How Big is a Transmission?

[DelHolden]

The size of a transmission varies significantly across different vehicle models. Additionally, there are differences between manual and automatic transmissions, as well as between imported and domestically produced ones. The engine displacement also affects the size. Transmission Introduction: A transmission is a gearbox that alters the gear ratio and the direction of motion. It is located between the clutch and the central drive. Functions of a Transmission: Its primary functions are: changing the driving force and speed of the vehicle (shifting gears) without altering the engine's speed and torque; enabling the vehicle to reverse (direction change); and allowing the engine to idle without stalling (neutral gear). Based on the transmission form, gear-type transmissions can be categorized into three types: dual-shaft, triple-shaft, and compound. The dual-shaft type has two main shafts (excluding the reverse gear shaft) and achieves speed reduction through a single pair of gears. The triple-shaft type has three main shafts (input shaft, intermediate shaft, and output shaft) and achieves speed reduction through two pairs of gears. The compound type consists of two transmissions connected in series or parallel, allowing for more gear positions with fewer gears.

[MarcusFitz]

When I ran my own auto repair shop, I frequently worked with transmissions. Typically, the transmission of a family sedan is about the size of a suitcase, measuring between half a meter to one meter in length and weighing anywhere from 70-80 to over 100 pounds. Automatic transmissions are larger than manual ones because they include additional components like the torque converter and hydraulic control system. I remember once disassembling a Japanese car's CVT transmission—the entire housing was about as wide as a computer tower, while German cars' dual-clutch transmissions were more compact. Nowadays, the single-speed transmissions in electric vehicles are as small as a shoebox, but traditional fuel-powered vehicles still require ample workspace during repairs, especially since transmissions are connected to the driveshaft and differential, taking up significant space during disassembly and installation.

[OSawyer]

Last time when helping a friend inspect a used car, I specifically researched transmission sizes. The transverse transmission in a typical front-wheel-drive car is about 60cm long, roughly the volume of a rolled-up yoga mat, weighing close to 100 pounds. The longitudinal transmission in rear-wheel-drive cars is about 10cm longer. I noticed American AT transmissions are particularly bulky, while Japanese manual transmissions are much more compact. To check for accident history, examine whether the space around the transmission in the engine bay appears orderly - if it's been deformed in a collision, it's very difficult to restore such a massive iron block to its original position during repairs.

[StevenAnn]

My car had its transmission replaced last year, and when it was lifted out, it looked like a small safe. The mechanic said the transmission for a compact car weighs about 40 kilograms, while those for mid-size SUVs are even heavier. Automatic transmissions are heavier due to the fluid, while manual ones are lighter but still weigh around 30 kilograms. Nowadays, electric vehicle transmissions are only about the size of a palm. The transmission was always the biggest headache for old gasoline car repairs. You can always see a few dismantled transmissions lying in the repair shop's pit, taking up most of the space.

[SanJames]

During a visit to an automobile factory, I observed the transmission production line and noticed significant differences among various models. The transmission used in compact cars is about the size of a microwave oven, while those for off-road vehicles can be as large as a small refrigerator. The engineers mentioned that the most challenging part of the design is fitting so many gears into a limited space. Automatic transmissions require additional space for hydraulic oil passages, making them bulkier than manual ones. Nowadays, many manufacturers use aluminum alloy casings to reduce weight, but veteran mechanics still complain about back pain when handling them during repairs—after all, metal components are notoriously heavy.