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How Many Gears Does a Semi-truck Have?

Whether you call it a big rig or a semi, the semi-trailer truck is an unbelievable feat of modern engineering and an intrinsic element to our infrastructure in almost every industry. But how do semi-trucks manage to stay so reliable and effective as they cross the country? It starts with highly specialized engine blocks with transmissions designed to keep the engine at the most efficient speed, hence the advanced series of semi-truck gears.

So, how many gears does a semi-truck have? It ranges from nine all the way up 18, though commonly semis will have two reverse gears and ten forward gears. Read on with the International Used Truck Centers specialists to get the full story.

The Finer Points of Semi-Truck Gears

The size and function of the engine determine, in part, the number of gears in a transmission. For semi-truck gears, they need to be able to define a narrow range of power and maneuverability to best utilize the frankly astounding power output of the engine they manage. The answer to “How many gears does a semi-truck have?” depends mostly on this incredible power of a semi’s engine.

For instance, trucks at the higher end of the range will likely use 18-gear transmissions to keep the engine running at optimal speed, even from idling up to highway speed. To prevent each gear from requiring higher RPMs, which would mean less fuel efficiency and more wear, a range of gears and split-gears are available to keep the truck and driver safe and functioning at their best.

The Range of Semi-Truck Engines

The engines of your semi-truck fleet will be attuned to the semi-truck’s classification, such as Class 5 and Class 6 for lighter-duty work or Class 8 like the Cummins ISX for much more serious trailering in 18-wheelers. Below are a few more things to keep in mind about the semi-truck engines:

  • Semi-truck engines should only be stopped for a few reasons, which is in stark contrast to passenger cars. Learn how to reduce fuel consumption while idling as you head to your next destination.
  • Although about six times larger than the average passenger car engine, semi truck engines aren’t particularly more complex–just expertly engineered for their high-power purposes.
  • You can expect that semi-truck horsepower ranges from 400 to 600 hp, while average lb-ft of torque ranges from an impressive 1,000 to a staggering 2,000.
  • The engines inside semi trucks can hold about 15+ gallons of oil. Compare this to the mere 4 to 6 quarts held by passenger car engines.

Learn More With the Semi-Truck Specialists at International Used Truck Centers

We’ve answered “How many gears does a semi-truck have?” but that’s only the beginning. While the immense power of semi-truck engines can scare off potential drivers, operating these machines comes down to understanding how they work. We’re here to help you every step of the way, whether you’re a longtime veteran or just getting your CDL. Contact us at International Used Truck Centers to stay up-to-date with all the latest and to find the heavily vetted and well-maintained semi-truck selection you need for your fleet.

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International Used Truck Centers 41.776180, -88.200918.