Automatic gearbox (Description): Description and operation

DESCRIPTION

The automatic transmission is a specially tailored version of the ZF 4HP22, used by many manufacturer’s of high performance vehicles.

A three element torque converter delivers the power to a four speed epicyclic transmission. First, second and third gears are reduction ratios but fourth is an overdrive gear for high speed cruising. A direct drive clutch, integral with the torque converter operates to engage fourth gear.

The gear selector has seven positions as follows:

P = Park provides a mechanical lock on the output shaft. R = Reverse gear. N = Neutral. D = Provides a 1st gear start and automatic shifts 1-2-3-4-3-2-1. 3 = Provides a 1st gear start and automatic shifts 1-2-3-2-1. 2 = Provides a 1st gear start and automatic shifts 1-2-1 or 3-2-1. 1 = Provides a 1st gear start with no up shifts, or 3-2-1.

All automatic shifts are automatically controlled by the valve block and an hydraulic governor driven by the output shaft.