Automatic Transmissions (week one)

  For the first week of transmissions we got to strip down a automatic transmission have a look at it and inspect it and then put it back together. We learnt the functions of most of the components in a transmission in practical and theory and how an automatic trans operates.

An automatic gear box is atype of veichle trans which can automatically change the gear ratios as the vehicle moves, this makes it easy for the driver to shift gears as he does not have to do it manually. To select the transmission operating mode, the driver moves a selection lever located either on the steering column or on the floor.

Funtion of the main parts in automatic trans:

Oil pump: The oil pump gives pressurized oil for the control systems in the transmission and also for cooling of the components and lubrication.

Torque converter:

 

Cars with an automatic transmission have no clutch that disconnects the transmission from the engine. Instead they use a torque converter. A torque converter is a type of fluid coupling, which allows the engine to spin independently of the transmission. 

There are four components inside the very strong housing of the torque converter:

•  Pump: The pump inside a torque converter is a type of centrifugal pump. As it spins, fluid is flung to the outside

•  Turbine is the driven member
•  Impeller is the driving member 
• Stator reverses the direction of the fluid. A one-way clutch (inside the stator) connects the stator to a fixed shaft in the transmission

The engine drives the impeller in the torque converter which in turn forces oil out in to the turbine. The tourqe will be moved down to the input shaft. There is a stator between the impeller and the turbine which redirects. The stator is there to redirect the oil flow as it enters the impeller and is also there to increase torque. This is so that the oil enters the impeller in the same direction as the impeller is turning

valve body controls the transmission the brain of automatic transmission. it connects to the oil pump, servo, clucth ,torque converter.There are two general types of valves, valves act on the shift valves at opposing ends of the valve to control the point at which

the transmission will shift gear.