US 2861491 A
Description (OCR text may contain errors)
Nov. 25, 1958 w. ROZMUS 2,861,491
RATCHET AND CAM ACTUATED TOOL Original Filed Feb. s, 1956 [\1 r l ci INVENTOR. 7/4/42 fiy BY fim 7 040 United States Patent.()
RATCHET AND CAM ACTUATED TOOL Walter J. Rozrnus, Whitesboro, N. Y., assignor to Kelsey-Hayes Company Original application February 8, 1956, Serial No. 564,165. Divided and this application January 2, 1958, Serial No. 706,800
2 Claims. or. 31-15 This invention relates to cam actuated tools, and more particularly to a closable jaw hand tool of light weight and rigid construction for crimping or indenting workpieces such as electrical connectors.
This application is a division of an application filed by Walter J. Rozmus on February 8, 1956, on an improved Ratchet and Cam Actuated Tool, Serial No. 564,165.
The primary object of this invention is to provide a movable jaw tool having a wide jaw opening, fast closure to a work position, high mechanical advantage through the work closing cycle, and assurance of completing afull work cycle whereby the jaws are required to close to a specific relative position before opening More specifically, an object of this invention is to provide a revolvable power cam having a peripheral surface defining a cam track, with an evenplurality of driven members each of which is provided with a rollable cam follower to take driving power from the cam surface, and the cam having definite recess pockets providing quick return from a maximum actuation position to a starting position. v When using plier-type tools for crimping electrical connectors and severing heavy workpieces, or other similar high pressure jobs, it is customary toprovide long handles to reduce operator fatigue, or to bring-the mechanical advantage to such a degree that the desired operation is possible. Long handles or levers require less input force to do the required work and provide a high mechanical advantage. Lengthening the handles, however, introduces other undesirable factors. The longer the handle, the wider is the spread between the ends of the handles, and this makes the long levered pliers unlikely for use in confined quarters, more difficult to use, and induces early oprator fatigue.
Another object of this invention, therefore, comprises the provision of pliers having a large mechanical advantage with a small span at the ends of the opened levers.
A further object of the invention is to provide a novel and improved hand tool in which a pair of crimping jaws are provided, each of which has a work performance end, a drive receiving lever portion, and a pivot interposed between the crimping end and the drive receiving lever portion, and in which such jaws are actuated by a power cam, revolvable about an axis between the drive receiving lever portions to actuate the jaws with a balanced wedge force, applied by opposite sides of the cam.
Further objects are to provide a short span lever actuated tool having a long lever characteristic, the jaws of tion may be had by referring to the following description and claims, taken in conjunction with the accompanying drawing in which:
Figure 1 is a side elevational view of a pivoted jaw tool designed principally for crimping electrical connectors, and in whichthe crimping action is obtained through the improved drive device of this invention; and,
Figure 2 is a fragmentary sectional view of the device of Figure 1 as seen from the plane indicated by the line 22 of Figure 1. v
In the past, reliance has been principally upon fulcrum type of tools, employing "single or multiple fulcrums. Sometimes these tools have been supplied with a link mechanism attached to the handlespermitting a variable mechanical advantage. The well-known bolt cutter is such a tool design. In this construction,zhandles are pivoted together and are rearward extensions of the opposed pivoted jaws. The ratios are fixed. The jaws will not open wide to receive work. They have terrific power at completion of the closure and no guarantees that the operator will complete the closure. This type of tool has stresses perpendicular to the length of the tool but provides no variation at the jaw from a uniform curve of force. Such tools are heavy, rugged, and the handles must be opened wide, making them one-stroke, twohanded tools. Later developments brought about the use of tools having a fixed anvil and a movable anvil. The movable anvil was generally actuated by means of a pivoted cam surface or a jack step device. Such devices require rugged actuation structures because of the very large reaction stresses placed upon the pivotal mounting for any such actuation device. As a result, a large amount of this input power is consumed in overcoming frictional loads and the pivotal supporting surfaces are subject to rapid deterioration under high wear conditions.
This invention is a further development of the basic principles set forth in an application entitled Ratchet Powered Tool filed January 17, 1956, and bearing Serial No. 559,605, and anapplication entitled Pivot Lever Retainer. for Ratchet Powered Devices filed January 30, 1956, and bearing Serial No. 562,253.
Referring to the drawing, a handle 10 is rigidly fixed to a frame structure 11. A second handle 12 is fixed to the frame structure in a relatively pivotable fashion. The handle 12 has a pair of end extensions 13 which are pivotally fixed to a drive pivot pin 14. The pivot pin 14 in turn is carried by a frame 11.
First and second jaw members 15, 16 are pivotally carried .on jaw pivots 17, 18 respectively. The tool as shown in the drawing is in a closed position for a crimping operation in a crimping region 20. A spring 21 is fixed to the jaws 15, 16 .to urge the jaws toward an open position.
The jaws 15, 16' are shifted from an open to a closed position by a novel and improved uni-directional drive mechanism. This drive mechanism includes a pair of,
ratchet Wheels 23 which are pivotally carried by the pin 14. The handle 12 carries a pair of drive pawls 24, only one of which is shown. As the handle 12 is pivoted to an open position, the pawls 24 index from one tooth to an adjacent tooth of the associated ratchet wheel 23. The handle 12 is then pivoted towards the handle 10 against the action of spring 25 to. cause the ratchet wheels 23 to advance. A pair of spring loaded detents, 26, only one of which is shown, are pivotally carried by the frame 11. The detents 26 index from tooth to tooth in the ratchet wheels 23 as the wheels are advanced by manipulation of handle 12. The detents hold the ratchet wheels against reverse rotation. A' jaw actuation cam 30 is fixed to the ratchet wheels 23 to pivot with them about the drive pivot 14. V
The jaws 15, 16 have drive receiving lever portion ends 32, 33 respectively, and are provided with cam riders 35,
and 26 respectively. The lever portion ends 32, 33 define an included field area. The cam 30 is 'located'in this field-area,..and itis in driving connection with roller cam riders 35, 36.
It will be seen that the axes of the rollers 35, 36 and the drive pivot 14 are inzparallel alignment s'o that drive forces :are applied to the :pivot in a :balanced rfashion, thereby minimizinglthezrequiredsize of the pivot. That is, since the jaws are: in :oppositionupon the same workpiece, and since both are substantially identical, the ends .32 and 33 willexertsubstantially equal resistance to outward separation movement, and will exert substantially equal reaction force. Riders .35 and 36;are placed in a straight linerelationship across theicam 20, which line is parallel through the pin 14.
Asa practical matter, because the .work receiving ends do swing about the pivot mounting, this line will shift somewhat with respectltorthe' fixed axis of;pin'14. Nevertheless, the line remains substantially at :such'a location that -it does pass through the 'pin 14. When'roller .cam riders are employed .the three axes ofathe itwo .rollers and the pin 14 are iniparallel'zalignment also. Thus, :the reaction .forces are balanced against one another across the cam with virtually :no effect on .the :pin=14. Thus, the pin :is quite small andhas no substantial performance requirements.
The .revolvable cam 30;has first and second drive surfaces 40, 41 and first and second pocket recesses '42, 43. In Figure 1, the rollers v35,-36;are;in contact with thedrive surfaces 40, 41 at the point'where the surfacesare the maximum distance from the axis of rotation. is .the conclusion of a crimpingcycle. As the cam Stlis indexed clockwise by the ratchet mechanism, therollers .drop into the pocket recesses 43, 42 as the jaws shift :under the urging of spring 21. This concludes a workcycleand the jaws assume an open position. To'connect a terminal to a wire the terminal and wire .are next aplacedzin the crimping region 20. The handle 12 is then manipulated to index the ratchet in a clockwise direction. Therr dllers 35,-36 quickly ride up onto the drive surfaces 40, 41. This causes a .quick closing of thejaws to start a work cycle. Thereafter a gradual and, high mechanical iadvantage'closing is achieved through the gradual eccentricity of the surface 40, 41 progressively forcing the .jaws closed as :the ratchet is advanced.
It will be seen that this particular construction has several inherent advantages. Quick closing of theijaws with low mechanical advantage to index them to work operation position is provided. Thereafter, very gradual closing under high mechanical advantage is achieved so that relatively high crimping :pressure can be obtained with 'a small hand tool. Further, the rotation of the 4 ratchet and cam is uni-directional so that'once a work cycle is started it must be completed before a workpiece can be removed, this assures a thorough crimping.
In the preferred and disclosed embodiment, there are two drive recesses and two pocket recesses. It will be recognized that to achieve balanced pressure on a pair of jaws and equal movement of thejaws, it is necessary that the cam surfaces be in multiples of two. To achieve the highest mechanical advantage with thesmallest tool possible, .the preferred arrangement has two such cams, and one work cycle requires degrees of ratchet rotation.
Although the invention has been described in its preferred form with acertain degree of particularity, 'it is understood that the 'present disclosure of the preferred embodiment is made only by way of example and that numerous changes "in the details of construction and the combination of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.
What is claimed is: g k
'l. -A work performing tool, comprising, .a first and a second pivoted and relativelyclosable.jaw, saidfirst jaw having a work performing-portion and a drive receiving leverportion with a pivot therebetween, said second jaw having-a work performing portion and a drive receiving lever portion with a pivot therebetween, each drive re ceiving .lever portion being mounted for movement in a WOIK'CYQIC path, the .two drive receiving lever portions being laterally spaced and jointly defining an included field area, .a rotatable cam member in said field area, said cam member having a peripheral cam surface revolvable aboutan axis of rotation, said cam surface composed of a first and a second drive surface area with a first and a second pocket recess spaced between the .first and second drive surfaces, .each of said first and second drive surfaces beginning at one of said pocket recesses and ending at the other, said first jaw drive receiving lever portion having a cam rider, said second jaw drive receiving lever portion having a cam :rider, means urging said cam riders toward the surface of said cam, arotatable ratchet wheel drivingly connected to said cam member, and .a lever and pawl in drive imparting relationship to drive said ratchet wheel. 7
, 2. A device of the type set forth in claim 1 wherein the cam riders are rollers and .the axis of each of the cam riders and the axis of cam rotation are substantially in parallel alignment, .such that forces applied to the cam are counter-balanced across the field area.
No references cited.