Multiple-gear-ratio portal gear box
A portal gear box assembly effective to lift and change the gear ratio of a wheel of an off-road vehicle includes a housing, an input gear sub-assembly, an output gear sub-assembly, and an idler gear sub-assembly effective for linking the input gear to the output gear. The input gear sub-assembly includes an input gear, the output gear sub-assembly includes an output gear, and the idler gear sub-assembly includes at least one idler gear and at least one removable adaptor effective for holding the idler gear in either a first position or a second position different from the first position. The sub-assemblies may also include bearings to facilitate movement of the gears.
1. A portal gear box assembly for an off-road vehicle that includes a driven shaft, the assembly comprising:
a housing that defines an first indent, an second indent, a third indent and a fourth indent;
a first gear subassembly comprising a first gear operably connected to the driven shaft, wherein the first gear subassembly is positioned within the first indent;
a second gear subassembly comprising a second gear operably connected to an output shaft, wherein the second gear subassembly is positioned within the second indent; and
the idler-gear subassembly comprising a removable adaptor and a third gear connecting the first gear to the second gear;
wherein the removable adaptor is selectively positionable in either the third indent or the fourth indent to change a position of the third gear in the idler-gear subassembly relative to the first gear and second gear, thereby permitting use of gears with different diameters and different numbers of teeth to alter a transmission ratio between the driven shaft and the output shaft.
2. The portal gear box assembly of claim 1 , wherein the transmission ratio between the driven shaft and the output shaft is adjustable by swapping the position of the first and second gears so that the first gear is connected to the output shaft in the second indent and the second gear is connected to the driven shaft in the first indent.
3. The portal gear box assembly of claim 2 , where the transmission ratio between the driven shaft and the output shaft is further adjustable by changing the size of the third gear.
4. The portal gear box assembly of claim 1 , wherein the third gear has fewer teeth than both the first gear and the second gear.
5. The portal gear box assembly of claim 1 , wherein the third indent is positioned on a first side of an axis running through the first and second indents and the fourth indent is positioned on a second side of the axis, opposite the first side.
6. The portable gear box assembly of claim 1 , wherein the removable adaptor has an outer profile that defines a circular shape.
7. The portable gear box assembly of claim 1 , wherein a distance between the second indent and the third indent is different than a distance between the second indent and the fourth indent.
8. The portable gear box assembly of claim 1 , wherein the portable gear box is adapted for use on an all-terrain vehicle (ATV) or a utility task vehicle (UTV).
9. A method for changing the transmission ratio of a portal gear box, the method comprising:
removing at least one of the first gear and/or the second gear from the claim 1 portal gear box assembly;
replacing the at least one removed gear with a different gear;
moving the idler-gear subassembly to a different third or fourth indent thereby permitting use of first and second gears with different diameters and different numbers of teeth to alter a transmission ratio between the driven shaft and the output shaft.
10. The method of claim 9 , further comprising removing and replacing both the first gear and second gear with different gears defining a different diameter and/or a different number of teeth.
11. The method of claim 9 , further comprising swapping the position of the first and second gears.
12. A portal gear box kit with an adjustable transmission ratio, the portal gear box kit comprising:
a housing that defines a first indent, a second indent, a third indent and a fourth indent;
a first gear adapted to couple to a driven shaft extending through the first indent;
an output shaft adapted to extend through the second indent;
a second gear adapted to couple to the output shaft;
a removable adaptor adapted to be selectively positioned in either the third indent or the fourth indent;
a third gear adapted to couple to the removable adaptor;
wherein positioning the removable adaptor in either the third indent or the fourth indent changes a position of the third gear coupled to the removable adapted relative to the first indent and the second indent thereby permitting use of first and second gears with different diameters and different numbers of teeth to alter a transmission ratio between the driven shaft and the output shaft when the kit is assembled as a portal gear box.