US1733098A

US1733098A - Centerless grinding machine

Info

Publication number: US1733098A
Authority: US
Publication date: 1929-10-22
Anticipated expiration: 1946-10-22

Description

Oct. 22, 1929. F, KERN 1,733,098

CENTERLESS GRINDING MACHINE Original Filed May 5. 1926 2 Sheets-Sheet l gvmwntot Fred M. Kern Oct. 22, 1929. F. M. KERN CENTERLESS GRINDING MACHINE Original Filed May 1926 2 Sheets-Sheet 2 Patented Oct. 22, 1929 UNITED STATES 1,733,,ll9ll PTENT FFlQlil FRED M. KERN, OF DE'IRQIT, IvIICHEGAN, ASSIGNOR, BY IEESNE ASSIGNYMENTS, T9 CIN- CINNATI GRINDER-S INCORPORATED, OF OZNCINNATI, fill-IEO, A CORPORATION OF OHIO CENTERLESS GRINDING MACHINE Application filed May 5, 1926, Serial No. 106,959.

This invention relates to grinding machines and more particularly to machines wherein work of round section is respectively ground and rotated by a rapidly rotated grinding wheel and a slowly rotated work regulating wheel.

One oi the objects of this invention is to provide a grinding machine of the abovementioned character that will be of thoroughly practical and rugged construction and that will be capable of dependable operation and efi'icient action in practical use. Another object is to provide a grinding machine having opposed grinding and regulating Wheels in which one or" the wheels is mounted and controlled with respect to the other in a manner will adapted to meet certain conditions met with in practice. Another object is to provide a pivoted mounting for one of the wheels in. a grinding machine of the above mentioned character that will be of inexpensive con struction, capable of rapid and ellicient control, and capable of achieving many thoroughly practical advantages. Another object is to provide a wheel mounting of the above-mentioned character that will be yielding and in which effective and reliable control of the yielding character of the mounting may be achieved. More particularly, another object of this invention is to provide a mounting of the above-mentioned character for the regulating wheel and to provide, also, for ease and reliability of control of the relation of the regulating Wheel to the grinding wheel. Another object is to provide a mounting for the regulating wheel in a grinder of the abovementioned character that will permit such a universal movement or control of the regulating wheel that certain peculiar classes of Work may be rapidly and ellicicntly ground.

As conducive to a clearer understanding oi certain of the more specific features of my invention, it may at this point be noted that it is often desirable to clean up or put a finish upon thin hollow bodies of substantially cylindrical shape, or solid or hollow bodies which are slightly out of round or slightly tapered but which are intended to be substantially cylindrical. It is not particularly Renewed January 9, 1929.

feasible, and often is impractica le, to attempt to clean up such bodies by grinding in the ordinary grinding machine because, it the body is irregular in shape by being slightly out of round or slightly tapered, too much stock mightbe removed from one end or from one side on account of the tendency of the machine to grind the body to a cylindrical form. in such an operation, if the body to be cleaned up were of a thin walled construction, one side of the wall might be ground too thin, or even ground completely through in certain spots. This, obviously, would be objectionable in bodies which were to be used for purposes requiring considerable strength or which were to be subjected to considerable pressure. It has been customary, heretofore, to clean up such bodies by hand so that they might be preserved by lacquering or the like.

It is, therefor another object of the present invention to provide a grinding machine adapted to clean up a non-symmetrical piece oi work without taking an excessive depth of cut at any point upon the work piece, and particularly a work piece of substantially cylindrical shape which is slightly out oi round or slightly smaller at one end than at the other.

Another obj set is to provide a grinding nia chine having a grinding wheel and regu. .t ing wheel that will be well adapted to meet certain varying conditions of hard practical use. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists features of construction, combinations t elements, and arrangements of parts ill be exemplified in the structure to be hereinafter described and the scope of the application 01"- which will be indicated in the following claims.

In the accompanying drawings, in which is shown one of various possible embodiments of my invention,

. Fig. l is an isometric view ot a machine en1- bodying the invention;

Fig. 2 is a plan view of the mounting for one of the wheels; and

n the Fig. 3 is an elevational view taken along; preferably provide for this purpose a roll 40 the line 3-3 of Fig. 2.

Similar reference cha actors refer to similar parts throughout the sever: l views t the drawings.

Referring now to the drawings and more particularly to Figure 1, there is shown a main frame or base suitabl upper left hand portion, as vie Vi i 1 to rotatably support the spind e 11 upon which mounted a grinding wheel 12. iue spindle 11. is provided with a pulley 11 by miaus of which, throiurh a belt 13, for c1;- ample, the spindle 11 and the grinding wheel 12 may be driven from a suitable source Ma. power to give the grinding wheel. 12 a speel si'iitable for grinding.

In order that the work and grinding wheel may be moved relatively so that the grinding wheel may come in contact with all points on the surface of the work and thereby c can the work satisfactorily, 1 provide an arrrni g'eiuent for n'loving one of. tee whee-s toward and away from the other so as to press agra inst the work and bring the work into grinding); contact with the grinding wheel in such a man nor that a substantially uniform dep; may be taken upon all point the work. A satisfactory animate-n 1. this purpose is indicated in the nu trated in the drawings wherein the vork refrulating wheel 15 is secured upon a spindle 1o mounted for rotation in s-iuitable hearings (not shown) each contained within a b i 1mg casing 17 mounted on a frame 18 (.l' 3). One end of the frame 18 secured to a sh: ft 19 held for rotary movement within a bearing 20 integral with a. plate 21, so that frame 18 may swing about the axis of shaft 19 and the other end is acted upon by means including a weight 22 (Fig. 1) adjustably mounted near one end of a lever arm 21-1 eecured upon a shaft 24 which is mounted for rotation in the trame of the in chine. it link 25 is pivotally secured at one end to the lever arm 23 and at the other end to a lug- 2f integral with the frame 18. The action of the weight 22 is to tend to swing; the frame 18, and hence the regulating); wheel 15, in a direction about the pivot shaft 19, ton. d the grinding wheel 12. The plate 21 is mounted upon a slide to turn about a pivot shaft 31 (see l i 'ure :2), and is provided with rollers 32 igure 3) adapted to travel in a passage 33 between the slide 230 and the L-shaped stop plate 34 seemed to the slide 2-10 by means of screws 35. The slide 3i) may be moved alongapprogn'iate slideways mounted on the frame of the machine by turn ine; a hand wheel 87 secured upon a. screw shaft 38 passing; through a nut 39 in the frame.

The work W may be maiutainm'l l etween the wheels for operating; thereon in any suitable manner. In the machine illustrated, 1

C1 in (Figure 23) mounted upon a shaft 41 for rotation in a pair of lugs 12 on bracket 4:3, which lQSLS upon. the plate 21 and the slide 80 and is secured to the latter by means of bolts a l. The regulating wheel 15 is brought in contact with the work 1V, to push the latter into rotative contact with the grinding wheel, by means of spring pressed plungers 15 each adapted to move in a sleeve-like pertien 46 in the frame 18 and rest upon a support at? on the plate 21. (inc end of each p ringer is reduced in diameter to pass rough a l earing' plug 19 which is threaded to one end of sleeve 4:6 and which is proced with a hexagonal projection 50 so that ti e plug may he turned for the purpose of adjusting the compressimi of a sprin 51 surri'iuudingi; each reduced portion of the plungers 415 and engaging the bottom of the plug 419. The spring 51 tends to press the plungers downwardl and out of the sleeves 46 and "the work regulating wheel 15 (about the an of :eiatt 19) towards the grinding wheel. The extent of this movement is limited by the provision of stop nuts 56 adjustably mounted upon the upper threaded end on the plungers d5.

:1 ac .zu'dauce with certain features of my areutiou the movable wheel may be moved it a suitable speed, prefe 'ably by the operz r, away from the other wheel so to per removal of the ground work and the insertion of new work. As illustrated, 1 provide a suitable mechanism for so moving the regulating wheel. This mecl anism n ay include a foot lever 50 1) pivotally securet. upon a shaft 61 mounted in the frame of the machin A link 62 is secured at one end to the lever (30 and at the other end to a crank arm (33 keyed upon .he shaft As already above noted, the link 25 (Figs. 1 and 3) is pivotally connected, at 26, to the auxilia ry frame 18 and at its other e id is pivotally connected. to one end of the lever arm 23 (Fig. 1) which is secured upon the shaft 24:. Iii moment of the foot t 'eadle 60, in response to trot pressure exerted thereon swings the shaitt 21: in clockwise direction, viewed in Fin: 1

n 1, thus pulling link 25 downwardly and thus swinging auxiliary frame 18 and the regulating wneel 15 (hi 8) in clockwise direction about the pivot 19. hlovement of the tlfrau'ie 15: in the above-inentioned direction about its pivot 19 moves the regulatin wheel 15 a my from the grinding wheel 12. This movement of the reggula Eng wheel 15 in a directiou away from the grinding wheel 12 takes place in opposition to the action of the springs 51 and of the weight 22. In order to hold the work il upon the roll d0 when the wheels are separated a blade 65 is mounted upon a bracket 66 integral with the plate 21. The blade 65, as will be clear from Figure is preferably of suflicient extent lengthwise of the grinding throat to dependably hold the work W on the work supporting roll 40 when the wheels are separated.

Suitable flexibility in the connections for supplying power to the movable wheel may be provided by an arrangement such as a slot (Figs. 1 and 2) in one end of the spindle 16 for slidably mounting a pin '71 secured upon the shaft 72. The shaft 72 may be rotated from any suitable source of power, but in the machine illustrated it is connected with the spindle 11 by means of the belt 74, vertical shaft 75, and associated parts. Thus, the belt 7% passes over a pulley (not shown) on the spindle 11 and under a pulley 76 on the shaft 77 of a pump 78 to a pulley (not shown) on a shaft 79 rotatably mounted in the frame 10 of the machine. Suitable gear mechanisms are provided within the

casings

80 and 81 for transmitting power from the shaft 79 to the

shafts

72 and 75. An idler pulley 82 is secured upon a shaft 83 in the casing of the pump 78 to press against the belt 7 1. An idler pulley 85 is mounted in a frame 86 pivotally mounted at the end of brackets 87 integral with the casing of the pump 78 and may be adjusted toward or away from the belt 74 by means of an adjusting screw 88 in the frame 86 adapted to engage astop (not shown) on the arm 87. A suitable grinding liquid may be supplied from a pipe 89 and directed upon the work W as desired.

operation, the grinding wheel 12 and the work regulating wheel 15 are rotated at rates suitable for respective grinding and rotating the work positioned therebetween by power supplied thereto through the belt 13 and associated parts. The regulating wheel 15 may be adjusted, by turning the hand wheel 37, to an appropriate position depending upon the size of the work "W. The operator then pushes upon the lever or pedal 60 which causes the frame 18 to swing in clockwise direction, as seen in Figure 3, and hence to cause the wheel 15 to move away from the grinding wheel so that a work piece V7 may be placed between the roll 40 and the blade 65. The operator then releases the lever 60, and the wheel 15 automatically returns to its original position, by the acion of weight 22 and springs 51, thus moving the work Va away from the blade 65 and into rotative contact with the grinding wheel 12 and regulating wheel 15. The regulating wheel 15 will then press against the work, due to the action of the springs 51 and the weight 22, so as to bring all points in the surface of the work into contact with the grinding wheel in substantially the same manner, and thereby cause a depth of cut to be taken upon the work of substantially the same amount all over its surface. If the work ll] is larger at one end than at the other, the regulating wheel mounting will turn about the pivot shaft 31 to bring the surface of the work entirely in contact with the grinding wheel 12. On the other hand, if the work is slightly out of round, the regulating wheel will move towards or away from the grinding wheel by turning about the pivot shaft 19 as required by the character of the work. In this manner the work piece may be cleaned up satisfactorily without danger of taking too much stock off its surface so that it may be used safely for purposes requiring considerable strength or resistance to internal or external pressure.

It may further be noted that the worn support-ing member 40, being mounted upon the carriage or plate member 21 partakes of the same movements, about the vertical axis of the pivot shaft 31, as does the regulatin wheel 15, so that effective supporting of the work l/V and dependable maintenance of rotating contact of the work W with the regulating wheel 15, during the grinding operation on the work W by the grinding wheel 12, are achieved. It will also be seen that the springs 51 dependably act to urge the regulating wheel 15 in a direction toward the grinding wheel 12 and that the range of action of the springs 51 may be dependably controlled or limited, as by the stop nuts 56 (Fig. 3). The weight 22 (Fig. 1) is, as above pointed out, adjustably mounted on the lever arm 23 and may be adjustably positioned to vary the action of the springs 51 to any desired extent, it being noted that the nearer toward the shaft 24L (Fig. 1) that the weight 22 is moved along the lever 23, the less does it contribute toward the yield ing action of the springs 51.

l/Vhen the grinding operation is completed, the operator steps upon the foot treadle 60, thus moving the regulating wheel 15, against the action of springs 51, in a direction away from the grinding wheel 12, whence the work piece W may be removed and replaced by a new work piece. Movement of the regulating wheel 15 in a direction away from the grinding wheel 12, due to the relation of the work supporting roll 40 to the two wheels, causes the work W to move in a direction away from the grinding wheel, preventing marring of the finished work piece by the grinding wheel. The blade 65 acts, as above noted, to hold the work piece W on the work supporting roll 40 when the wheels are separated.

It will thus be seen that there has been provided in this invention a grinding apparatus in which the several objects hereinabove noted, as well as many thoroughly practical advantages, are successfully achieved.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A grinding machine comprising a grinding wheel, means for rotating the grinding wheel rapidly to grind the work, and means to support a piece of work rota tively in contact with the wheel which permits free relative movement between the grinding wheel and work angularly and laterally of their axes whereby work having an uneven or non-symmetrical surface may be ground.

2. A grinding machine comprising a rapidly rotated grinding wheel and a slowly rotated work regulating wheel, means for i'i'iaintaining a non-symmetrical work piece between the wheels, and means for mounting one of the wheels so as to move freely towards and from the other wheel as well as angularly, as required by the shape of the work to be ground to press the work into rotative contact with the grinding wheel.

3. A grinding machine comprising a rapidly rotated grinding wheel and a slowly rotated work regulating wheel, means for n'iaintaining a work piece between the wheels, and a movable mounting for one of the wheels adapted. to move about a pair of distant angularly disposed pivot points so as to permit movement of the wheel toward and away from the other wheel and hold the work in rotative contact with the grinding wheel.

i. A grinding machine comprising a rapidly rotated grinding wheel and a slowly rotated work regulating wheel, means for maintaining a work piece between the wheels, and a freely movable mounting for the work regulating wheel constructed and arranged to turn required by the shape of the work about a pair of axes, one substantially parallel and the other substantially perpendicular to the work axis so that the regulating wheel may assume a position such as to press against and bring all points on the surface of the work in rotative contact with the grinding wheel.

5. A grinding machine comprising a grinding wheel and a work regulating wheel, one of which is pivotally mounted to move toward and away from the other, means for rotating the grinding wheel rapidly and the work regulating wheel slowly to respectively grind and rotate the work, means for maintaining a work piece between the wheels, and a manually controlled device for moving the mounting for said movable wheel to withdra it and permit the removal and insertion of work between the wheels.

6. A grinning machine comprising a grindin wheel. and a work regulating wheel, one of which is pivotally mounted to move toward and away from the other, means for rotating the wheel rapidly and the work regulating wheel slowly to respectively grind and rotate the work, means for maintaining a work piece between the wheels, a manually controlled derive for moving the mounting for said movable wheel to with draw it and permit the removal of ground work, and means for automatically returning said wheel to its initial position.

7. In grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, and means for rotatably supporting one of said wheels, said last-mew tioncd means including a pair of carriages, one of which is mounted for free oscillation about an axis and the other of which is mounted for free oscillation about an axis and upon the other carriage and is provided with bearing means for rotatably supporting said wheel, one of said axes being substantially parallel to the axis of the work and the other axis being substantially at rightangles to the axis of the work.

8. In grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, and means for rotatably supporting one of said wheels, said last mentioned means including a pair of carriages, one of which is mounted for free oscillation about an axis and the other of which is mounted for free oscillation about an axis and upon the other carriage and is provided with hearing means for rotatably supporting said wheel, one of said axes being substantially parallel to the axis of the work and the other axis being substantially at right angles to the axis of the work, and spring means acting upon one of said carriages.

9. In grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, an auxiliary frame member having bearing means for rotatably supporting said regulating wheel, said auxiliary f'ame member being pivotally mounted upon an axis so to permit said regulating wheel to be moved toward or away from said grinding wheel when said auxiliary frame member is swung about its pivotal support, and mechanism for controlling the movement of said auxiliary frame member about its pivotal support.

10. In grinding apparatus, in combination,

a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative rela ion to said two wheels, an auxiliary frame member having bearing means for rotatably supporting said regulating wheel, said auxiliary frame member being pivot-ally mounted upon an axis so as to permit said regulating wheel to be moved toward or away from said grind ing wheel when sai l auxiliary frame member is swung about its pivotal support, spring means urging said auxiliary frame and regulating wheel supported thereby toward the grinding wneel, thereby to cause the regulating wheel to urge the work toward the grinding wheel, and means for opposing the action. of said spring means and adapted to permit said regulating wheel to be moved away from the grinding wheel, thereby to permit removal and insertion of work between said wheels.

11. In grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substan tially round section in operative relation to said two wheels, an auxiliary carriage mounted to swing about an axis substantially at right angles to the axis of the work, a frame member pivotally supported upon said auxiliary frame and rotatably supporting one of said wheels, said frame member being adapted to oscillate about an axis substantially parallel to the axis of the work and thereby to permit movement of the wheel carried thereby toward or away from the other wheel, and means urging said auxiliary frame member in a direction to urge the wheel carried thereby toward the other wheel.

12. In grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, means mounting one of said wheels to permit it to be moved toward or away from the other, means mounting one of said wheels to permit its active work-engag ing face to be positioned in substantial parallelism with the axis of the work and to be thrown out of parallelism therewith, ant means operative upon said mounting means to urge one of said wheels toward the other and to cause the active portion of the operative face of one of said wheels to aline itself with axially extending irregularities in the surface of the work.

13. In grinding apparatus, in combination, a rinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, means for urging one of said wheels toward the other during the operation of ti apparatus, and means mounting said rating wheel to permit it to swing about an axis substantially at right angles to the axis of the work, thereby to permit the operative surface of said regulating wheel to aline itself with axially extending irregularities in the surface of the work.

14. ln grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substan tially round section in operative relation to said two wheels, means for urging one of said wheels toward the other during the operation of the apparatus, means mounting said regulating wheel to permit it to swing about an axis substantially at right angles to the axis of the v-ork, thereby to permit the operative surface of said regulating wheel to aline itself with axially extending irregularities in the surface of the work, and means for separating said wheels to permit the removal and insertion of work.

15. In grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, means mounting one of said wheels to permit it to be moved toward or away from the other, means mounting one of said wheels to permit its active work-engaging face to be positioned in substantial parallelism with the axis of the work and to be thrown out of parallelism therewith, means .operative upon said mounting means to urge one of said wheels toward the other and to cause the active portion of the operative face of one of said wheels to aline itself with axially extending irregularities in the surface of the work, and means for separating said wheels to permit the insertion or removal of work, said work-holding means being constructed to retain work substantially in operative position even though said wheels are relatively separated.

16. In grinding apparatus, in combination, a main frame, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, a slide carried by said main frame and movable toward or away from the grinding wheel, an auxiliary frame member having bearing means for rotatably supporting said regulating wheel, means pivotally mounting said auxiliary frame member upon said slide to pivot about an iii) axis so as to permit said regulating wheel to be moved toward or away from said grinding wheel. when said auxiliary frame member is moved about its axis, and mechanism including yielding means for controlling the movement of said auxiliary frame about said axis.

17. In grinding apparatus, in combination, a main frame, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a rein tively low speed, means for holding work of substantially round section in operative relation to said two wheels, a slide carried by said main frame and movable to ard or away from the grinding wheel, an auxiliary frame member having bearing means for rotatably supporting said regulating wheel, means pivotally mounting said auxiliary frame member upon said slide to pivot about an axis so as to permit said regulating wheel to be moved toward or away from said grinding; wheel when said auxiliary frame memoer is moved about its axis, means for predetermining the position of said slide relative to said grinding wheel, and means operating upon said auxiliary pivoted frame member (0 swing it about said axis for changing the distance between the grinding wheel and the regulating wheel to permit insertion or removal of a work piece relative to said wheels.

18. in apparatus of the character described, in combination, a grinding wheel rotatable at a inding speed; a work rotating wheel rotated at a speed much slower than said grinding wheel; said wheels forming a grinding throat therebetween and being rotated in respective directions so that the work rotating wheel controls the rotation of a round work piece in said grinding throat; means for holding work of round section in operative relation to said wheels; and means for conditioning said grinding throat for insertion or removal of work, comprising means mounting one of said wheels for oscillation about a pivot in a direction toward or away from the other wheel, and means for shifting the position of the pivot about which said mounting means may oscillate.

if). in apparatus of the character described, in combination, a grinding wheel rotatable at a grinding speed; a work rotating wheel rotated. at a speed much slower than said grinding wheel; said wheels being rotated in respective directions so that the work rotating wheel controls the rotation of work of round section during the grinding operation thereon by the grinding wheel; means for holding work of round section in operative relation to said wheels; means mounting one of said wheels for oscillation about a pivot in a direction toward or away from the other wheel; and means permitting change of the angularity between the axis about which said mounting means may oscillate and the operative face of the other of said wheels.

20. In grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, an auxiliary frame member having bearing means for rotatably supporting said regulating wheel, said auxiliary frame member being pivotally mounted upon an axis so as to permit said regulating wheel to be moved toward or away from said grinding wheel when said auxiliary frame member is swung about its pivotal support, yielding means for yieldingly urging said auxiliary frame nien'ibcr to swing in one direction about said axis, and means for causing said auxiliary frame member to swing in the other direction about said axis.

21. In grinding apparatus, in combination, a grinding wheel adapted to be rotated at a relatively high speed, a regulating wheel adapted to be rotated at a relatively low speed, means for holding work of substantially round section in operative relation to said two wheels, an auxiliary frame member having bearing means for rotatably supporting said regulating wheel, said auxiliary frame member being pivotally mounted upon an axis so as to permit said regulating wheel to be moved toward or away from said grin: ing wheel when said auxiliary frame member is swung about its pivotal support, yielding means for yieldingly urging said auxiliary frame member to swing in one direction about said axis, and means for limiting the range of action of said yielding means.

Signed at Detroit, Michigan, this 29th day of April, 1926.

FRED M. KERN.