What is the working principle of the reverse gear in a transmission?
3 Answers
The working principle of the reverse gear in a transmission varies depending on the type: 1. For manual transmissions, the reverse gear works by shifting the gear lever to switch the driving gear on the intermediate shaft, engaging different gear combinations with the power output shaft to alter the torque and speed of the driving wheels. 2. For automatic transmissions, the reverse gear operates using a planetary gear mechanism to change speed automatically based on the degree of throttle pedal pressure and vehicle speed changes, requiring the driver to only control the speed via the accelerator pedal. The functions of a transmission include: 1. Changing the transmission ratio to expand the range of torque and speed variations for the driving wheels. 2. Enabling reverse driving without altering the rotation direction of the engine crankshaft. 3. Interrupting power transmission to the driving wheels during engine start, idle operation, gear shifting, or when stopping to output power. 4. Allowing neutral gear, where the transmission does not output power when the clutch is engaged.
I learned the principle of reverse gear in transmissions from a mechanic friend. Simply put, in manual transmissions, the reverse gear is ingeniously designed. The engine power is transmitted through the main shaft to the gearbox, but an additional idler gear is inserted in between, converting the original clockwise rotation into counterclockwise output, causing the wheels to move backward. In automatic transmissions, the direction is changed by combining planetary gear sets, with the hydraulic system controlling different rotation modes of the planetary gears to achieve reverse motion. Reverse gear doesn’t change the engine's direction—the engine still rotates forward—but the gear system cleverly reverses the power path. This design prevents accidental gear engagement at high speeds, which could lead to accidents, so most vehicles require pressing a button or lifting a collar to shift into reverse. Remember, reverse gear is frequently used, but don’t switch to it before the car comes to a complete stop to avoid damaging the gears. Additionally, older models might experience sluggish reverse gear engagement, signaling you to check the transmission fluid level or worn components to ensure safe reversing.
As a frequent driver, shifting into reverse is part of my daily routine. In a manual transmission vehicle, I need to press the clutch pedal and move the gear lever to the R position. At this point, the idler gear inside the transmission changes direction, allowing power to be transmitted in reverse to the wheels. For automatic transmissions, simply shifting to D or R allows the vehicle's computer to automatically reverse the direction through the planetary gear set. The core principle of reverse gear is to create a reverse path through gear combinations—while the engine output moves forward, the gear system causes it to act in reverse on the wheels. When driving, extra caution is needed when reversing to ensure no people or obstacles are nearby, using mirrors and cameras for assistance. Reverse gear is designed for convenience in daily parking and turning, but it should not be misused. For example, when reversing on a slope, the handbrake should be engaged for safety. Gear wear can lead to difficulty engaging reverse or unusual noises. Regular maintenance of transmission fluid can extend the lifespan of the reverse gear mechanism.
