US769982A - Pawl-and-ratchet device. - Google Patents

Description

No. 769,982. PATENTED SEPT. 13, 1904. A. B. GASE- PAWL AND RATGHET DEVICE.

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Patented September 13, 1904.

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ADELBERTB. CASE, OF SPRINGFIELD, MASSACHUSETTS.

PAWL-AND-RATCH ET DEVICE.

SPECIFICATION forming part of Letters Patent N0. 769,982, datedSeptemloer 13, 1904.

Application filed February 4, 1903- Serial No. 141,795. (No model.)

To all whom it nury concern.-

Be it known that I, ADELBERT B. CASE, a citizen of the United States of America, re. siding in Springfield, in the county of Hampden and State of Massachusetts, have invented new and useful improvements in pawl-andratchet devices adapted to be employed as shafts for lawn-mowers and in parts operatively connected therewith, of which the following is a specification, reference being had to the accompanying drawings, and letters of reference marked thereon, in which drawings like letters of reference indicate like parts.

Figure 1 is a side elevation showing the cutter-shaft of a lawn-mower, together with a portion of the frame in which the shaft is mounted, showing also a traction-wheel and some of the operative parts mounted on said shaft. Fig. 2 is a plan view of an end portion of the cutter-shaft. Fig. 3 is a transverse sectional view of the pinion, shaft, and pawl, taken upon line 3 3 of Fig. 1. Figs. 4;, 5, and 6 are plan views of the end portion of a cutter-shaft, showing modifications in the shape of the openings in the shaft.

The invention relates to the construction of a shaft adapted to be employed in lawn-mower constructions and in the parts operativelyconnected therewith.

The object of my invention is to provide an improved construction of shaft and parts operatively connected therewith especially relating to a pawl-and-ratchet mechanism adapted to be applied to a lawn-mower construction, whereby the cost of construction is lessened and life of the device is increased; and my object is also to provide a construction which while being economical in cost of manufacture will be serviceable and efficient in operation and require the minimum expenditure of time and labor in maintaining the device in condition for its highest efliciency; and my invention therefore consists in the construction herein set out whereby the objects of my invention are attained.

As the subject-matter of this application relates largely to the shaft 60 and as the shafts of lawn-mowers and other like machines have prior to my invention been found diflicult and expensive to manufacture and unsatisfactory when manufactured, I will explain in detail the best method of procedure to produce the shaft and the objections heretofore existing as known to me, both as to the method of manufacture and the shaft when completed and also the advantages of my construction.

The shaft ratchet-and-pawl mechanism and parts directly operative therewith in the construction of lawn-mowers and other like mechanisms has heretofore been considered the weak, expensive, and defective portion of construction and the most difficult in which to produce ease in operation and lasting qualities.

Heretofore in the manufacture of lawnmowers and other similar mechanisms requiring a shaft adapted to be rotated in one direction by the engagement of a pawl mounted in the shaft and engaging internally-arranged pawl-teeth in a pinion-gear or other operative devices mounted on the shaft it has been found extremely difficult and expensive to form suitable pawl-receiving openings in the shaft, and the shaft when completed has been defective and unsatisfactory. v

In some constructions of lawn-mowers the ratchet-and-pawl mechanism is arranged between the cutter-shaft and pinion and in others between the driving-shaft and pinion.

Shafts of the character referred to are subjected to very severe torsional strain, and it is desirable that the shaft while being light and of a fine quality of i'naterial shall contain solid metal between the pawl-slot and the end of the shaft in order to give to the shaft the requisite strength to stand the torsional strain to which it is liable to be subjected, and in order to enable the manufacturers to employ such construction to advantage it is requisite that the pawl-openings be cheaply and rapidly made without distorting the metal adjacent to such openings. Heretofore it has been common to make such shafts of cast grey or malleable iron, the pawl-receiving openings in such shafts being cored. The openings thus formed, however, have not been accurate and uniform, so as to give the pawl its proper bearing, and it has been found necessary to finish the pawl-openings after the shaft is cast and annealed, and as smooth accurate shafts are required it then became necessary to turn down the whole length of shaft to the requisite size, or in some instances the ends only of the shaft have been cast so as to form the pawl-openings therein as before explained, these ends being attached to the cutter-frame or mounted as extensions to the end portions of the shaft. It will be readily observed that a shaft in Whole or in part of cast metal is objectionable because of liability of fracture and is expensive because of. the necessity of the several operations required in order to produce the required accuracy. An effort has also been made to provide suitable pawlw openings in steel bars or shafts by slotting the end of the shaft and then inserting a block in the slot at its end. This has been found expensive on account of the cost of milling into the ends, construction and insertion of the block, and finishing after the block is in place, and very defective, as the torsional strain to which the shaft is liable to be subjected is liable to distort and open the end portions. Such shafts have also been constructed from a piece of material of the diameter of the finished shaft by drilling two or more openings through the same at the points where the pawl-openings are to be located and then filing out the material to form a substantially rectangular opening. This is objectionable on account of the time and expense of filing out the material around the drilled openings, and to avoid the delay and expense of filing the openings have in some instances been broached. This, however, unless done with extreme care spreads the metal and renders it necessary to finish the exterior of the shaft after the broaching operation, all of which is slow and very expensive, and when so formed no slot or recess adjacent to the pawl-opening is provided.

In the production of my shaft I follow a method which enables me to expeditiously, economically, and efiectively form a pawlopening through a round shaft Without weakening or distorting the shaft and so as to leave solid metal betweenthe pawl-opening and the end of the shaft and at the same time provide an oil-recess adjacent to the pawl-opening. This I accomplish by first forming a slot or opening, preferably by milling into one side of the shaft toward its axis, and then punching out a pawl-opening from the bottom of said slot to the other side of the shaft.

The necessity of first forming an opening in the surface of the shaft by milling or otherwise prior to the punching operation will be seen in the fact that it is a mechanical impos sibility to punch an accurate opening through a round shaft of metal without first forming a recess upon one side, as it is found in practice that the punch will creep if first applied to the round surface of the shaft, and the shaft 'erenee in curved lines.

is liable to turn slightly in its seat, so that the punched opening will not be formed with the accuracyrequired for the mechanical construction before referred to.

The mechanical appliances employed by me to carry out this method, and as at present believed by me to be the best, comprises a suitable fixture, a mill to cut the longitudinal slot in the surface of the shaft, and a suitable punch and die to punch out the pawl-opening from the bottom of the slot to the other side of the shaft. I am thus enabled to provide a shaft made of a fine quality of bright cold-rolled material of the diameter of the finished shaft,

thus preserving the hard outer shell or skin on such material, which being the hardestpart will wear longer than if this outer skin should be destroyed. It has also been found difficult in prior constructions to properly lubricate the operative parts mounted on the shaft, and in some instances the manufacturers have formed oil-openings in the side of the traction-Wheel for the introduction of oil to provide for proper lubrication, and as the pinion is wholly inclosed this method of lubrication is difficult, and hence proper lubrication is often neglected, thus, of course, lessening the life of such bearing and lessening the life of the machine and seriously interfering with its efficiency. A multiplicity of openings for the introduction of oil is always objectionable, especially in a machine constantly exposed to sand and dust, as the danger of the entrance of grit to the bearings is increased as the number of oil-openings is increased.

In my pawl-and-ratchet mechanism as applied to a lawn-mower the shaft is provided with a pawl-receiving opening, the preferred shape of said opening being that illustrated in Fig. 1 of the drawings and comprising a slot or opening parallel with the axis of the shaft and a pawl-receiving opening extending laterally through said shaft from the bottom of said first-mentioned recessto the other side of the shaft, these openings being formed in the manner before described. The pawl is mounted and operates in the pawl-opening. The end portions of the pawl engage the internal ratchet-teeth on the pinion. The pinion g is rotatably mounted on the shaft and is provided with internally-arranged ratchetteeth adapted to engage the pawl. The pinion by preference has bearings upon both sides of the pawl-opening, and the external teeth of the pinion engage the internal teeth of the traction-wheel it in the well known man ner. The bottom of the slot or opening 0 pitches toward the lateral opening Z) by pref- The opening for the introduction of lubricant is so located that oil inserted therein will be carried to a point where the same will enter the slotted recess 0, and thus lubricate the pawl and also the bearings located in proximity to said slot, so

that while the slot 0 serves a useful purpose in the production of the shaft, as before described, it also serves as an oil reservoir and conduit.

I find in practice that if the slot or recess 0 be filled with a heavy lubricant it will be sufficient in some instances to oil the pawl-andratchet mechanism and the pinion-bearing and bearing 6 during an entire season. In some instances, especially where a light oil is employed, I fill the opening '5 at each side of the pawl with tow, felt, or other absorbent and saturate this with oil, so that the oil will be gradually given off, and it will be observed that the construction is such that all said parts will be lubricated from this fountain-head and that a single opening for the introduction of lubricant serves to conduct oil indirectly to all the working parts.

While the preferred form of pawl-opening is substantially rectangular in cross-section, it will readily be seen that the exact shape is not material. The better shape, however, is substantially as shown in Fig. 2, thus giving a large bearing-surface in the shaft and large engaging surface for the end portions of the pawl with the ratchet-teeth of the pinion and taking from the shaft a minimum of material in the direction of its diameter, so that its strength is not seriously impaired, and by forming the pawl-opening longer in the direction parallel with the shaftapawlof sufficient strength may be inserted to stand the requisite strain and wear, and while the parts are easily supplied with lubricant and are automatically oiled from the oil-reservoir the shaft is solid between the pawl-opening and the end.

In prior constructions the ratchet-teeth on' the pinion have been located on the inner end of the pinion, and the twisting strain resulting from the engagement of the pawl with the ratchet-teeth tends to produce unequal wear of the bearing, and therefore a long bearingof the pinion on the shaft is desirable, as it adds to thelife of the bearing, and hence to the life of the machine, and a double bearing-@'. 0., a bearing at both sides of the engaging pawlserves tog give a more uniform wear and is easier to operate, but more diflicult to lubricate unless my construction be employed.

While, as before stated, I consider a pawlopening substantially rectangular in crosssection the better, it will readily be observed that if the walls either at the sides or ends are curved more or less such change in shape will not be a departure from my invention.

Having therefore described my invention, what I claim, and desire to secure by Letters Patent, is-

1. A shaft for lawn-mowers and other like mechanisms having a longitudinally-disposed slot in one side thereof, said slot being deeper in the central portion than at the sides thereof, and a pawl-opening extending from the deepest portion of said slot laterally through the shaft to the other side.

2. Apawl-and-ratchet mechanism, comprising a shaft havinga substantially rectangular pawl-opening arranged laterally in the shaft and a slotted recess in one side of and parallel with the shaft and opening into said pawl opening, and extending at both sides thereof, the bottom being inclined upwardly from the pawl-opening, a pawl mounted in the pawl-opening and a pinion having internal ratchet-teeth mounted on the shaft in position for the pawl to engage said teeth.

3. The combination of a shaft having a laterally-arranged pawl-opening, a slot in the side of the shaft extending both sides of said opening and constituting an oil-chamber in the side of the shaft opening into said pawlopening, a pawl in said pawl-opening and a pinion having internal ratchet-teeth mounted on the shaft, and having bearings on the shaft on both sides of the pawl.

4:- In a lawn-mower, a shaft, a frame in which the shaft is rotatably supported in suitable bearings, the shaft having a longitudinally-disposed slot extending from within the shaft-bearing in the frame to a point outside said bearing toward the end of the shaft, and having a pawlopening extending from the bottom of the longitudinal slot through the shaft; a pinion having internal ratchet-teeth, and a pawl in said pawl-opening, said pinion and shaft bearing in the frame substantially inclosing said longitudinal slot in the shaft.

ADELBERT B. CASE.

IVitn esses:

W M. H. CHAPIN, K. I. ()LnMoNs.

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