Epicyclic Gear Box or Wilson Gear Box:

The epicyclic gear box is illustrated in Figure. It provides four forward speeds and one reverse speed. The two sun wheels S₁ and S₂ are keyed to the input shaft through the engine. There are four internal gears such as I₁, I₂, I₃ and I_r. P₁, P₂, P₃ and P_r are planet gears. B₁, B₂, B₃ and B_r are brake bands that are utilized to lock several internal gears. G and F give cone clutch arrangement. For applying I gear, the brake band B₁ is applied to lock annulus I₁. The power is transmitted through simple epicyclic gear train consisting S₁, P₁ and I₁.

For II gear, just the brake band B₂ is applied so that annulus I₂ is locked. The power is transmitted from the compound epicyclic gear train S₂, P₂, I₂ and S₁, P₁, I₁.

For III gear, just the brake band B₃ is applied so that sun gear S₃ is locked. The power is transmitted from three epicyclic gear trains S₃, P₃, I₃; S₂, P₂, I₂ and S₁, P₁, I₁.

For top gear, cone clutch is engaged to avoid a relative motion and it shall make output shaft D to rotate at similar speed equivalent to that of input shaft E.

For reverse gear, just the brake band B_r is applied to lock annulus I_r.

Epicyclic Gear Box