If you operate a semi-truck for a living, it’s important to have a working knowledge of its transmission. Familiarity with this auto part ensures that you follow maintenance recommendations and schedule timely transmission repairs. The type of transmission depends on the truck you drive. Here are a few basic varieties you might encounter. 

What You Need to Know About Truck Transmissions

Why Are Transmissions So Important?

Think of your transmission as the truck’s wheel power regulator. It delivers the correct amount of power to the wheels in relation to how fast you are driving by shifting gears. The part also helps the truck deal with varying terrain. When you drive uphill, for example, you need more power than when you drive on a flat road.

Although manual transmissions used to be the norm, many semi-trucks now have automatic transmissions. Automatic varieties shift gears using planetary gearsets, clutches, and torque converters. If the vehicle features a manual transmission, you change the gears to accommodate different terrain and speeds using a clutch and moveable gear selector, with the latter part frequently called the stick shift.

What Are the Types Used in Trucks?

transmission repairCommercial trucks typically feature nonsynchronized transmissions compared to standard cars and trucks with synchronized transmissions. 

Unlike synchronized transmissions, which have a network of gears in a gearbox for easy shifting, nonsynchronized — or nonmeshed — transmission gears remain stationary while a select gear is used. Shifting requires increasing engine power and utilizing the one-way drive clutch so the new gear moves at the same speed as the gear in use. The clutch overruns during new gear engagement to avoid grinding actions and noises.

Engaging and disengaging the clutch may require more work; however, nonsynchronized models offer simplistic design and reliability that avoids frequent transmission repairs.


Rely on Northwest Truck Repair to provide efficient transmission repairs for your recreational or commercial truck. The Kalispell, MT-based business has served truck drivers since 1972, providing engine and transmission rebuilds, electrical repairs, and other services that keep your vehicle on the road. Call (406) 755-9762 today to schedule a consultation or learn more about transmission repair services online