4-Speed: Hydraulic Action by Range

Oil circuit diagrams and text for each range and shift: neutral, drive left first speed (the front unit is in reduction with the coupling empty and the rear unit in reduction through the rear sprag), reverse with the reverse blocker that stops reverse above about 10 mph, and forced downshifts. A forced 2-1 downshift is only possible below about 5 to 7 mph.

What this section covers

• Drive left and drive right shifts
• Reverse and reverse blocker
• Detent and forced downshifts
• Coupling and sprag states
• Governor and throttle valve oil