What makes it go, faster

The transmission gives power to the wheels


Components of the Transmission

Did you ever wonder how the transmission works?  Let me explain it to you.

The components of the transmission consist of:

  • Clutch
  • Torque converter
  • Gears
  • Shift lever
  • Synchronizer
  • Driveshafts

The transmission is a device for transmitting power from the engine to the wheels. The transmission converts power from the high RPM and low torque of the engine to the lower speeds and higher torque needed by the wheels to drive the car.

The crankshaft of the engine is connected to the transmission through the CLUTCH or TORQUE CONVERTER. The two basic kinds of transmission are MANUAL, where the driver selects the gear, and the AUTOMATIC, where the transmission selects the appropriate gear ratio for varying loads.

The standard transmission converts the engine power by means of a system of gears. The gears provide a variety of ratios between the engine and the wheels. When starting the vehicle from a stop, the transmission is placed into low, or first gear in order to produce high torque at slow wheel speed. As the car accelerates, the transmission is shifted into a higher gear. With each higher gear, the wheels turn faster but with less power and torque. For instance, 1st gear has a ratio of about 3:1. That is the crankshaft turns three times for every one revolution of the wheel. 2nd gear is about 2:1. 5th gear is approximately 1:1. Different vehicles have different gear ratios depending on vehicle weight and power output of the engine.


Detailed view of the Transmission

The driver selects gears by manipulating a SHIFT LEVER. The shift lever is connected to the transmission by a mechanical linkage. Manual transmissions are sometimes called synchromesh transmissions, in which SYNCHRONIZERS allow the gear teeth to be in constant mesh, turning freely on their shafts. The shifting action causes the gears to turn the same speed and synchronizes the combination of gears to the same speed, then locks them together so that power is transmitted through them to the wheels.

The DRIVESHAFTS are designed to transmit the torque of the engine through the transmission to the wheels. The driveshafts consist of a thick rod that has a knuckle on each end. Each knuckle contains a precision bearing covered by a rubber boot, that is designed to swivel about eight to ten degrees in all directions. This swivel allows the suspension to move up and down freely, transmitting the power of the engine to the wheels at all times. The sealed boot covering the knuckle contains grease that lubricates the bearings constantly. The knuckles on an axle are also known as “constant velocity joints” because the velocity on one end of the shaft is exactly the same as the other end.

Automatic transmissions use a torque converter to transmit power from the engine to the wheels. The torque converter is a fluid coupling in which one rotating member causes the transmission fluid to rotate. The fluid, in turn, rotates another member that is connected to the transmission. The torque from the torque converter is flexible, allowing slippage when the car is stopped and the wheels are not moving. As the car gains in speed, the slippage is reduced, and at cruising speeds the drive member turns almost as fast as the driven member does. The transmission contains a set of gears with clutches for engaging the desired gears. In later model cars, a computer selects the optimum gear ratio for all driving conditions. For optimum longevity of your transmission, when  starting cold, shift from PARK to DRIVE first, then REVERSE if necessary. This is recommended because the transmission clutches are pressurized more rapidly when the transmission is shifted to DRIVE first. The clutches in the transmission will last longer if this becomes a habit.

Honda has developed a new design of automatic transmission called a CVT (constant velocity transmission). This transmission has no gears at all. It uses a multilink chain between two varying diameter pulleys. This results in a transmission that delivers maximum power through the entire power range of the engine, thereby increasing mileage considerably, and making for a very smooth acceleration.

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