US2381412A - Lever - Google Patents

Description

' Aug. 7, 1945.-v V (l-l. M. RoEE I 2, 2

v LEVER Filed April 8, 1944 I plane 3-3 of Fig. 2.

Patented Aug. 7, 1945 UNITED s ATE 7 U LEVER ,Harry M. Roeser, Chicago, Ill., assignor to poration of Illinois Streeter-Amet'Company, Chicago, 111., a cor- Application April 8,1944, Serial No; 530,217

3 Claims. -(o1. 308-2) This invention relates to levers and the like employing knife edge and similar pivots, and among other objects aims to provide a simple and improved knife pivot construction for adjusting the lever ratio and for other purposes, The nature of the invention may be readily understood by reference to one construction embodying the invention and shown in the accompanying drawing. T 1

Insaid drawing, r

Fig. 1 is an elevation-of a typical scale lever system. o

Fig. 2 is anenlarged elevation (nearly full scale) of an adjustable lever pivot; and

Fig, 3 is .a transverse plan section taken on the In levers for scales and other systems for transmitting force or movement, it is common to employ so-called knife edges or similar structures ,to form the pivots and 'fulcrums. Generally the knife edges are provided by hard steel sections- (often of so-called pear-shaped section) having their extremities sharpened to a knife edge and locked in adjusted position or the knife edge was not firmly locked in the rotatable member. Knife edges are subjected to great stresses and adjustability is not practical unless the knife edge can be held in adjusted position practically as firmly as though the'parts were integral.

'In the present improvement both the knife edge and its rotary bearing are firmly locked in adjusted postion. In the illustrative construc tion, the knife edge'is represented by an insert [0 of hard steel or the like, sharpened to provide a knife edge I l. The sides of the knife edge section are advantageously rectangular soas to make it possible to provide an insert of uniform dimensions.- Standard tool steel stock may be used. This may be finished to uniform thickness With the knife edge parallel to sides and base of the section. Intermediate its ends, the knife edge is provided with the bearing l2of circular sectioncomprising a separate locking member l3 having therein an. opening M of a shape and size to I receive the knife edge insert I 0. The locking inserted through an opening in the lever, the

the locking member. l3 so that thelatter may fit sharpened knife edge" portions projecting' from the opposite sidesof thelever. vWhen a knife edge becomes dull, it may be sharpened either by re-stoning the old knife edge or replacing it with anothersharp knife edge. In either case, it is very difficult to provide sharp knife edges without changing the lever ratio or otherwise disturbing the relation between the knife edges of the lever. Thesedifiiculties are caused, among other reasons, by the circumstance that in forming or sharpening a knife edge, it is practically member I3 is mounted in an opening l5 in the beam or lever 9 of substantially the diameter of closely in the opening. The locking member may impossible to control the location of the "sharp-j ened edges with reference to the axis or some other fixed part of the'knife edge section. The knife edge is usually sharpened by grinding or stoning the bevel faces of the hard steel gi nsert until a sharp edge results. Removal of too much metalfrom one face of the bevel displaces the knife edge'from its proper position. A displacement as little as .002 of an inch would be multiplied ten times in a lever having a ten to one ratio. Yet it is practically impossible by any sim- *pl'e measuring means to determine whether or not the sharpened edge is within .010 of its original or correct position. 7

Efforts have been made heretofore to provide I adjustment by making the knife edge rotatable in the beam, but the knife edges were not held in adjusted position sufficiently firmly. Either the rotatable member in which the knife edge was seated for rotary adjustment was not firmly steel stock which is characterized by uniformity in dimension. The opening I5 is advantageously formed by drilling so as to be of exact size and exactly square with the beam. Opening M in the locking member is machined therein with its sides parallel to the axis 14 of the cylindrical periphery ofthe locking member l3, so that upon rotation the knife edge l2 moves parallel to itself.

The opening IS in the leveris located as closel as maybe in ordinary shop practice to provide the proper lever ratios. Correction of the lever ratios is effected after the locking members and knife edges have been inserted in the several openings of the lever, by rotating the knife edge and its locking member" in one direction or other to shift the knife edge H in relation to the'ful- 'cru'm or otheropivot' points of the lever and thereby'to establish the correct lever ratios. This may conveniently be done simply by placing a Wrench over a projecting portion of the knife edge and twisting it in the desired direction. Thereafter the knife edge and its locking member are firmly secured in adjusted position.

In the improved construction both the knife edge and its bearing or locking member are firmly locked in adjusted position by expanding the periphery of the locking member so as to fasten it tightly in the lever and simultane- "elements which are deflectable both inwardly and outwardly. As here shown, these deflectable portions constitute small portions of the locking member made deflectable by slotting the look-- ing member as at l6. The slots inthis instance extend from the periphery a substantial dis-- tance through the locking member and terminate at H, a short distance from :the periphery of the locking member. Thusythe outer'portions I8 are resilient to deflect outwardly for locking the locking member in .the lever and the'inner portions H! are defiectable inwardly to lock the knife edge tightly in the locking member.

Neither effects its locking action at theexpense of the other. The extremity of .theslotill tor-,- minates in .a large opening to prevent development of cracks in the locking member. .Similarly the corners 20 of the opening [-4 lare similarly provided with rounded surfaces to prevent the development of cracks. The-outer and inner portions 18 and 19 are in this instancedeflected by taper pins 2| which are driven-tightly into'enlarged -holes-22 in the slots l6when the knife edge has been properly adjusted, Thus the knife-edge .is locked in the bearing simuh taneously with the locking of the latterin the lever, and in each-case full. surface contact .between each of the parts is maintained. The

knife edge may be released for adjustment simply by driving the taper pins in the-reverse direction with an appropriatetool.

The rectangular sections of the knife @e'dge.

greatly facilitate grinding and sharpening .of the knife edge ll,'so that it lies parallel toithesside faces-23 and theintervening base-of the vknife edge; This, together with the .locationof the axis of the opening I5. s-quarewith the lever (-a simple operationhmaking it relativelyeasy to locate knife edges parallel with-each other'and perpendicular to the lever. It is not serious that the knife edge .11 be displaced from the center plane -24 "of th -body of therknifeedge since appropriate correction may be made by rotating the knife edge as:aforesaid and-there after looking it in position. a a I In Fig. '1 is "illustrated a typical scale lever= system equipped with adjustable knife edges. It

will be understood, however, that this lever-system is only one example of many in which "the present invention may be advantageously .employed. Itis important that the distance from the fulcrum -25 .to the pivot-2B be accurately maintained. And similarly that the distance of the pivots 21 and 28 from the fulcrum .29 ,be constant. -Any disturbance in .the relation of the various vknife edges forming the respectivepivots and fulcrums would produce substantialv error The present .invention makesit possible respective knife edges be maintained. wise the lever will be twisted or laterally displaced with reference to the connections at 26, Heretofore in providing sharpened knife edges, it -has often been necessary to resort to laborious readjustment of the fulcrum stand i32-and other make-shift adjustment in sealing the scale as a result of displacement of the re-sharpened knife edges from their original position. These laborious sealing operations are completely dispensed withby the present invention.

The present invention also makes possible substitutions of levers and beams in scale and other lever-Systems without laborious adjustments to restore the proper leverratios. I

Obviously,-the invention is notlimited to the details of the illustrative construction since these may be variously modified, Moreover, it is not indispensablet-hat all features of the invention be used conjointly since various features may be .used to advantage indifferent combinations and sub-combinations.

Having described my invention, .1 claim:

1. An adjustable pivot for'a lover or the like comprising in combination a knife edge body, a locking member having a periphery of circular sectionand an opening therein of a shape "to 1 receive and engage the knife edge body, said opening having its longitudinal axis parallel with that at its periphery, means for expanding the said periphery and contracting said opening, a lever having an opening therein'of :a size and shape to receive said locking member in its unexpanded condition, said locking member being located in the openings in said lever and expanded therein; I

2.-A locking memberfor knife edges comprising in combination a body having a periphery of circular section, an opening through said body of a shape to receive a knife edge, said body having resilient ,portions defiectable to expand said periphery and contract said opening, and means for deflecting said resilientportions.

'3. A locking member for knife edges comprising in combination a body having a cylindrical exterior of .circular section, an opening through said body of a shapeto, receive a knife edge, said body being slotted to provide deflectable portions for expanding said exterior and contracting said opening, and wedge means for deflecting said portions.

HARRY M. ROESER.

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