US3727886A

US3727886A - Release mechanism for ratchet-type power unit

Info

Publication number: US3727886A
Application number: US00122755A
Authority: US
Inventors: R Cain
Original assignee: American Gage and Manufacturing Co
Current assignee: American Gage and Manufacturing Co
Priority date: 1971-03-10
Filing date: 1971-03-10
Publication date: 1973-04-17
Anticipated expiration: 1990-04-17

Abstract

Release mechanism for a ratchet-type power unit utilizing a ratchet drum upon which a flexible tension member is wound. Rotation of the drum is produced by oscillation of a lever arm having a ratchet catch pivotally mounted thereon. The release mechanism of the invention permits pivoting of the catch between a drum engaging ratcheting position, and an untensioning or ''''let down'''' position where the catch clears the ratchet teeth of the drum. The catch includes a torsion spring exerting a constant biasing force thereon about the catch pivot, and a leaf spring mounted on the catch is selectively engageable with a movable spring compressor which selectively permits the leaf spring to overcome the torsion spring bearing force. The spring compressor is mounted upon a slidable carriage for accessible manual operation and positioning, and the catch includes a manually operable portion disposed adjacent the spring compressor carriage.

Description

Unite States Patet 91 Cain [ 1 Apr. 17, 1973 RELEASE NIECHANISM FOR RATCI-ET-TYPE POWER UNIT [75] Inventor: Robert L. Cain, West Lafayette,

Ind.

' [73] Assignee: The American Gage 8: Manufacturing (30., Wauseon, Ohio [22] Filed: LMar. 10, 1971 H [21] Appl. N02 122,755

52 us. ca. ..254/l64, 254/167, 74/149 51' Int. Cl. ..A63b 61/04 [58] ,Field of Search ..254/l64, 167; p 7 74/149, 154

[56.15. 1 References Cited v UNITED STATES PATENTS 3,003,359 10/1961 Maas dam ..254/l67 X 512,908 1/1894 Scheer ..74/ 149 X 2,507,889 5/1950 Coffing ..74/154 X Primary Examiner-Evon C. Blunk Assistant Examiner-Merle F. Mafi'ei AttorneyBeama.n & Beaman Release mechanism for a ratchet-type power unit utilizing a ratchet drum upon which a flexible tension member is wound. Rotation of the drum is produced by oscillation of a lever arm having a ratchet catch pivotally mounted thereon. The release mechanism of the invention permits pivoting of the catch between a drum engaging ratcheting position, and an untensioning or let down position where the. catch clears the ratchet teeth of the drum. The catch includes a torsion spring exerting a constant biasing force thereon about the catch pivot, and a leaf spring mounted on the catch is selectively engageable with a movable spring compressor which selectively permits the leaf spring to overcome the torsion spring bearing force. The spring compressor is mounted upon a slidable carriage for accessible manual operation and positioning, and the catch includes a manually operable portion disposed adjacent the spring compressor carriage.

10 C, 6 Drawing Figures PATENTED APR 1 H975 SHEET 1 [1F 2 INVENTOR ROBERT 4 CAIN ATTORNEYS PATENTEDAPR 1 H915 3'. 727. 886

SHEET 2 BF 2 INVENTOR ROBERT L. ,Gfldfi ATTORNEYS RELEASEMECHANISM FOR RATCHET-TYPE murowsauurr I BACKGROUND OF THE INVENTION The invention pertains to power units of the ratchet V The'spring compiressor member is mounted upon a which is of the manually operated type and maybe used for lifting, stretching, bracing, pulling, or other'applications wherein it is desired to produce a tension force. Such power units have found wide applications of use and may be used to raise or lower loads, stretch fence, tighten guy wires, pull stumps, tie down cargo, or similar applications. I

Basically, such power units include a frame upon which a ratchet drum is rotatably supported, the drum including a member having ratchet teeth concentrically formed thereon. The tension member, such as a rope, chain or cable, is wound on the drum, and the frame in- 'cludes a pawl which prevents rotation of the drum in the unreeling or unwinding direction. A lever arm is mounted upon the frame for pivotal oscillation about the drum axis,-and a catch mounted on the lever arm engages the drum ratchet teeth to producedrum rotation in a winding or tensioning direction. Thecatch of the lever arm engages the ratchet teeth during tensioning, and when it is desired to release the tension the catch is positioned so as not to engage the drum ratchet teeth, but may function to cooperate with the pawl to permit a tooth by tooth release of the drum in an indexing manner to remove the cable tension. Such av structural relationship, and operation, is disclosed in US. Pat. No. 2,50l,2 53.

While the structure of the aforementioned patent permits an operable power unit to be produced, im-

provements in the catch release positioning apparatus SUMMARY OF THE INVENTION It is an object of the invention to provide'a release mechanism for ratchet-type power unit catches wherein the mechanism is of an economical, readily manufacturable nature, easily operated by users of conve'ntional skill, self-indicating with respect to the condition of the release mechanism, and capable of manual operation in order to produce a versatility of lever arm movement and action and permit operation in the event ofa catch spring failure.

In the practice of the invention the catch forthe drum ratchet includes a hub having an extending finger adapted to engage the drum ratchet teeth. Additionally, an extension radially projects from the hub for permitting manual operation of the catch. A releasing leaf spring is affixed to the catch in a mannerwhich minimizes the likelihood of spring breakage, and the leaf spring includes a free end adapted to be selectively engageable by a movable spring compressor member mounted upon the lever arm.

carriage or slide linearly movable on the lever arm. Compression of the free end of the leaf spring overcomes the biasing force normally imposed on the catch by a torsion spring tending to engage the catch with the drum ratchet teeth and, the positioning of the slide and spring compressor determines whether the catch is in a release or drum winding condition.

The spring compressor and leaf spring are effective to maintain the catch in the release position, yet the biasing force exerted on the catch by the leaf spring x'may be overcome by engagement with the pawl during the hoist untensioning or letdown operation.

The extension defined on the catch extends from the lever handle adjacent the spring compressor carriage and the condition of the catch may be manually changed without utilizing the spring compressor, if desired. However, normal operation of the release mechanism entails use of the spring compressor and leaf spring mounted upon the catch.

In order to reduce the likelihood of spring breakage of the catch release mechanism, the leaf spring associated with the catch is anchored to the underside of the catch extension remote from the catch hub. The leaf spring then passes about the hub through an are greater than and a depression is defined in the spring adjacent the hub for permitting clearance between the spring compressor and leaf spring. The outermost free end of the spring extends toward a guide plate mounted upon the lever arm in which a slot is defined which slidably receives the spring compressor carriage and the free end of the spring extends toward this slot for selective engagement by the spring compressor. This manner of supporting the leaf spring prevents a localized high stress bending location from occurring within the leaf spring, resulting in extending the spring life.

It is therefore one of the basic objects of the inven- I tion to provide a release mechanism for aratchet-type power unit which is economical to manufacure, positive in operation. and readily adjustable by the unskilled, while providing an improved versatility of operation.

BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned objects and advantages of the invention will be apparent from the following description and accompanying drawings wherein:

FIG. I is a side elevational view of a power unit constructed in accord with the invention illustrating the lever-arm at the beginning of a power stroke for winding of the tension member on the drum,

FIG. 2 is enlarged, detail, plan view of the drum, catch mechanism, and pawl as taken from the top of FIG. 1,

FIG. 3 is an enlarged, detail, partially sectioned, side elevational view of the lever arm and catch structure illustrating the structure in the catch release position,

FIG. 4 is a detail, sectional view of the catch structure similar to that shown in FIG. 3, illustrating the components in the tensioning or winding condition,

FIG. 5 is a top, enlarged, detail view of the catch, the guide plate being broken away for purpose of illustration, and

FIG. 6 is an elevational, sectional view taken through the catch extension and leaf spring fastening means along Section 6.6 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The basic relationship of components constituting a power unit of the type with which the improved release mechanism is employed will be appreciated from FIGS. 1 and 2. The power unit includes a frame formed by a pair of elongated strap members maintained in spaced parallel relationship at their central region by

bolts

12 and 14 inserted through spacer sleeves, not shown. The end regions of the members 10 are deformed toward each other as at 16, FIG. 2 wherein the ends of the members may contiguously be connected by a bolt 18, at one end, to which the hook and swivel fitting 22 are attached. At the other end of the frame the ends of the members 10 are maintained in contiguous relationship by a bolt 24 which also serves to mount the tension member guide 26 upon the frame.

The ratchet drum 28 is rotatably mounted upon the frame central region by axle bolt 30 extending across the frame members 10, and the drum includes a circular end plate 32, and an end plate 34 upon which ratchet teeth 36 are concentrically formed about bolt 30. The flexible tension member, such as the cable 38, is wound upon the drum 28 and extends throught the U-shaped guide 26 terminating in a hook 40, FIG. 1.

The rear side of the ratchet drum 28 is preferably encased by a shield 41 of sheet metal which is mounted on the frame members 10 by small rivet pins 43. The shield protects the drum 28, particularly when the power unit is located near the ground or other surface.

Rotation of the drum 28 is accomplished by the lever arm 42 pivotally mounted to the frame for oscillation about the drum axle bolt 30. In the described embodiment the lever arm is in the form of a cylindrical tube having a synthetic plastic handgrip 44 attached at the outer end and the handle is split and bifurcated at 46 to form a pair of flattened straps 48 which are bent parallel to each other adjacent their inner end regions for embracing the ratchet drum 28 and are pivotally connected to the drum axle bolt 30.

Rotation of the ratchet drum 28 in the unreeling or untensioning direction, i.e., counterclockwise, FIG. 1, is prevented by the pawl 50 pivotally mounted upon the spacer sleeve of the bolt 12. The pawl includes a finger portion 52 which engages a drum ratchet tooth to prevent counterclockwise drum rotation, and torsion spring 54 disposed about the pawl hub maintains a biasing force on the pawl, clockwise when viewed in FIG. 1, for maintaining the pawl finger in engagement with a ratchet tooth 36, one end of the torsion spring being connected to the pawl, while the spring end 56 is affixed to a frame member 10. The pawl 50 also includes a resiliently mounted abutment 58 on the finger 52 and As described above, the bifurcated end of the lever arm 42 includes straps 48 and the spacing between these straps is maintained by a spacer sleeve 60 mounted upon a bolt 62 engaging the inner surfaces of the lever arm straps, and the catch 64 is mounted for pivotal movement upon the spacer sleeve 60.

The configuration of the catch 64 is best appreciated from FIGS. 3 through 5. The catch is preferably formed of a cast metal and includes an elongated hub 66 of a generally cylindrical configuration. The hub is axially bored at 68 to receive the spacer sleeve 60 and a finger 70 is homogeneously defined on the hub and extends therefrom in a substantially radial direction. The finger 70 is provided with an abutment surface 72 at its outer end which is adapted to conform to, and engage with the drum ratchet teeth 36 when interconnection between the lever arm and ratchet drum is desired.

An extension 74 is also homogeneously defined on the hub 66 and extends from the central region thereof in a radial direction away from the finger 70. The extension 74 includes oppositely disposed

sides

76 and 78, and is of an arcuate configuration terminating at its free end in a flattened portion 80 which extends from between the lever arm straps 48 for accessibility by the operator. The accessibility of the extension portion 80 permits manual operation of the catch, and its location adjacent the catch release mechanism further contributes toward the versatility and convenience of the release mechanism.

The catch is continuously biased in a clockwise direction, FIGS. 3 and 4, about the bolt 62 by a torsion spring 82 circumscribing the hub 66 and including a free end 84 hooked about the extension side 78, while the other spring end 86 is connected to the lever arm by the lanced anchor 88. This clockwise biasing of the catch tends to maintain the finger abutment surface 72 in engagement with the drum ratchet teeth 36, and engagement of the finger with the ratchet teeth will limit the clockwise catch pivotal displacement.

When unreeling or untensioning the tension member it is desired that the catch 64 be released from the ratchet teeth whereby pivoting of the lever arm will not produce a rotation of the ratchet drum. The release position of the catch is illustrated in FIG. 3 wherein the finger abutment surface 72 is radially located from the drum axle bolt 30 sufficiently to clear the drum ratchet teeth 36. Of course, in order to maintain the catch in the release position of FIG. 3 it is necessary to overcome the biasing force continuously imposed on the catch by the torsion spring 82 and the torsion spring biasing force is overcome by means of a second biasing force imposed on the catch tending to produce rotation of the catch in a counterclockwise direction, FIG. 3, and the second biasing force is of a greater magnitude than that produced by the torsion spring.

The release biasing force is imposed on the catch 64 by a leaf spring 90 mounted on the catch. The leaf spring 90 is of a width substantially equal to the width of the extension 74 and is formed of spring steel. The anchored end 92 of the leaf spring is affixed to the abutment side 78 by a rivet pin 94 pressed into a hole 96, FIG. 6, drilled into the extension. The leaf spring then extends toward the hub 66 and passes about the catch hub in an arc slightly greater than It will be noted from the drawings that the portion of the leaf spring extending about the catch hub is closely received on the catch hub, and a depression 98 is defined in the spring free end upon leaving the hub. The free end of the leaf spring is now disposed adjacent the extension side 76, and the outermost end 1110 of the leaf spring extends away from the extension side 76 to the position shown in FIG. 4, when the leaf spring compressor is in the inactive position.

The selective control of the biasing force imposed upon the catch 64 by the leaf spring 911 is produced by control means mounted upon the lever arm 42. This control means includes a guide plate 102 extending across the lever arm bifurcation straps 48 and having tab extensions 104 extending to the catch bolt 62 as to be affixed thereto by holes, not shown, defined in the tabs through which the bolt extends. Also, smaller tabs 106 extend from the guide plate 102 and are attached to the lever arm straps 48 by small rivets 108, FIGS. 1 and 2.

The flat guide plate 102 is centrally provided with an elongated slot 110 disposed parallel to the longitudinal length of the power unit, and disposed immediately above the free end of the leaf spring 90. A carriage or slide 112 is slidably received within the plate slot 110 and includes a button or manually engaging portion 114 disposed adjacent the plate side 1116. On the underside of the plate, adjacent the plate side 118, the carraige includes a spring compressor abutment 120 which extends from the carriage toward the leaf spring 90. The carriage 112 may be formed of a plastic material wherein both the button 114 and the spring compressor 121) are nonmetallic. The carriage includes a narrow neck 122, FIG. 4, slidably received within the slot 110 interconnecting the button and carriage and as the dimensions of the button and spring compressor are greater than the slot, the carriage will be retained in the slot shiftable between the slot ends as apparent in,

FIGS. 3 and 4.

When the carriage or slide 112 is in the position of FIG. 4 the spring compressor 121) is disposed opposite the spring depression 28, and is therefore out of engagement with the leaf spring 90. In this position the only biasing force imposed upon the catch 64 is that produced by the torsion spring 82, which will produce engagement between the catch finger 76 and the drum ratchet teeth 36 to transfer rotation of the lever arm 42 to the ratchet drum and tension the cable 38 upon oscillation of the lever arm. This position of the carriage 112 is indicated as the up position by indicia located on the guide plate surface 116, FIG. 2. Under these conditions, it will be noted, FIG. 4, that the leaf spring free end 100 only lightly engages the underside 118 of the guide plate 102, and the biasing force on the catch in a counterclockwise direction produced by this engagement of the leaf spring 911 and the guide plate is insufficient to overcome the torsion spring 62.

When it is desired to pivot the catch 64 to the release position of FIG. 3, thecarriage 112 is moved in the slot 110 to the position shown in FIG. 31 designated the down condition by the indicia formed on the guide plate surface 116. Movement of the carriage from the position of FIG. 4 to that of FIG. 3 causes the spring compressor 120 of the carriage to engage the spring free end portion 1116 and bias the spring outer free end away from the guide plate 102 toward the extension 74. This deformation of the leaf spring 90 produces a biasing force on the catch 64 in a counterclockwise direction greater than the clockwise biasing force produced by the torsion spring 82. Thus, the catch will be rotated in the counterclockwise direction, FIG. 3, to the position as shown wherein the finger abutment surface '72 is out of alignment with, and clears the ratchet teeth 36.

In the release position shown in FIG. 3 the lever arm 42 may be pivoted about the drum axle bolt 30 without producing rotation of the ratchet drum. Movement of the lever arm to its maximum extent in a clockwise direction, FIG. 1, causes the catch finger 711 to engage the release abutment 58 defined on the pawl 50 lifting the pawl from the engaged ratchet tooth, and the engagement of the release abutment 58 with the pawl simultaneously produces a force on the catch finger toward the ratchet teeth 36 to overcome the biasing force of the leaf spring 9% and thereby align the finger surface '72 with the ratchet teeth so as to engage a ratchet tooth when the pawl 50 is released from its associated tooth. Thereupon, the lever arm is moved several degrees in a counterclockwise direction, FIG. 1 away from the pawl which permits the pawl to again align with a ratchet tooth 36 and upon engagement with an aligned tooth release the force being imposed upon the catch, and permit the leaf spring to pivot the catch out of alignment with the ratchet teeth. Movement of the lever arm again toward the pawl 50 repeats the aforedescribed releasing or untensioning-of a ratchet drum 2%, and the ratchet drum is able to index in a tooth by tooth manner to unwind the tension member 38 and remove the tension therefrom. This type of catch and pawl operation is known in the art and described in US. Pat. No. 2,501,253.

The catch extension portion 86 is disposed adjacent the guide plate 1112, and the operator is able to manually position the catch 64 by means of the extension end portion. During normal operation, such manual catch operation is not required. However, should the operator desire to manually lift the catch from the ratchet teeth when the carriage 112 is in the up position during return movement of the lever arm the operator may manually depress the extension portion 811 during the lever arm return stroke. Furthermore, during release of the pawl the operator may desire to sense the position of the catch with his finger, and this may be accomplished through the extension portion 86. The extension '74 also permits depression thereof manually to augment the counterclockwise rotation produced in the catch by the leaf spring 90, and the presence of the extension portion permits the catch to be manually operated in the event either springs 62 or 911 break.

The utilization of the leaf spring 90, and the simplified positioning of the carriage 1 12 makes the operation of the power unit by unskilled operators feasible, andas the position of the carriage button 114 is readily observable, the operator is able to immediately ascertain the position of the catch, and the sequence of operation that will be produced by the oscillation of the lever arm.

It is appreciated that various modifications to the inventive concept may be apparent to those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. A release mechanism for a ratchet-type power unit wherein the power unit includes a rotatable drum having ratchet teeth defined thereon, a tension member wound on the drum, a movable pawl selectively engaging the drum teeth to prevent drum rotation in an unwinding direction and a lever arm mounted for pivotal movement about the axis of drum rotation comprising, in combination, a catch pivotally mounted upon the lever arm about a pivot axis, said catch including a ratchet tooth engageable abutment surface radially spaced from said pivot axis adapted to be aligned with and engage the drum ratchet teeth at a first pivot position of said catch and adapted to clear the ratchet teeth at a second pivot position of said catch, a first resilient spring mounted on said lever arm imposing a biasing force on said catch about said pivot axis biasing said abutment and catch toward said first pivot position, a second resilient spring mounted on said lever arm selectively imposing a biasing force on said catch greater and opposite to that of said first resilient spring for selectively biasing said catch to said second pivot position, and control means movably mounted on the lever arm for selectively rendering said second resilient spring operative and inoperative.

2. In a release mechanism for a ratchet-type power unit as in claim 1 wherein said control means includes a spring compressor movable between a second position engageable with said second resilient spring to com press said second resilient spring and bias said catch to said second pivot position and a first position out of engagement with said second resilient spring.

3. In a release mechanism for a ratchet-type power unit as in claim 1 wherein said control means includes a guide mounted on the lever arm, a spring compressor slidably mounted on said guide movable between a second position engageable with said second resilient spring to compress said second resilient spring and bias said catch to said second pivot position and a first position out of engagement with said second resilient spring.

4. In a release mechanism for a ratchet-type power unit as in claim 1, a guide plate mounted on the lever arm adjacent said catch, a slot defined in said guide plate transversely disposed to said catch pivot axis, a manually operated carriage element slidably mounted within said slot, a spring compressor mounted upon said carriage, said carriage being movable in said slot between a second position wherein said compressor compresses said second resilient spring to bias said catch to said second pivot position and a first position wherein said compressor is out of engagement with said second resilient spring.

5. In a release mechanism for a ratchet-type power unit as in claim 4 wherein said guide plate includes a first side readily accessible to the power unit operator and a second side disposed toward said catch, said carriage element including a finger engageable button disposed adjacent said guide plate first side, said spring compressor being disposed adjacent said guide plate second side.

6. In a release mechanism for a ratchet-type power unit as in claim 1 wherein said second resilient spring comprises a leaf spring having a free end extending toward said control means and an anchored end affixed to said catch, said leaf spring1 extending around said catch pivot axis from said anc ored end prior to defining said free end.

7. A release mechanism for a ratchet-type power unit wherein the power unit includes a rotatable drum having ratchet teeth defined therein, a tension member wound on the drum, a movable pawl selectively engaging the drum teeth to prevent drum rotation in an unwinding direction and a lever arm mounted for pivotal movement about the axis of drum rotation comprising, in combination, a catch pivotally mounted upon the lever arm about a pivot axis, said catch including a hub, a finger extending from said hub having an end adapted to be aligned with and engage the ratchet teeth at a first pivot position of said catch and adapted to clear the ratchet teeth at a second pivot position of said catch, an extension extending from said hub in a direction away from said finger having a manually operable outer end extending from the lever arm, a first spring imposing a biasing force on said catch about said pivot axis biasing said catch toward said first pivot position, a leaf spring mounted on said catch having a free end radially spaced from said hub and an anchored end fixed to said catch, a manually operated carriage slidably mounted on the lever arm for movement toward and away from said leaf spring free end and a spring compressor defined on said carriage adapted to selectively engage said leaf spring free end to deform said spring free end and bias said catch to said second pivot position.

8. In a release mechanism for a ratchet-type power unit as in claim 7, a guide plate mounted upon the lever arm, an elongated slot defined in said guide plate, said carriage being slidably mounted within said slot.

9. In a release mechanism for a ratchet-type power unit as in claim 8, said leaf spring free end being of an elongated configuration substantially perpendicularly related to said catch pivot axis and including a first portion extending away from said guide plate and a second portion extending toward said guide plate, said slot being in alignment with and disposed adjacent said leaf spring elongated free end, said spring compressor engaging said free end second portion upon said carriage being aligned therewith and said free end first portion clearing said spring compressor upon said carriage being aligned therewith.

10. In a release mechanism for a ratchet-type power unit as in claim 7 wherein said catch extension includes a first side disposed toward said carriage and a second slide disposed away from said carriage, fastening means fastening said leaf spring anchored end to said extension second side, said leaf spring free end extending about said catch hub and being disposed adjacent said first side and toward said carriage.

fl k

Claims

2. In a release mechanism for a ratchet-type power unit as in claim 1 wherein said control means includes a spring compressor movable between a second position engageable with said second resilient spring to compress said second resilient spring and bias said catch to said second pivot position and a first position out of engagement with said second resilient spring.

6. In a release mechanism for a ratchet-type power unit as in claim 1 wherein said second resilient spring comprises a leaf spring having a free end extending toward said control means and an anchored end affixed to said catch, said leaf spring extending around said catch pivot axis from said anchored end prior to defining said free end.