US2352474A - Sheave - Google Patents

Description

June 27; 1944. l D. Fll R TH ET AL v 2,352,474 v SHEAVE Filed Aug. 6, 1942v s Sheets-Sheet 1 I v j il/8722 5715 June 27, 1944. FIRTH ET'AL 2,352,474

SHEAVE Filed Aug. 6, 1942 3 Sheets-Sheet 2 Q Ill/8723715.

D0 naZdjrZaz/er Patented June 27, 1944 SHEAVE David Firth, South Bend, and Donald P. Lower, Mishawaka', I nd., assignors to Dodge Manufac turing Corporation, Mishawaka, Ind.; a corporation of Indiana Application August 6, 1942, Serial No. 453,829

6 Claims. (Cl. 74-23011) This invention, pertaining to sheaves, has been evolved in an eifort to further the national program of conservation of metals. In the present emergency it becomes important to conserve cast iron in addition to other metals. With a view to effecting a substantial saving of metal, the inventors have given thought to the utilization of wood for. the construction of sheaves for multiple V-belt drives and other machinery drives of the belt and sheave type. This invention provides a construction in accordance with which strong wood sheaves can be produced in various forms and dimensions to meet difierent requirements as to pitch diameters and numbers of sheave grooves, such wood sheaves being of practicable character for service under many conditions in lieu of cast iron sheaves of corresponding sizes. Specifically this invention contemplates the production in wood of practicable and efficient sheaves of the split contractible hub type.

.The accompanying drawings show illustrative embodiments of the invention in wood sheaves for multiple V-belt drives. Fig. l is a section taken longitudinally of and through the axis of one simple form of V-belt sheave embodying the invention.

Fig. 2 is a view of said sheave half in end elevation and half in cross section on the line 2-2 of Fig. 1.

Fig. 3 is a section taken longitudinally of and through the axis of a double web sheave embodying'the invention.

Fig. 4 is a view of said last mentioned sheave half in end elevation and half in cross section on the line 4-4 of Fig. 3.

. Fig. 5 is a diagram illustrating a method of utilizing pieces of scrap lumber in fabricating a sheave lamination.

, Fig. 6 is an enlarged cross section taken on the line 66 of Fig. 5. Fig. 6 represents a cross section taken through any of the joints in Fig. 5, and also represents a cross section taken on'the line 6-6 of Fig. '7.

Fig. 'l is a diagram illustrating a method of utilizing pieces of scrap-lumber in fabricating a lamination for a sheave rim extension. Figs. 8 to 11, inclusive, illustrate steps or stages in one method of manufacture of a sheave embodying the invention, the first three of these figures being on a reduced scale and'Fig. 11 being on the same scale as Figs. 1 and 2.

Fig. 8 is a central longitudinal section of a laminated structure composed of adhesively united wood discs fabricated from pieces of scrap lumber, from which structure is to be made the principal part of a laminated wood sheave of the form shown in Figs. 1 and 2; said discs providing the laminations of such sheave other than those of its rimext'ensions. I

Fig. 9 is an end elevation of the laminated structure or pile of adhesively joined wood discs shown in Fig. 8 with an indication in dotted lines of the hub bore, openings, slots and cuts which are to be made in said pile of wood discs.

Fig. 10- is a view corresponding to Fig. 9, showing the same structure after saidhub bore, openings, slots and cuts are made therein and after the addition of rim rings to provide laminations of the rim extensions of the sheave.

Fig. 11 is a section taken on the line C--D of Fig. 10, showing in dotted lines the form to which the sheave body is tobe shaped.

Fig. 12 is a front elevation of the sheave produced by shaping the structure of Fig. 11.

Describing first the sheave shown in Figs. 1 and 2, it comprises huband rim portions and a connecting web portion in a body of laminated wood, preferably hard wood such-for exampleas hard maple, the plies or laminations thereof being arranged and adhesivelyjoined in'planes at right angles tothe sheave axis; thereby obtaining the great extra strength of a laminated wood structure with the grain of the wood running transversely of the sheave axis in difierent directions in'the different laminations. The plies or laminations of the wood sheave body include discs I forming intermediate laminations of the web and correspondinglaminations. of the hub and rim, and discs 2 formingouter laminaticns of the web and corresponding laminations of the hub and rim. Additional hub. laminations. are provided by the discs 3 of smaller diameter than the discs I and 2, thesehub discs 3 being divided into half parts by the hereinafter mentioned radial slots II. Thehub could be further extended by additional hub discs-of the same diameter as the outer faces of the. discs 3. Laminations of extendedrim portions of the sheave are formed by the rim rings 4 and end rim rings 5. In the periphery of the sheave body are formed a plurality of V-belt grooves 6, the inclined side walls of which are provided in this instance by. confronting beveled faces vofadjacent laminations.

of the rim portion of the heave. 1

This laminated wood sheave body is formed with a pair of openings 1 extending therethrough at opposite sides of and spacedfrom the hub bore 8 andlyingpetween thehub and; opposite segments of the rim portion of 'the; sheavelthese openings 1 being intersected by a diametric plane and having dimensions transversely thereof much greater than the diameter of the hub bore. In the specific form shown the openings 1 appear as symmetrically arranged half-moon lik openings with fiat inner walls 9 and arcuate outer walls 10, said inner walls 9. being parallel and perpendicular to the diametric plane AB which bisects both openings. Preferably said inner walls 9 are tangent to the circular ends of the sheave hub, as shown in Fig. 2. The portion of the sheave structure between the two openings 1 is' divided longitudinally by slots .1 I extending radially from the hub bore 8 to diametrically ,QDDQr site points beyond the circumferenceof the hub. The diametric plane C-D, which is th medial wood discs and rings the majority of which are shown as identical in form and size with corre- .sponding elements of the sheave body of Figs. 1

plane of the slots l I, is midway between the opena ings 1 and at right angles to the first mentioned diametric plane AB which bisects said openings. The slots II, as well as the openings I, extend longitudinally clear through the sheave as shown in Fig. 1. There is thus provided a split hub unitary with the surrounding portion of the sheave but readily contractible without deformation or undue straining of the rim portion of the sheave.

The parts of the sheave hub at opposite sides of the slots 1 l are connected by bolts I 2 arranged transversely of said slots, these bolts consisting preferably of rods having screw threaded end portions engaged by the nuts l3 which are accommodated in the openings 1. Flat metal washers M are preferably interposed between the bolt nuts l3 and inner walls 9 of said openings 1, these walls forming opposite sides of the hub. By tightening said nuts, the sheave hub can be contracted on a contractile bushing IE to clamp the sheave to the bushing and the latter to the sheave shaft, whereby to secure the sheave in fixed relation to the shaft. I

The bushing I is preferably a wood bushing split longitudinallyby a slot l-B extending the full length of said bushing. In its uncontracted state, the bushing l5 fits the hub bore of the sheave and the shaft to which the hub is to be applied, though in view of the contractibility of the bushing the shaft may be of slightly less diameter than the bore of the bushing. The sheave can be used with wood bushings of different inside diameters to adapt it to shafts of difierent diameters.

The sheave shown in Figs. 3 and 4 is generally similar to the other but, in view of its having a greater number of belt grooves and 2. correspondingly longer rim portion, the sheave of Figs. 3 and 4 is formed with a double web or a plurality of spaced webs in order to give it additional strength and provide a correspondingly wider web portion and to avoid unduly long overhanging parts of the rim portion. The wood plies or laminations of this sheave include discs l of the sam form as the discs I in Fig. 1. These discs l form the laminations of spaced laminated webs and also corresponding laminations of the sheave hub and of rim portion of the sheave. Between and spacing the two webs are hub discs l1 and rim rings I8. A hollow space between the discs l1 and rings [8 is designated by the numeral 19. Additional laminations of the rim portion of the sheave are provided by the rim rings 4 and end rings 5 of the same forms as the rings 4 and -5 in Fig, 1. Additional laminations of the hub are provided by the hub discs 3 of progressively decreasing diameters, forming tapered hub "extensions beyond the sheave webs. In Figs. 3 and 4-, the openings l slots H hub'bore 8 bushing l'5 ',and

and 2. Conversely, sheave bodies of the single web type shown in Figs. 1 and 2 can be made up in various forms from wood discs and rings of the kind used for making sheave bodies of the double webbed type shown in Figs. 3 and 4. In the case of sheaves having a great number of belt grooves, say ten or more, sheaves of the character shown in Figs. 3 and 4 can be made with three or more spaced webs. In the manufacture of sheaves of any given pitch diameter, the manufacturer may make up and carry in stock the wood discs and rings for building up the sheave bodies of that diameter, and from these he can make up sheave bodies of various specific forms and longitudinal dimensions and numbers of sheave grooves to meet the requirements of different multiple V-belt drives.

The laminated wood bodies of the sheaves shown in Figs. 1 to 4 maybe described as composed of main discs forming web laminations and corresponding hub and rim laminations, complemental halves of so-called hub discs forming hub laminations other than those formed by said main discs, and rim rings forming laminations of the rim portions of the sheaves other than those formed by said main discs. All of these main discs, hub disc halves and rim rings may be one piece elements or formed as or from one piece plies, or some or all of them may be composite elements or fabricated as composite plies com-' posed of suitably jointed smaller wood pieces.

In the fabrication of these sheave bodies, it may be desirable to utilize small pieces of scrap lumber for purposes of economy as Well as to obtain favorable disposition of thegrain of the wood, it being desirable that the grain of the wood should be crosswise of the wearing surfaces of the belt grooves in the sheave peripheries. Examples of methods by which scrap lumber can be advantageously utilized are illustrated in Figs. 5 to '7; r

In Fig. 5 there is shown a wood'slab-composed of parallel stripsZO dovetail-jointed and glued together, a cross section through any of the lines of joinder being as shown in Fig. 6. -As represented in Fig. 6, the wood strips composing the slab are formed with interengaging tongues and grooves. preferably of the type to form dovetail joints. From the Wood slab shown in Fig. 5 there may be cut or sawn a wood disc 'I indicated in dotted lines in said figure. The joints between wood strips composing such discs are indicated at 2| in Figs. 5, 6, 8, 9, 10, 11 and'12.-. 1

In Fig. 7 there is shown in dotted lines a rim ring 4 composed of segments having ab'utting ends glued together. In Figs. '7, 1"0-,- l1 and 12, joints in such rim rings are indicatedat 23. As represented-in full lines in Fig. l, an individual segment of a wood rim ring maybe fabricated from a composite wood slab composed "of strips 24 dovetail-jointed and glued together. "A cross section through the line of joinder in the strips 24 of Fig: 7 may be the same as in Fig; 6.

Where the wood plies or laminations of the sheave bodies are fabricated as composite elements, the several plies are arranged or so fabricated to break joints, or, in other words, the joints in individual plies are lapped by unjointed portions of adjacent plies. For example, if the discs I and 2 in Figs. 1 and 2 or the discs I in Figs. 3 and 4 are made in accordance with the method shown in Figs. 5 and 6, the several discs are arranged or fabricated with their joints 2| running in different directions in the different such discs, or so that the joints in each of such discs run crosswise or transversely of the joints of the adjacent disc or discs. So also if the rim rings 4 and 5 of Figs. 1 and 2 or the rings 4", 5 and l8 of Figs. 3 and 4 are made in segments as represented in Fig. 7, the said rings are arranged or fabricated so that the joints 23 of each such rings are staggered relative to those of the adjacent such ring or rings.

One practicable method of making a sheave embodying the invention will be described with reference to Figs. 8 to 12. Assume that it is intended to make a sheave of the form shown in Figs. 1 and 2, which is a simple form for illustration. First there is built up or fabricated a laminated wood body to provide the lam nations for the hub and web and intermediate portion of the rim of such sheave. Such a laminated body isrepresented in section in Fig. 8 and in end ele'- .vation in Fig. 9 (disregarding for the moment the dotted lines in Fig. 9). This body comprises a pile of adhesively joined wood discs or generally circular wood plies or layers. In this instance there are shown in Fig. 8 four intermediate wood discs I of larger diameter and outer wood discs 3 of smaller diameter. The larger diameter discs l correspond to the four main discs designated by the reference numerals I and 2 in Figs. land 2, and the smaller diameter discs 3 correspond to hub discs 3 in Figs. 1 and 2. All of these discs may be one-piece elements or sawn from one-piece planks. However, the discs I are in this instance made in accordance with the principle disclosed in Figs. 5 and 6. One of such discs appears in elevation in Figs. 9 and 10, in which figures the lines of joinder of the wood pieces or strips composing such disc are indicated at 2 I. It will be understood that such lines of joinder in the several discs I of the pile or body represented in Fig. 8 run in different directions, so that such joint lines of each such disc are overlapped by unjointed portions of the adjacent such disc or discs. As appears in elevation-in Figs. 9 and 10, the discs 3 toprovide the laminations of the hub ends are formed in sectors glued together, the joints therein being indicated at 25. As is apparent from Fig. 9, it so happens that in this particular structure that the middle joints 2| in the discs I and the several radial joints 25 in the discs 3 are in planes which in tersect at the center of the structure, in consequence of which there appears a center line 25 inFig. 8. This line 26 in Fig. 8 merely represents such line of intersection, and should not be mistaken for a joint or line of division in the lami- -arately bored with center holes to provide the hub bore. Next, the openings 1 are cut through said body, with the inner walls of said openings perpendicular to a diametric line. Then the said body is split by sawing through it on the diametric line CD perpendicular to the first mentioned diametric line, using a thick saw through the part of the body which is to form the hub and a part of the web, so as to provide the slots H, and using a thin saw through the surrounding or outer portion of the laminated body, thus cutting through the peripheral portion thereof on said line CD. The said laminated body is thus divided into two identical half parts. Now the holes for the hub bolts are drilled in said body parts, and the bolt rods l2 are inserted in said half parts, which are then glued back together again; or, after inserting said bolt rods, the said two half parts may be suitably keyed together by keys (not shown) engaging grooves therefor which may be formed in said half parts at the end faces thereof which abut on the line CD, such keys being dovetailed in the respective half parts. The bolt nuts I3 are now applied.

ter these operations, there are added to the laminated wood body the necessary groups of flat wood rings 4 to provide the laminations of the rim extensions of the sheave, such rings being adhesively united to said body and to one another. There is thus produced the unfinished structure shown in end elevation in Fig. 10 and in section on a larger scale in Fig. 11. As the section shown in Fig. 11 is taken on the line CD, namely on the line of division and joinder of the two aforesaid half parts of the structure shown in Figs. 8 and 9, only the rings 4 and the hub bolts l3 appear cross hatched in Fig. 11L The four wood rings 4 shown in Fig. 11, two at either side of the web portion of the sheave, correspond to the rim rings designated by the numerals 4 and 5 in Figs. 1 and 2. These rings 4 in Fig. 11, one of which is shown in side ele-' vation in Fig. 10, are composed of segments, the joints 23 of each of such ringsbeing staggered with relation to those of the adjacent-such ring, as appears more clearly in Fig. 12. f

The dotted lines in Fig. 11 indicate the form to which the wood body structure shown therein in full lines is to be reduced. Having made'the said structure as hereinbefore described, it is now put into a lathe and shaped to the form shown in dotted lines in Fig. 11, completing'the making of a sheave shaped and finished in the form shown in Figs. 1 and 2.- It will be seen' that the sheave so made embodies identical laminated segments abutting and joined on the diametric line CD, the two segments being clamped together by the hub bolts as well as bound by continuous rim extensions formed by the rings 4 The finished sheave isshown in front ele vation in Fig. 12. It is to be fitted with a Wood bushing such as heretofore described.

In making by the method above described a sheave of the double webbed type shown in Figs. 3 and 4, there is firstbuilt upa laminated wood body structure to provide the hub and webs and so much of the rim portion as is longitudinally coextensive with the web portion, or, in other words, to provide the main discs I hub discs 3*? and I1, and rim rings I8. The ensuing opera-- tions are the same as described for the making of a sheave of the type shown in Figs. land 2.

Either of the illustrative sheaves shown in Figs. 1 to 4 can be madev with one piecemain discs, half hub vdiscs and rimrings by a method which involves completely pre-forming the several wood components thereof and assembling and adhesively uniting them in proper relationship, with the holes and slots in the discs in registration to provide the hub bore 8, openings 1 and slots ll of Figs. 1 and 2 or the corresponding features 8 1 and H of Figs. 3 and 4. The components can be conveniently assembled in an interiorly cylindrical mold having its bottom shaped to conform to a side of the sheave, and they can be adhesively joined under pressure with the use of a presser head slidably fitting in such mold and shaped to conformto the op posite side of the sheave. In making in this manner the sheave of Figs. 1 and 2, the holes for the bolts I2 may be formed by mating grooves in the confronting faces of the adjacent discs I, and the hub bolts can be introduced in regular order in the course of assembling the wood components. In making in the same manner the sheave of Figs. 3 and 4, the bolt holes may be drilled through the pre-formed hub discs 3*- next to the sheave webs and the bolts I'Z may be placed in said discs beforethey are assembled with the other components.

Sheaves embodying the invention may be made in a number of ways, and the invention in its broadest aspect is not intended to be limited to any particularmethod of manufacture. On the other hand, the invention embraces different structural species which may be made respectively in the two different ways described.

Wood sheaves embodying the invention are practicable for manufacture, easily installed and of strong and sturdy character. Although a cast iron sheave ma be able to stand heavier duty than a wood sheave of the same size embodying the invention, yet in a great many installations of multiple V-belt drives it would be practicable to use sheaves embodying the invention for the duties for which cast iron sheaves of corresponding sizes are commonly employed. The invention therefore offers opportunity for extensive utilization of wood in the construction of new machinery drives, as well as for replacement of existing cast iron or other metallic sheaves by wood sheaves embodying the invention, with resulting release of much valuable metal for other essential purposes.

Though hard wood is considered the most satfactory for use as a substitute for wood; therefore the invention is not intended to be limited to constructions of wood as distinguished from such other non-metallic material as may be suitable for the construction of sheaves, considering the duties to be imposed upon them.

, In the illustrative structures shown in the drawings, the sheave grooves 6 have their side walls formed each in a single lamination,i however individual side walls of the sheave grooves could be in two or more laminations.

We claim:

1. A sheave having a split contractible hub and an unsplit annular rim portion unitary therewith, said hub being composed of adhesively united wood discs and said rim portion being composed of a plurality of said discs and a plurality of flat-sided rim rings adhesively united to said discs and to one another, said discs having registering center. holes to provide the hub bore and registering slots extending radially from said holes and having closed outer ends in said discs, the hub being divided longitudinally by said slots, said discs being formed to provide flat hub sides parallel with said slots, there being open spaces between said fiat hub sides and opposite segments of the rim portion of the sheave, the discs which form laminations of the rim portion having registering openings to provide said open spaces and annular portions forming web laminations encircling said openings and slots in said discs, and bolts arranged transversely of said slots and connecting the split hub parts, by the tightening of which bolts the hub can be contracted on a contractible bushing to clamp the sheave to the bushing and the latter to a shaft.

2. A sheave comprising. a body composed of laminations of wood or other suitable non-metallic material adhesively united in planes perpendicular to the sheave axis and having extending 1ongitudinally therethrough a central hub bore and a pair of radial slots extendin diametrically oppositely from said bore and a pair of openings at opposite'sides of and spaced from said slots and bore, said body having an unsplit rigid unitary annular outer portion formed with peripheral V-shaped belt grooves concentric with said bore, said openings being bisected by a diametric plane perpendicular to said slots and having. dimensions transverse of said plane much greater than the diameter of said bore, said slots extending midway between said openings through and beyond the portion of the body therebetween and having closed outer ends in said body, thereby providing a split contractible hub the halves of which are unitary with and connected by said annular outer portion of the body, and bolts extending transversely of said slots through and connecting the hub halves, by the tightening of which bolts the hub can be contracted on a contractible bushing to clamp the sheave to the bushing and the latter to a shaft.

3. A sheave of the type described in claim 2 having said bolts so arranged that they draw against portions of the hub including components forming laminations of the surrounding portion of the body.

4. A sheave of the type described in claim 2 wherein said bolts consist of wire rods having screw threaded portions and nuts engaging said portion, and having fiat metal washers interposed between said nuts and sides of the hub.

5. A pulley comprising a centrally bored body of non-metallic material formed in laminations adhesively united in planes perpendicular to the pulley axis, said bodycomprising a hub and an annular rim portionand a connecting web portion comprising a plurality of longitudinally spaced circular laminated webs composed of disks forming the laminations thereof and also forming corresponding laminations of the hub and rim portion, there being cut through the webs at opposite sides of the hub and spaced inwardly from the rim portion openings bisected by a. diametric plane and having. dimensions transverse thereof much greater than the diameter of the hub bore, and the hub being split for its full length midway of said web openings by radial slots extending diametrically oppositely from said bore and having closed outer ends in said webs, the halves of the hub separated by said slots being held in spaced relation by the rim portion of the body, and bolts arranged transversely of said slots and connecting the hub halves, by the tightening of which bolts the hub can be contracted on a contractible bushing. to clamp the pulley to the bushing and the latter to a shaft.

6. -.A pulley comprising a, centrally bored body of non-metallic material formed in laminations adhesively united in planes perpendicular to the pulley axis, said body comprising a circular laminated web portion and longitudinally extended hub and rim portions composed in part by the body laminations forming the web portion and in part by additional hub and rim laminations, there being cut through the web portion at opposite sides of the hub and spaced inwardly from the rim portion openings bisected by a diametric plane and having dimensions transverse thereof much greater than the diameter of the hub bore, the hub being split for its full length midway of saidopenings by radial slots extending diametrically oppositely from said bore and having closed outer ends in said web portion, that part of the body which comprises the hub and web portion and so much of the rim portion as is longitudinally coextensive with the web portion being in two semi-circular" halves with abutting ends joined in a. diametric plane which is the medial plane of said slots, and the rim portion including circumferentially continuous extensions beyond the web portion, the hub halves separated by said slots being held in spaced relation by the rim portion, and bolts arranged transversely of said slots and connecting the hub halves, by the tightening of which bolts the hub can be contracted on a contractible bushing to clamp the pulley to the bushing and the latter to a shaft.

DAVID FIRTH. DONALD P. LOWER.

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