US1845644A

US1845644A - Portable electric saw

Info

Publication number: US1845644A
Application number: US372507A
Authority: US
Inventors: Martin W Bardwell
Original assignee: Individual
Current assignee: Individual
Priority date: 1929-06-20
Filing date: 1929-06-20
Publication date: 1932-02-16
Anticipated expiration: 1949-02-16

Description

M. W. BARDWELL PORTABLE ELECTRIC sAw Feb 16, 1932 Filed June 20, 1929 2 Sheets-Sheet 1 llll ill.

|| ll l l mlliltlll Feb. 16, 1932. M. w. BARDWELL 1,845,644

PORTABLE ELECTRIC SAW Filed June 20, 1929 2 Sheets-Sheet 2 Patented Feb. 16, 1932 UNITED. STATES MARTIN w. BALRDWELL, or BELGHERTOWN, amssaonusnrrs PORTABLE ELECTRIC saw Application filed June 20,

My invention relates to electrically driven power devices, and for purposes of, explanation and description I have shown the same as exemplified in a portable saw structure.

The general object of the invention is to provide a device of simple construction which is compact and is capable of utilizing with great eiiiciency the energy generated by the power device employed for actuating the 0 operating mechanism thereof.

It is a further object of the invention to provide means whereby a relatively long stroke of a tool or other object may be attained by the operation of mechanism which 5 is adapted to be located in a relatively small space.

A still further object of the invention is to provide means interposed between the driving and the driven elements whereby the wearing effect upon the driving element by the contact of the driven element therewith is reduced to a minimum.

To the foregoing and other ends the invention comprehends the construction and arrangement of parts as hereinafter described n CI in detail, particularly pointed out in the claims, and as illustrated in the accompany ing drawings wherein I have illustrated the invention in the form which is at present pre- (5 ferred by me. However, it should be understood that the invention is susceptible of embodiment in other forms of construction than that shown and that mechanism within the m, inventionmay be employed for the actuation Fig. 2 is a similar view of a fragmentary portion of the structure with the parts enlarged and with certain parts, not shown in Fig. 1, being indicated in dash lines and with a portion broken away and sectioned to show a detail of construction;

1929. Serial No. 372,507.

Fig. 3 is a transverse sectional view taken along the line 3-3 of Fig. 1

Fig. 4 is a sectional view taken along the line 44 of Fig. 1; and

Fig. 5 is a transverse sectional view taken on the line 5 5 of Fig. 1.

In the drawings I have shown a casing 1 of rectangular shape one side of which is open and is adapted to be closed by means of a cover plate 2 secured in place by means of fastening rods 3 which extend through the casing near the top and bottom edges thereof, as indicated in the drawings. The casing may be of solid box-like formation, as shown, or may consist of any other formation of a character to support. the operating mechanism of the structure which will be herein after set forth in detail. The casing is provided upon oneof its sides near its rear end with an integral tubular projection 4 having a lateral flange 5 to which a motor 6 of any known suitable construction is attached; The motor is provided withthe usual motor shaft, indicated at 7, and is connected by means of reduction gearing, indicated as a whole at 8, with a worm shaft 9 supported in antifrictional thrust bearings 10 and 11 provided upon the casing 1 inside of and in adjoining relation to its rear end. The casing is provided with a bracket 12 upon which may be mounted any suitable form of switch 13 for opening and closing the circuit 14 through the motor 6 for operating the latter. A spring, as indicated at 15, or any other suit able means may be employed for normally holding the switch in open position, and the closing of the said switch may be effected in opposition to the action of the saidspring by a finger or hand-piece 16. A worm 20 is supported upon andkeyed to an enlarged por tion 20 of the shaft 9, as shown in Fig. 2, and is in engagement with a gear 21 which is. mounted upon a cylindrical bushing 22 which in turn is supported upon a pin 23 which projects outwardly from the bottom of the casing 1 toward the cover 2 which closes the open sidethereof. The bushing 22 not only fits in the opening through the gear 21 but also projects into and practically through a similar opening 24 in agear 25. The bush ing is provided with elongated projections constituting gibs 30, which gibs are in engagement with grooves or slots 31 and 32 provided in the openings through the gears 21 and through which the bushing 22 extends. The gear 25 is in mesh with a gear mounted upon the intermediate portion of a pin 36 supportedin parallel relation to the pin 23. The bushing 22 with the gears 21 and 25 thereon is rotatable upon the pin 23 wh-i-lethe gear 35 is rotatable upon the pin 36. The

pins

23 and 36 are retained in openings 37 provided in the bottom of the casing 1 by means of binding screws 40.

The shaft 9 is held against axial movement by collars 40 one side of each of which engages the shoulders formed by the enlarged porti0n20 of the shaft and the opposite ends of the worm 20, and the opposite or outer sides of which are seated against the bear ings 10 and 11.

For the purpose of providing a supplemental bracing and steadying support for the upper ends of the pins 23 and 36 I have provided-amember of T-shape having a portion 41 which extends between the opposite sides the top and bottom sides) of the casing 1 and secured thereto by means of connecting screws 42, and also having a portion 43 which extends at right angles to the portion 41 and is connected at its outer end by means of connecting screws 44 to the adjoining end of the casing 1. Theupper end portions of the

gear supportingpins

23 and 36 are reduced, as indicated at 50, and the said end portions pro- .ject into openings 51 in the underneath side of the portion 41 previously referred to. It willbe obvious that'the

pins

23 and 36 are supported at their opposite ends, thereby greatly increasing their capacity for withstanding and resisting forces which may be applied laterally thereto. For the purpose of actuating a saw 52 or other object I have provided a supporting rod 53 or'the like, having'means such, for example, as that shown at 54 for supporting the said saw or other tool. The supporting member 53 is guided at its outer end in 'a split bearing 55 removably mounted in an opening which is provided in the outer end wall of the casing 1. The inner end of the supporting rod or bar 53 termi nates in a 'T-head or enlargement having a notch in-its outer side or edge into which extendthe overlapping outer ends of links 56 which are held in place within said notch 'by'a pivot'bolt or pin 57. The links 56 constitute parts of a lazy tong structure, indicated as a whole at 59. The outer ends and the intermediate portions of the links constituting-the said structure are pivotally connected together in the usual manner. For the purpose of causing the expanding and contracting movements of the lazy tong structure .59 .to take place in a substantially single plane, or in other Words, to prevent lateral vibration thereof, I have connected the same to guide

blocks

60 and 61 the opposite or upper and lower edges of which are supported in grooves 62 provided upon the inner edges of guide bars 63 which are supported upon the inner side of the bottom of the casing 1, being connected thereto by means of screws 64. The guide block 60 and the terminal T-head of the supporting member 53 are formed integrally so that the said block and supporting member constitute a single integral structure possessing a high degree ofrigidity; One of the pivots 65 by which the middle portions of the links of the lazy tong structure are connected together extends into and is supported upon the guide "block 61. By this means the lazy tong structure is supported at its inner and outer ends, whereby its in-and-out movements (causedlby means hereinafter to be described) are effected in straight lines; in other Words, lateral vibration of the actuating link structure is prevented. Of course the connecting rod or bar 53 is further guided by means of the bearing 55 through which it operates.

For the purpose of causing pivotal movements of'the links of the lazy tong structure with respect to each other and thereby causing in-and-out rectilinear movement thereof I have provided the innermost links and 71 of the said structure with enlarged rear end portions which are provided with openings 72 and 73 therethrough, within which openings are located disks 74-and 75 which are mounted upon and eccentrically of the gears 25 and 35.

The centers of these disks are connected to the gears 25 and 35 by means of

pins

76 and 77 located eccentrically of the said gears respectively. The said disks 74 and 75 are provided respectively with openings 80 and 81 located. eccentrically thereof through which the pins or

posts

23 and 36 project. By the engagement of the disks 74 and 75 with both the

pins

76 and 77 and 23 and 36 it will be apparent that the forces transmitted through the said disks are resisted by both pins, thereby preventing a concentration of forces upon the

pins

76 and 77 which might result'in'the breaking thereof. If preferred, the disks 74 i and 75 may be formed integrally with the gears 25 and The disks 74 and 75 are located between the gears 25 and 35 and the ends of projections 82 provided upon the inner side of the portion 41 which constitutes a supplemental supporting means for the

pins

23 and 36.

By reducing the diameters of portions, as

indicated at 50., of the pins or posts .23 and 36 I also am enabled to reduce the sizes or of the drawings. During the rotation-of the 1 gears 25 and 35 and of the disks Hand mounted thereon it will be apparent that when in certain positions the outer edge portions of the disks will overlap each other. For example, if the said disks and gears be rotated through 180 from the positions in which they are shown in Fig. 1 of the drawings, it will be apparent that at such time the edge portions of the disks 7 4c and 7 5 will overlap each other. To permit such overlapping in the construction as shown in the drawing a lower portion of the disk 7 42 is cut away, as indicated at 82, and likewise a portion as indicated at 82 of the outer end of the link 7 0 is cut away. These cut-out or cut-away portions are located in proper positions to permit the edge portion of the disk 7 5 to project thereinto as the said disks 7 4 and 75 move into overlapping relation with respect to each other.

In the operation of the device the worm 20 is rotated toward the right, thereby causing the gear 21 and the connected gear 25 to rotate in an anti-clockwise direction, as indicated by the arrows 83 shown in Fig. 2 of the drawings. The gear 25 is in mesh with the gear 35, so that rotation of the latter in a clockwise direction (as indicated by the arrow 84 in Fig. 2 of the drawings) is effected.

As illustrated in Figs. 1 and 2, the

pins

76 and 77 and the disks 74- and 7 5 are located in positions the farthest apart of any occupied by them during the operation of the device. Movement of the gears 25 and 35 from the positions shown in Figs. 1 and 2 in the directions of the

arrows

83 and 84 causes a movement of the pins 7 6 and 77 toward the right along circular paths and toward each other, the disks 74 and 75 being thereby caused to revolve about the reduced portions 50 of the pins 23 and 3 6. The pins 7 6 and 77 moving in the directions just indicated act through the disks 74 and 7 5 to cause pivotal movement of the links of the lazy tong structure and to effect rectilinear outward movement of the latter as a whole to cause outward movement of the saw or other device having connection therewith and which is to be actuated thereby. This cutward movement, which begins at a moment just before the

pins

76 and 77 arrive at the points shown in the drawings, is begun slowly and then speeds up, the movement slowing down as the lazy tong structure approaches the end of its outward movement. When the

pins

76 and 77 and the disks 74 and 75 have reached certain points in their movements the lazy tong structure as a whole begins a movement in the reverse or opposite direction. This movement likewise is at first slow and then speeds up, and finally slows down as the lazy tong structure as a whole approaches the limit or end of its reverse movement. Thus a reciprocating rectilinear movement of the lazy tong structure as a whole is effected whichy maylbe utilizedinthe actuation of a saw or of any other device for which it may. be adapted.

,Thepivotal movement of the

links

70 and 71 and the corresponding movementsofv the remaining links of the lazy tong structure to drive the tool 52 or other device to effect the work desired to be performed thereby results .in the imposition of stresses and forces upon the gears 21, 251 and 35 and upon the worm 20. As a result of the stresses and forces thus applied between the engaging driving and driven gears theremay be considerable. wear of the contacting surfaces, particularly the. surfaces of the driving face of, the wor1n20. I have discovered that by the employment of a bushing- 22 for-connecting the two gears 21and 25 the wear of the engaging surfaces of the gear teeth of the gear 21 and of the worm 20 is greatly reduced. Particularly is this true of the driving surface ofthe worm 20. This is true notwithstanding the fact that the-bushing 22 has rigid connection with the said gears 21 and 25, the fit between the said bushing and-the the means employed thegears 35 and 25.1nust be driven in directions related to each other as illustrated in the accompanying drawings, in order that the lazy tong structure may be actuated for elfectingreciproeatory movement of the rod or bar 53 by means of which the Work to be effectedmay be performed.

It may be noted that for the purpose of facilitating and rendering more convenient the handling of the device I have so related the parts of the structure that the center of gravity is located at some point within the motor 6 or at some point directly and immediately above the said motor, so that when the device is supported by means of a suspending means the casing will occupy a horizontal position, with the motor 6 depending therefrom. To further facilitate the transportation of the device I have provided the casing with a handle 85 which is located preferably directly above the motor 6.

It will be seen that by my invention I have provided a device of the character indicated which is simple, compact, strong, and durable, and which may be employed for various purposes. One of the uses for which the inventionis adapted when embodied in a portable saw structure, such as is exemplified in the acine zcompa'nying drawings, is that of sawing or cutting limbs tro-m trees. The device being light :may be hoisted readily upwardly into proper relation to thelimb of a tree which it is desired to remove.

Having thus described my invention, what lclaim and'desireto' secure by LettersPatent is:

1. A power driven saw comprising a casing, :a motor supported thereon, a worm shaft mountedwithinthe casing and driven by the motor, a worm wheel geared to the worm shaft, "a gear wheel yieldingly secured to the worm wheel, a second gear wheel meshing therewith, an eccentric on each of said gear wheels, a 'lazy tong device supported within said casing and having the terminal links on one end thereof in the form of eccentric straps, one of which is in operative engagement with each of said eccentrics, a connecting rod attached to'the opposite end of said lazy tong device and extending to 'the exterior of said casing, and a saw secured to said connecting r0 1 2. In a power driven tool the combination of a casing, a motor supported thereon, a worm shaft .carried'by the casing and driven by the motor, a worm wheel geared to the worm shaft, .a gear wheel yieldingly secured tothe worm wheel, a second gear wheel meshing therewith, an eccentric on each of said gear wheels, a lazy tong device within said casing and having the terminal "links on one 35 end in the form xof eccentric straps one of which is in operative engagement witheach of saideocen'trics,guide blocks secured to said lazy tong device, a guideway for said guide blocks von said casing, and a connecting rod 40 attached to the opposite endof said lazy tong device and projecting from said casing.

In testimony that I claim the foregoing as my invention I .havehereunto signed my name thisl lthday of June, A. D. 1929.

MARTIN W. BARDWELL.