Tensioning apparatus

1 . A tensioning apparatus for a belt, the tensioning apparatus comprising:

a pulley defining an outer surface to receive the belt;

a trolley including a mount configured to support the pulley for rotation, a first bushing, a second bushing, and an interior cavity;

a biasing member disposed within the interior cavity; and

an adjustable length arm assembly including a fixed-length portion and an adjuster portion, wherein the fixed-length portion includes a pivot mount for rotatably mounting the tensioning apparatus,

wherein the adjuster portion includes a fastener threaded to the fixed-length portion, and the adjuster portion includes an engagement member that engages and deforms the biasing member in response to adjustment of the fastener,

wherein the first bushing and the second bushing establish a sliding interface along an outer surface of the adjustable length arm assembly for movement of the trolley.

2 . The tensioning apparatus of claim 1 , wherein the mount is disposed on an outer surface of the trolley and is proximal to the second bushing.

3 . The tensioning apparatus of claim 1 , wherein the trolley includes

a main body,

a first end cap, and

a second end cap, wherein the first and second end caps partially close ends of the main body, and wherein the second end cap and the main body are constructed of a single piece.

4 . The tensioning apparatus of claim 3 , wherein the trolley includes a retaining ring and wherein the first end cap is received in the interior cavity between the biasing member and the retaining ring.

5 . The tensioning apparatus of claim 1 , wherein the adjuster portion includes a sleeve having a ledge, wherein the engagement portion contacts the ledge.

6 . The tensioning apparatus of claim 5 , wherein the fixed-length portion includes an arm having a flat portion fastened to the pivot mount, wherein the pivot mount includes a key, and wherein the flat portion is configured to face the key.

7 . The tensioning apparatus of claim 1 , wherein the pivot mount defines a pivot axis and wherein the pivot mount includes a plurality of flanges that extend radially outward relative to the pivot axis.

8 . The tensioning apparatus of claim 1 , wherein the adjuster portion includes a sleeve having a portion provided with indicia.

9 . The tensioning apparatus of claim 8 , wherein in a tensioned position, the portion with indicia and the second bushing partially overlap along an adjustment axis.

10 . A tensioning apparatus for a belt, the tensioning apparatus comprising:

a pulley defining an outer surface to receive the belt;

a trolley including a mount configured to support the pulley for rotation and an interior cavity;

a biasing member disposed within the interior cavity; and

an adjustable length arm assembly including a fixed-length portion and an adjuster portion, wherein the fixed-length portion defines an adjustment axis, the fixed-length portion includes a pivot mount for rotatably mounting the tensioning apparatus, wherein the adjuster portion includes a fastener threaded to the fixed-length portion, and the adjuster portion includes an engagement member that engages and deforms the biasing member in response to adjustment of the fastener along the adjustment axis,

wherein a first interface is defined between a cross section profile of the trolley and a cross section profile of the adjustable length arm assembly at a location of axial overlap along the adjustment axis of the trolley and the adjustable length arm assembly,

wherein the first interface includes an excess clearance that is set to achieve a predetermined rotational allowance of the trolley about the adjustment axis relative to the adjustable length arm assembly.

11 . The tensioning apparatus of claim 10 , wherein the predetermined rotational allowance of the trolley about the adjustment axis relative to a neutral orientation is between −8 degrees and +8 degrees.

12 . The tensioning apparatus of claim 10 , wherein the trolley includes

an end cap configured to retain the biasing member, the end cap having a projection,

a groove configured to receive the projection, and

a retaining ring and

wherein the end cap is received in the groove and is disposed between the biasing member and the retaining ring such that the end cap is axially fixed along the adjustment axis.

13 . The tensioning apparatus of claim 10 , wherein the pivot mount define a pivot axis, wherein the pivot axis is perpendicular to the adjustment axis, and wherein the trolley and the pulley are configured to rotate about the pivot axis.

14 . A tensioning apparatus for a belt, the tensioning apparatus comprising:

a pulley defining an outer surface to receive the belt;

a trolley including a mount configured to support the pulley for rotation, a first end and a second end opposite the first end, and an interior cavity;

a biasing member disposed within the interior cavity; and

an adjustable length arm assembly including a fixed-length portion and an adjuster portion, wherein the fixed-length portion defines an adjustment axis, the fixed-length portion includes a pivot mount for rotatably mounting the tensioning apparatus, wherein the adjuster portion includes a first fastener threaded to the fixed-length portion, and the adjuster portion includes an engagement member that engages and deforms the biasing member in response to adjustment of the first fastener,

wherein the biasing member is disposed between an interior of the trolley and an exterior of the adjustable length arm assembly, wherein the biasing member engages the engagement member and the first end of the trolley such that the trolley is moveable on the adjustable length arm assembly along the adjustment axis in response to the biasing member expanding.

15 . The tensioning apparatus of claim 14 , wherein the fastener of the adjuster portion is received in an interior of the fixed-length portion.

16 . The tensioning apparatus of claim 14 , wherein the fixed-length portion includes an arm coupled to the pivot mount via a second fastener and wherein the first fastener and the second fastener are coaxial.

17 . The tensioning apparatus of claim 14 , wherein the pivot mount includes a pivot body, a pin, and a third fastener, wherein the pivot body receives the pin, and wherein the third fastener couples the body to the pin.

18 . The tensioning apparatus of claim 17 , wherein the pivot body pivot mount defines a pivot axis and wherein the third fastener is configured to axially fix the trolley relative to the pivot axis.

19 . The tensioning apparatus of claim 14 , wherein the pivot mount includes a key that protrudes from the pivot mount in a direction parallel to the adjustment axis.

20 . The tensioning apparatus of claim 14 , wherein the trolley and the adjuster portion are coaxial.