US2356437A

US2356437A - Chain saw construction

Info

Publication number: US2356437A
Application number: US397194A
Authority: US
Inventors: Donald J Smith
Original assignee: REED PRENTICE CORP
Current assignee: REED PRENTICE CORP; REED-PRENTICE Corp
Priority date: 1941-06-09
Filing date: 1941-06-09
Publication date: 1944-08-22
Anticipated expiration: 1961-08-22

Description

, Aug. 22, 1944. z D J SMITH I 7 2356 437 CHAIN SAW, CONSTRUCTION Filed Jun 9, 1941 for engagement with the saw,

' is made up of inner Patented Aug. 22,, 1944 2,356,437 g V CHAIN saw CONSTRUCTION,

Donald J. Smith,

. Canada, assignor Worcester,

setts Application June 9, 1941, se'rn1N0.39 7,'194 r 2 Claims. (c1. 143-135) a V v I 5 to flex-around the sprocket The lattenas will= The present invention relates to chain saws and-particularly toa drive sprocket construction by which to obtain a positive and substantiallyfriction free drive for the saw chain.

In prior devices of this character, the driving element has been provided with rollers or pins as shown for example in the Arsneau Patent No. 2,060,547.

Vancouver, British C olumbia, to Reed-Prentice Corporation,-

Mass., in. corporation of Massachuand chain While in the patented construction,-the driving element is adapted to have line contact with the saw chain, the contact between the sprocket and the chain is relatively small and the wear on the parts is excessive. One of therprincipal objects of the present invention is to provide a sprocket and chain, so arranged that the sprocket has fiat driving surfaces of substantial area in contact with corresponding flat, surfaces on the links of the chain, and with these surfaces 'so positioned that there is no frictional drag between the chain and sprocket as the chain is engaged by the sprocket.

In the Brown et al. Patent No. 596,802, the

be understood; is suitably attached to :a-d'rive shaft, not shown,.and the :saw chain-risdriven. by the sprocket as the latter rotates in the direc-' tion of the arrow. l I

Each of the outer links 2, as shown,.is centrally notched, as at 5, to receive and to engage with the outer end of the teeth 4a of the sprocket, and these outer links, by engagement with the, sprocket teeth, tend to support the saw chain. in a predetermined radial position with respect to the-sprocket, as it will be apparent that the chain" cannot move radially inwardly on the. sprocket while the links are in engagement with the teeth.' The outer links, being spaced apart thus have a substantially broad surface contact with the ends of the sprocket teeth and twisting or sidewise rocking of the chain on the sprocket is prevented.

driving element is provided with notches to receive inwardly extending lugs formed on the outer links of the chain, and between the notches V the element engages with the inner links to suprock on the sprocket, and will always be held at a predetermined of the sprocket.

Other and further objects and advantages of radial distance from the axis the invention will hereinafter-appear from the following detailed description taken in connec- 7 tion withjthe accompanying drawing, in which- Fig. 1 is a side elevation of the sprocket embodying the invention, with a saw chain in position on a part thereof.

Fig. 2 is a sectional view alon the line 2-2 of Fig. 1, looking in the direction of the arrows. Fig. 3 is a fragmentary view of the chain with the outer links removed.

With reference to the drawing, the saw chain links I pivotally connected by outer links 2, with pins 3 providing a pivotal connection between the links to permit the chain tion of which, when the chain with the notches 5 in the The rearward face of each of the inner links I has a fiat angularly disposed surface 6, the posiis wrapped around the'sprocket, is precisely parallel to and in en-, gagement with the leading fiat driving surface 1 of a sprocket tooth and in a position to engage ,with the tooth 4asubstantially over the entire length thereof, as shown in Fig. 1. It will be obvious that the inner link surfaces 6 are proportioned accurately with respect to the notches r 5 so that as the chain flexes around the sprocket the sprocket teeth surfaces 1 will still engage the surfaces 6' while the points thereof engage 'outer links. 1

The forward lower corner of eachinner link I is cut away, as at 8, so that there is no'engagement between the rearward surface of each sprocket tooth and thefollowing inner link, so that any frictional drag onthe sprocket or chain from the non-driving surfaces of the sprocket teeth and chain links is howeventhat the inner edge of each inner link I may have a relatively secting' with the surface 6 and in position to engage'with the corresponding surface' I 0 on the 7 sprocket.

It will be understood that the angularity of the surfaces 6 and l on an inner link and on the sprocket respectively is such that the angular thrust exerted on the link by the sprocket tooth does not tend to urge the teeth outwardly with respect to the sprocket, but transmits practically all of the driving power tangentially of the sprocket, as will be apparent. 'The drivingsurface 1 onthe leading face of each sprocket tooth preferably extends at an angle of approximately avoided. It will be noted,

small flat surface 9 internortion receivable between adjacent teeth of the sprocket, and providing a fiat end surface .closei 'ivengageable with the leading flat driving sur- {ace ofasprockettooth when thechain is curved withthe'iorwardedge of the next succeeding 10 v pairs, with each of said inner links having a =15' around; the; sprocket for driving the'same, and I link, of the-chain being cut away to avoid engagement with the trailing face of a sprocket tooth, each pair of ;links in said o uter serie's pro viding alined" notchesv in theirlower edges to engagewiththeiend. of a. tooth of said sprocket,

Ionsupportingg the chain radiallyof the sprocket axis, and to prevent rocking of the chain on a sprocket, as the chain is driven by the engaged flat surfaces ofa sprocket-tooth and inner link.

2. A chain saw construction, comprising in combination a'rotatabiy driven sprocket having radial teeth each providing a flat driving surface and a chainsaw cooperating with said sprocket comprising a series of inner links pivotally connected on opposite sides by series of outer links arranged inpairs, with the combined widths of an inner link and two outer links sub stantially equal to the width of a sprocket tooth, each pair of outer links providing alined notches in their lower edges to engage with the end of a teeth of said sprocket to support the chain ra- 'dially of the sprocket axis and thereby prevent rocking of the chain 'on the sprocket, and with each inner link providing a fiat driving surface in complete 'face-to-face engagement with the leading iiat driving surface of a: sprocket tooth when the chain is curved-around thesprocketi DONALD J. sMrrH."