4th GEAR

WARNING: This page is about a different car, the 2013 Subaru Forester, 2012 Subaru Forester, 2011 Subaru Forester, and 2010 Subaru Forester. However, it is still accessible from the selected car via links, so may be relevant.

When the 4th gear is selected, the high clutch and the 2-4 brake are engaged. The engaged high clutch causes the front planetary carrier to rotate, whereas the engaged 2-4 brake causes the front sun gear to be locked to the transmission case.

The front planetary carrier rotates at the same speed as the input shaft. The rotation of the front planetary carrier causes the front pinion gears to revolve around the stationary front sun gear, which causes the front internal gear to rotate faster than the input shaft.

As a result, the reduction drive shaft is driven at a higher speed than the input shaft.

In the 4th gear, the one-way clutch is freewheeling because the low clutch is rotating clockwise. Since the drive power is transmitted without passing through the one-way clutch, the backward driving force from the wheels is transmitted through the reduction drive shaft to the input shaft; this makes the engine braking effect available.

Operating condition of components

2-4 brake: engaged
High clutch: engaged

Power flow (in acceleration)

Fig 1: Identifying Gear Train Components (4th Gear)

Courtesy of SUBARU OF AMERICA, INC.