US2943710A - Reversible ratchet - Google Patents

Description

July 5, 1960 H. c. LINDMARK REVERSIBLE RATCHET Filed March 27, 1959 w u l D-(canard L ind m a r mln J United States atent REVERSIBLE RATCHET Howard C. Lindmark, Howard Engineering Inc., 1206 Kishwaukee St.', Rockford, Ill.

Filed Mar. 27, 1959, Ser. No. 802,476

4 Claims. (Cl. 183-823) The general object of the present invention is to improve upon the reversible ratchet disclosed in my Patent 2,849,089, by increasing the range of over center movement of the spring of the pawl latch and by a well defined third or dead center position to which the pawl may be shifted conveniently and held positively.

The invention aims to achieve the foregoing by a novel shaping of the abutting surfaces of the latch and pawl and correlation of these surfaces with the engaging surfaces on the pawl and its pivot pin.

Other objects and advantages of the invention will become apparent from the following detailed description taken in connection with the accompanying drawings, in which Figure 1 is a fragmentary elevational view of a reversible ratchet embodying the novel features of the present invention.

Fig. 2 is a fragmentary side view.

Figs. 3 and 4 are fragmentary views of part of Fig. 1 showing different positions of the parts.

Fig. 5 is an enlarged view of a part of Fig. 4 showing steps in the reverse movement of pawl.

As described more fully in the aforesaid patent, the improved ratchet is especially adapted for controlling the winding and unwinding of a cable on a rotatable winch (not shown) journaled in the side walls of a box-like frame and having a spur gear 11 journaled therein adjacent one wall and meshing with the teeth 12 of a pinion 13. The latter is fast on a shaft 14 extending through and journaled in a boss 15 on the frame wall and carrying a hand crank 16 for turning the pinion and the winch.

The pinion may be held against turning in either direction or released for free turning according to the angular position of a relatively fiat pawl 17 disposed in the plane of the pinion and fulcrumed on a shouldered pivot pin 18 bolted to the frame 10 parallel to the shaft 14 and offset outwardly from the periphery of the pinion. By grasping an outwardly projecting handle 19, the pawl may be swung through an angle a in either direction away from an intermediate or neutral position b shown in Fig. 1 to a selected limit position 0 or d, the latter of which is shown in phantom in Fig. 4.

On the inner end of the pawl and projectingtoward the pinion are teeth 20 and 21 laterally spaced apart equidistantly from and on opposite sides of the longitudinal center line of the pawl, each being shaped to mesh or fit closely in the interdental spaces between the pinion teeth 12 as shown in Fig. 4. In this position with the tooth 21 in mesh with the pinion, the pawl is blocked against counterclockwise turning, thus holding the pinion against clockwise turning. In a similar way, the pawl is blocked and the pinion held against counterclockwise turning' when the pawl is in the other limit position c with" the tooth 20 in mesh with the pinion teeth. When the pawl is in the intermediate position b Shown in Fig. 1', both of the pawl teeth are out of mesh rice with the teeth of the pinion and the latter is free to turn when the winch cable is under tension.

The pawl is held in the respective limit positions by the over-center action of a spring 24 acting on the pawl through the medium of a latch 25 which, in accordance with the present invention, also utilizes the force of the spring to provide a detent action by holding the pawl more or less positively in the intermediate position b. Herein, the latch comprises a fiat plate disposed between the pawl and the frame wall and extending generally tangentially of the pinion with one end 26 receiving the hooked end of the spring 24. The latter is a helical coil hooked at its outer end into a hole 27 in the frame wall and thus maintained under a tension suflicient to produce the desired detenting action.

Intermediate its ends, the latch plate is formed with an elongated transverse slot 28 loosely receiving the pivot pin 18 of the pawl and having one side wall 29 specially shaped as later described and urged against one side of the pin under the force of the spring 24. To control the centering and over-centering of the pawl, the latch is coupled to the pawl through a special pivotal connection 30 which includes a squared lug 31 bent up into the plane of the pawl from the end of the latch opposite the spring. This lug projects into a notch 32 substantially wider than the lug and formed in the edge of the pawl substantially parallel to slot 29 and centered relative to a line 34' through the anchor point 27 of the spring and the axis of the pin 18. The bottom of the slot is countersunk to provide a narrower and squared slot 33 also centered on the line 34 and having a depth and width slightly greater than the lug so as to receive the latter loosely when the pawl is in the neutral position (Fig. 1) and the center line of the latch coincides with the line 34. The surfaces 35, 36 of the bottom of the notch 32 outwardly beyond the notch 33 are preferably rounded slightly as shown in Fig. 5 and inclined slightly in diverging outwardly to the'side walls 37, 38 of the notch. The lug is so located on the latch along the line 34 that it will be seated by the spring 24 in. the notch 33 when the adjacent or outer side wall of the slot 28 is engaging the pin 18 with the pawl in the intermediate position.

In accordance with the present invention, theslot wall is shaped in a novel manner to coact with the pin 18 in providing a positive detenting action for maintaining the neutral position of the pawl and also to coact with the lug 31 and the bottom of the notch 32 in bringing the latch and point into detenting relation. To these ends, the slot Wall is defined by the edges of two generally V- shaped projections 40, 41 equidistantly spaced laterally from the center line of the latch for engagement of their tips with the pin 18 on opposite sides of the line 34 when the latch is centered on this line. Thus the projections provide between them a well defined notch 42 in which the pin is held seated by the spring to produce the desired detent action.

On opposite sides of the notch 32, the sides 43, 44 of the projections 40, 41 diverge away from the pin 18 substantially to the ends of the slot 28. Each of these surfaces, when engaged by the pin, acts under the force of the spring as a cam' for swinging the latch laterally and through the lug 31 for shifting the pawl of]? center until the corresponding pawl tooth becomes fully seated between the teeth of the pinions as shown in Fig. 4.

Considering now the operation of the improved ratchet, let it be assumed that the parts are disposed in the neutral positions as shown in Fig. 1 with both teeth of the pawl out of mesh with pinion, the lug 31 being seated in the small notch 33 and the projections 40", 41 bearing against the 'pivot pin 18 under the force ofthe spring 24 which acts along the dead center line through the center of the pin 18. Now assume that by a force normally applied to the handle 19, the pawl 17 is swung counter clockwise to the position shown in Fig. 4 to seat the tooth 21 between two of the pinion teeth. In the initial part of this movement of the pawl, the side wall 38 bears against the lug 31 so as to shift the latch along with the pawl thus sliding the projection 41 up the curved surface of the pin 18. This also shifts the latch endwise and lifts the lug 31 out of the notch by the time that the tip of the projection has passed over-center relative to the pin 18. As the rocking of the pawl continues and under the action of the over-center force of the spring, the lug 31 snaps over and past the side 37 of the notch 33 and comes against the wall 37 of the notch 32 as shown in Fig. 4. With the inclined surface 44 of the slot thus engaging the pin 18 at a point well over-center, the latch is cammed quickly to the limit position as shown in Fig. 4, thus seating the tooth 21 against the pinion with the pawl in position d. By virtue of the substantial offsetting of the line of the spring from the dead-center position due to the substantial width of the notch 32, the pawl is always held firmly in the selected limit position.

Assume now that the pawl is swung clockwise from the limit position shown in Fig. 4 to the dead-center or neutral position shown in Fig. 1. In the initial part of this movement, the lug 31 remains against the outer wall 37 of the notch 32 and its point of contact with the inclined bottom surface 35 rolls outwardly along this surface. This action lifts the latch and raises the projections 40, 41 away from the pin 18. When the pawl nears the dead center position shown in Fig. 5, the lug 31 will still lie against the wall 37 and the projections 40, 41 will be raised above the pin 18 to the position shown in dotted outline and thus adapted to pass over the top of the pin 18. Thus, the latch will be disposed short of the dead center position by an angle x the magnitude of which will depend on the slope of the bottom surface 35. At this time, the force of the spring becomes effective to slide the lug 31 down the incline 35 and thereby shift the projection 41 laterally across the line 34 and over-center relative to the pin 18. When the trailing end of the lug reaches the'wall 37 and is ready to drop into the notch 33, the lug and the projections will be positioned as shown by the dot-dash lines in Fig. 5. With the projections 40, 41 thus straddling the pin, they will come into full engagement with the latter as the lug slips off from the ledge 37 and becomes seated in the notch 33. i

It will be apparent that the detenting action for retaining the pawl positively in the dead-center position is made possible by coaction of the lug 31 with the bottom and side edges of the notch 32 in lifting one of the projections 40, 41 away from the pin and then carrying the leading projection over the top of the pin to a position for proper engagement with the pin when the latch is again released by the pawl surface 35.

I claim as my invention:

1. A reversible ratchet having, in combination, a toothed pinion rotatable about a fixed axis, a fixed pin paralleling said axis and spaced outwardly from the periphery of said pinion, a pawl fulcrumed on said pin to swing back and forth in the plane of the pinion between two limit positions through an intermediate dead center position, laterally spaced teeth on said pawl facing toward the periphery of said pinion and both disposed out of engagement with the pinion teeth when saidpawl is in said intermediate position, said teeth meshing with said pinion one in one of said limit positions and the other in the other limit position, a latch plate lying adjacent said pawl and having an elongated transverse slot therein receiving said pin, a tension spring attached to one end of said latch plate and urging the same endwise to hold one wall of said slot against said pin, a squared lug upstanding from the other end of said latch plate into the plane of said pawl, a square sided notch in said pawl substantially wider than said lug and receiving the latter, a second squared notch narrower and shallower than said first notch and formed in the bottom of the latter to receive said lug, and two V-shaped projections formed on said slot wall intermediate the ends thereof and laterally spaced along the latter for bearing of the tips thereof against said pin in said intermediate position of said pawl and with said lug seated in said notch under the action of said spring, one end wall of said second notch acting on said lug in the initial tipping of said pawl out of said intermediate position to shift said latch plate and carry one of said tips across and over-center relative to said pin and also to shift said lug laterally toward and against the end wall of said first notch.

2. A reversible ratchet having, in combination, a toothed pinion rotatable about a fixed axis, a fixed pin paralleling said axis and spaced outwardly from the periphery of said pinion, a pawl fulcrumed on said pin to swing back and forth in the plane of the pinion between two limit positions through an intermediate dead center position, laterally spaced teeth on said pawl facing toward the periphery of said pinion and both disposed out of engagement with the pinion teeth when said pawl is in said intermediate position, said teeth meshing with said pinion one in one of said limit positions and the other in the other limit position, a latch plate lying adjacent said pawl and having an elongated transverse slot therein receiving said pin, a tension spring attached to one end of said latch plate and urging the same endwise to hold one wall of said slot against said pin, a squared lug upstanding from the other end of said latch plate into the plane of said pawl, a square sided notch in said pawl substantially wider than said lug and receiving the latter, a second squared notch narrower and shallower than said first notch and formed in the bottom of the latter to receive said lug, the end portions of said notch bottom diverging outwardly and away from the sides of said second notch and the side walls of said first notch determining said limit positions, and two V.-shaped projections formed on said slot wall intermediate the ends thereof and laterally spaced along the latter for bearing of the tips thereof against said pin in said intermediate position of said pawl and with said lug seated in said second notch under the action of said spring, one of said end portions and the adjacent side wall of said first notch acting on said lug during swinging of said pawl out of one of said limit positions to shift said latch plate endwise and carry said tips away from said pin until the leading tip has passed over-center relative to said pin and then release the latch plate for seating in said second notch.

3. A reversible ratchet having, in combination, a toothed pinion rotatable about a fixed axis, a fixed pin paralleling said axis and spaced outwardly from the periphery of said pinion, a pawl fulcrumed on said pin to swing back and forth in the plane of the pinion between limit positions through an intermediate dead center position, laterally spaced teeth on said pawl facing toward the periphery of said pinion and both disposed out of engagement with the pinion teeth when said pawl is in said intermediate position, and teeth meshing with said pinion one in one of said limit positions and the other in the other limit position, a latch plate lying adjacent said pawl and having an elongated transverse slot therein receiving said pin, a spring urging said latch plate endwise to hold one wall of said slot against said pin, 9. lug upstanding from said latch plate into the plane of said pawl, a notch in said pawl substantially wider than said lug and receiving the latter, the side walls of said notch determining said limit positions of said latch plate, a second notch narrower and shallower than said first notch and formed in the bottom of the latter to receive said lug, the end portions of the bottom of said first notch diverging outwardly from said second notch, two V-shaped projections formed on said slot wall intermewi y diate the ends thereof and laterally spaced along the latter for bearing of the tips thereof against said pin in said intermediate position of said pawl and with said lug seated in said notch under the action of said spring, said lug coacting with one side and the bottom of said first notch during swinging of the pawl from one limit position to said neutral position to lift said projections away from said pin while said latch plate is being moved toward dead center position.

4. A reversible ratchet having, in combination, a toothed pinion rotatable about a fixed axis, a fixed pin paralleling said axis and spaced outwardly from the periphery of said pinion, a pawl fulcrumed on said pin to swing back and forth in the plane of the pinion between limit positions through an intermediate dead center position, laterally spaced teeth on said pawl facing toward the periphery of said pinion and both disposed out of engagement with the pinion teeth when said pawl is in said intermediate position, said teeth meshing with said pinion one in one of said limit positions and the other in the other limit position, a latch plate lying adjacent said pawl and having an elongated transverse slot therein receiving said pin, a spring urging said latch plate endwise to hold one wall of said slot against said pin, a lug upstanding from said latch plate into the plane of said pawl, a notch in said pawl substantially wider than said lug and receiving the latter, the side walls of said notch determining said limit positions of said latch plate, a second notch narrower and shallower than said first notch and formed in the bottom of the latter to receive said lug, two V-shaped projections formed on said slot wall intermediate the ends thereof and laterally spaced along the latter for bearing of the tips thereof against said pin in said intermediate position of said pawl and with said lug seated in said notch under the action of said spring.

No references cited.

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