Multispeed winch

Claim 2

A mechanical power transmission device for converting rotational input into unidirectional output with two transmission ratios determined by the direction of rotation of said input; said device comprising: an input shaft, a variable cam rotated by said input shaft having two eccentricities, the employment of each being determined by the direction of rotatiOn of said input shaft, a cam follower driven by said variable cam, guide means by which said cam follower is constrained to follow said variable cam in a linear manner, a plurality of opposed pawls pivotally hinged to said cam follower, a ratchet wheel rotated in one direction by said cam follower acting through said pawls, and output means driven by said ratchet wheel.

Claim 3

The same device as defined in claim 1, wherein said variable cam comprises two elements, an eccentric having a center of rotation coincident with the center of rotation of said input shaft and rigidly fixed thereto, and a cam having a center of relative rotation with respect to said eccentric coincident with the center of figure of said eccentric, and means for constraining said elements from rotating relative to each other through more than a predetermined angle.

Claim 4

The same device as defined in claim 2, wherein said means for limiting the relative rotation between said variable cam elements comprises a slot located on one of said variable cam elements, and a stop located on the other of said variable cam elements and positioned within said slot.

Claim 5

A three-speed winch comprising: a winch drum, a ratchet wheel rigidly fixed to said winch drum, an input shaft, a variable cam rotated by said input shaft having two eccentricities, the employment of each being determined by the direction of rotation of said input shaft, a cam follower driven by said variable cam, guide means by which said cam follower is constrained to follow said variable cam in a linear manner, a plurality of opposed pawls pivotally pinned to said cam follower which act to rotate said ratchet wheel in one direction, means for preventing rotation of said winch drum in a direction opposite to that direction in which said winch drum is driven by said plurality of opposed pawls acting through said ratchet wheel, locking means whereby said winch drum is constrained to rotate with said input shaft, means for disabling said locking means, and positioning means preventing relative linear motion between said guide means and said input shaft and said winch drum.

Claim 6

A three-speed winch comprising: a winch drum, a ratchet wheel rigidly fixed to said winch drum, an input shaft, a variable cam rotated by said input shaft having two eccentricities, the employment of each being determined by the direction of rotation of said input shaft, a cam follower driven by said variable cam, guide means by which said cam follower is constrained to follow said variable cam in a linear manner, a plurality of opposed pawls pivotally pinned to said cam follower which act to rotate said ratchet wheel in one direction, means for preventing rotation of said winch drum in a direction opposite to that direction in which said winch drum is driven by said plurality of opposed pawls acting through said ratchet wheel, locking means whereby said winch drum is constrained to rotate with said input shaft, means for disabling said locking means, and positioning means preventing relative linear motion between said guide means and said input shaft and said winch drum.

Claim 7

The same device as defined in claim 4, wherein said variable cam comprises two elements, an eccentric having a center of rotation coincident with the center of rotation of said input shaft and rigidly fixed thereto, and a cam having a center of relative rotation with respect to said eccentric coincident with the center of figure of said eccentric, and means for constraining said elements from rotating relative to each other through more than a predetermined angle.

Claim 8

The same device as defined in claim 5, wherein said means for limiting the relative rotation between said variable cam elements comprises a slot located on one of said variable cam elements, and a stop located on the other of said variable cam elements and positioned within said slot.

Claim 9

The same device as defined in claim 6, wherein said means for preventing rotation of said winch drum in one direction comprises: a ratchet wheel rigidly fixed to said winch drum and a plurality of pawls pivotally pinned to said positioning means so as to engage said ratchet wheel.

Claim 10

The same device as defined in claim 7, wherein said locking means comprises: a ratchet wheel rigidly fixed to said input shaft, an element rigidly fixed in said winch drum, a pawl pivotally pinned to said element and positioned to prevent relative rotation of said ratchet wheel with respect to said pawl; and wherein said means for disabling said locking means comprises a means for pivoting said locking pawl so that said locking pawl does not engage said locking ratchet wheel.

Claim 11

The same device as defined in claim 8, wherein said input shaft, said variable cam, said cam follower, said guide means, said plurality of opposed pawls, said means for preventing rotation in a direction opposite to the driving direction of said opposed pawls, said locking means and said means for disabling said locking means are all positioned within said winch arM.