved to the drive gear.
Correction: Increase mesh clearance. Move the driven gear away from the drive gear by replacing the differential side bearing shim.
Outward displacement on the working side of the tooth - outward displacement on the non-working side of the tooth
Condition: Incorrect mesh clearance. The driven gear is moved away from the drive gear.
Correction: Reduce the clearance in the engagement. Move the driven gear towards the drive gear by replacing the differential side bearing shim.
Inward displacement on the working side of the tooth - inward displacement on the non-working side of the tooth
Condition: Incorrect mesh clearance. The driven gear is moved to the drive gear.
Correction: Increase mesh clearance. Move the driven gear away from the drive gear by replacing the differential side bearing shim.
Offset to the top of the tooth
Condition: Drive gear moved away from driven gear.
Correction: Move the drive gear towards the driven gear by increasing the thickness of the drive gear shim.
Offset to the root of the tooth
Condition: The drive gear is moved to the driven gear.
Correction: Move the drive gear away from the driven gear by reducing the thickness of the drive gear shim.