1. Service Engineering Synchronizer Maintenance

2. Service Engineering Synchronizer: What is it? The Synchronizer is a device that helps match engine speed (input shaft) Engine RPM’s Axles/Tires Road Speed to road speed (output shaft), allowing easy engagement of the collar and gear.

3. Service Engineering Synchronizer: What is it? Types of Synchronizers Driver –Driver performs synchronization to complete main box shifts. Mechanical Device –Mechanical device in range box completes range shift synchronization.

4. Service Engineering Synchronizers: What is it? Driver Lever shifts require the driver to be the synchronizer –Speeds are synchronized by double clutching (3 step process). The first clutching is to reduce torque on the collar, so the collar can easily be slid out of gear. The driver then changes the engine (input) speed to match the road (output) speed. (synchronizing) When the speeds are matched, he clutch again (reduce torque) and moves the collar into gear.

5. Service Engineering Synchronizer: What is it? Mechanical Synchronizer Shift collar with friction material discs on both sides of the collar. Shift collar is centered between the friction material discs by six pins. When the collar is shifted, the appropriate friction discs engage the mating gear to synchronize the shift. Shift collar engages when synchronization of speeds (input vs. output) is achieved.

6. Service Engineering Synchronizer: What is it? Component Identification Auxiliary Low Gear Auxiliary Low Friction Disc Range Shift Collar Auxiliary High Friction Disc Auxiliary High Gear Guide Pins (6 Total) Springs (3 Total)

7. Service Engineering What happens when I shift from Low to High Range? 1. Driver Pre-selects, then moves main box collar to Neutral (No Torque). 2. Shift collar and High Friction Disc move forward. Shift collar is stopped at the blocker. The High Friction Disc engages the cone of the auxiliary high gear. 3. High Friction Disc synchronizes gear and collar. Once synchronized the speed overcomes spring force holding the shift collar at the blocker. 4. When the speed is synchronized, collar overcomes the blocker and engages gear. Main box still in Neutral (No Torque). 5. Main box collar is shifted into gear. Torque is reapplied.

8. Service Engineering Types of Synchronizer Failures Burned Material Stepped Teeth Broken PinsWorn Clutching Teeth Worn Forks

9. Service Engineering General Synchronizing Failure Causes Worn Teeth – Worn Forks Improper Clutch Adjustment Shifting without the clutch (float shifting) Not matching engine speed to road speed (i.e. not synchronizing)

10. Service Engineering General Synchronizing Failure Causes Stepped Teeth Torsional Vibrations can cause a step to be formed on the clutch collar These vibrations come from the engine, driveline or both

11. Service Engineering Synchronizer Failure Corrections Worn Teeth – Worn Forks – Stepped Teeth Properly adjust the clutch and check adjustment on a regular scheduled interval Shift using the double clutching technique and modulate the engine RPM to match road speed Spec vehicles with a LTD (soft damp) clutch Maintain proper ride height and proper driveline angles Pre-select Range Shifts

12. Service Engineering Range Synchronizer Failures Two Types BurnedBroken Pin

13. Service Engineering Range Synchronizer Failures Burned Heat is generated due to friction between the synchronizer ring and cone while torque is being applied to system Excessive heat can cause the cone angle to change Friction material does not always appear to be worn- out Cone Ring

14. Service Engineering Range Synchronizer Failure Corrections Burned Driver must Pre-select all Range Shifts. Pre-selecting gives the synchronizer the maximum amount of time. The synchronizer is then able to complete the shift prior to gear engagement. Do not try to “beat the shift” with rapid gear changes. Verify proper function of the neutral switch.

15. Service Engineering Range Synchronizer Failures Broken Pins What is this caused by? Torsional Vibrations –Vibrations are transmitted through the drive train. –Vibrations are caused by: Improper Driveline Angles Improper Ride Height Improper Driveline Phasing Improper Axle Angle

16. Service Engineering Range Synchronizer Failures Broken Pins Torsional Vibrations, if large enough, are capable of overcoming the spring force of the synchronizer. 1.When this occurs a constant “banging” of the collar occurs on the pins. 2.The “banging” creates recurring compressive and tensile stress loads on the pins. 3.Pins eventually fail due to high cycle fatigue.

17. Service Engineering Synchronizer Failure Corrections Check and Correct: 1.Driveline Angles 2.Ride Height 3.Driveline Phasing 4.Axle Angle 5.Driveshaft Balance

18. Service Engineering What if I need HELP?

19. Service Engineering Technical Support Center 800-535-5560  Driver Instruction  Technical Information  Advanced Troubleshooting and Diagnostics  Return Material Authorization  Warranty Approval  Parts Ordering Assistance  Fast Feedback to ZFM Engineering  Backup support from ZFM Service Engineer Technical Support Specialist

20. Service Engineering TSC Hours of Operation Monday - Friday  8:00 a.m. - 6:00 p.m.  All other times - Answering Service  TSC personnel available via pager and cell phone until 10:00 p.m. Saturday, Sunday & Holidays  Answering Service  TSC personnel available via pager and cell phone from 8:00 a.m. to 10:00 p.m.

21. Service Engineering Technical Literature Technical Bulletin No. 28 Maintenance Manual MM-96147 TMC RP-632

22. Service Engineering Driveline Angle Analysis Available in MM-96147

23. Service Engineering Electronic Vibration Analyzer 2

24. Service Engineering We Support…. Thank You