Motion transmission drive

Claim 2

A power transmission drive comprising in combination, a pair of shafts arranged in parallel relaTionship; a pulley on each of said shafts; an endless traction transmitting member connecting said pulleys, the length of said member being such as to provide a predetermined amount of sag between said pulleys under no load conditions; means for providing load-responsive tension on said member during startup and lightly loaded conditions of said drive and means for providing a predetermined tension on both slack and tight sides of said member beyond a predetermined load including means for limiting the ratio of slack-side-sag to tight-side-sag to a predetermined value during operation of said drive, and means for limiting the ratio of slack-side-sag to tight-side-sag to a predetermined value during operation of said drive.

Claim 3

The power transmission drive of claim 1 in which there is provided a member operable in one direction and said providing means comprising a torsion spring normally fully compressed and which tends to rotate said operable member for causing one of said pulleys to engage one side of said member and a compression spring having available limited movement under no load conditions for causing another of said pulleys to engage to other side of said member.

Claim 4

The drive of claim 2 provided with means whereby said compression spring goes solid under appreciable load conditions whereby the ratio of tight side tension to slack side tension is limited to a predetermined value.

Claim 5

The drive of claim 1 in which the limiting means comprises a spring for preloading said member under no-load and light-load conditions, and means including a member operable in one direction to limit separation of opposite sides of said member under any appreciable load.

Claim 6

The drive of claim 1 in which the length of said member is sufficient to provide a minimum wrap of approximately 180* on each of said pulleys.

Claim 7

The drive of claim 1 in which each pulley is of adjustable pitch with respect to the other.

Claim 8

The drive of claim 1 wherein said pulleys are of adjustable pitch and there is provided pitch controller means, means utilizing said pitch controller means for changing the pitch of each pulley, said pitch controller means being arranged and disposed simultaneously to increase pitch on one pulley and decrease pitch on the other pulley.

Claim 9

The drive of claim 7 provided with a housing and wherein each pulley has on e flange relatively fixed rotationally and axially with respect to its shaft and another flange movable axially with respect to its shaft and the relatively fixed flange; said pitch changing means comprising first pulley pitch changing means adapted selectively to move one of said movable flanges axially and pulley pitch changing control means being operably connected to the first and second pulley pitch changing means and arranged to move the first pulley pitch changing means and the second pulley pitch changing means simultaneously in opposite directions; said endless traction member having traction surfaces disposed to transmit traction forces to and from traction surfaces on the pulley flanges; said tension providing means comprising a pair of traction member tensioning rollers bearing rotatably on the outer peripheral surfaces of the traction member at points between the pulleys; tensioning roller mounting means guided by means pivotally connected to the housing; and resilient tensioning connection means between the roller mounting means for each respective roller, arranged and disposed to urge the rollers towards each other with one of the pair bearing on the outer peripheral surface of a member which is in tension and the other of the pair bearing on the outer peripheral surface of a member side which is in slack.

Claim 10

A drive according to claim 1 wherein said tensioning means comprises a pair of tensioning rollers bearing rotatably on the outer peripheral surfaces of the traction member at points between the pulleys, tensioning roller mounting means for each roller and resilient connection means between the tensioning roller mounting means aRranged and disposed to urge the tensioning rollers towards each other with one of the pair bearing on the outer peripheral surface of a portion of the member which, during operation of the drive, is in tension and the other of the pair bearing on the outer peripheral surface of a portion of the member which, during operation of the drive is slack.

Claim 11

A drive according to claim 1 in which each pulley comprises a first pulley flange member relatively fixed rotationally and axially with respect to a shaft of the drive, having an attached elongate sleeve; a second pulley flange member relatively movable axially with respect to the first pulley flange member and its shaft, having an attached elongate sleeve concentrically disposed with respect to the elongate sleeve of the first pulley flange member; camming means on said sleeves, and ratio control means comprising an arm operatively associated with said camming means, said ratio arranged to provide a relatively short axial movement of said second pulley flange member in response to a relatively long movement of the drive ratio control means.

Claim 12

The drive of claim 1 in which the traction transmitting member has an outer surface adapted for substantially continuous engagement with said tension providing means, and has a multiplicity of regularly spaced traction surfaces on each side thereof for traction engagement with the adjacent faces of said pulleys.

Claim 13

The drive of claim 11 in which said traction surfaces are disposed substantially along the longitudinal centerline of said traction transmitting member.

Claim 14

The drive of claim 11 in which said traction surfaces are longitudinally extending land surfaces disposed on both sides of said member for transmitting traction forces to said pulleys.

Claim 15

The drive of claim 11 in which the area of said traction surfaces is so chosen as to maintain a coefficient of traction sufficient to avoid slip at any anticipated load.

Claim 16

The drive of claim 11 in which the areas of said traction surfaces are such that the relationship between the coefficient of friction and the maximum contact pressure falls within the area designated A in the graph of FIG. 4 of the drawings.

Claim 17

In the drive of claim 1, a traction member comprising, in combination a multiplicity of chain links, each link being of substantially rectangular cross section in the direction of chain movement and having a traction surface on at least one side thereof; a laterally disposed substantially cylindrical connection protrusion at one end and a laterally disposed substantially cylindrical connection hole at the other end; and a multiplicity of roll pins connecting said links assembled with the connection protrusions fitted in each instance into the connection holes of adjacent links.

Claim 18

In a traction drive member according to claim 16, the improvement comprising a chain link of generally rectangular cross section, having a traction surface on each side thereof, a laterally disposed substantially cylindrical connection protrusion at one end and a laterally disposed substantially cylindrical connection hole at the other end, said connection hole being arranged to be assembled with a connection protrusion of an adjacent link of said chain.

Claim 19

The drive of claim 1 in which the length of the member is determined by the formula length equals wherein c is the distance between pulley centerlines, D and d are the pulley diameters and s is the desired amount of sag.