US1837390A

US1837390A - Valve seat reconstruction tool

Info

Publication number: US1837390A
Application number: US340771A
Authority: US
Inventors: Frans O Albertson
Original assignee: Albertson and Co Inc
Current assignee: Albertson and Co Inc
Priority date: 1929-02-18
Filing date: 1929-02-18
Publication date: 1931-12-22
Anticipated expiration: 1948-12-22

Description

F. o. ALBERTSON 1,337,390

VALVE SEAT RECONSTRUCTION TOOL I Filed Feb. 18, 1929 2 Sheets-Sheet 1 L/ZI/GIZZZI'.

@WM M 24446.

1931- F. o. ALBERTSON VALVE SEAT RECONSTRUCTION,TO0L

Filed Feb. 18, 1929 2 Sheets-Sheet 2 hen/fir jam 0. alerisam' Patented Dec. 22, 1931 UNITED STATES PATENT OFFICE FRANS O. ALBERT SON, OF SIOUX CITY, IOWA, ASSIGNOR '1O ALBERTSON & COMPANY,

INCL, F SIOUX CITY, IOWA, A CORPORATION OF IOW VALVE SEAT RECONSTRUCTION 'roor.

Application 'filed February 18, 1929. Serial No. 340,771.

The present inventionrelates to valve seat reconstruction tools, and is particularly concerned with tools for refacing or reconstruct ing valves of internal combustion engines.

.5 Thetools of the present invention may be.

used both for refacing the valve seat by means of reamers orother surfacing tools, or they 7 at any other angle to the surface of the'block.

Another object is the provision of improved valve seat reconstruction tools, whereby a valve seatmay be refaced or reconstructed with its aXisin accurate alignment with the axis of a valve guide.

Another object is the provision of an improved method of valve seat reconstruction, in which the alignment and support of the cutting members is accomplished principally by a pilot stem which is accurately and fixedly secured in a valve seat guide.

so Another object is the provision of an improved valve seat reconstruction tool which is adapted to reinforce and support a pllot.

stem in an aligned position, while depending upon said pilot stem to perform the function 3 of alignment.

Another object of the invention is thepro vision of tools of the class described which are more simple, economical and more sturdy than the tools of the prior art.

Another object is the provision of an assembly of valve seat reconstruction tools. which is capable of performing heavy cutting operations without the tool binding in its bearings, and which is capable of operation with a minimum of effort.

Another object is theprovision of a tool of the class described having an improved gauge and feed mechanism capable of feeding the cutter without changing ts :t'tllglk ment. .v

Other objects and advantages of the invene tion will be apparent from the following description and from the accompanying drawings in which similar characters of reference indicate similar parts throughout the several views.

Referring to the drawings, of which there aretwo sheets:

Fig. 1 is a view in perspective of the tool applied to an engine block;

Fig. 2 is a cross-section;

Fig. 3 is a sectional view taken on the plane of the line 33 of Fig. 2;

- Fig. 4 is a sectional view taken on the plane of the line H of Fig. 3;

Fig. 5 is a sectional view taken on the plane of the line 55 of Fig. 3. In the embodiment chosen toillustrate the lnventlon, 20 indicates the valve seat recon struction tool assembly of Fig. 1 in its entire ty. The tool preferably includes a cutter 21, a pilot stem 22, a bearing 23, a tool holder 24, and means for actuating the cutter which may consist of a ratchet lever 25, or other actuating devices. a I The ratchet lever 25"may be of any conventlonal type, and as any type of actuating device may be used, the ratchet lever will not bedescribed in detail.

'Many of the advantages of the invention may be realized without employing all of the elements shown in the complete assembly, and it should be understood that the invention includes the use of the various sub-combinations-and permutations of all of the elements described, wherever such combinations will be advantageous, and the scope of the invention is to be limited only by the terms of the appended claims. i

Referring to Fig. '1, the conventional 'internal combustion engine block 26 is provided with a plurality of valve openings 27 having valve seats 28 formed therein, and witha plu-' rality of stud bolts 29 for securing the motor head to the. block. The valve seat tool assembly 20 is illustrated in the operation-of reconstructing a valve seat 28 by cutting arecess adapted to receive a metal member forming anew valve seat.

plan viewof thetool in partial The valve seat tool is preferably provided with a pilot stem 22 of the type illustrated in the prior application of Frans O. Albertson, Serial No. 310,600, filed October 5, 1928, which is peculiarly adapted to accurately center itself axially of any Valve stem guide such as the guide 30, and adapted to be fixedly mounted in the valve guide 30 by expanding the parts 31 of a tripartite end.

The pilot stem 22 is provided with a frustoconical portion 32 spaced from the end 31 and adapted to engage the inner and upper edge of the cylindrical valve guide 30, automatically centering the pilot stem at this point. The lower end of the pilot stem 22 is split three ways as at 33, forming three split portions 31 of equal thickness and adapted to be cammed apart by a camming member 34, which extends longitudinally of the pilot stem in the bore 35. The camming member 34 is provided with threads 36 adjacent its upper end adapted to be received in complementary threads carried by the bore 35 and the camming member is provided with a noncircular head 37.

The functions of such a pilot stem are fully set forth in the application above mentioned, so that it will suffice to say that since three points determine the location of a circle, the tripartite end is peculiarly adapted to accurately center the lower end of the pilot stem. 22 axially of the valve guide 30 in a manner which cannot be accomplished by any pilot stem not constructed according to the present invention. As the p1lot stem is already centered at the point 38 of the valve guide 30 by the cone 32, it will be observed that the pilot stem is accurately located with its axis coinciding with the axis of the valve guide 30, and the pilot stem is thus adapted to accurately support a cutter 21, or other resurfacing tool, so that it may form a valve seat having its axis accurately located in the axis of the valve guide.

The pilot stem 22 is also peculiarly adapted to have the camming member 34 placed in a state of compression with the pilot stem 22 in a state of tension, so that the pilot stem becomes extremely stiff when located within a valve guide 30, as shown in Fig. 3.

It will thus be observed that the pilot stein ofthe present invention is peculiarly adapted to be accurately centered and fixedly secured axially within a valve guide 30, so that the pilot stem may guide a cutter or surfacing tool for accurately forming or resur; facing a valve seat 28. As the valve seats 20' are surfaces of revolution, it is of the utmost importance that the seats be formed with their axes accurately located in the axis of the valve stem guide, so that the valves will seat equally at every point upon the seat.

It should be noted that in the present invention the pilot stem 22 is adapted to perform the function of alignment, support and guidance of the cutter 21 upon the tool holder 24, as distinguished from devices in which the pilot stem is merely employed for determining the approximate axial position of the cutter, and it should also be noted that the present method of operation is capable of mathematical accuracy as distinguished from the methods in which a pilot stem is loosely rotated until it assumes the most free position. The latter method merely locates a pilot stem in the approximate axial position, and the accuracy of the latter method depends upon the play between the pilot stem and a worn valve guide.

Above the cone 32 the pilot stem 22 is provided with an elongated cylindrical portion 39, which is accurately machined to lit within an elongated and accurately cylindrical bore 40 in the tool holder 24. By means of the complementary elongated cylindrical sur faces 39 and 40, the tool holder 24 is accurately located axially of the valve guide 30 and supported for rotation and reciprocation upon the pilot stem 22.

At its upper end the pilot stem 22 may be provided with flattened portions 41 for engagement with a wrench in manipulation of the pilot stem, and the bore 40 is of sufficient length so that it is adapted to receive the pilot stem and the head 37 of the camming member in any position to which the tool holder may be fed when used on modern internal combustion engines.

The cutter 21, which has been chosen to illustrate one embodiment of the invention, is of the type employed for cutting a recess in an engine block for the insertion of a new valve seat, and the cutter may comprise a substantially cylindrical metal body 42 made of tempered tool steel and provided with a centrally located frusto-conical aperture 43, which is tapered to form a close frictional fit with the tapered or frusto-conical portion 44 of the tool holder 24.

The cutter body 42 is provided with a slot 45, the walls of which clamp a blade 4'7 of tool steel and the blade 47 is provided with

cutting edges

48 and 56 at substantially right angles to each other and adapted to cut an annular recess 121 of substantially rectangular cross-section adapted to receive a new valve ring driven into close frictional fit with the walls of said recess.

The cutter and ring may be of the type described in detail in the co-pending application of Frans O. Albertson, filed February 18, 1929, Serial No. 340,770, and as the present tool may be used either with such a cutter or with reamers or other resurfacing tools, the cutting tool will not. be described in detail.

In order to provide means for forcibly feeding a cutter or surfacing tool against the work or valve seat, the complete tool assembly preferably includes a body member 61, which is adapted to be secured to the enginei block: 26;. preferably: by meanso the stud bolts 29 with which the engine block bear upon the upper end of: the tool holder are resisted by the bearing'23 of the body member 61, and so, that the bearing 23 may react against the body 61 to force the cutter into engagement with the work. p

In order that the valve seat tool may be used upon all types of engines, including those in whichithe valve guide 30 is not disposedi at rightanglesito the upper surfacetof the engine block 26', the tool is provided with i a bearing portion 72 having a pivotal connection 19 with thebody 61, and the bearing 1301110117215 adapted to be rotated on an axis transverse to the axis of the bearing 23 to bring the bearing 23 into approximate alignment with any valve guide '30 disposed at an angle to the face of the engine block 26.

The body member 61 may comprise an elon gated cast metal member having one or more lower flatsurfaces 18 for flatlyengaging the upper face of the engine block 26. In the present embodiment, the flat surfaces 18 are formed longitudinallyof the body 61 ad a-i centthe sidesthereof, so as to increase the stability of the body member 61 when secured.

* to a flat engine block. The body 61 is also providedwith anupper'flat. surface 17 which is adapted to be engaged by aclamping member 16 for securing the body 61 to the engine block.

The clamping member I s16 compr ses an elongated cast metal body provided with flat. surfaces 14 on its lower side adjacent eachend for engaging the body 61 and a spacingmember 15', and the clamping member is also'provided with. an elongated slot 13' adapted to receive a stud bolt 29 in anyof: a' plurality of different positions. The clamping member 16 may be provided witha pair of

walls

11 and 12 extending upward at substantlally right angles to the'flat surfaces 1 1 and having upper. flat surfaces 10 for engaging beneath a washer 9 carried by stud bolt 29, and. the

walls

11 and 12 maybe tapered in height from each end toward the middle .of the clamping member to increase the. strength and tobring-the height of'the' complete assembly to a point most convenient to be clampedby the conventional stud bolt on the engine bloek. c g

The spacing.- member: 1 5 merely comprises:

a flat bar ofmetal preferably tool steel have ingv plane sides and adapted to be used inqa plurality ofdifferent positions with the cla-mpmgmember 16 for clampingthe body to an engine block. The unequal dimensions of the spacing member 15 make it adaptable for providing a spacing member of different thicknessfor different assemblies. 7

Referring to Fig. 1, the assembly of the tool and engine block in this figure is exemplary of the mode in which the tool body may be clamped to the engine block. The body 61 is disposed on one side of a stud bolt 29-with the flat surfaces 18 engaging the upper flat. surfaces of theblock, and the spacing meme ber 15 is disposed on the opposite sideof stud bolt 29' relative'to body 61. The clamping member 16 may and the washer and nut7 5 are placed upon stud bolt 29 and the clamping member 16".

forced into firm engagement with the top of the spacing member and the on top of the body 61. r

The body of the tool may thus be clamped in any of a plurality of different positions uponthe engine block and the tool is of uni versal application being capable of use in any commercial internal combustion engine; In some embodiments the upper flat. surface 17 may be eliminated since the position of the tool body is determined by the engagement of its bottom with the engine block. The tool body is also preferably long enough to extend over any ordinary cylinder bore, so that it may be'used in positions where the tool must lie acrossthe bore of the cylinder.

The body 61 is preferably provided with an elongated bore 50 which may be accurately machined at 51 and counterbored at-52 to formbearings'for a shaft or bolt 53, and pro vided with slots 54 adjacent one end for slidably receivinga pin 55 carried by bolt 53. The pin 55 may be secured by frictional engagement within a transverse bore 57 inbolt '53. i

V The belt 53is provided with an enlarged cylindrical portion 122 adapted to be reed to receive cylindrical portion 122 of bolt 53. Flange 126 may also beprovided with counterbore 128 for receiving the head 123 of bolt. 53, and the

upper surfaces

129 and 130 of the flanges 124; and 126'are cylindrical be placed over stud bolt 29 fiat surface 17 the bearing surfaces, formed with the center of bolt 53 as an axis. The

surfaces

129 and 130 may be marked. with scale divisions 131 and indicia 132 to indicate the relative positions of the body member 61" and bearingi 23, the indioia for accurately locating the bore 23 in vertical "position.

The flange 126 is also provided with a fiat surface 133 adapted to abut against the flat surface 125 and the bearing portion 72 may be clamped in any adjusted angular position by tightening the nut 134 on bolt 53. The parts are permanently secured together, however, by providing the pin 55, which prevents the bolt 53 from being removed from body 61, and which permits the ho t to slide relative to the body, but prevents rotation so that it is unnecessary to hold bolt 53 when wrench is applied to nut 134.

In order to forcibly cause the cutter 21 to progress into the work, the tool is preferably provided with'a feeding member 76 for supporting the bearing 23, and the bearing portion 72 of the body is provided with a vertically extending bore 77 internally threaded to receive the externally threaded portion 78 of the feeding member 76. The feeding member 76 comprises an annular metal member having a substantially cylindrical portion 7 9 provided with relatively fine external threads 7 8 and having an axially and contrally located bore 80 of substantially larger size than the size of the bearing member 60, providing considerable play at 81 between these members.

At its upper end, the feeding member 76 is substantially increased in diameter, having an enlarged cylindrical surface 82, which is knurled to facilitate a bett or grip with the hand of the operator or with tools, and forming an annular shoulder 83 for use in gauging the depth to which a recess is to be cut in an engine block.

The enlarged portion 82 of the feeding member 76 is provided with counterbore 84 adapted to receive the outer raceway 85 of a bearing 23, and the upper edge of the feeding member 76 is made relatively thin as at 86, so that the edge 86 may be turned over, as shown in Fig. 3, to retain the parts of the bearing 23 in an assembled relation.

The inner bearing member 60 comprises a substantially cylindrical member, substantially smaller than the bore 80 of the feeding member, leaving sufficient clearance for a limited universal movement between the feeding member 76, and the inner bearing member 60 is provided with a reduced cylindrical portion 87, forming an annular shoulder 88 for definitely limiting the position of the inner race member 89. The inner race member 89 comprises an annular tempered steel mem ber having a pair of

circular grooves

90 and 91 formed in its outer surface and having a centrally located bore 92 adapted to receive the reduced portion 87 of the inner bearing member with a forced frictional fit.

A sheet metal washer 93 may be confined between the inner race 89 and the shoulder 88 for closing the upper end of the annular space or clearance 81. The ball bearings 94 are assembled in the

grooves

90 and 91, and supported in staggered relation to each other by a ball ring 95, and the outer race 85 is provided with a single concave groove 96 of circular cross-section, which is adapted to perniit a universal movement between the outer race 85 and the inner race 89, the ball bearings 94 moving with the inner race 89.

The counterbore 84 may be provided with a flexible fabric washer 97, after which the inner bearing member 60, inner race 89, balls 94 and outer race 85 may be placed in counterbore 84. A second flexible fabric washer 98 may be placed above the bearing, after which a plurality of spring washers 99 may be placed about the reduced portion 87. A sheet metal washer 100 may then be placed above the spring washers 99 and secured in place by riveting over the upper end 101 of the reduced portion 87.

The bearing assembly may be retained within the feed member 7 6 by a dished sheet metal member 102, having an enlarged bore 103, and having its outer edge 104 secured between the race 85 and the turned over edge 86 of the feed member 76. The dished portion of the dished member 102 is adapted to provide space for the spring washers 99, and it should also be noted that the metal washer 100 is of smaller size than the dished portion of the member 102, so as to permit the washer 100 to slide about in the dished member 102 when pivotal or universal movement takes place between the feeding member 76 and the inner bearing member 60.

The inner bearing member 60 is provided with an accurately machined, centrally and axially located bore 107, adapted to slidably and rotatably receive the cylindrical outer surface 108 of the tool holder 24. The upper end of the tool holder 24 may be provided with a transverse bore 109 for receiving hand levers or rods used in oscillating the tool holder 24 and with a non-circular end or head 110 adapted to receive the ratchet lever 25.

It will thus be observed that the bearing member 23 is adapted to rotatably support the tool holder 24 and cutter 21 upon an axis which is determined by the position of the pilot stem 22, and the inner bearing member 60 is adapted to pivot universally to permit the tool holder 24 to assume the position determined by the pilot stem. The universal movement of the bearing member 60 also permits its lower edge 69 to engage flatly on the upper surface 58 of the cutter body 42 to force the cutter into engagement with the work.

The bearing 23 constitutes an anti-friction thrust hearing which is adapted to permit limited universal movement, so that the feeding member 7 6 will provide a substantially axial feeding force upon, the cutter 21 at all times. The cutter may be fed intowthe. valve seat by rotating the feeding member in a clockwise direction in Fig. 1, causing the inmibearing member '60. to progress axially of the pilot stem 22. When the feeding-.mems ber 7 6 is thus actuated,iand the cutter 21 is employed for resurfacing or cutting a recess, the force which is brought to bear upon the cutter 21- may be increased as desired although the amount of friction-which would,

be present in an ordinary bearing'would be such as to require a large. proportion of the effort for merely overcoming the friction of the bearing asdistinguished from acutting operation. With the present construction, however, the cutter 21 may be fed quite rapidly into the engine block and the out ac complished with .ease; thereby, greatly decreasing the amount of time and labor consumed in reconstructing a valve. 7

Furthermore, it should be' observed that the universal anti-friction bearing is peculiarly adapted to permit thepilot stem to perform the aligning function conforming tothe position of the valve guide, and incidentally the bearing 23 is adapted to resist lateral forces applied to the head 110 of tool holder 24: by ratchet lever 25, which forces might otherwise tend to bend a relatively slender pilot stem- The bearing portion 72 of the body member 61'i's 'prefera'b'lyprovided with a bore 111 extending substantially parallel to. the bore 77 and adapted to slidably receive apin 112 having a head 113. The bearing portion 72 is also provided with a threaded bore 114 extending transverselyto the bore 111 and communicating therewith, and the bore 114;. is adapted to slidably receive the cylindrical end 115 of the threaded bolt .116. The bolt'116 is provided with'a transverse bore 117 adapted to register with the bore 111 and adapted to receivepin 112, and a spring washer 118 and a wmgnut119 are provided, securing the bolt 116.

When the parts are in the position: of i Fig. 3, and the wing nut 119'is threaded ina clockwise direction 'onqbolt 116, .the'bolt 1 16 is drawnout of its bore 114, clampingagainst the pin 112, and securing the p1n-1 12 many adjusted position. The pin 112'w1th1ts-securing means comprises an ad ustable gauge .for determining theamount offeed required to make a predetermineddepth of cut.

The present valve seat tool may be em ployed with roughing reamers or other surfacing tools for accurately resurfacing valve seats and theoperation of resurfacingavalve seat ened by the use of the, present tool. The feeding devicei's adapted to permit a heavy force to be brought to bear upon the roughlng reamer, so that theoperation may berdone is greatly simplified and thelabor lessk in a small portion of the time otherwisenecessary, and the universal bearing provided is adapted to permit the feeding operation without disturbing the alignment determined .bythe pilot stem fixed in the valve guide j 7 It will thus be observed that the present device is adapted toeifect a rapid audaccurate resurfacing of valves with a minimum of effort. Y I 1 I 3 The device may also be employed for entirely removing the metal-surface ofan old valve seat, forming a recessadapted to receive a newmetal ring for forming a new valve seat. 1 i

The mode of operation of the valve seat tool is as follows: The pilotstem 22 may be inserted in the valve guide. 30 and given a slight tap with'a hammer to seat the-cone '32 in the guide 30 and center the pilot stem at cone 32. A wrench or other tool may then 5 be applied to the head 37 of the camming member and by turning in a clockwise dire c'tion the ramming member will "force the tripartite end 31 apart, engaging the valve guide 30 and accurately centering the lower end of the pilot stem. The pilot stem 22 is "holder being sli'da-bly and rotatably received .on the pilot; stem. Since the pilot stem is.

' located with its axis in theaxis of the valve guide 30, any surface or recess formed by T the cutter21 will haveqits axis accurately located in the axis of the valve guide 30, and the valve can be seated upon such a surface with equa'lsealing effect at all points.

'61 and the bearing portion 72: may be set The nut 134 may then be-loosene'd on body atany predetermined angu'larityrelative to Q the base 18 of the body. Ifthe tool is to be used with valve guides at right angles to the face of the engine block 26',the indicating 'inark on surface 129will "be set at'zero, but 7 if t isknown that-the valve guides are at a some other specified angle, the bearing portion 7 2 will be set at such predetermined angle ,and clamped relative to ,body"61,.by

nut 134. v

" Thebearing 23 maythen be placed over clamp-ed upon the engine block after'theinanner shown in Fig. 1,;by means of clamping member '16,- stud bolt29 and spacing 'mem- "the tool holder 24: and thebody ;61' may' be p her 15. The body 61 will, of course, be located upon the engine block at any point where it flatly engages the face of the ensine block, but the position of the bearing ment is permitted between the inner bearing member 60 and the body member 61. If the combustion chambers are counterbored, a cutter spacer may be inserted between the upper surface of the cutter and the lower surface of the inner bearing member 60.

The washer 9 is exemplary of the type of spacers which may be employed, except that the spacers are usually of suitable thickness and spacers may be employed wherever necessary to fit the device to the stud bolt or to the location of the valve seat.

The cutter 21 may now be fed downward by rotating the feeding member 7 6 in a clockwise direction, so that the feeding member progresses downward in the bore 77, carrying with it the bearing 23, including the inner bearing member 60. The inner bearing member 60 is brought into engagement with the top of the cutter body 42, after which the inner bearing member 60 reacts against the ball bearings 94 by means of

grooves

90 and 91, and the ball bearings react against groove 96, which permits the inner bearing member to adjust itself universally, but which is adapted to resist axial thrust.

Any desired pressure may be brought to bear upon the cutter 21 by means of the universal ball bearing 23 without causing the bearing to bind, and the cutter may be rotated with ease by applying the ratchet lever 25 or other tool to the non-circular head 110.

It should also be noted that the universal bearing 23 is peculiarly adapted to permit the cutter 21 to be constantly maintained aligned in axial position with valve guide 30 by pilot stem 22, and this constant alignment could not be accomplished by an ordinary bearing. It is practically impossible to cut a feeding member 7 6 with threads 7 8 which are located accurately relative to the axis of the feeding member, because the threads are commonly cut with a cutter which feeds and guides itself, and if the metal is softer on one side, the threads will be cut deeper, and where the metal is harder, the threads will be more shallow. Consequently, it will be observed that the alignment of a threaded member may change as the threaded member progresses, but in the present device, the cutter may be maintained in alignment by means of the universal bearing used at the upper end of the tool holder.

If the operation to be performed is merely a resurfacing operation, it is unnecessary to use any gauge, and the resurfacing tool is merely actuated by the ratchet lever 25 until every part of the surface has been refinished.

It should be noted that the new surface cut is a surface of revolution, which has its axis accurately located in the axis of the valve guide 30, since the alignment of the present device does not depend on the use of a loose pilot supported in a position in which it rotates most freely, but the alignment is accomplished by a self-centering pilot, permanently fixed with its axis in the axis of the valve guide 30. The alignment of the cutter axis with the axis of the valve guide may thus be accomplished with mathematical exactitude.

Where the reconstruction tool is employed for inserting a new valve seat ring, the tool is first set up as shown in Fig. 3, with the cutter blade 417 resting upon the upper edge of the engine block 26, the ring 120 which it is proposed to insert is held with its upper sur face against the shoulder 83, and the head 113 of the pin 112 is moved up until it engages the bottom of the ring 120, the pin being secured by turning wing nut 119 clockwise.

After this, the cutter may be rotated by means of the ratchet lever 25 while the feeding member 7 6 is also constantly fed downward by rotating said feeding member clockwise, and the cutting operation proceeds quickly until an annular groove 121 of a shape complementary to the ring 120 is formed in the engine block 26. The feeding movement my progress until shoulder 83 engages head 113 of the gauge member 112, when the depth of groove 121 will correspond to the thickness of ring 120. The cutter 21 has, of course, been constructed with its outer cutting edge 56 so located relative to the axis of cutter 21 that the diameter of the recessed portion of the valve seat is slightly less than the outside diameter of the ring 120,

so that the ring 120 may be driven into a close frictional fit with the walls of groove 121.

The new valve seat ring may then be inserted in recess 121 according to the method described in the co-pending application, but as the present application is particularly directed to the structure of the present tool, the method will not be described in detail herein.

If the valve seat ring protrudes above the surface of the block the ring may be faced off flush with the block by using the cutter 21, after which the valve seat may be cut in the usual manner with a reamer or surfacing tool.

it will thus he observed that the valve seat tools of the present invention are peculiarly adapted to be aligned with mathematical accuracy with the cutter axis coinciding with the axis of a valve guide, and the accurate alignment of the tool is accomplished by means of a pilot stem fixedly secured in the valve guide. The separate parts of the machine are, of course, of general application and may be used with any pilot stem, but the most accurate results can only be obtained when the pilot stem actually fits valve guide 30, or when a pilot stem of the type described, capable of accurate, axial centering, is use-d.

The present valve seat tool is adapted to be used where the axis of the valve seat is not perpendicular to the face of the engine block as well as where the axis of the valve seat is perpendicular to the face of the engine block, and consequently, the present tool is of universal application to practically all types of internal combustion engines.

lNhile I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims. 1

Having thus described my invention, what I claim is new and desire to secure by Letters Patent of the United States, is:

1. In a valve seat reconstruction tool, the combination of a pilot stem adapted to be fixedly secured in axial and centered position in a valve guide, with a tool rotatably and slidably mounted 011 said pilot stem, a supporting body adapted to be secured to an engine block, a thrust bearing for resisting axial forces on said tool and a pivotal connection between said thrust bearing and said body to permit alignment of said thrust bear ing with said pilot stem.

2. In a valve seat reconstruction tool, the combination of a pilot stem adapted to be fixedly secured in axial and centered position in a valve guide, with a tool rotatably and slidably mounted on'said pilot stem, a'supporting body adapted to be secured to an engine block, a thrust bearing for resisting axial forces on said tool, a pivotal connection between said thrust bearing and said body to permit alignment of said thrust bearing with said pilot stem and 'means for securing said bearing in any of a plurality ofiadjusted positions.

3. In a valve seat reconstruction tool, the combination of a pilot stem adapted to be fixedly secured in axial and centered position in a valve guide, with a tool rotatably and slidably mounted on said pilot stem, a supporting body adapted to be secured to an engine block, a thrust bearing for resisting axial forces on said tooland a pivotal connection between said thrust bearing and said body to permit alignment of said thrust bearing with said pilot stem, said thrust bearing including a pair of races and balls, and'said races being adapted for universal movement relative to each other.

4. Ina valve seat reconstruction tool, the

edly secured in axial and centered osition in a valve guide, with a tool rotata ly and slidably mounted on said pilot stem, a supporting body adapted to be secured to an engine block, a thrust bearmg for resisting axial forces on said tool, a pivotal; connection between said thrust bearing and said body to permit alignment of said thrust bearing with said pilot stem and, a feeding member interposed between said pivotal con-.

nection and said bearing.

5. In a valve seat reconstruction tool, the

races being adapted for universal movement relative to each other, and a feeding member interposed between said pivotal connection and said bearing. I

6. A valve seat reconstruction tool, comprising an elongated metal body having a flat lower surface, a bolt extending longitudinally of said body, a second body portion for supporting a tool bearing, adjustably secured to said body by said bolt, and a thrust bearingcarried by said second body portion.

7'. vA valve seat reconstruction tool, comprising an elongated metal body having a flat 7 lower surface, a bolt extending longitudinally of said body, a second body portion for supporting a tool bearing, adjustably secured to I said body by said bolt, a thrust bearingcai ried by said second body portion and means for indicating the vertical adjustment of said Y bearing relative to said body.

8. A valve seat reconstruction tool, comprising an elongated metal. body having a flat lower surface, a bolt extending longitudinally of said body, a second body portion for supporting a tool bearing, adjustably secured to said body by said belt, a thrust bearlng carried by said second body portionand means for preventing rotation of said bolt in said body. 7

V 9. In a valve seat reconstruction tool, the combination of a pilot stem adapted to be fixedly secured in axial and centered position in a valve guide, with a cutting tool rota"'-.

ably and slidably mounted on said pilot stem, a supporting body adapted to be secured to an engine block, a thrust bearing for resisting axial forces on said tool, a pivotal connection between said thrust bearing and said body to permitalignment of said thrust bearing: with said body to said block comprising a threaded member carried by the block, a spacingmem= pilot stem, and means for-securing said her, and a clamping member engaging said spacing member on one side of said threaded member and engaging said supporting body on the other side of said threaded member.

In Witness whereof, I hereunto subscribe my name this 12 day of Febr., 1929.

FRANS O. ALBERTSON.