US 2563164 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Aug. 1951 R. A. FLETCHER 2,553,164
Filed July 12, 1948 Patented Aug. 7, i951 UNITED STATES PATENT O FF'I' CE Y LEWIS V.
- Ralph A. iFletcher, Westford, Mass; assigncr to '-H.=iE. -F1etcher'-Go.,' Chelnisford;=Ma'ss.," a corporationwof Massachusetts 7 "Apjilica'tidniJfly '12, 1948; Serial'N0.'38,2 2 1 --6' Claims.
This inventionrelates to "an improved lewis or the type in which two'dovetailed'sectionsare held apart by means of a central key element, outer sloping sides of the dovetailed sections "thus being supported ina-position such that they may be 'wedgedagainst corresponding dovetailed lewisslot sides formed in a block of granite or other heavy body whicn'isto be lifted.
An object of the 1 invention is to provide "an :Jimproved stone lewis memberw ch is of 'simple design," cheap to maii-ufactureieasy tc installgan'd exceedingly effective in its holding capabilities. More specifically, it' is" an obj ect of the invention "to deal with the problems encountered in'co'n- "nectionwith lewismembers 'breaking out or the lewis slotand 'acci'dentally becoming disengaged 1 from ablock of stone during the periodin which the stoneis being oonveyed fromone place'to another. Difficulty-develops in -many'instances from faulty adjustment of 'the lewisin the lewis slot 50 that a relatively= -great 1 amount-mistress is brought tobea'r against relatively weak portions of the stone immediately adjacent to the slot, and especially 'the"relatively thin stone portions formingthe upper I edges-of the r5101 f -In--some cases these relatively weaker portions-=maystart to crumble and breakaway .thus allowing the lewis member'tobe puued'eut. V w
I The nature of the invention and its' ff-urther objects and novel features' 'will' be 'more fully-undrstdod' and appreciated from; the following description of one preferred embodiment of the invention, selected for purposes of illustration and shown in the accompanying drawings, in which Fig. 1 is an enlarged cross section and partial elevation of the stone lewis member of the invention shown in a wedged position in a lewis slot formed in a block of stone;
Fig. 2 is a plan cross-sectional view taken on the line 2-2 of Fig. 1; and
Fig. 3 is a plan cross section taken on the line 3-3 of Fig. 1.
In the structure shown in the drawings, in denotes a recessed body which may for example consist of a block of granite which has been separated from a larger body of granite at a quarry. Numeral l2 indicates a dovetailed lewis slot of the type usually employed for receiving a key lewis member. It often happens in quarrying operations that the separated block of granite may occur at appreciable depths below the ground level or other points to which it is desired to convey the block for further processing operations. It is necessary therefore to very solidly :secure'the lewis member-inthe stone "in order that "it may support the block "of granite in a suspended'position safely and forso'me little time if 'so'desired. I 4 As afurther aid to understanding the need for 'a'device of the character about to'bedescribed, it is also pointed "out that the operation of forming the dovetailed lewis slot I2 is a-rela- 5 tively troublesome one. The commonly followed method is first to form a hole by drillingwi'th the drill" being supported in an angular position. A second hole isthen drilled with the 'd'rillb'eing held' at-approximatelythe same angle of inclination as the first -hole but opposed relation-to l-5 it. As' a 'practical-matter,it"is extremely difficult 'to'drill the second hole without somedivergence rrom the desired "angle of -inclination. Upo'n breaching-out intervening "portions of stone-and "-inser't'ingkey lewis sections in the resultingdove- -'20 tailed not; 'it' frequently "happens that the lewis -sectiorls 'do not -bear' evemy against the 1 sides o'f the slot thus causing the difficulties above "de- 5 scribed; I
In accordance with the invention a'igreat"deal 'of' the difficulty is resolved'by'providing lewis --senons|w and 16 and forming "them with recessed outer surfaces I8 and 20. These surfaces occur along intermediate and 'upper' portions of 'the'lewissectionsl' B'y 'mear'is of such a construe! 'tion 3 there are obtained "two" opposite inclined -bearing' surfaces generally denoted by arrow/s22 and 24. Thesebearing' surfaces extend from' 'the "lowermost portions of the dovetailed lewis sections upwardly along opposite and equal paths which are characterized by a constant degree of inclination or slope for an appreciable distance. In relation to the bearing surfaces, the recessed areas deviate inwardly toward one another along a varying angle of inclination which bends away 0 from immediately adjacent surfaces of lewis slot sides of the block of stone l0. Numeral 32 indicates a clevis or shackle which is formed with two free ends having openings located therethrough and adapted to receive a pin transversely disposed through the upper ends of the lewis sections and key element, thus providing a means of attaching a lifting device.
It will be observed that when the two sections In and I6 are forced apart and held in wedged relation by a key element 26 the bearing surfaces will come to bear against the lowermost surfaces of sides of slot l2, and even in the event of these slot sides being somewhat uneven in pitch, contact will be established well down in the bottom of the lewis slot. As a result the stress developed will be distributed throughout those portions of block I!) which occur in the lowermost parts of the slots rather than near the relatively thinner and weaker top edges 28 and 30. In practice this improved distribution of stress has been found to greatly reduce breaking out of the lewis member and less care is required in forming lewis slots and installing the lewis therein.
Another desirable feature incorporated in the lewis of the invention is the provision of rounded lewis surfaces which are so shaped as to coincide generally with the arc of curvature of the drill opening formed in the rock. Such openings are necessarily of rounded contour and by having the lewis bearing surface correspondingly curved, they are enabled to contact the drill opening throughout a relatively greater surface area, thus further adding to the desirable distribution of stress throughout those portions of a stone body which occur adjacent to the lower portions of a drill hole formed therein. This type of lewis construction differs materially from the standard type of lewis construction which is usually approximately rectangular in cross section and which therefore tends to meet the drilled hole surface throughout a smaller bearing area.
Having thus disclosed my invention and described in detail illustrative embodiments thereof, I claim as new and desire to secure by Letters Patent:
1. An improved lewis member for use in a dovetailed slot formed in a body of stone or similar material, the lewis member presenting two oppositely disposed dovetailed tenons adapted to be received in the dovetailed slot, a key member for holding the tenons in spaced-apart relation so that the surfaces of the tenons are locked against adjacent opposite surfaces of the dovetail slot the upper portions of the lewis member tenons being formed on two opposite sides with relieved surfaces to provide a clearance between the lewis member and each of two adjacent exposed edges of the slot when the tenons are in a'locked position.
2; A structure as defined in claim 1 in which the tenons are formed with curved bearing surfaces. 7
3. An improved lewis member for use in a slot of the type having two oppositely inclined undercut edges, the lewis member presenting two oppositely disposed dovetail tenons adapted to be received in the slot substantially throughout their length, key means interposed between the tenons for holding them in spaced-apart relation so that the outer surfaces of the tenons are locked against opposite surfaces of the inclined undercut edges the upper portion of the lewis member being formed on two opposite sides with relieved surfaces so located as to lie in spaced relation to each of the undercut edges of the I slot when the lewis tenons are received therein clination corresponds substantially to that of adjacent surfaces of the dovetailed slot, each of said sides being relieved along their upper portions to provide a clearance between the lewis sections and upper exposed edges of the slot when the lewis sections are in locked relation therewith.
6. An improved lewis member for use in a dovetailed slot which is characterized by concave end surfaces, the lewis member including two lewis sections, a key element arranged between the sections for the purpose of holding each of the sections in engagement with a respective concave end surface of the slot, the lewis sections presenting :lower convex bearing surfaces which coincide substantially with the concave end surfaces of the slot, the upper portions of the lewis sections being relieved to provide a clearance between the lewis sections and adjacent upper edges of the slot when the bearing surfaces are in contact with the end surfaces of the slot.
' l RALPH A. FLETCHER.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name -Date 361,927 Cartwright Apr. 26, 1887 822,769 Quist June 5, 1906 1,047,267 Merrill Dec. 17, 1912