Gearbox maintenance means your lorry will be off the road, so when picking whether you want an automated manual gearbox or a non-synchro gearbox, downtime is a factor. But there are other factors, too (some of which we’ve covered in this article).
Typical maintenance schedule on an AMT gearbox
This is an example of a potential schedule for maintenance on an AMT gearbox. Some of the tasks are done less frequently than with non-synchro gearboxes, so servicing costs can be cheaper if nothing goes wrong, but AMTs are more expensive to repair.
| Maintenance Task | Frequency | Description |
|---|---|---|
| Oil Changes | Every 250,000-300,000 miles or as per manufacturer | Replace transmission fluid with specified type |
| Filter Replacement | With every oil change | Replace internal transmission filter |
| Clutch Inspection | Every 100,000-150,000 miles | Check for wear and adjust if necessary |
| Software Updates | As released by manufacturer | Update ECU software for improved performance |
| Wiring Harness Inspection | Annually | Check for corrosion, loose connections, or damage |
| Sensor Calibration | As needed or during major service | Ensure accurate readings for optimal operation |
| Actuator Inspection | Every 200,000 miles | Check pneumatic or hydraulic actuators for wear |
| Leak Checks | During routine service | Inspect for oil leaks around seals and gaskets |
| Lubrication | As per manufacturer’s schedule | Grease external components if applicable |
| Clutch Hydraulics | Every 50,000 miles | Check and possibly replace clutch fluid |
Following the manufacturer’s recommended maintenance schedule will help prevent costly breakdowns, and keeping the transmission’s external parts clean can help detect leaks or other issues early.
Regular oil analysis can help determine if oil changes are needed more frequently based on operating conditions. Using the correct type of transmission fluid is crucial for proper operation and longevity.
Trucks operating in extreme conditions (very hot, cold, or dusty environments) may require more frequent maintenance.
Regular diagnostic scans can identify potential issues before they become major problems. Many AMTs have built-in diagnostic capabilities that can alert drivers or technicians to potential issues.
Encouraging drivers to report any unusual behaviour (rough shifting, unusual noises, etc.) can help catch issues early.
Technicians may require specialised training to properly maintain and repair AMTs due to their complexity. Manufacturers occasionally release hardware upgrades that can improve reliability or performance.
Typical maintenance schedule on a non-synchro gearbox
| Maintenance Task | Frequency | Description |
|---|---|---|
| Oil Changes | Every 50,000-100,000 miles or annually | Replace transmission fluid with specified type |
| External Inspection | Every 10,000-15,000 miles | Check for leaks, damage, or loose components |
| Clutch Adjustment | Every 20,000-30,000 miles | Check and adjust clutch free play |
| Linkage Lubrication | Every 5,000-10,000 miles | Grease shift linkage and pivots |
| Shift Pattern Check | Every 50,000 miles | Ensure smooth shifting through all gears |
| Bearing Inspection | Every 100,000 miles | Check for unusual noise or wear |
| Synchronizer Rings Check | Every 100,000 miles | Inspect for wear (if applicable to some gears) |
| Gasket and Seal Inspection | During oil changes | Check for leaks and replace if necessary |
| Gear Oil Analysis | Every other oil change | Analyze oil for metal particles and contaminants |
| Clutch Inspection | Every 50,000-75,000 miles | Check clutch disc, pressure plate, and release bearing |
Using the correct grade and type of transmission oil is crucial for proper lubrication and heat dissipation; some older non-synchro gearboxes may use straight mineral oil instead of modern multi-grade oils.
Proper double-clutching technique can significantly reduce wear on the transmission components. Gearbox training for HGV drivers, and awareness of the problems that can be caused by floating gears, not block shifting, and other poor examples of use can be considered part of the “maintenance” program.
While not always equipped with temperature sensors, monitoring transmission temperature (if possible) can prevent overheating and excessive wear. Regular checks for unusual noises or vibrations can help identify issues early. Any changes in shift quality or increased difficulty in engaging gears should be investigated promptly.
The clutch system is integral to the operation of a non-synchro gearbox and should be maintained according to manufacturer specifications.
Maintenance intervals may need to be adjusted based on operating conditions (e.g., frequent starts and stops, heavy loads, extreme temperatures).
Unlike more modern transmissions, non-synchro gearboxes are often rebuilt rather than replaced. A full rebuild might be considered after 500,000 to 1,000,000 miles, depending on usage and wear.
Darren has owned several companies in the automotive, advertising and education industries. He has run driving theory educational websites since 2010.