Introduction

Each of the transmissions (all four-speed units) is of the same basic design. The main components are the torque converter (1), three-speed planetary gearbox (2), hydraulic control system (3) and overdrive (4th gear) unit (4). However, some differences do exist between the various types.

Transmission Assembly:

1. Torque converter
2. Planetary trains P1 and P2
3. Hydraulic control system
4. Overdrive unit P0 (4th gear)

The AW71 is a reinforced version of AW70, while AW72L affords different ratios by employing sun wheels of different diameters in planetary trains P1 and P2. Most AW72L transmissions are also equipped with a kickdown inhibitor between 3rd and 4th, as are some AW71s.

AW70 and AW71 are available either with or without mechanical locking of the torque converter (a function known as lock-up). Versions with this feature are designated AW70L and AW71L respectively. All AW72L units are equipped with lock-up.

Hydraulic System:

Means of controlling the mechanical power transmission system are required. This is provided by an hydraulic system. The system consists of the following main components: Hydraulic oil pump, centrifugal governor and control system (valve system). The control system is supplemented by three accumulator pistons which contribute to smoother gear shifting. For more information refer to "HYDRAULIC CONTROL SYSTEM". Description and Operation