should have its automatic transmission fluid and filter changed on a regular schedule, based on the manufacturer's specifications for severe service. Ensure the vehicle is on level ground or a lift and let the oil drain into a proper catchment device.

The draining of the transmission can be accomplished in one of the following three ways:

1. Removing the drain plug

2. Loosening the dipstick tube

3. Removing the oil pan

CAUTION

Oil drained from automatic transmissions contains heavy metals and is considered hazardous waste and should be disposed of according to local naval station instructions.

Once the oil is drained, remove the pan completely for cleaning by paying close attention to any debris in the bottom of the pan. The presenceofa high amount of metal particles may indicate serious internal problems. Clean the pan; set it aside.

All automatic transmissions have a filter or screen attached to the valve body. The screen is cleanable, whereas the filter is a disposable type and should always be replaced when removed. These are retained in different ways: retaining screws, metal retaining clamps, or O rings made of neoprene. Clean the screen with solvent and use low-pressure air to blow-dry it. Do not use rags to wipe the screen dry, as it tends to leave lint behind that will be ingested into the hydraulic system of the transmission. If the screen is damaged or is abnormally hard to clean, replace it.

Draining the oil from the pan of the transmission does not remove all of the oil - draining the oil from the torque converter completes the process. To do this, remove the torque converter cover and remove the drain plug, if so equipped. For a torque converter with-out a drain plug, special draining instructions may be found in the manufacturer's service manual. Before performing this operation, clear it with your shop supervisor.

Refilling the Transmission

Reinstall the transmission oil pan, the oil plug, and the fill tube. Fill the transmission with the fluid prescribed by the manufacturer to the proper level. With the brakes applied, start the engine and let it idle for a couple of minutes. Move the gear selectorthrough all gear ranges several times, allowing the fluid to flow through the entire hydraulic system to release any trapped air. Return the selector lever to park or neutral and recheck the fluid level. Bring the fluid to the proper level. Run the vehicle until operating temperature is reached, checking for leaks. Also, recheck the fluid and adjust the level as necessary.

CAUTION

Overfilling an automatic transmission will cause foaming of the fluid. This condition prevents the internal working parts from being properly lubricated, causing slow actuation of the clutches and bands. Eventual burning of the clutches and bands results. DO NOT OVER- FILL AN AUTOMATIC TRANSMISSION.

REVIEW 3 QUESTIONS

Q1. In a vehicle equipped with an automatic transmission, operator control is limited to the selection of the gear range by moving a control lever. (T/F)

Q2. In a torque converter, when does torque multiplication occur?

Q3. What is the purpose of the stator in the torque converter?

Q4. What are the three members of a planetary gearset?

Q5. What is thepurpose of the multiple-disc clutch in an automatic transmission?

Q6. Where is the hydraulic pump of an automatic transmission located?

TRANSAXLES

Learning Objective: Identify components of the manual and automatic transaxles. State the differences between transmissions and transaxles.

A transaxle is a transmission and differential combination in a single assembly. Transaxles are used in front-wheel drive vehicles. A transaxle allows the wheels next to the engine to propel the vehicle. Short drive axles are used to connect the transaxle output to the hubs and drive wheels.

Vehicle manufacturers claim that a transaxle and front-wheel drive has several advantages over a