Systems and methods for gearbox and geardrive assemblies

1 . A gearbox assembly, comprising:

a gearbox including:

a worm housing; and

a cover configured to engage with the worm housing to define a housing interior between the worm housing and the cover;

a worm shaft located at least partially within the housing interior;

a worm gear located within the housing interior and operably engaged with the worm shaft, the worm gear having a central bore, a first axial face, and a second axial face;

a gearbox shaft that extends along a gearbox shaft axis;

a torque limiter positioned between central bore of the worm gear and the gearbox shaft to inhibit relative rotation between the worm gear and the gearbox shaft when a relative torque between the worm gear and the gearbox shaft about the gearbox shaft axis is below a maximum torque and to permit relative rotation between the worm gear and the gearbox shaft when the relative torque between the worm gear and the gearbox shaft about the gearbox shaft axis is at or above the maximum torque;

a first bearing operably engaged with the gearbox shaft at a first axial position along the gearbox shaft axis;

a second bearing operably engaged with the gearbox shaft at a second axial position along the gearbox shaft axis;

a first spacer adjacent to the first axial face of the worm gear; and

a second spacer adjacent to the second axial face of the worm gear;

wherein the gearbox shaft includes multiple axial segments and an axial rim face defined by the gearbox shaft between adjacent segments of the multiple axial segments;

wherein the first spacer is between the axial rim face and the first axial face of the worm gear;

wherein the second spacer is between the second bearing and the second axil face of the worm gear; and

wherein the torque limiter, the first bearing, and the second bearing are engaged with a respective axial segment of the multiple axial segments.

2 . The gearbox assembly of claim 1 , wherein an axial length of the torque limiter is about 0.25 to about 2 times a nominal diameter of the torque limiter.

3 . The gearbox assembly of claim 1 , wherein the housing interior contains only an oil-based lubricant.

4 . The gearbox assembly of claim 1 , wherein the housing interior contains both an oil-based lubricant and a grease-based lubricant.

5 . The gearbox assembly of claim 1 , wherein:

the multiple axial segments of the gearbox shaft include an axial segment defining a nominal segment diameter;

the torque limiter defines a nominal inner diameter; and

the nominal inner diameter of the torque limiter is about 1% to about 10% less than the nominal segment diameter before being engaged with the axial segment of the gearbox shaft.

6 . The gearbox assembly of claim 1 , wherein:

the central bore of the worm gear defines a nominal inner diameter;

the torque limiter defines a nominal outer diameter; and

the nominal outer diameter of the torque limiter is about 1% to about 10% more than the nominal inner diameter of the central bore before being engaged with the central bore of the worm gear.

7 . The gearbox assembly of claim 1 , wherein the worm gear defines a chamfered insertion edge proximate the central bore.

8 . The gearbox assembly of claim 1 , wherein:

one of the worm gear and the gearbox shaft defines multiple grooves;

the torque limiter defines contours;

the contours are seated with mating ones of the multiple grooves to inhibit relative movement between the torque limiter and the one of the worm gear and the gearbox shaft defining the multiple grooves.

9 . The gearbox assembly of claim 8 , wherein the contours are configured to resiliently compress within an elastic material property range of the torque limiter nominally radially inward when engaged between the worm gear and the gearbox shaft.

10 . A gearbox assembly, comprising:

a gearbox including:

a worm housing; and

a cover configured to engage with the worm housing to define a housing interior between the worm housing and the cover;

a worm shaft located at least partially within the housing interior;

a worm gear located within the housing interior and operably engaged with the worm shaft, the worm gear having a central bore;

a gearbox shaft that extends along a gearbox shaft axis;

a torque limiter positioned between central bore of the worm gear and the gearbox shaft to inhibit relative rotation between the worm gear and the gearbox shaft when a relative torque between the worm gear and the gearbox shaft about the gearbox shaft axis is below a maximum torque and to permit relative rotation between the worm gear and the gearbox shaft when the relative torque between the worm gear and the gearbox shaft about the gearbox shaft axis is at or above the maximum torque;

a first bearing operably engaged with the gearbox shaft at a first axial position along the gearbox shaft axis; and

a second bearing operably engaged with the gearbox shaft at a second axial position along the gearbox shaft axis;

wherein the gearbox shaft includes multiple axial segments;

wherein the torque limiter, the first bearing, and the second bearing are engaged with a respective axial segment of the multiple axial segments; and

wherein the multiple axial segments of the gearbox shaft further comprising:

a first axial segment that defines a first diameter;

a second axial segment adjacent to the first axial segment that defines a second diameter;

a third axial segment adjacent to the second axial segment that defines a third diameter, the third diameter is greater than the first diameter;

a fourth axial segment adjacent to the third axial segment that defines a fourth diameter, the fourth diameter is approximately the same diameter as the first diameter;

a fifth axial segment adjacent to the fourth axial segment that defines a fifth diameter, the fifth diameter is approximately the same diameter as the third diameter; and

a sixth axial segment adjacent to the fifth axial segment that defines a sixth diameter, the sixth diameter is approximately the same diameter as the first diameter.

11 . The gearbox assembly of claim 10 , further comprising:

a first spacer and a second spacer; and

a first axial face and a second axial face of the worm gear;

wherein the first spacer is adjacent to the first axial face of the worm gear; and

wherein the second spacer is adjacent to the second axial face of the worm gear.

12 . The gearbox assembly of claim 11 , further comprising:

an axial rim face defined by the gearbox shaft between adjacent segments of the multiple axial segments;

wherein the first spacer is between the axial rim face and the first axial face of the worm gear; and

wherein the second spacer is between the second bearing and the second axil face of the worm gear.

13 . The gearbox assembly of claim 10 , wherein the second diameter of the second axial segment and the third diameter of the third axial segment are approximately the same diameter.

14 . The gearbox assembly of claim 10 , wherein:

the first bearing is seated at the first axial segment;

the torque limiter is seated at the fourth axial segment; and

the second bearing is seated at the sixth axial segment.

15 . A gearbox assembly, comprising:

a gearbox including:

a worm housing; and

a cover configured to engage with the worm housing to define a housing interior between the worm housing and the cover;

a worm shaft located at least partially within the housing interior;

a worm gear located within the housing interior and operably engaged with the worm shaft, the worm gear having a central bore;

a gearbox shaft that extends along a gearbox shaft axis;

a torque limiter positioned between central bore of the worm gear and the gearbox shaft to inhibit relative rotation between the worm gear and the gearbox shaft when a relative torque between the worm gear and the gearbox shaft about the gearbox shaft axis is below a maximum torque and to permit relative rotation between the worm gear and the gearbox shaft when the relative torque between the worm gear and the gearbox shaft about the gearbox shaft axis is at or above the maximum torque;

a first bearing operably engaged with the gearbox shaft at a first axial position along the gearbox shaft axis; and

a second bearing operably engaged with the gearbox shaft at a second axial position along the gearbox shaft axis;

wherein the gearbox shaft includes multiple axial segments;

wherein the torque limiter, the first bearing, and the second bearing are engaged with a respective axial segment of the multiple axial segments; and

wherein the central bore of the worm gear defines multiple grooves in an inner surface of the central bore.

16 . The gearbox assembly of claim 15 , further comprising:

a spacer adjacent to an axial face of the worm gear; and

wherein the second bearing is adjacent to the spacer; and

wherein the respective axial segments define at least three discrete diameters.

17 . The gearbox assembly of claim 15 , wherein:

the multiple axial segments of the gearbox shaft define an axial rim face; and

an axial face of the worm gear is adjacent to the axial rim face.

18 . The gearbox assembly of claim 15 , wherein:

the worm gear defines a chamfered insertion edge proximate the central bore; and

the multiple grooves extend from the chamfered insertion edge along the inner surface.

19 . The gearbox assembly of claim 18 , wherein the multiple grooves define substantially parallel side edges.

20 . The gearbox assembly of claim 15 , wherein a maximum depth of the multiple grooves from the inner surface is about 180 to about 300 micrometers.