US3527125A - Full stroke compelling mechanism - Google Patents

Description

Sept 8, 19170 v, P. Dl FILIPPO 3,527l,l25

FULL STROKE COMPELLING MECHANISM Filed Feb. '7, 1968 United States Patent O U.S. Cl. Sil-i113 6 Claims ABSTRACT OF THE DISCLOSURE A mechanism for insuring proper jaw closure in a tool having a pair of handles which are linked to each other and to the jaws. The mechanism includes a pawl having a pawl housing which is pivotally connected to a pair of links. Each handle is pivotally connected to the other end of each link. A ratchet housing and guide means is provided which houses a ratchet and which guides the pawl rectilinearly along the ratchet upon closure of the handles. The pawl and ratchet mechanism prevents opening of the handles and, therefore, the jaws prior to the attainment of a predetermined force applying position of the jaws.

BACKGROUND OF THE INVENTION Various types of hand tools are in use today which are provided with two or more force applying dies which are moved together to apply their force to a workpiece. For example, hand tools have been provided which have crimping dies for crimping one portion of a ferrule directly upon an electrical conductor. Such hand crimping tools include various types of full stroke compelling mechanisms to insure a completed crimping operation prior to opening of the jaws. One such tool is set forth in Carlson Pat. No. 2,618,993. The Carlson patent relates to a plier like hand tool having a full stroke compelling mechanism which includes a pawl and ratchet assembly. The pawl and ratchet assembly is contained in a link which is pivoted at one end to an upper portion of one of the handles and which is pivoted at its other end to a lower portion of the other handle. Upon closure of the handles, the link is telescopically collapsed until the pawl overrides the ratchet and is telescopically extended upon opening the handles.

Other prior art full stroke compelling mechanisms are similar to the motion compelling mechanism set forth in Filia Pat. No. 3,157,075. The Filia patent has a ratchet which is adjustably connected to one of the handles of a plier like crimping tool and has a cooperating pawl pivotally connected to the other handle so that, upon closure of the handles, the pawl overrides the ratchet to prevent reversal of the handles prior to the desired jaw closure. In the Filia patent the pawl and ratchet mechanism is located relatively close to the pivotal connection between the handles.

Although these prior art full stroke compelling assemblies perform their intended functions, they have certain disadvantages. The provision of pawl and ratchet housing which comprises a link extending from an upper portion of one of the handles to a lower portion of the other handle, such as shown in Carlson Pat. No. 2,618,993, results in a tool having an element between the handles which may tend to pinch the operators hand when the handles are closed. Moreover, if an object is trapped between the pawl and ratchet housing and one of the handles during closure of the Carlson tool, it may be impossible to remove such an object until the pawl overruns the ratchet, thereby causing the application of further pressure on the object by the ratchet housing.

ICC

Although this problem is not as acute in the device shown in the Filia patent, the location of the pawl and ratchet mechanism close to the pivot point between the handles results in a relatively large reaction force on the pawl and ratchet if the handles are released prior to the time when the pawl overruns the ratchet. This reaction force is transmitted by the workpiece being crimped since that piece tends to spring back to an uncrimped condition and, since the pawl and ratchet will not permit reversal of the handles prior to the time when the pawl overruns the ratchet, the reaction force of the partially crimped workpiece applies considerable force to the point of engagement between the pawl and ratchet.

Prior art hand tools having a pawl and ratchet assembly to insure a full stroke must be returned to the manufacturer in order to replace worn ratchets, since those ratchets are pivotally connected to a portion of the tool. The expense involved in returning those tools and in replacing the ratchet assembly usually induced the user to buy a new tool.

SUMMARY OF THE INVENTION According to this invention a force applying hand tool is provided which overcomes these prior art problems. The tool includes a mechanism for insuring a full stroke and for insuring the attainment of a desired force applying position by the jaws of the tool. The full stroke insuring means according to this invention includes a pawl which is linked to at least one of the handles of the tool and includes a ratchet which is mounted on a guide member. The guide member guides the pawl in a straight line toward the jaw end of the tool during closure of the handles so that the pawl engages the ratchet during such movement and cannot be moved in the reverse direction until the jaws have attained a desired force applying position. The ratchet may comprise a threaded cylindrical member which may be adjusted so that the desired force applying position (the point at which the pawl leaves the last tooth of the ratchet) may be adjusted. The ratchet may easily be replaced by unscrewing it from the guide means and without the disassembly of the tool.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view, with portions broken away for clarity, of a hand tool having a full stroke insuring mechanism according to this invention.

FIG. 2 is an enlarged, fragmentary view, with certain portions broken away for clarity, of the full stroke insuring mechanism.

FIG. 3 is a cross-sectional view, the plane of the section being indicated by the line 3--3 in FIG. 2.

FIG. 4 is a cross-sectional view, the plane of the section being indicated by the line 4-4 in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION A crimping tool 10 comprises a pair of levers 11 and 12 having a U-shaped cross section. The levers 11 and 12 are pivotally connected at a pivot point 13 and are spring biased in a normally separated condition by a spring 14. In the drawings the handles 11 and 12 of the tool 10 are illustrated in a closed position. The levers 11 and 12 are pivoted at their upper ends to a pair of jaw plates .15 and 16, respectively, by a pair of pins 17 and 18.

The jaw plates 15 and 16 are pivoted for relative rocking movement about a rocking pin 19 and are connected to each other by pivot pins 20 and 21 which extend through the jaw plates 15 and 16 and by two straps 22. When the levers 11 and 12 are moved toward each other,

the jaw plates and 16 are pivoted about the pivot points and 2.1 and rock about the rocking pin 19 to assume the position shown in FIG. 1.

The jaw plates 15 and 16 are provided with opposed ferrule forming die portions and 26, respectively, which may be designed to provide any desired crimp to a ferrule when the jaws are actuated by the levers 11 and 12. The die portions 25 and 26 may be designed to crimp the ferrule portion of a terminal or connector directly onto a conductor to provide a solderless electrical connection.

The levers 11 and 12 have an adjustable locking, full stroke compelling or insuring mechanism associated therewith. As is shown, this mechanism comprises a pawl 27 and a ratchet 28. The pawl 27 is pivotally mounted on a pin 29 and is normally held in the position illustrated in FIGS. 2 and 4 by a tension spring 30. The spring 30 is connected at one end to a pin 31 which extends through a reduced end portion 32 of the pawl 27 and is connected at its other end to a pin 33 which is press tted into a pawl housing 34.

The pawl housing is mounted for rectilinear movement within a guide housing 35. The guide housing 35 has parallel face plates 36 and 37 which are joined by a web portion 38. The pin 29 to which the pawl 27 is pivotally connected extends outwardly beyond the pawl housing 34 and into slots 39 and 40 which are respectively provided in the plates 36 and 37. A pin 41 extends through the other end of the housing 34 and extends into each slot 39 and 40 so that the pawl housing 34 may be guided rectilinearly in the guide housing 35.

The web portion 37 is provided with a longitudinal bore which is threaded to receive the ratchet 28. The ratchet 28 comprises a threaded pin having a slotted end portion 42. Prior to the installation of the ratchet 28, a portion of the web 38 is ground away so that a portion of the threaded surface of the ratchet 28 is exposed to a tooth 43 on the pawl 27. The guide housing 35 is pivotally connected to the pin .13 so that the slots 39 and 40 have axes which intersect the center of the pivot pin 13.

The pawl housing is rectilinearly driven within the guide housing 35 by links 44 and 45. One end of the link 44 is pivoted to the lever 11 by a pin 46 and one end of the line 45 is pivoted to the lever 12 by a pin 47. The pins 46 and 47 are located equidistant from the pivot pin 13. The other end of each line 44 and 45 is pivotally connected to the pin 41.

Upon closure of the levers 11 and 12, the links 44 and 45 drive the pawl housing 44 toward the pivot pin 13. As the pawl housing 34 is driven in this manner, the pawl 27 is turned in a clockwise direction from the position illustrated in FIG. 2 so that the pawl tooth 43 rides along each tooth on the ratchet 28. During this movement, the levers 11 and 12 may not be opened since the position of the pawl cannot be reversed until the pawl tooth 43 leaves the last ratchet tooth to permit the pawl to return to the position illustrated in FIG. 2. When the pawl tooth 43 has overrun the last ratchet tooth in this fashion, the levers 11 may be opened by the spring 14 since the pawl may travel over the ratchet 28 and away from the pivot pin 13 by being rotated in a counterclockwise direction upon engagement of the ratchet.

Since the last ratchet tooth must be traversed in order to permit the lever 11 and 12 (and therefore the jaw plates 15 and 16) to open, the position of the last ratchet tooth determines a desired force applying position of the jaws. The position of the last tooth may be varied by inserting a screw driver between the plates 36 and 37 and into the notch 42 and by turning the ratchet 28 within the web 38. Such an adjustment may be made by moving the levers 11 and 12 together until the jaws establish a desired force applying position. Such a force applying position may be established without actual jaw contact by inserting a shim between the jaws, closing the jaws on the shim, and by unscrewing the ratchet 28 until the pawl tooth 43 leaves the last ratchet tooth. Such a force applying position may be established with the jaws closed and in contact with each other by closing the levers 11 and 12 until the jaws touch and by unscrewing the ratchet 28 until the pawl tooth 43 leaves the last ratchet tooth. This adjustment may be effected with the handles flexed together after jaw contact so that in a crimping operation the pawl tooth 43 will not leave the last ratchet tooth until after there is jaw contact and handle flexure.

The invention is not restricted to the slavish imitation of each and every detail set forth above. Obviously, devices may be provided Which change, add, or eliminate certain details without departing from the scope of the invention.

What is claimed is:

1. In a tool having force applying jaws which are moved together to a desired force applying position by closing a pair of pivotally connected handles, the irnprovement comprising full stroke insuring means to prevent opening of the jaws prior to the attainment of said desired force applying position, said full stroke insuring means including a pawl member and a ratchet member, rst linkage means linking one of said members to at least one of said handles, second linkage means attached to a pivotal connection between the handles, the other of said members being fixed to said second linkage means, said second linkage means having means for guiding said one of said members in a straight line toward said pivotal connection and in ratcheting relationship relative to the member fixed to said second linkage means during closure of the handles.

2. The improvement according to claim 1 wherein said other of said members is adjustable relative to said second linkage means.

3. The improvement according to claim 1 wherein said one of said members comprises the pawl member and wherein said other of said members comprises the ratchet member.

4. The improvement according to claim 1 wherein said rst linkage means comprises a pair of links, each of said links having one end pivotally connected to its own one of said handles at pivotal connections which are equidistant from the pivotal connection between the handles.

5. In a tool having force applying jaws which are moved together to a desired force applying position by closing a pair of handles which are linked to the jaws and to each other, the improvement comprising full stroke insuring means to prevent opening of said jaws prior to the attainment of said desired force applying position, said full stroke insuring means including a pawl member and a ratchet member, linkage means comprising a pair of links, each link being pivotally connected at one end to its own one of said handles, the other end of each link being pivotally connected to said pawl, a ratchet housing, said ratchet housing having said ratchet mounted thereon and including guide means for guiding the pawl in a straight line toward said jaws and in ratcheting relationship relative to the ratchet during closure of the handles.

6. In a tool having force applying jaws which are moved together to a desired force applying position by closing a pair of handles which are linked to the jaws and pivotally connected to each other, the improvement comprising full stroke insuring means to prevent the opening of the jaws prior to the attainment of said desired force applying position, said full stroke insuring means including a pawl member and a ratchet member, a pair of links each of said pair of links having one end pivotally connected to its own one of said handles, the other end of each of said pair of links having said pawl pivotally connected thereto, a ratchet housing pivotally connected to the pivotal connection between the handles, said ratchet housing comprising a pair of plates connected by a web portion, guide means in each plate cooperating with said pawl for guiding said pawl in a straight line toward said pivot point, said ratchet comprising a threaded cylinder 5 6 partially mounted in said web portion and having teeth 2,737,070 3/ 1956 Dibner 74-175 X cooperating with said pawl in ratcheting relationship with 2,737,071 3/ 1956 Dibner 74-17.5 X

said pawl during closure of the handles.

ROBERT C. RIORDON, Primary Examiner References Cited 5 R. V. PARKER, JR., Assistant Examiner UNITED STATES PATENTS 953,507 3/1910 Beale s1-3i3 X U-S- Cl- X-R 2,618,993 11/1952 Carlson 81-313X 72-409

Images