The transmission is a critical component in any on-road or off-road vehicle. The better your transmission works, the more of an engine’s power is translated to performance. Even if a powerplant has 800 horsepower, it won’t matter if those horses can’t reach the wheels.

But there are a lot of moving parts in a transmission, and they all need to work in harmony for your truck or SUV to go. Below, experts have explained what components are in a transmission for both manual and automatic designs. This will give you a better understanding of how a transmission works to help with upgrades and repairs.

Parts of a Manual Transmission

•          Flywheel — A metal disc made of extremely rigid metal. It’s what connects the engine to the clutch when the latter is engaged and also provides rotational mass.
•          Clutch — This connects the flywheel to the input shaft. When disengaged, the transmission rotates independently of the engine.
•          Clutch Pedal — A hydraulic part that is pressed to disengage the clutch.
•          Input Shaft — What drives the countershaft gears using power supplied by the engine.
•          Countershaft — Also called the layshaft, it contains an assortment of gears that connect to the output shaft gears and rotate constantly.
•          Gears — The parts that control the vehicle’s speed and torque. Bigger gears produce more torque while smaller gears have a higher top-end speed.
•          Output Shaft — The section that connects to the differential so power can be transferred to the wheels.
•          Selector Fork and Collars — Used to lock a gear in place so torque can be sent to the output shaft.
•          Dog Clutch — A special clutch permanently connected to the output shaft that engages it with the desired gear.
•          Synchronizers — A part with frictional plates that slow down gears so they’re running at the same speed as the output shaft and thus can be engaged.

Parts of an Automatic Transmission

•          Clutch — Like with a manual transmission, the clutch transfers power from the engine. However, the automatic transmission clutch pack has a drum with four discs that are squeezed together by a piston.
•          Gears — Modern automatic transmissions use a mechanical planetary gear design with a sun gear, planet gears and ring gear that interact to achieve the desired speed and torque.
•          Bands — Steel rings surrounding the clutch drum that tighten under pressure to stop the drum from turning so the vehicle can shift or stop.
•          Hydraulic System — Consists of a valve body, transmission fluid, oil pump, seals and gaskets to provide the needed pressure to control the clutch and bands. This is sometimes called the “brains of the transmission.”
•          Governor and Modulator — These decide when the gears will shift by monitoring the vehicle’s throttle position and speed.
•          Torque Converter — An “idling clutch” between the engine and gears that disengages the transmission when the vehicle is stopped so the engine doesn’t stall.

Advance Adapters has a large collection of off-road transmissions and components for DIYers. Shop for new transmissions, rebuilt transmissions, shifters, gears and other products to get the power you need.