FREE FALL WINDLASS

Abstract: A power-operated windlass having a motor (12) that reverses direction to control taking in and paying out of a cable (21) and a shifting mechanism (13) respon­ sive to changes in motor direction which selectively locks and unlocks the cable pulley (11) against rotation in an unwinding direction.

Description: BACKGROUND OF THE INVENTION The invention relates to a windlass, particularly though not exclusively a windlass which automatically lowers, locks, or raises an anchor by selective application of power. Recreational boats, as well as other craft of similar size, represent a large market for a power-operated windlass capable of automatically dropping, locking or raising up an anchor. Ideally, this type of windlass permits free fall of the anchor in one mode of operation and power raising of the anchor in another mode. When the anchor has reached bottom and enough cable has been paid out, the windlass, in a simple manner, should be capable of locking up to prevent further extension of the cable (the term "cable" as used herein includes ropes, wire ropes and chains). In the recreational boating field and other similar duty applications, an ideal windlass is constructed of components that are few in number, simple in design, inexpensive to produce and assemble, and durable in service. Further, a windlass of good design can be shifted between dropping, locking, and raising action from a remote location without extra manual effort and without the complexity and cost of related servomechanisms and their attendant controls. SUMMARY OF THE INVENTION There is hereinafter described a power-operated windlass mechanism that shifts between anchor dropping, locking, and raising modes by a simple reversal in rotary motor direction. The mechanism, in addition to a reversible motor, is embodied with an anti-feed clutch and shifting means for alternatively connecting or disconnecting both the anti-feed clutch and the motor from a cable pulley in response to a change in the direction of rotation of the motor. The energy of the motor drives the shifting means so that manual effort or auxiliary servo systems are unnecessary to accomplish this task. When the motor is initially operated in a down direction, the cable pulley is disconnected from the anti-feed clutch and the motor, and the anchor is allowed to drop free to the bottom. The mechanism permits the motor to be de-energized after this initial short period of operation in the down direction. Oppositely, initial motor operation in the up direction causes the cable pulley to be connected to both the anti-feed clutch and the motor. By taking advantage of this characteristic of the mechanism, the cable pulley is locked up simply by running the motor up for a short period sufficient to change the state of the shifting means and energize the anti-feed clutch. The motor is immediately shut off. When it is desired to raise the anchor, the motor is again operated in its up direction until the anchor is at a desired height. The windlass mechanism is ideally suited for remote operation, since all of its functions can be controlled by selectively directing two-way power to the reversible motor. US Patent US-A-4,566,674 describes a winch for hoisting a boat onto a trailer in which a gear may be axially disengaged from another gear using a handle. In British Patent Application GB-A-2,041,317, there is described a power-operated windlass comprising a pulley for feeding out or taking in a cable, means supporting the pulley for rotation about an axis, a reversible motor for driving the pulley, and drive means operatively interconnecting the pulley and the motor, the drive means including rotary members mutually engageable and disengageable by axial movement of one of the members along a rotary shaft of the motor, the axial movement being effected by mutually interengaged helically threaded surfaces on the rotary shaft and in the said member, means limiting axial movement of the member on the shaft and means preventing rotation of said member when the rotary shaft rotates in such a direction as to effect said axial disengagement and also effectively preventing rotation of the pulley in the cable feedout direction while said members are interengaged, the arrangement being such that rotation of the shaft by the motor in one direction holds said members in engagement such that cable feedout is prevented and such that cable may be drawn in by operation of the motor and rotation of the shaft by the motor in the other direction disengages the members and releases the pulley for rotation without restriction by the rotation preventing means. The arrangement is, however, complex with the axially interengageable members on the same rotary axis and provided with drive clicks on their facing surfaces. The rotation preventing means is a ratchet. In contrast, the windlass construction hereinafter described and illustrated has few components, is of simple design, and is capable of being mass-produced with limited tooling investment, fabrication costs, and labour. The various operative elements can be readily sized and stressed for high durability without a significant penalty in cost, bulk or weight. In accordance with the present invention, there is provided a power-operated windlass, a pulley for feeding out or taking in a cable, means supporting the pulley for rotation about an axis, a reversible motor for driving the pulley, and drive means operatively interconnecting the pulley and the motor, the drive means including rotary members mutually engageable and disengageable by axial movement of one of the members along a rotary shaft of the motor, the axial movement being effected by mutually interengaged helically threaded surfaces on the rotary shaft and in the said member, means limiting axial movement of the member on the shaft and means preventing rotation of said member when the rotary shaft rotates in such a direction as to effect said axial disengagement and also effectively preventing rotation of the pulley in the cable feedout direction while said members are interengaged, the arrangement being such that rotation of the shaft by the motor in one direction holds said members in engagement such that cable feedout is prevented and such that cable may be drawn in by operation of the motor and rotation of the shaft by the motor in the other direction disengages the members and releases the pulley for rotation without restriction by the rotation preventing means, characterised in that said members are respectively a spur gear and a pinion, the spur gear being rotationally fixed to the pulley for rotation about said pulley axis, said pulley axis being parallel to the axis of the rotary shaft such that the pinion has a first axial position in which it is in driving engagement with the spur gear and a second axial position in which it is fully disengaged from the spur gear, and in that the rotation prevention means comprises an anti-feed gear rotatable in only one direction about an axis parallel to the pulley axis and to the axis of the rotary shaft, the anti-feed gear being continuously meshed with the pinion in all its axial positions. The continuous meshing of the pinion and the anti-feed gear can be simply achieved by providing sufficient axial tooth lengths. BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic cross-sectional plan view of a preferred embodiment of a windlass according to the invention, in a locked or anchor raising condition. FIG. 2 is a cross-sectional view of the windlass of FIG. 1 in an anchor dropping condition. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, there is shown a windlass 10 including a rope pulley 11, power operated by a rotary motor 12 through a drive system 13. The drive system includes spur gears 16-18. Rope 21 is taken in or paid out by the pulley 11, depending on its direction of rotation. The spur gear 16 is rotationally and axially locked on a shaft 22 by a suitable keyway or spline 25 and a retaining snap ring 23, respectively. Similarly, the rope pulley 11 is fixed by suitable means to an outboard end of the shaft 22. The inboard end of the shaft 22 is supported in a bearing 24 carried on a fixed wall or base 26 of the windlass 10. The shaft 22 is axially fixed relative to the bearing 24 by suitable means, such as by a press fit therein. The motor 12 is preferably a reversible electric motor, but other known types of reversible or two-way motors are adaptable to the present invention. The motor 12 includes a shaft 31 on which the spur gear or pinion 17 is assembled. The motor 12 and its associated shaft 31 are suitably axially fixed relative to the wall 26. A snap ring or split washer 32 fitted on a groove on the shaft 31 is abutted by a thrust washer 33 on a side opposite the motor. The spur gear 17 has internal threads 34 in engagement with complementary external threads 35 on the motor shaft 31. By virtue of the threads or helical camming surfaces 34, 35, the spur gear 17 is capable of shifting axially on the shaft 31, depending on the direction of rotation of the motor 12 and resultant relative rotations of the gear 17 thereon. The spur gear 17 is resiliently biased in the direction of the motor 12 by a compression spring 37 assembled about the shaft and retaining thereon by a snap ring 38 received in a groove on the outboard end of the motor shaft 31. A thrust washer 39 is interposed between the spur gear 17 and spring 37. A portion 41 of the shaft 31 outboard of the threads 35 is sufficiently long to receive the spur gear 17 thereon, as well as a compressed length of the spring 37. The lead edges 42 of the teeth 43 of the spur gear 17 may be beveled or otherwise shaped in a known manner to facilitate proper tooth engagement with the rope pulley gear 16. The spur gear 18 is supported on a pin 44 by conventional one-way roller clutch members 46. The pin 44 extends through a hole in the wall 26 and is fixed to the wall by a nut 47, which draws an integral shoulder 48 against the wall. The pin 44 has its longitudinal axis parallel to that of the rope pulley shaft 22 and motor shaft 31. The one-way roller clutches 46 support the associated spur gear 18 for rotation in only one rotary direction about the axis of the pin 44. A compression spring 51 assembled on the outboard or free end of the pin 44 is compressed between a pair of thrust washers 52 at each of its ends and is retained on the pin by a split ring 53 received in an annular groove on the pin. The spring 51 operates as a friction brake through the thrust washer 52 on the assembly of the spur gear 18 and one-way clutches 46 to retard this assembly slightly in rotation in the operative direction of the clutches. The threads 35 on the motor shaft 31 are, for example purposes, left-hand. The motor 12 is most conveniently a reversible electric unit operating, for example, on 12 volts DC. Appropriate electrical cables and a control switch remote from the windlass 10 connect the motor 12 to a source of electrical energy such as a DC battery. The control switch and electrical circuitry are effective to apply the proper polarity and current to the motor to run it in either rotary direction or stop it from running. In the condition illustrated in FIG. 1, the motor 12 has been most recently run in the rotary direction indicated by the arrow 54, i.e., the portion of the motor-driven shaft 31 above the plane of the drawing is moving to the left. This rotary motion, due to the left-hand cut of the motor shaft threads 35, has caused the pinion or control gear 17 to tighten against the thrust washer 33, thereby releasably rotationally locking the gear in a positive connection to the shaft and causing the rope pulley gear 16 to positively rotate in the opposite rotary direction. Such rotation causes an anchor to be raised as rope 21, wound on the pulley 11, is taken in. A pressure bar (not shown) of generally known construction can be provided to prevent the rope from slipping on the pulley 11. The one-way clutches 46, operating through the associated spur gear 18, prevent any counter-rotation of the motor shaft spur gear 17 in a direction opposite that indicated by the arrow 54. Thus, by operating the motor 12 in a rotary direction, indicated by the arrow 54, the anchor can be raised to a desired height. When the motor 12 is caused to stop rotation, the one-way or rope anti-feed clutches 46 hold the anchor in position. When it is desired to drop the anchor, the motor 12 is operated in a rotary direction opposite that of the arrow 54. Initially, this motor shaft rotation causes the spur gear 17 to move axially by forces developed by the mating threads 34, 35. As shown in FIG. 2, eventually the spur gear 17 shifts axially out of engagement with the rope pulley gear 16, at which point the latter gear, as well as the rope pulley 11, is free of restriction against rotation imposed by the one-way or anti-feed clutches 46. Note that, as indicated in FIG. 2, the relative lengths of the gears are such that gears 17 and 18 are still in engagement when gears 16 and 17 are out of engagement. Separation of the threads 34, 35 limits axial movement of pinion 17 away from the gear 16. At this time, the anchor is allowed to drop by gravity and the strand or rope 21 feeds out from the pulley 11. When this shift occurs, the motor operation, if desired, can be discontinued. Regardless of whether or not motor operation in the down direction is continued, the anchor will drop until it reaches bottom. When it is determined that sufficient rope 21 has been let out, the rope pulley 11 can be locked up against further letting out by momentarily operating the motor 12 in the up direction indicated by the arrow 54. This momentary operation of the motor 12 in the direction of the arrow 54 causes the spur gear 17, under the influence of the compression spring 37 and resistance to rotation imparted by the friction brake spring 51, to shift axially from the non-engaged position indicated in FIG. 2 to that of full engagement with the gear 16 indicated in FIG. 1 in the manner of a positive engagement clutch. As will be understood from the foregoing discussion, once the spur gears 16,17 are interengaged, the anti-feed gear 18 and associated clutches 46 prevent rotation of the rope pulley shaft 22 in the feedout direction. Consequently, motor operation can be discontinued and the rope pulley 11 is unable to let out further rope.

Claims: 1. A power-operated windlass (10) comprising a pulley (11) for feeding out or taking in a cable (21), means (22, 24, 26) supporting the pulley (11) for rotation about an axis, a reversible motor (12) for driving the pulley (11), and drive means operatively interconnecting the pulley (11) and the motor (12), the drive means including rotary members (16, 17) mutually engageable and disengageable by axial movement of one of the members (17) along a rotary shaft (31) of the motor (12), the axial movement being effected by mutually interengaged helically threaded surfaces (34, 35) on the rotary shaft (31) and in the said member (17), means (38, 32) limiting axial movement of the member (17) on the shaft (31) and means (18, 44, 46) preventing rotation of said member (17) when the rotary shaft (31) rotates in such a direction as to effect said axial disengagement and also effectively preventing rotation of the pulley (11) in the cable feedout direction while said members (16, 17) are interengaged, the arrangement being such that rotation of the shaft (31) by the motor (12) in one direction holds said members (16, 17) in engagement such that cable feedout is prevented and such that cable may be drawn in by operation of the motor and rotation of the shaft (31) by the motor (12) in the other direction disengages the members (16, 17) and releases the pulley (11) for rotation without restriction by the rotation preventing means (18, 44, 46), characterised in that said members (16, 17) are respectively a spur gear and a pinion, the spur gear (16) being rotationally fixed to the pulley (11) for rotation about said pulley axis, said pulley axis being parallel to the axis of the rotary shaft (31) such that the pinion (17) has a first axial position in which it is in driving engagement with the spur gear (16) and a second axial position in which it is fully disengaged from the spur gear (16), and in that the rotation prevention means (18, 44, 46) comprises an anti-feed gear rotatable in only one direction about an axis parallel to the pulley axis and to the axis of the rotary shaft (31), the anti-feed gear (18, 44, 46) being continuously meshed with the pinion (17) in all its axial positions.

Inventors: SANTOS, JOSE
Applicants: THE SCOTT FETZER COMPANY
Application year: 1988
Main classification: B66D1
IPC codes: B66D1