How do the maintenance requirements differ on automated manual gearboxes vs non-synchro gearboxes?

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.