Rigidly attached (or integral) gears 5 and 6 slide along square guide a of shaft 1. When driving shaft 1 rotates, driven shaft 2 can have either of two speeds depending on whether gear 5 meshes with gear 3 or gear 6 meshes with gear 4. The corresponding transmission ratios are i₁₂=-z₃/z₅ and i₁₂=-z₄/z₆ where z₃, z₄, z₅ and z₆ are the numbers of teeth of gears 3, 4, 5 and 6.
$2844$CxG,SR$