4th Gear

WARNING: This page is about a different car, the 2008 Acura TSX, 2007 Acura TSX, 2006 Acura TSX, 2005 Acura TSX, and 2004 Acura TSX. However, it is still accessible from the selected car via links, so may be relevant.

Hydraulic pressure is applied to the servo valve to engage the reverse selector with the countershaft 4th gear and reverse selector hub while the shift lever is in forward range (D, D3, and M positions).
Hydraulic pressure is also applied to the 4th clutch, then the 4th clutch engages the mainshaft 4th gear with the mainshaft.
The mainshaft 4th gear drives the countershaft 4th gear and the countershaft.
Power is transmitted to the final drive gear, which in turn drives the final driven gear.

Fig 1: 4th Gear Power Flow Diagram
Courtesy of AMERICAN HONDA MOTOR CO., INC.