AN AUTOMATIC LOAD RESPONSIVE WINCH

Abstract: An automatic load responsive winch includes a base (43), a winch drum (14, 110) rotatably mounted on the base, and a rotatable drive shaft (12, 100) for driving the winch drum. At least two gear trains are mounted on driven shafts (44, 45, 102, 104, 106) and are linked between the drive shaft and the drum for rotating the drum in response to rotation of the drive shaft. One of the two gear trains produces a different drum speed than the other gear train. When a variable torque load is applied to one of the shafts via the drum, a mechanism (26) is displaceable vertically with respect to one of the shafts in response to changes in torque load. The mechanism includes a means (29, 30) for engaging one of the gear trains at a first vertical position of the mechanism and for disengaging the one gear train at a second vertical position to isolate the gear train and provide for rotation of said drum by the other gear train.

Description: AN AUTOMATIC LOAD RESPONSIVE WINCH This invention relates to winches and has been devised particularly though not solely for use in winches employed on marine craft such as yachts. Such winches are known and are used extensively in yachting for tensioning sheets, halyards and other running rigging of yachts. The tensioning is effected by winding a handle which turns a winch drum through a plurality of gear trains of differing velocity ratios ' so that by progressively, selectively increasing the velocity ratios, a sheet, for example, can be quickly brought up to the required tension. In prior art two- speed winches, selection of the appropriate velocity ratio is effected by reversal of the direction of rota- tion of the operating handle. In some prior art three- speed winches, the third velocity ratio is offered by vertical movement of a handle shaft to cause a dog clutch to be engaged or disengaged from a direct drive connection to the winch drum. In U.S. Patent No. 4,054,266, a three-speed winch is disclosed in which a lever is operated to engage a first gear train (the gear train which is normally used first and has the lowest velocity ratio). The winch handle is rotated in one direction in first gear, then in the opposite direction to automatically engage second gear (a gear train of intermediate velocity ratio) and then the winch handle is again reversed to engage third gear (the gear train of highest velocity ratio) . In European Patent Specification Publication No. 0 159 095, a three-speed winch is disclosed in which a number of gears are provided, one set mounted on a shaft fixed to a base and other sets being mounted on a rotatable carrier which is rotatable on the base and which is spring-loaded to engage under zero or minimum load on the winch drum a first gear train out of three gear trains, the first gear train including a gear on the shaft fixed to the base. If the handle is rotated in one direction, say clockwise, in these conditions, the first gear train is operated instead of a third gear train so long as the carrier is not caused by operation of the handle in the opposite direction to move against the loading spring. Operation of the handle in the opposite direction results in engagement of the second intermediate velocity ratio gear train, and the engagement remains until the direction of rota¬ tion of handle is again reversed to the original direc¬ tion. A spring-loaded pawl acts on a selected gear to prevent reverse rotation of the winch in the first speed. This three-speed winch is not load responsive in the sense that the operable gear train is dependent on the torque load on the winch, which is generated by the sheet load. The description gives emphasis to the fea¬ ture that the transition between the three-gear trains takes place fully automatically only by changing direc¬ tion of rotation of the driving gear, and this winch must always start in first gear even if the initial sheet load is high so that the winch .operator is re¬ quired to start cranking the winch in the second gear direction in order to shift the winch out of first gear into third gear via the second gear. International Application PCT/AU88/0053 (Interna¬ tional Publication No. WO88/06565) describes a three- speed winch having three gear trains. Drive is trans¬ ferred between two of the gear trains by displacement of a gear of one of the gear trains between an inopera¬ tive and operative position. This particular winch has the disadvantage that it is reasonably complex and, therefore, expensive to manufacture. Still further, the complexity adds to the weight of the winch. A still further disadvantage is that the winch does not lend itself for adapting to the configuration of existing winches. It is the object of the present invention to over¬ come or substantially ameliorate the above disadvan- tages. In accordance with one aspect of the invention, an automatic load-responsive winch is provided, which includes a base, a winch drum rotatably mounted on the base, and a rotatable drive shaft for driving the winch drum. The winch also includes at least two gear trains mounted on driven shafts and linked between said drive shaft and said drum for rotating said drum in response to rotation of the drive shaft. One of the two gear trains produces a different drum speed than the other of the gear trains for the same rotational speed of the drive shaft. During operation, a variable torque load is applied to one of the shafts by operation of a line or rope wound on the winch drum. The winch includes a mechanism displacable verti¬ cally with respect to the one shaft in response to changes in the variable torque load. The mechanism in¬ cludes a means for engaging one of the gear trains at a first vertical position of the mechanism and for disen¬ gaging the gear train at a second vertical position to isolate the one gear train and provide for rotation of the drum by the other gear train. In accordance with one aspect of the invention, the mechanism is mounted for rotation with the one shaft and includes a cylindrical opening for receiving the shaft. The opening includes a plurality of longitu¬ dinally extending splines and the shaft also has a plurality of longitμdinally extending splines engaging the splines of the mechanism. .The mechanism rotates in response to rotation of the shaft, but is slidable longitudinally with respect to the shaft from the first vertical position to the second vertical position. The mechanism reciprocates up and down and is spring biased to the first vertical position and slidable against said bias to the second vertical position. The shaft splines engage the mechanism splines to produce fric¬ tion that increases as the torque load on the winch increases. The mechanism is maintained in the second vertical position when the friction is increased in response to the torque load to an amount sufficient to overcome the spring bias on the mechanism. In accordance with another aspect of the invention, the mechanism described in the paragraph immediately above includes a . plurality of ramps protruding verti¬ cally upwardly therefrom and being spaced in an arc around the mechanism. The ramps periodically engage a plurality of ramps located in a fixed vertical position with respect to the shaft. The ramps of the mechanism ride over the ramps fixed with respect to the shaft to displace the mechanism vertically and reciprocally. When the friction reaches a point where the friction overcomes the bias, the mechanism is held in the second vertical position by the friction between the splines. In accordance with another embodiment of the in¬ vention, vertical displacement of the mechanism is achieved in another manner. A camming element is located in a fixed vertical position with respect to the one shaft. The camming element includes at least one cam surface shaped in an arcuate relation with respect to the shaft, and most preferably, a helical relation. The displacable mechanism includes a cam follower that- rides on the helical cam surface. The cam follower rides on the camming surface in response to changes in the torque load to move the mechanism from the first vertical position to the second vertical position. In a preferred embodiment of the invention, the camming element includes a plurality of protrusions that extend longitudinally from the camming element toward the mechanism. The mechanism includes a plural¬ ity of like protrusions. The protrusions have mirror image helical faces that ride against each other and move the mechanism vertically in response to increases in the torque load. As described above, the mechanism is displacable vertically in response to changes in the torque load. The mechanism is operably connected to a transfer member. The transfer rotates with the one shaft and is slidable vertically on the shaft in response to vertical movement of the mechanism. The transfer member includes a plurality of pawls biased radially outwardly of the transfer member. The one gear train includes an annular gear having internal ratchet teeth that are engaged by the pawls. The annular gear has external gear teeth for driving one of the gear trains. The pawls are biased radially outwardly of the transfer member into engagement with the ratchet teeth in the first vertical position of the transfer member. The. pawls are movable radially inwardly against the bias out of engagement with the ratchet teeth in the second vertical position. In accordance with one aspect of the invention, the winch includes an annular flange extending radially inwardly of the internal ratchet teeth, and the flange retains the pawls out of engagement with the ratchet teeth in the second verti- cal position. Preferably, the flange includes a radial face that retains the pawls out of engagement once the transfer member has moved longitudinally with respect to the gear having the internal ratchet teeth. In accordance with a preferred embodiment of the invention, the annular flange includes a ramp on top surface thereof for moving the pawls radially inwardly as the transfer member moves downwardly with respect to the annular gear. As can be appreciated, the winch according to the present invention is responsive to variations in torque load placed on the winch. If the load is very high, the winch operates in one gear train. If the load is low, the winch operates in another gear train. Other advantages of a winch in accordance with the present invention will be apparent from the following detailed description. Brief Description Of Drawings FIGURE 1 is a schematic part section side eleva¬ tion of a three-speed winch for use on a yacht; FIGURES 2, 3 and 4 are schematic side elevations of the central drive portion of the winch of FIGURE 1, in ' three driving modes wherein FIGURE 2 shows the winch wherein the drum rotates at the highest speed with the lowest power; wherein FIGURE 3 shows the winch wherein the drum rotates at a medium speed with medium power transmitted; and wherein FIGURE 4 shows the winch wherein the drum rotates at the slowest speed and the maximum power is transmitted; FIGURE 5 is a schematic part exploded perspective view of the central drive portion of the winch of FIGURE 1; FIGURE 6 is a perspective view of another winch in accordance with the present invention; FIGURE 7 is a top view of the winch shown in FIGURE 6; FIGURE 8 is a sectional view along the plane 8-8 of FIGURE 7; FIGURE 9 is a view similar to that shown in FIGURE 8, except that the button on the top of the winch has been depressed and retained in a depressed position; FIGURE 10 is a perspective view of the ramp shown in FIGURES 8 and 9; FIGURE 11 is a perspective exploded view of the essential components for shifting between gear trains in respect to variations in torque load; FIGURE 12 is a perspective view of the bottom of one of the parts shown in FIGURE 11; FIGURE 13 is a partial section view along the planes 13-13 of FIGURE 7; FIGURE 14 is " a sectional view along the plane A-A Of FIGURE 13; FIGURE 15 is a sectional view along the planes 15-15 of FIGURE 7; and FIGURE 16 is a sectional view along the plane B-B Of FIGURE 15. Detailed Description In respect to FIGURE 1, it should be appreciated that the winch illustrated is sectioned by two vertical planes which intersect along the axis of drive shaft 12. One plane passes through the axis of driven shaft 44 and the other plane passes through the axis of drive shaft 45. The winch 10 has a central drive assembly 11 with an input drive shaft 12. The shaft 12 has an upper- splined socket 13 which is engaged by a crank handle not shown. Surrounding the shaft 12 is a winch drum 14 which rotates clockwise when viewed from above. Refer¬ ring to FIGURE 2, when the shaft 12 is initially driven in a clockwise direction as shown by the arrow, rota¬ tion of the shaft 12 produces the highest rotational speed of the drum 14. If the rotation of the shaft 12 is reversed as shown in the arrow in FIGURE 3, the next highest or medium speed ' of the drum 14 is achieved. Again, the rotational direction of the drum 14 is clockwise, despite the counter-clockwise rotation of the shaft 12. If the rotational direction is again reversed as shown by the arrow in FIGURE 4 and the shaft 12 driven in a clockwise direction, the slowest speed of the drum 14 is produced. Again, the rota- tional direction of the drum 14 is clockwise. This analysis of the various speeds of the drum 14 is based upon a predetermined rotational velocity of the shaft 12. The various gear arrangements associated with each of the discussed speeds of the winch 10 is schematically depicted, respectively, in FIGURES 2, 3 and 4. Mounted on and driven by the shaft 12 is the drive assembly 11, which drive assembly 11 includes an upper gear 17 which forms part of the gear train providing the second highest speed (FIGURE 3). The gear 17 has internal splines 15, which engage the splines 16 of the shaft 12; splines 15 and 16 prevent rotation of gear 17 with respect to shaft 12 but permit 17 to slide longi¬ tudinally with respect to shaft 12. The drive assembly further includes an intermediate gear 18 which forms part of the gear train of the lowest speed (FIGURE 4. The gear 18 has internal splines 19 which are engaged with the splines 16. The highest speed gear train includes a gear 20, which forms part of the drive assembly 11. The gear 20 is selectively driven by a ratchet and pawl mechanism 21. The ratchet and pawl mechanism includes a base 22 which has internal splines 23 meshed with splines 16. The base 22 is also provided with external splines 24 which engage the internal splines 25 of a transfer member 26. The transfer member 26 is provided with a pair of pivotally mounted pawls 27 which are resili- ently biased radially outward by means of springs 28. The pawls 27 engage ratchet teeth 29 formed internally on the gear 20. The gear 20 is also provided with an annular flange 3.0 that extends radially inwardly. The base 22 is fixed to the shaft so as not to be movable longitudinally thereof. On the other hand, the transfer member 26, gear 18 and gear 17 are movable longitudinally of the shaft 12. Referring to FIGURES 2-4,. extending between the base 22 and gear 18 are springs 31, while extending between the transfer member 26 and the gear 18 are springs 32. To provide an abutment for the springs 32, the gear 18 is provided with an annular flange 33 that extends radially outwardly. Rotation of the gear 18 relative to the transfer member 26 is prevented by screws 34a, which are fixed to the transfer member through insertion in threaded holes 34b, but pass through apertures in the flange 33, so that the gear 18 may move longitudinally of the shaft relative to the transfer member 26. Extending between the gears 17 and 18 is a spacer sleeve 35, best shown in FIGURES 2-4. Referring to FIGURES 3 and 5, the gear 17 has an annular flange 36 provided with a plurality of spaced- apart ramp surfaces 37. Positioned above the gear 17 is a plate 38 which has a plurality of spaced-apart ramp surfaces 39 positioned to ride over the ramp sur¬ faces 37, which cause gear 17 to reciprocate longitu¬ dinally with respect to plate 38. As shown in FIGURE 3, the gear 17 has been forced downwardly by a distance equal to the height of one of the ramps 37 and 39. The plate 38 has annularly extending slots 40 which receive one.or more pins 41 to hold the plate 38 stationary. Referring to FIGURE 1 ' , the winch 10 has a main body 42 with with a base plate 43 to be secured to a support¬ ing structure. The base plate 43 and the associated gear housing support a pair of parallel driven shafts 44 and 45, as well as rotatably supporting the drive shaft 12 by bearings 46 and 47. The drum 14 is rota¬ tably supported on the body 42 by bearings 48 and 49. The bearings 49 engage a spacer 50 which also rotatably supports the shaft 12 via a bearing 51. A thrust bear¬ ing 52 extends between the spacer 50 and an abutment surface 53 of the drum 14. The spacer 50 finds support on the base plate 43. Rotatably supported by the shaft 44 is a gear mem¬ ber 54, which includes a first gear 55 meshingly en¬ gaged with the gear 20. The gear member 54 has an upper gear 56, which is meshingly engaged with a further gear 57 rotatably supported by the shaft 45. The gear 57 engages an internal ring gear 58 which is part of the drum 14. Also rotatable about the shaft 44 is a gear 59 which is meshingly engaged with the gear 18. The gear 59 engages the gear member 54 via ratchet teeth 60 and pawls 61. The pawls 61 are pivotally mounted on the gear member 56 and are provided with springs to bias them radially outward into engagement with the ratchet teeth 60. Also rotatably supported on the shaft 45 via the gear 57 is a gear 62. The gear 62 engages the gear 57 via pawls 63 which are pivotally mounted on the gear 57. The pawls 63 engage ratchet teeth 64 formed on an internal surface of the gear 62. The gear 62 is mesh¬ ingly engaged with the gear 17, with the gears 17 and 62 providing the intermediate speed (FIGURE 3). In operation of the above described winch 10, when the shaft 12 is initially rotated in the clockwise direction, the drum 14 is driven clockwise via the gears 20, 55, -56, 57 and 58. Since the gear member 54 has a relatively high rotational speed, the pawls 61 override the ratchet teeth 60 so that there is no trans¬ fer of motion between the gear 59 and gear member 54. Accordingly, the gear 18 is effectively isolated. The gear 17 is also effectively isolated since the pawls 63 override the ratchet teeth 62 since the gear 64 is being driven in the wrong direction. This particular arrangement gives the highest rotational speed to the drum 14 for a given rotational speed of the shaft 12. When the rotational direction of the shaft 12 is reversed, that is it is rotated counter-clockwise, the drum 14 is driven by the gears 17, 62, 57 and 58. The pawls 63 " engage the ratchet teeth 64 as they are being driven in the correct direction. The pawls 27 and 61 override their respective teeth 30 and 60 since they are being driven in the opposite direction for driving engagement. Accordingly, gears 18 and 20 are effec¬ tively isolated. This particular gear arrangement gives the next highest rotational speed to the drum 14 for a given rotational speed of the shaft 12 in an counter-clockwise direction. The lowest rotational speed of the drum 14 is pro¬ vided by the gears 18, 59, 56, 57 and 58. The rotational power is transferred via the gear member 54 and pawls 61 and ratchet teeth 50. However, for power to be transferred via these gears, it is necessary to isolate the gear 20. This is achieved by axial down- ward movement of the transfer member 26 so that its pawls 27 are pushed radially inwardly and are retained by the flange 30 so that they are no longer engaged with the ratchet teeth 29. This then effectively isolates the gear 20. Movement of the transfer member will now be des-- cribed. The transfer member 26 needs to be moved down¬ wardly and longitudinally of the shaft 12 to isolate the gear 20. Upward movement of the transfer member 26 is also required to reinstate connection between the transfer member 26 and the gear 30. This movement of the transfer member 26 is effected by the springs 31, 32 and interaction of the ramp surfaces 37 and 39. In the initial position, the pawls 27 are engaged with the teeth 29 to transfer power between the transfer member 26 and the gear 20. When in this position, the springs. 31 bias the gear 18 together with the spacer 35 and gear 17 upward. However these items are caused to reciprocate vertically due to the ramp surfaces 37 riding over ramp surfaces 39. The relative movement between the gear 18 and the transfer member 26 is accommodated by the springs 34. It should be appre¬ ciated that the transfer member 26 cannot move downward to a position causing disengagement of the pawls 27, due to the pawls 27 being engaged with the ratchet teeth 29 and abutting the radial upper surface of the flange 30. When the rotational speed of the shaft 12 is re¬ versed to drive via the gear 17, the gear 17 is moved downward to the position shown in FIGURE 3 due to the engagement of the ramp surfaces 37 and 39, forcing with it the sleeve 35 and gear 18. The gear 17 is retained in this downward position by the friction between the splines 15 and the splines 16. More specifically, an increase, in friction is generated by the increased load being transferred between the splines 15 and the splines 16. By being retained in a downwardly-spaced position, the gear 17 compresses the springs 31 and 32 biasing the transfer member 26 downward. Since the pawls 27 are now going in the opposite direction to their driving direction, they are being continually displaced radially inward by a distance sufficient to clear the flange 30. At the same time, due to the transfer member 26 being biased downward, the pawls 27 will eventually be retained radially inwardly by the flange 30. Accordingly, when the rotational direction of the shaft 12 is again reversed, the gear 20 is effectively isolated due to the pawls 27 being retained radially inwardly by flange 30 and being disengaged from the teeth 29. Thus, the drum 14 will be driven by the gears 18 and 59. When the torque load on the winch falls below an amount which created sufficient friction between the splines 15 and the splines 16 to retain the gear 17 in the downward position, the gear 17 is biased upwardly to the position shown in FIGURE 2 wherein the pawls 27 once again engage teeth 29 to drive the winch at the highest speed. To prevent "chattering" engagement between the ramps surfaces 37 and 39 when the gear 17 is held in its downwardly spaced position, the plate 37 is not fixed to the body 42. Accordingly, the plate 38 is permitted to fall from engagement with the pins 41 and therefore rotate with the gear 17. Referring to FIGURES 6 through 16, another em¬ bodiment of a winch in accordance in the present invention will now be described. The winch shown in these FIGURES has four speeds. Referring primarily to FIGURE 7, but also FIGURES 8, 13, and 15, the winch includes a main drive shaft 100 which is driven from below in a conventional manner. The winch also includes three driven shafts 102, 104, and 106. As shown in FIGURE 6, 7, 8, and 9, the winch includes a top ' drive button 108 for manually engaging the initial gear of the winch. The drive button 108 and its associated transfer mechanism 109 is held within the winch drum 110 by a top cover plate 112 which covers the internal components of the winch and retains button 108. The engagement of the initial gear train will now be described. Referring to FIGURES 8 and 9, the ini¬ tial gear train is driven by engagement of pawls 114 with ratchet 116 of an annular gear 118 that is con¬ nected to drum 110. More specifically, referring to FIGURE 9, pawls 114 are biased outwardly into engage¬ ment with ratchet teeth 116 when the button 108 is in the downward position of FIGURE 9. At this point the shaft is rotating in a clockwise direction when viewed from above. The shift from this initial gear to the first gear will be described by comparison between FIGURES 8 and 9. Referring to FIGURE 8, when the button 108 is re¬ leased and moved vertically upwardly to the position shown in FIGURE 8, the pawls 114 as they move upwardly contact ramp 120 and are urged radially inwardly against the bias on the pawls to a position wherein the pawls are retained out of engagement with ratchet teeth 116. More specifically, the pawls are retained by the radial face 122 out of engagement so that when a drive shaft 100 rotates in the clockwise direction, the pawls 114 are out of engagement with respect to the ratchet teeth 116. The principal by which pawls 114 are re¬ tained radially inwardly against engagement with rat¬ chet teeth 116 is better described with respect to FIGURE 11, which is a different pawl mechanism within the winch, but this pawl mechanism functions in a similar manner. The operation of button 108 will now be described. FIGURE 8 shows the button in a first vertical position while FIGURE 9 shows the button in a second vertical position wherein the button has been moved downwardly. The button is mounted to a second drive shaft section 126 and is slidable vertically with respect to the main section 101 of drive shaft 100. The second shaft section 126 is biased longitudinally upwardly by the spring 128 and is movable vertically downwardly to compress the spring 128 as shown in FIGURE 9. The main section of shaft 100 includes a radial opening 130 that has a pin 132 movable out of the opening and biased by a spring 134. The internal cylindrical surface of shaft section 126 includes a pin receiving detent 136. As shown a comparison between FIGURES 8, when the button 108 is pushed downwardly, pin 132 fits within detinet 136 to retain said button in the lower vertical position and provide for engagement of pawls 114 with ratchet teeth 116. The drive shaft 100 is rotating in a clockwise direction in the initial gear speed. In order to change speeds, the person operating the winch rotates the drive shaft in a counter-clockwise direction and the winch will be in second speed. After the shaft 100 has been rotated through an angle of at least 180 degrees, the pins 138, which extend radially outwardly of drive shaft section 126, ride up on ramps 140. The ramps 140 are best shown in FIGURE 10 which shows a cylindrical support 142 that has ramps 140 protruding upwardly therefrom. The ramps are located 180 degrees apart, and provide a surface which urges pins 138 vertically upwardly as the drive shaft 100 is rotated in a counter-clockwise direction. A spring clutch 141 permits rotation of support 142 in a clockwise direc¬ tion and locks support 142 against rotation in a counter-clockwise direction. The force of pins 138 against ramps 140 is sufficient to overcome the spring 134 that retains pin 132 into engagement with detent 136. Thus, the button 108 pops vertically upwardly from the position in FIGURE 9 to the position shown in FIGURE 8, which disengages the pawls 114 from the ratchet teeth 116. Once the person operating the winch sees that the button has popped up, he can continue to rotate the drive shaft in a counter-clockwise direction and will be in second gear. As will be described in detail later, if the drive shaft is rotated in the clockwise direction, the winch will be in the first or third gear, depending on the torque load. In both the initial speed and the first speed of the winch, the shaft is rotated in the same direction, and thus, the interaction between pawls 114 and 116 must be removed in order for the shaft 100 to drive the winch in the first speed via gear 124. As can be appreciated, the winch includes a wide variety of thrust bearings which are generally indi¬ cated by circular spheres shown at reference character 144. The winch also includes a wide variety of roller bearings 146 .which are generally indicated by an X through a rectangular box. These are of conventional operation and need not be described further. Thus, a person operating the winch gets into the initial winch . speed by pressing down button 108 and rotating the shaft in a clockwise direction. As soon as the person rotates the drive shaft in a counter¬ clockwise direction, the button moves upwardly and disengages the initial speed and thus engaging pawls 114 with ratchet teeth 116. At this point in time, the person rotating the shaft has two options. He can continue to rotate the shaft in a counter-clockwise direction and drive the winch in the. second speed, which is the only winch speed that is driven by rotation of the drive shaft in a counter-clockwise direction. The person has the option of rotating the drive shaft in -a clockwise direction and the winch will be in first or third gear, depending on the torque load. The automatic load responsive feature of the winch will now be described by comparing FIGURES 13 and 14 on the one hand with FIGURES 15 and 16 on the other hand. It would be helpful for the reader to align FIGURES 13 and 15 in side-by-side relation so that the vertical move¬ ment of certain components on driven shaft 102 can be seen. FIGURE 13 shows the winch in the first speed, which is a speed that is between the initial speed and the second speed. FIGURE 15 shows the winch in the third speed, which is the slowest speed. In both the first speed and the third speed shown in FIGURES 13 and 15, the drive shaft 100 rotates in a clockwise direc¬ tion. When the winch has a substantial torque load, the winch is in the position shown in FIGURE 15. If the torque load slackens, the winch is in the position shown in FIGURE 13. Referring to FIGURES 13 and 15, a camming element 150 is located in a fixed vertical position with re- spect to driven shaft 102. A cam follower mechanism 152 moves from a first vertical position shown in FIGURE 13 to a second vertical position shown in FIGURE 15. The parts described with respect to FIGURES 13 and 15 are also shown in exploded perspective view in FIGURES 11 and 12. In the right-hand side of FIGURES 13 and 15, the camming element 150 and the cam follower mechanism 152 is shown in a side sectional view so that the working of the camming surfaces and the camming element can be better understood. As shown in FIGURES 13 and 15, the displacable cam follower mechanism 152 is movable from the first verti¬ cal position shown in FIGURE 13 to the second vertical position shown in FIGURE 15. In addition, the mecha¬ nism 152 rotates from a first rotational position to a second rotational position offset from said first rota¬ tional position by a distance 154 shown in FIGURE 15. The camming element 150 includes at least one and preferably several camming surfaces 156 shaped in an arc, and preferably shaped in a helical relation with respect to the shaft 102. The camming surface 156 abuts a cam follower 158 on said mechanism 152. Thus, the mechanism 152 moves in a helical pattern from the position shown in FIGURE 13 to a position shown in FIGURE 15. The mechanism 1S2 is biased upwardly to the posi¬ tion shown in FIGURE 13 by a series of conical springs 160 which are also known as "Belleville" springs. The Belleville springs 160 urge mechanism 152 upwardly. The mechanism 152 is movable downwardly against the bias springs 160. In accordance with one aspect of the invention, the springs are accessible by cover 162 so that the spring tension can be changed if desired. As the torque load on the winch increases, the mechanism 152 begins to move vertically and rotate from the position shown in FIGURE 13 to the position shown in FIGURE 15 through the transmission of a torque load into vertical displacement of member 152. As will be described subsequently, the difference in position of the mechanism 152 provides for engagement of different gear trains. The specific structure of the helical camming sur- faces will now be described with reference to FIGURES 11, 12 and 13. The camming element includes a plura¬ lity of protrusions 164 that extend longitudinally from the camming element 150 toward the mechanism. The protrusions of the camming element 150 are essentially the mirror image of the cam followers 166 of mechanism 152. Each camming surface 164 and 166 includes a face 168 that is bounded by two edges 170 and 172. The edges 170 and 172 are part of two concentric helices that extend in a helical shape with respect to shaft 102. The face 168 lies in a line 174 that passes between both edges 170 and 172 and the axis of the shaft wherein the line is perpendicular to the shaft axis. More specifically, referring to FIGURE 11, line 174 is perpendicular to shaft axis 176 and intersects both edge 170 and edge 172. In addition, if one were to envision moving the line vertically and rotating it at the same time, the face 168 would always be coinci¬ dent with the lines 174, in the preferred embodiment of the invention. In accordance with a preferred embodiment of the invention on both the mechanism 152 and the camming element 150, there are four camming protrusions for each part located in a circular path with respect to the shaft axis. Each camming protrusion 166 on the mechanism 152 has a mirror image camming protrusion 164 and the camming element 150. The camming protrusions are spaced apart and have located therebetween a series of rectangular protru¬ sions 165 and 167 spaced equally about the shaft axis 176 in the same circular path. These protrusions 165 and 167 form stop surfaces that define the first and second positions of the mechanism 152. More particu¬ larly, referring to a comparison between FIGURES 13 and 15, the surface 178 of protrusion 165 contacts the surface 180 of the protrusion 167 when the mechanism moves from the position shown in FIGURE 13 to the position shown in FIGURE 15. Preferably, the camming element 150 as shown in FIGURES 11 through 15 has the mirror image of the pro¬ trusions of mechanism 152 including the various stop surfaces and the camming protrusions. The mechanism 152 also includes outwardly extending gear teeth 182 that engage with ' similar teeth on shaft 106 as shown in FIGURE 15. The mechanism 152 preferably includes a transfer member 184 that is shown in perspective in FIGURE 12 5 and that is shown in two sectional views in FIGURES 14 and 16. The transfer member is preferably integral with mechanism 152 and includes a series of pawls 186 that are biased radially outwardly by springs 188 as shown in FIGURE 14. • The pawls are movable radially iθ inwardly against the bias of spring 188 as shown in FIGURE 16. As shown in FIGURE 12, the pawls 188 are inserted into pawls cavities 190 and the transfer member 184. Spacer elements 192 are shown in FIGURE 11 are inserted after the pawls have been inserted. 15 The pawls 186 drive an annual gear 194 which has internal ratchet teeth 196 and external drive teeth 198. In the position shown in FIGURE 13, the pawls 186 are biased radially outwardly into engagement with rat¬ chet teeth 196. Thus, when shaft 102 is turned, the 20 pawls engage ratchet teeth 196 and drive the gear. In the position shown in FIGURE 15, the transfer member and the pawls have moved longitudinally downwardly so that the pawls 186 are retained radially inwardly out of engagement with ratchet teeth 196. More specifi- 25 cally, an annular flange 200 extends beneath the inter¬ nal ratchet teeth. The flange 200 includes a radial face 202 that retains the pawls out of engagement with the ratchet teeth 196. Preferably, the annular flange includes a ramp ' 204 from the upper surface thereof 30 which helps urge the pawls radially inwardly as the transfer member moves downwardly. As best shown in a comparison between FIGURES 14 and 16, the pawls 186 are now retained radially inwardly and out of engagement with ratchet teeth 196 by the face 202. •When the winch is in the second speed, and the drive shaft 100 is being rotated in a counter-clockwise direction, the - teeth 182 of the mechanism 152 are always engaged, and the torque load on the winch is sensed by the camming element 150 sliding with respect to the cam follower mechanism 152. When the direction of drive shaft 100 is changed from counter-clockwise to the clockwise motion, if there is a heavy torque load on the winch, the ratchets 186 are held out of engagement with internal ratchet teeth 196 and, therefore, annular gear 194 is effec¬ tively isolated. In the event that the tension load falls, the cam follower mechanism 152 moves vertically upwardly to re-engage pawls 186 with ratchet teeth 196 to drive the winch. In order to better understand the operation of each of the four gear trains, each gear train will now be described in detail. Initial Gear Train Drive shaft 100 is rotated clockwise. This rotates the drum 110 by means of pawls 114 and ratchets 116. When the winch is driven in the initial gear, it is also driving portions of the first gear and third gear drive trains. Since both of these gears are slower speeds, the winch actually overruns these gears by means of pawls and ratchets. First gear is trying to drive the winch through gear 301 in FIGURE 8 which is fixed to the input shaft 100. Gear 301 drives gear 304, in FIGURE 13. Gear 304 is part of shaft 104 which drives integral gear 305. Gear 305 drives gear 198 in FIGURE 11. ' Pawls 186, which are part of mechanism 152, engage ratchets 196 and drive mechanism 152. This torque is transferred through the protrusions to cam¬ ming element 150. Combining element 150 has pawls 306 which ride in it and try to drive ratchets 307 in drive pinion 308. The ratchets 307 are moving faster than the- pawls 306 due to the drum 110, which is being driven through the initial drive, being attached to the ring gear 310 which drives gear 309 which is part of pinion 308. This explains how first gear is overrun. Third gear is also being driven but it too is being overrun. Third gear is driven from gear 311 on the drive shaft 100, FIGURE 15, driving gear 312. Gear 312 has ratchets 313 cut on its inside diameter which trey to drive pawls 314. Pawls 314 are actually overrunning the ratchets 313. This is caused by first gear driving gear 152 which drives gear 315 on the shaft 106 which causes pawls 314 to overrun ratchets 313. Pawls 314 ride in ratchet hub 316 which is attached to shaft 106. A clockwise rotation of shaft 100 causes pawls 302 to ratchet on ratchet 303. These are the second speed ratchets. This ratcheting disables second gear from driving. First Gear Train First gear is also driven by a clockwise rotation of input shaft 100. Button 108 must be in the up position and the winch must only be lightly loaded to drive in this gear. First gear must only be lightly loaded to drive in this gear. First gear is driven through gear 301 in FIGURE 8 which is fixed to the drive shaft 100. Gear 301 drives gear 304 in FIGURE 13 Gear 304 is part of shaft 104 which also has part of it gear 305. This gear drives gear 198 in FIGURE 11. Pawls 186, which are part of mechanism 152, engage ratchets 196 and drive mechanism 152. This torque is transferred through to camming element 150. Camming element has pawls 306 which ride in it and drive ratchets 307 in pinion 308. . This drive pinion 308 which includes gear 309. Gear 309 drives ring gear 310 which drive the drum 110. Third gear is also being driven but it too is being overrun. Third gear is driven from gear 311 on the . drive shaft 100, FIGURE 15, driving gear 312. Gear 312 has ratchets cut on its inside diameter which try to drive pawls 314. Pawls 314 are actually overrunning the ratchets 313. This is caused by first gear driving mechanism 152 which drives gear 315 on the shaft 106 which causes pawls 314 to overrun ratchets 313. Pawls 314 ride in ratchet 316 which is attached to shaft 106. A clockwise rotation of shaft 100 causes pawls 302 to ratchet on ratchet 303. This ratcheting disables second gear from driving. Second Gear Train Second gear is driven by a counter-clockwise rota¬ tion of shaft 100. Gear 317 which is fixed to shaft 100 has pawls 302 which engage ratchets 303. This drives gear 318 which has gear teeth 300. This drives gear 182 which is part of mechanism 152. This torque is transferred through to camming element 150. Camming element 150 has pawls 306 which ride in it and drive ratchets 307 in pinion 308. This drives pinion 308 which includes gear 309. Gear 309 drives ring gear 310 which drives the drum 110. The counter-clockwise rota¬ tion of shaft 100 also tries to drive first gear and third gear backwards. This action just ratchets pawls. When driving first gear in a counter-clockwise direction, gear 301 drives gear 304. Gear 304 is attached to shaft 10 ' 4 which has gear 305. Gear 305 is 5 part of annular gear 194 which has ratchets 196. These ratchets ride over pawls 186, driving third gear in a counter-clockwise rotation drives gear 311 which drives gear 312. Gear 312 has ratchets 313 which ratchet on the pawls 314 thereby not driving in third gear. • .10 Third Gear Train Third gear is driven by a clockwise rotation of the drive shaft 100 when the winch is highly loaded and the top drive button is in the up position. Third gear drives through gear 311 which is attached to the drive 15 shaft 100 and drives gear 312. The ratchets 313 on the inside diameter of gear 312 drive pawls 314 which are positioned in ratchet hub 316, which drives shaft 106. Gear 315, which is part of shaft 106, drives gear 182. Gear 182 is part of mechanism 152. This torque is 20 transferred through to camming element 150. Camming element 150 has pawls 306 which ride in it and drive ratchets 307 in pinion 308. This drives pinion 308 which includes gear 309. Gear 309 drives ring gear 310 which drives the drum 110. First gear is trying to 25 drive the inch through gear 301 in FIGURE 8 which is fixed to the drive shaft 100. This drives gear 304 in FIGURE 13. Gear 304 is part of shaft 104 which also has part of it gear 305. Gear 305 drives gear 198 in FIGURE 11. Pawls 186, which are part of part 152, are 30 held closed and unable to engage ratchets 196 by ring 202, thereby eliminating first gear. A clockwise rotation of shaft 100 causes pawls 302 to ratchet on ratchet 303. This ratcheting disables second gear from driving. In summary, it should be understood that a winch in accordance with the present invention has a torque load sensing capability that enables the winch to shift to the appropriate gear speed in response to variations in torque load. This is done in a particularly simple manner without parts that wear to a significant degree. It should be understood that although specific embodiments of the invention have been described herein in detail, such description is for purposes of illustration only and modifications may be made thereto by those . skilled in the art within the scope of the invention. What is claimed is:

Claims: 1. An automatic torque load-responsive winch compris¬ ing: a base; • a winch drum rotatably mounted on the base; a rotatable drive shaft for driving said winch drum; at least two gear trains mounted on driven shafts and linked between said drive shaft and said drum for rotating said drum in response to rotation of said-drive shaft, one of said two gear trains producing a different drum speed than the other of said gear trains for the same rotational speed of said drive shaft; means for • applying said variable torque load to one of said shafts to rotate said one shaft; a mechanism displacable vertically with respect to one of said shafts in response to changes in said torque load, said mechanism including means for engaging one of said gear trains at a first vertical position of said mechanism and for disengaging said one gear train at a second vertical position to isolate said one gear train and provide for rotation of said drum by said other gear train. 2. A winch according to claim 1 wherein: said mechanism includes a cylindrical opening therein for receiving said one shaft, said opening including a plurality of longitudinally extending splines, said shaft having a plurality of longi¬ tudinally extending splines engaging said splines of said mechanism to rotate said body in response to rotation of said one shaft and for transmitting said torque load, said mechanism being slidable longitudinally with respect to one shaft from said first vertical position to said second vertical position; said mechanism being biased to said first vertical position and slidable against said bias to said second vertical position, said shaft splines • engaging said body splines to produce friction that increases as said torque load increases, said mechanism being maintained in said second vertical position when said friction is increased in response to said torque load to an amount sufficient to overcome said bias on said mechanism. 3. A winch according to claim 2 and further including means for moving said mechanism reciprocally with respect to -said shaft when said friction between said splines is an amount insufficient to overcome said bias on said mechanism and wherein said one shaft is the drive shaft. 4. A winch according to claim 3 wherein said mecha¬ nism includes a plurality of ramps protruding vertically upwardly therefrom, said ramps being spaced in an arc around the body, said ramps periodically engaging a plurality of ramps located in a fixed vertical position with respect to shaft, said ramps of said body riding over the ramps fixed with respect to said shaft to displace the mechanism vertically and reciprocally. 5. A winch according to claim 2 wherein said engaging and disengaging means for said gear train comprises: said one gear train including an annular gear having internal .ratchet teeth, said gear having external gear teeth for driving said one gear train; a transfer member rotating with said shaft and slidable vertically on said shaft in response to vertical movement of said mechanism, said transfer member slidable from a first vertical position • to a second vertical position, said transfer member including a plurality of pawls biased radially outwardly of said transfer member into engagement with said ratchet teeth in the first vertical position of said transfer member, said pawls being moveable radially inwardly against said bias out of engagement with said ratchet teeth in said second vertical position; and means for retaining said pawls out of engage¬ ment with said ratchet teeth in said second vertical position of said transfer member.. 6. A winch according to claim 5 wherein said retain¬ ing means for said pawls comprises an annular flange extending radially inwardly of said internal ratchet teeth, said flange including a radial face that retains said pawl out of engagement with said ratchet teeth when said transfer member is moved longitudinally with respect to said gear to said second vertical position of said transfer member. 7. A winch according to claim 7 wherein said winch has at least three speeds including a first speed wherein the drum rotates at a high speed, a second speed wherein the drum rotates at a medium speed, and a slow speed wherein said drum rotates at a slow speed, and wherein said first speed is accomplished by rota¬ tion of said drive shaft in one direction, said second speed is accomplished by rotation of said drive shaft in an opposite direction and said third speed is accomplished by rotation of the drive shaft in said one direction, and wherein said first gear train is driven by said annular gear, said pawls associated with said transfer member engaging the internal ratchet teeth on said annular gear and turning said gear in said one direction, said pawls overriding said ratchet teeth when said shaft is rotated in said opposite direction in said second speed, said transfer member moving longi¬ tudinally with respect to said annular gear during said second winch speed to a position wherein said pawls are engaged by said radial face of said annular flange; said third speed being provided by rotation of said - shaft in said one direction, said pawls being retained out of engagement with said ratchet teeth during rotation of said shaft in said one direction during third speed. 8. A winch according to claim 7 wherein said body releases from said second vertical position when said friction is decreased in response to reduction of the torque load, said bias overcoming said friction to force said body to said first vertical position, said . transfer member moving vertically with respect to said annular gear thereby moving said pawls out of retaining engagement with said annular flange and into engagement with said ratchet teeth so that the winch as in said first speed. 9. A winch according to claim 4 wherein one set of ramps is on the upper surface of said mechanism, and wherein the other set of ramps is on the lower surface of a generally circular plate, said plate being mounted for longitudinal sliding movement with respect to said drive shaft between an upper vertical position wherein the ramps on the plate override • the ramps on the mecha¬ nism to produce said reciprocal movement to a lower vertical position wherein said plate rests on said mechanism and rotates with said mechanism about said shaft, said plate including means for retaining said plate against rotation with respect to said drive shaft in said upper vertical position and permitting rotation of said plate with respect to said shaft when said plate is said lower vertical position. 10. A winch according to said claim 9 wherein said means for alternatively preventing and permitting rotation of said plate comprises a plurality of arcuate slots adjacent the periphery of said plate, said arcu- ate slots being adapted to receive a stationary pin that extends downwardly into at least one of the slots when said plate is in said upper vertical position to retain said plate against rotation, said plate in its lower vertical position moving out of engagement with said pin to permit rotation of said plate with said mechanism. 11. A winch according to claim 1 wherein said mecha¬ nism has a first rotational position corresponding to said first vertical position of said mechanism and a second rotational position offset from said first rota- tional position and corresponding to said said second vertical position of said mechanism, said mechanism moving in an accurate path between said first vertical position and said second position in response to an in¬ crease in said torque load. 12. A winch according to claim 11 wherein said mecha¬ nism is biased toward said first vertical position and is moveable by an increase in said torque load against said bias to said second vertical position. 13. A winch according to claim 12 wherein said bias is adjustable. 14. A winch according to claims 1 and 13 and further including: a camming element located in a fixed vertical position with respect to said one shaft, said mechanism being movable from a position adjacent said camming element to a position spaced from said camming element, said camming element includ¬ ing at least one cam surface shaped in arcuate relation with respect to said one shaft, said displacable ' mechanism including a cam follower that rides on said helical cam surface, said cam follower riding over said camming surface in response to changes in said torque load to move said mechanism from said first vertical position to said second vertical position. 15. A winch according to claim 14 wherein said cam surface of said camming element comprises at least one protrusion that extends longitudinally from said cam¬ ming element toward said mechanism, said protrusion including a face having two edges, said edges forming two helices, said helices being concentric with respect to the axis of said one shaft. 16. A winch according to claim 15 wherein said face of said cam surface lies in a line that passes between both said edges and the axis of said one shaft and wherein said line is perpendicular to said shaft axis. 17. A winch according to claim 16 wherein said cam follower of said mechanism rides on said face. 18. A winch according to claim 17 wherein the cam follower of said mechanism comprises at least one protrusion that extends longitudinally upwardly from said mechanism, said protrusion including a helical camming surface that has a face that engages said face of said protrusion of said camming element. 19. A winch according to claim 18 wherein both said mechanism and said camming element include a plurality of protrusions, said protrusions being located in a circular path with respect to said shaft axis, each protrusion on said mechanism having a protrusion from said camming element associated therewith. 20. A winch according to claim 19 further including means for limiting rotation of said mechanism with respect to said camming element between said first rotational position of said mechanism and said second rotational position of said mechanism. 21. A winch according to claim 20 wherein said means for limiting rotation comprises a stop surface on said camming element which engages a stop surface on said mechanism when said mechanism is in said first rota- tional position, said camming element including a second stop surface that engages a second stop surface on said mechanism when the mechanism is in said second rotational position. 22. A winch according to claim 21 wherein: said camming element includes a plurality of protrusions having helical camming surfaces thereon, said camming element further including a plurality of protrusion interspersed between adjacent camming protrusions. Said interspersed protrusions including said stop surfaces of said camming element; and said mechanism includes a plurality of protrusions having said camming surfaces thereon, said mechanism further including a plurality interspersed protrusions between camming" protrusions, said protrusions including said stop surfaces of said mechanism. 23. A winch according to claim 22 wherein said stop protrusions have a generally rectangular cross section, said stop protrusion having two faces aligned in a plane that passes through the axis of said shaft and a third surface that is perpendicular to said two surfaces. 24. A winch according to claim 11 wherein said engaging and disengaging means for said gear train comprises: said gear train including an annular gear having internal ratchet teeth, said gear having external gear teeth for driving one of said gear trains; a transfer member rotating with said shaft and slidable vertically on said shaft in response to vertical movement of said mechanism, said transfer member slidable from a first vertical position to a second vertical position, said transfer member including a plurality of pawls biased radially outward of said transfer member into engagement with said ratchet teeth in the first vertical position of said transfer member, said pawls being movable radially inwardly against said bias out of engagement with said ratchet teeth in said second vertical position; and means for retaining said pawls out of engage¬ ment with said ratchet teeth in said second verti¬ cal position of said transfer member. 25. A winch -according to claim 24 wherein said trans¬ fer member is integral with said displacable mechanism. 26. A winch according to claim 25 wherein said retaining means for said pawls comprises an annular flange extending radially inwardly of said internal ratchet teeth, said flange including a radial face that retains said pawls out of engagement with said ratchet teeth once a transfer member is moved longitudinally with respect to said gear to said second vertical position of said transfer member. 27. A winch according to claim 26 wherein said said annular flange includes a ramp on the top thereof for moving the pawls radially inwardly as the transfer members moves with respect to annular gear. 28. A winch according to claim 24 wherein said winch has at least three speeds including a first speed wherein the drum rotates at a high speed, a second speed wherein the drum rotates at a medium speed, and a slow speed wherein the drum rotates at a slow speed, and wherein said first speed is accomplished by rota¬ tion of said drive shaft in one direction, said second speed is accomplished by rotation of said drive shaft in an opposite direction, and said third speed is accomplished by rotation of said drive shaft in said one direction, and wherein said first gear train is driven by said annular gear, said pawls associated with said transfer member engaging the internal ratchet teeth on said annular gear and turning said gear in said one direction, said pawls overriding said ratchet teeth when said shaft is rotated in said opposite direction in said second speed, said transfer member moving longitudinally with respect to said annular gear as said torque load increases to a position wherein said pawls are engaged by said radial face of said annular flange, said third speed being provided by rotation of said drive shaft in said one direction, said pawls being retained out of engagement of said ratchet teeth during rotation of said drive shaft in . said one direction in said third speed. 29. A winch according to claim 28 wherein said displacable mechanism is mounted on a driven shaft. 30. A winch according to claim 28 wherein said winch has an additional speed and has at least four speeds, including an initial speed wherein the drum rotates at a speed higher than said first speed and wherein said initial speed is accomplished by rotation of said drive shaft in said one direction, and further including means for manually engaging said initial speed. 31. A winch according to claim 30 and further includ¬ ing means for automatically disengaging said initial speed in response to rotation of said drive shaft in said other direction at least 180 degrees. 32. A winch according to claim 31 wherein said drive shaft includes a main section and a second section that rotates with said main section and that is movable longitudinally with respect to said main section of said shaft from a first vertical position to a second vertical position, said second section of said drive shaft ' being displacable manually from said first vertical position to said second vertical position and further including means for retaining said second sect- ion of said shaft in said second vertical position. 33. A winch according to claim 32 wherein said means for retaining comprises a retaining pin mounted in a radial hole in said main section of said shaft, said pin biased radially outwardly by a spring and movable against said bias ' to a position withdrawn inside said shaft, said second section of said shaft comprising a cylindrical tube fitting over the cylindrical end of the main section of said shaft, said retaining pin being located in the cylindrical end of the main section of said shaft, said cylindrical second section of said shaft having a detent for receiving the pin in the second vertical position of said second shaft section, said retaining pin moving radially inwardly into said detent when said second section of said shaft is in its second vertical position, said pin maintaining said second section of said shaft against vertical sliding movement. 34. A winch according to claim 33 wherein said second section of said drive shaft is biased towards said first vertical position and movable manually against said bias to said second vertical position. 35. A winch according to claim 34 and further includ¬ ing a means for disengaging said pin to permit said second section of said shaft to move to back to the its first vertical position. 36. A winch according to claim 35 wherein said means for disengaging comprises a camming pin extending radially outwardly from said second section of said shaft, said pin being freely rotated with second sec- tion of said shaft, wherein the main section of said shaft and said second section of said shaft is rotated in said one direction, and further including a ramp for forcing said pin longitudinally upwardly to disengage the biased pin in said detent of said shaft and permit said section section of said shaft to move up to its first vertical position. 37. A winch according to claim 36 wherein said initial gear speed includes an initial gear train that has an annular gear having internal ratchet teeth for driving said initial gear train. 38. A winch according to claim 37 and further including a transfer member rotating with said second section of said shaft, said transfer member including a plurality of pawls biased radially outwardly out of said transfer member, said pawls being movable radially inwardly against said bias out of engagement with said ratchet teeth in said first vertical position and mov¬ able radially outwardly with said bias into engagement with said ratchet teeth in said second vertical posi- tion and further including means for retaining said pawls out of engagement with said ratchet teeth in said vertical position of said second shaft section. 39. A winch according to claim 38 wherein said retaining means for said pawls comprises an annular flange that includes a radial face that retains said pawls out of engagement with said ratchet teeth when said second shaft section is in the first vertical position. 40. A winch according to claim 39 wherein said pawls are moved out of engagement with said flange in said second vertical position of said shaft section to permit said shaft to engage said initial gear train. 41. A winch according to claim 40 wherein said pawls of said second shaft section are in engagement with said ratchet teeth of said initial gear train, said pawls being associated with said second shaft section being retained out of engagement with said ratchet teeth during said first gear .speed to thereby isolate the said initial gear train. 42. A winch for comprising: a base; a winch drum rotatably mounted on the base; a rotatable shaft for driving said winch drum; at least two gear trains driven by said shaft for rotating said drum in response to rotation of said shaft, one of said two gear trains producing a different drum speed and the other of said gear trains for the same rotational speed of said shaft; one said gear train including an annular gear having internal ratchet teeth for driving said one gear train; a transfer member rotating with said shaft and slidable vertically on said shaft, said trans¬ fer member being slidable from a first vertical position to a second vertical position, said transfer member including a plurality of pawls biased radially outwardly of said transfer member into engagement with said ratchet teeth in said first verti¬ cal position of said transfer member to drive said one gear train, said pawls being movable radially inwardly against said bias out of engagement with said ratchet teeth in said second vertical position to isolate said one gear train and to provide for rotation of said drum by said second gear train; and means for retaining said pawls out of engage¬ ment with said ratchet teeth in said second vertical position of the transfer member. 41. A winch according to claim 40 wherein said retaining means for said pawls comprises an annular flange extending radially inwardly of said internal ratchet teeth, said flange including a radial face that retains said pawls out of engagement with said ratchet teeth when the transfer member is moved longitudinally with respect to said gear to said second vertical position of said transfer member. 42. A winch according to claim 41 wherein said annular flange includes a ramp for slowly and smoothly disengaging said pawls from engagement with said ratchet teeth as said transfer member is displaced vertically from said vertical position to said second vertical position. 43. An automatic torque load-responsive winch compris¬ ing: a base; a winch drum rotatably mounted on the base; a rotatable drive shaft for driving said winch drum; at least two gear trains mounted on driven shafts and linked between said drive shaft and said drum for rotating said drum in response to rotation of said drive shaft, one of said two gear trains producing a different drum speed than the other of said gear trains for the same rotational speed of said drive shaft; means for applying said variable torque load . to one of said shafts to rotate said one shaft; a mechanism displacable with respect to one of said shafts in response to changes in said torque load, said mechanism including means for engaging one of ' said gear trains at a first position of said mechanism and for disengaging said one gear train at a vertical position to isolate said one gear train and provide for rotation of said drum by said other gear train. 44. A winch according to claim 42 wherein said mecha¬ nism has a first rotational position and a second rotational position offset from said first rotational position, said mechanism moving between said first position and said second position in response to an increase in said torque load. 45. A winch according to claim 44 wherein said mecha¬ nism is biased toward said first position and is moveable by an increase in said torque load against said bias to said second position. 46. A winch according to " claim 45 wherein said bias is adjustable. 47. A winch according to claim 45 wherein said engaging and disengaging means for said gear train comprises: said gear train including an annular gear having internal ratchet teeth, . said gear having external gear teeth for driving one of said gear trains; a transfer member rotating with said shaft, said transfer member including a plurality of pawls biased radially outward of said transfer member into engagement with said ratchet teeth in the first position of said mechanism, said pawls being movable radially inwardly against said bias out of engagement with said ratchet teeth in said second position of said mechanism; and means for retaining said pawls out of engage¬ ment with said ratchet teeth in said second posi¬ tion.

Inventors: FERRAMOLA GUILLERMO, RESCH BRUNO, FERRAMOLA, GUILLERMO, RESCH, BRUNO
Applicants: IMI BARIENT INC, IMI BARIENT, INC.
Application year: 1991
Main classification: B66D1
IPC codes: B66D1