CA1122790A - Method of rebuilding valve bridges - Google Patents
Method of rebuilding valve bridgesInfo
- Publication number
- CA1122790A CA1122790A CA263,915A CA263915A CA1122790A CA 1122790 A CA1122790 A CA 1122790A CA 263915 A CA263915 A CA 263915A CA 1122790 A CA1122790 A CA 1122790A
- Authority
- CA
- Canada
- Prior art keywords
- lash adjuster
- oversized
- sockets
- lash
- valve bridge
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
- F02B3/00—Engines characterised by air compression and subsequent fuel addition
- F02B3/06—Engines characterised by air compression and subsequent fuel addition with compression ignition
Landscapes
- Valve-Gear Or Valve Arrangements (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
An improved method is disclosed for rebuilding valve bridges that are utilized as part of the mechanism to actuate the exhaust valves in larger internal combustion engines, such as locomotive diesel engines and that have oversized lash adjuster sockets due to wear.
An improved method is disclosed for rebuilding valve bridges that are utilized as part of the mechanism to actuate the exhaust valves in larger internal combustion engines, such as locomotive diesel engines and that have oversized lash adjuster sockets due to wear.
Description
BACKGROUND.AND SUMMARY OF THE INVENTION
The present invention relates to an improved method for rebuilding valve bridges, and more particularly, to an improved, novel method for rebuilding or salvaging a valve bridge wherein one or both of the lash adjuster sockets therein have been worn oversized during usage.
In larger, internal combustion engines, such as, for example, diesel engines used in locomotives, a valve bridge comprises a part of the mechanism utilized to actuate the two exhaust valves that are associated with an engine cylinder. Each such valve bridge includes a main body 10 portion and a cross arm portion whose outer, distal ends cooperate with the valve stems of the two associated exhaust valves. The rocker arm assembly of the engine periodically causes the valve bridge, and thus the exhaust valves, to be moved in a direction parallel to the longitudinal axes of the exhaust valves so as to open the valves.
Lash adjusters have long been used with valve bridges to improve the operation of the exhaust valves and thus, the overall operation of the engine. More particularly, a lash adjuster socket is formed in each of the outer, distal ends of the cross-arm portion of a valve bridge, and a lash adjuster is press-fit within each of these sockets. The lash adjusters 20 are positioned so that they are in direct contact with the upper ends of the valve stems. The use of lash adjusters minimizes clearance problems in the exhaust valve actuating mechanism and compensates for thermal expan-sion and wear in this mechanism. The lash adjusters also serve to auto-matically adjust the exhaust valve actuating mechanism for smooth efficient operation and to reduce maintenance of the associated parts of that mechanism.
It has long been an accepted practice in the industry to rebuild the valve bridges in an engine as a part of a regular engine maintenance ,~
-1- ' q~
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program. The rebuilding or maintenance of a valve bridge generally includes the replacement of the lash adjusters carried by the valve bridge with either new or "remanufactured" lash adjusters. However, after a valve bridge has been rebuilt two or three times, it has frequently been found that one or both of the lash adjuster sockets have become so oversized, out of round, etc. due to wear that standard size new or re-manufactured lash adjusters can no longer be press-fit within the sockets.
Insofar as the industry has been concerned, valve bridges that have such worn lash adjuster sockets are no longer considered as being usable, and it has been the general practice in the industry to discard or scrap such worn valve bridges.
There are approximately eighteen million valve bridges presently in use at the present time. I am aware of one major company in the industry that has discarded over two hundred thousand worn valve bridges in the last several years and of another company that has over one hundred and fifty thousand worn valve bridges now awaiting scrapping. Since thè cost of a new valve bridge is presently over thirty dollars, the industry practice of discarding or scrapping worn valve bridges is of one consider-able economic significance.
Accordingly, the industry has for years been attempting to solve the problem of how to avoid having to discard or scrap these worn valve bridges when, in effect, most of these worn valve bridges still have a long, useful life, aside from the fact that their lash adjuster sockets have been worn - oversize. In this regard, some persons have been rebuilding or repairing worn valve bridges by "filling" the worn lash adjuster socket with a weld-ment and then reaming or grinding out the socket to its original, inner dian--eter dimension. While this method of rebuilding worn valve bridges does generally produce satisfactory results, it is a tinle consuming ll;~Z790 procedure and thus is relatively expensive.
Others have proposed, as a solution to this long-standing problem, that the outer distal ends of the cross-arm portion of the valve bridges be swedged, through the use of a press, so as to reduce the inner diameter dimension of a worn lash adjuster socket and thereby to enable a standard sized lash adjuster to again be press-fit within the socket. The difficulty with this proposal is that there is a tendency for the cross-arm portions of the worn valve bridges to crack as a result of this swedging action. In addition, it has been found to be difficult to ascertain the amount of swedging 10 force needed to porperly resize the lash adjuster sockets without cracking the cross-arm portion of the valve bridge.
Still others in the industry have proposed, as a solution to this long-standing problem, to dip worn valve bridges in chrome plating solutions so as to plate the valve bridges, including the inside of the lash adjuster sockets. The sockets are then reground to their original inner dimension so that standard size new or remanufactured lash adjusters can be press-fitted therein. However, this proposal has not been widely adopted by the industry because frequently particles o the plating "flake off" and get into the hydraulic oil used with the lash adjusters thereby tending to cause the 20 lash adjusters to "freeze". It has also been suggested that the inside surfaces of a worn lash adjuster socket be knurled so that the socket will be thereby sized so as to again accept a standard size new or ret~lanufactured lash adjuster, This knurling suggestion has also not found acceptance in the industry because of the expense involved and because it did not really provide a satisfactory rebuilt valve bridge.
In summary then, the industry has, for many years, followed the practice of discarding or scrapping used valve bridges which were zz790 structurally sound except that one or both of their lash adjuster sockets were oversized, out of round, etc. This practice has prevailed even though the industry has long recognized that this practice presents a serious economic problem with respect to minimizing the cost of maintaining and repairing internal combustion engines. Although a variety of solutions to this longstanding problem have been proposed, none of the proposed solutions has received widespread acceptance in the industry, and consequently, large numbers of worn valve bridges are still being discarded or scrapped each year, even though as noted these valve bridges were perfectly capable of continued usage in engines but for the fact that one or both of their lash adjuster sockets therein had been worn oversized.
My improved method of rebuilding worn valve bridges provides a novel, inexpensive, and practical solution to this problem which has faced the industry for many years.
According to the present invention there is provided an improved method of rebuilding a used valve bridge that is utilized in a diesel locomotive engine to actuate the exhaust valves associated with an engine cylinder in the diesel locomotive engine and that includes a cross-arm portion having lash adjuster sockets formed therein, adjacent to each of its distal ends, with the lash adjuster sockets being adapted to have a lash adjuster press-fitted therein for providing smooth efficient operation of the exhaust valves and with at least one of the lash adjuster sockets having an oversized inner diameter dimension due to wear so that a standard size lash adjuster can no longer be properly press-fitted therein, the improved method consisting essentially of the steps of: maintaining a stock of oversized lash adjusters which each include an outer cylindrical wall having a radially outwardly extending rib formed thereon that is adapted to be in surface to surface contact with the inner surface of the lash adjuster sockets and that has an outer diameter dimension machined so as to be larger, in diameter, than the outer diameter dimension of the corresponding rib on 1.~, . i ~lZZ790 a standard size lash adjuster and which each have indicia on their outer bodies for indicating the size of their outer diameter dimension so as to facilitate selection of an oversized lash adjuster having a particular over-sized outer diameter dimension; disassembling the used valve bridge, includ-ing removing the used lash adjusters from each of the lash adjuster sockets;
cleaning the valve bridge, including the lash adjuster sockets formed therein, without machining the lash adjuster sockets in the valve bridge; measuring the inner diameter of each of the oversized lash adjuster sockets in the valve bridge; selecting an oversized lash adjuster from said stock of over-sized lash adjusters having an outer diameter dimension comparable to the measured inner diameter dimension of each of the oversized lash adjuster sockets; and reassembling the valve bridge including press-fitting the selected oversized lash adjuster into the measured oversized lash adjuster socket so that the radially outwardly extending rib formed thereon is in surface to surface contact with the inner surface of the measured oversized lash adjuster socket.
The performance of my improved method can be expeditiously accomplished by having available groups of oversized lash adjusters, with the adjusters in each of the groups being oversized by a specific, predeter-mined amount. For example, one group would be oversized by fifteen thousandths of an inch, the second by thirty thousandths of an inch and the third by forty-five thousandths of an - 4a -inch over the standard diameter of a lash adjuster. Thus, a person rebuilding worn valve bridges need only measure the inner diameter dimension of a worn lash adjuster socket and then readily select an over-sized lash adjuster from the group of lash adjusters having an oversized dimension comparable to the measured inner diameter dimension of the worn socket. To enable a person using my improved method to quickly select the comparable oversized lash adjuster, color coding can be applied to the oversized lash adjusters, which color coding will indicate the amount that a particular la~adjuster is oversized with respect to the dimension 10 of the standard size lash adjuster.
Although from a superficial viewpoint, it might appear that the basic concept underlying the improved method of my present invention should have been obvious to a person having ordinary skill in this industry, the fact remains that the industry has been aware of the problem for which my method provides such a ready and practical solution for over twenty years and yet prior to my invention, no one had developed a satisfactory solution to this problem, much less developed a method similar to my improved method as described and claimed herein. In this regard, literally millions of used valve bridges have been discarded or scrapped by 20 those in the industry over the years even though but for the fact that their lash adjuster sockets were oversized, these used valve bridges were structurally sound and capable of many more years of satisfactory perform-ance in internal combustion engines. In addition, there certainly was an incentive to those in the industry to develop a solution to this longstanding problem since a new valve bridge costs over $30. 00; whereas, a new lash adjuster costs under $2. 00 and a remanufactured lash adjuster costs even less. Furthermore, even though my improved method has only been ~2Z790 available to the industry for only a few months, it has already been accepted by and recognized by persons in the industry as being a practical answer to this longstanding problern and one that is significantly superior to the methods which have heretofore been proposed to overcome this proble m.
Accordingly, it is a primary object of my present invention to provide an improved method of rebuilding a valve bridge wherein one or both of the lash adjuster sockets therein have become oversized, out of round, etc. due to wear. Another object of my present invention is to 10 provide an improved method of rebuilding or repairing a valve bridge of the type described wherein the improved method includes the steps of removing the old, used lash adjusters from the lash adjuster sockets in the valve bridge, cleaning the valve bridge, measuring the inner diameter dimension of each of the worn lash adjuster sockets, selecting a new or remanufactured oversized lash adjuster having outer diameter dimension comparable to the inner diameter dimensions of the measured lash adjuster sockets, and then reassemblying the valve bridge by press-fitting the oversiæed lash adjusters into the measured lash adjuster sockets. A
still further object of my present invention is to provide an improved 20 method as described wherein each oversized lash adjuster includes an indicia on its body indicating the size of its outer diameter dimension so as to facilitate the selection of the oversized lash adjuster having an outer diarneter dimension comparable to the inner diameter or dimension of an oversized lash adjuster socket.
These and other objects and advantages of my present invention will become apparent from the following description of the preferred embodiment of this invention, described in connection with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a partial, perspective view of a portion of an internal combustion engine showing a part of the mechanism utilized to actuate the two exhaust valves associated with one of the cylinders in the engine.
FIGURE 2 is a side, plan view of a valve bridge wherein one lash adjuster is sho~,vn press-fit within one of the lash adjuster sockets of the valve bridge and wherein a second lash adjuster, with its component parts shown in an exploded position, is disposed adjacent to the other lash adjuster socket of the valve bridge.
FIGURE 3 is a side, plan view of an oversized lash adjuster made for use in connection with the improved method of my present invention.
FIGURE 4 is a vertical cross-section view taken along the line 4-4 in FIGURE 3.
FIGURE 5 is a partial vertical cross-section view taken along the line 5-5 in FIGURE 2 and illustrates the difficulties which may occur when a standard size lash adjuster is disposed within an oversi~ed lash adjuster socket.
FIGURE 6 is a cross-sectional view similar to that shown in FIGURE 5 and illustrates the fit between oversized lash adjuster socket 20 and an oversized lash adjuster selected so that its outer diameter dimension is comparable to the inner diameter dimension of the lash adjuster socket.
Throughout the various figures of the drawings, the sarne reference nurrlerals will be used to designate the same parts or components.
Moreover, when the terms "right", "left", "upper", "lower", "up", and "down" are used herein, it is to be understood that these terms have reference to the structure shown in the drawings as it would appear to a person viewing the drawing.
~Z279 DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIGURE 1 of tl~e drawings, a portion of a conven-tional internal conlbustion engine is indicated generally at 10. The engine 10 may, for example, be a large diesel engine of the type utilized in locomotives and includes a cylinder 12 which has two exhaust valves 14 and 16 associated therewith. The mechanism utilized to actuate the exhaust valves 14 and 16 includes a cam shaft, not shown, a rocker arm assembly, shown generally at 18 and a valve bridge assembly shown generally at 20. Except as hereinafter noted, the valves 14 and 16, cam shaft, rocker arm assembly 18 and valve bridge assembly 20 are of conventional design and construction, and they all function in a conventional manne r.
During the operation of the engine 10, rotation of the cam shaft causes the rocker arm assembly 18 to depress the valve bridge 20 so as to, in turn, cause the exhaust valves 14 and 16 to be moved away from their seats 22 and 24 in the cylinder lZ. During normal engine operation the exhaust valves 14 and 16 are opened and closed in the range of 800-900 times per minute depending on the R.P.M. of the engine 10, and proper exhaust valve action is a critical factor in efficient engine operation.
As best shown in FIGURE 2, the valve bridge assembly 20 includes a valve bridge 26 comprising a transverse cross-arm portion 28 and a longitudinal main body portion 30. Lash adjuster sockets 32 and 34 are forrned in the outer, distal ends 36 and 38, respectively, of the cross-arm portion 28. The sockets 32 and 34 open downwardly tov.~ard the exhaust valves 14 and 16, respectively, and the central longitudinal axes of the sockets 32 and 34 are parallel with the central longitudinal axis of n~ain body portion 30 of the valve bridge 26.
~lZZ790 To facilitate the action of the exhaust valves 14 and 16, lash adjusters 40 and 42 are press-fit in the sockets 32 and 34, respectively, in the distal ends 36 and 38 of the cross-arm portion Z8 of the valve bridge Z6 and are disposed between the distal ends 36 and 38 and the upper ends of the valve stems of the exhaust valves 14 and 16. The use of the lash adjusters 40 and 4Z minimizes any clearance in the valve actuating mechanism and compensates for thermal expansion and wear in this mechanism. In addition, tha lash adjusters 40 and 4Z automatically adjust the exhaust valve actuating mechanism so as to provide smooth efficient operation of the exhaust valves and reduce the maintenance of the associated parts of the mechanism.
The valve bridge 26, as shown in FIGURE Z, has been used for a substantial period of time, and as a result, the inner diameter dimension of the sockets 32 and 34 have become enlarged due to wear. However, when the valve seat 22 was initially manufactured, the inner dimensions of the sockets 32 and 34 were machined so that standard size lash adjusters could be press-fit therein and so that the lash adjusters would remain properly positioned within the sockets during normal operation of the engine 10. In this regard, the standard outer diameter dimension of conventional lash adjusters has for years been 0. 8755 inches.
The lash adjusters 40 and 42 are structurally and functionally identical except as explained hereinbelow, the outer diameter of these adjusters 40 and 42 may be different since in accordance with the principles of my invention, the outer dimension of these lash adjusters are selected so as to be comparable with the inner diameter dimensions of the worn, over-sized sockets 32 and 34 in which they are press-fit. In view of the structural identity of the lash adjusters 40 and 42, only the adjuster 42, as shown in FIGUI?ES 2-4, is described in detail.
The lash adjuster 42 includes a generally cylindrical outer body 44 having a radially outwardly extending flange 46 formed at its lower end 48.
The outer diameter of the flange 46 is greater than the inner diameter dimension of the socket 34 so that the inner radial surface 50 of the flange 46 abuts against the annular portion 51 of the cross-arm portion 28 immediately surrounding the socket. The upper end 52 of the body 44 has a generally frustoconical shape and has a relatively small diameter, oil 10 inlet passage 54 disposed therein such that the central longitudinal axis of the passage 54 is coaxial with the central longitudinal axis of the body 44 of the lash adjuster 42, The passage 54 is adapted to be connected with a source of oil or hydraulic fluid, not shown.
The body 44 has a bore 56 and a smaller diameter counter-bore 58 formed therein. The bore 56 communicates the exterior of the body 44, adjacent to the lower end 48 and with the counterbore 58 which, in turn, communicates with the passage 54. The bore 56 and counterbore 58 are forrned in the body 44 such that their central longitudinal axes are coaxial with each other and with the central longitudinal axis of the body 44.
A cylindrical plunger 60 is disposed in the bore 56 so that relative, sliding movement may occur between the plunger 60 and the body 44. The plunger 60 includes a cylindrical recess 62 which faces the upper end 52 of the body 44, when the plunger 60 is positioned within the body 44, and whose central longitudinal axis is coaxial with the central longitudinal axis of the body 44.
A cylindrical, stepped dialneter retainer 64 is press-fit within the counterbore 58 and extends from the counterbore 58 to~ard the lower end llZZ~O
48 of the body 44 so that its smaller diameter, lower projecting end 66 is disposed within the recess 62 of the plunger 60. A relatively small, cylindrical recess 68 is formed in the upper, larger diameter end 70 of the retainer 64 and is in direct fluid communication with the passage 54. A passage 72 is formed in the upper end 70 of the retainer 64 and extends between the recess 68 and the interior of the bore 56. The central longitudinal axes of the retainer 64, its ends 66 and 70, and the recess 68 therein, are coaxial with the central longitudinal axes of the body 44 while the longitudinal axis of the passage 72 is disposed at an acute angle with respect to the central longitudinal axis of the body 44.
A ball 74 is positioned within the recess 68 of the retainer 64. The diameter of the ball 74 is larger than the diameter of the passage S4 so that when the ball 74 is adjacent to the passage 54, the ball blocks flow through the passage 54. The diameter of the ball 74, however, is less than the diameter of the recess 68.
A coil compression spring 76 is disposed within the recess 62 of the plunger 60 and extends between the lower end 78 of the plunger 60 and the shoulder 80 formed on the retainer 64 between the lower and upper ends 66 and 70 thereof. The spring 76 urges the plunger 60 downwardly in the bore 56, away from the retainer 64. A snap ring 82 is positioned within a groove 84 formed in the bore 56, adjacent to the upper end 48 of the body 44, and serves to retain the plunger 60 within the bore 56.
During operation of the engine 10, oil or other hydraulic fluid is present within the passage 54, the recess 68, the passage 72, the recess 62 and that portion of the bore 56 between the upper end 52 of the body 44 and the lower end 78 of the plunger 60. As the cam shaft of l:he engine 10 rotates, the rocker arm assembly 18 forces the valve bridge assembly 20 11;~2790 to move downwardly toward the exhaust valves 14 and 16. During this downward movement, the plunger 60 tends to move inwardly against the force of the spring 76. The oil trapped in the body 44 forces the ball 74 to close the oil inlet passage 54. The continued downward movement of the valve bridge assembly 20 causes the exhaust valves 14 and 16 to move away from their seats 22 and 24. Some of the oil trapped in the body 44 leaks down through the clearance between the plunger 60 and the bore 56 during this relative mcv ement between the plunger 60 and the bore 56.
Continued cam shaft rotation allows the valve bridge assembly 20 to move 10 upwardly. When the valves 14 and 16 are again seated on their seats 22 and 24, respectively, the pressure on the lash adjuster plunger 60 is ~lo~n ~1 rdJ~
relieved. The lash adjuster spring 76 then moves the plunger 60 u~ard~, relative to the bore 56, and this permits the ball 74 to move away from the passage 54 so that oil is again permitted to enter the recess 68, through the passage 54, and from there, flow through the passage 72 into the interior of the lash adjuster body 44 so as to replenish any oil leakage that occured during the downward stroke of the valve bridge assembly 20. This cycle of operation is repeated each time the cam shaft actuates the rocker arm assembly 18.
As shown in FIGURE 3, the outer cylindrical wall of the body 44 has a raised rib 86 formed thereon adjacent to the flange 46. The outer diameter dimension, indicated by the letter "A" in FIGURE 3, of the rib 86 is less than the outer diarr~eter of the flange 46 and is machined so as to be comparable, in diameter, to the inner diameter dimension of the socket 34, in which the lash adjuster is to be press-fit. More specifically, the rib 86 includes an annular radially outwardly facing surface 88 whose central longitudinal axis is coaxial to the longitudinal axis of the body 44 ~Z;~790 and which is adapted to be in surface to surface contact with the inter surface of the socket 34. The diametrical dimension "A" of this surface 88 is selected so that when the lash adjuster 42 is positioned within a lash adjuster socket 34, a press-fit will exist between the lash adjuster and the lash adjuster socket such as shown in FIGURE 6.
In accordance with my present invention, when it is desired to rebuild a valve bridge such as the valve bridge 26, the bridge is removed from the engine 10. Initially, the used lash adjusters are removed from the lash adjuster sockets 32 and 34 in the bridge. The bridge, including the sockets 10 32 and 34, is then cleaned, and the inner diameter dimensions of the sockets 32 and 34 are measured by any conventional means. Oversized lash adjuster 40 and 42 are then selected, with reference to their diameter dimensions "A", so that their dimensions "A" match the measured inner diameter dimensions of the oversized sockets 32 and 34. Thereafter, the selected adjusters 40 and 42 are press-fit within the sockets 32 and 34, respectively, and the rebuilt valve bridge 26 is again ready for use in the engine 10.
FIGURE 5 illustrates the relationship which would occur between a lash adjuster and a lash adjuster socket if a person attempted to use a standard 20 size lash adjuster in an oversized, worn lash adjuster socket such as the socket 34. However, when a properly selected oversized lash adjuster, such as the adjuster 42, is press-fit within an enlarged lash adjuster socket 34, in accordance with the principles of my invention, the relation-ship between the adjuster and socket is as illustrated in FIGURE 6 and is similar to the relationship which exists between a standard size lash adjuster and a standard sized socket in a newly manufactured valve bridge. Further-more, a valve bridge assembly which has been rebuilt, pursuant to my ll~Z7~0 improved method, will function in the same manner as a new valve bridge assembly; whereas, if a person attempts to use a standard size lash adjuster with an oversized worn socket, such as shown in FIGURE 5, the valve bridge assembly will not function properly.
In accordance with the basic principle underlying my invention, the diameter dimension "A" of the surface 88 of the lash adjuster 42 is machined so that it has an outer diameter dimension greater than the standard 0. 8755 inch dimension. To facilitate the selection of the proper oversize lash adjuster to be used with a particular oversized worn lash 10 adjuster socket, groups of lash adjusters can be machined to different oversize dimensions. For example, a frist group of oversized lash adjusters can be made having a diameter dimension "A" of 0. ~G0 (+ ~ 000, - . 0005); a second group of oversized lash adjusters can be made ~ ~57~
having a dimension "A" of :~ (+ . 000, - . 0005); while still a third group can be made having a diameter dimension "A" of 0. 88000 (+ . 000, - . 0005). In this regard, and to enable a workman to distinguish between the first, second and third groups, the first group might be coded with indicia consisting of a single colored band or stripe being applied around the outer surface of its body 44 between the rib 86 and the upper end 52.
20 Similarly, the oversize lash adjusters in the second group could be coded by having two bands or stripes of the same or differing colors being applied around the body 44 while the oversize lash adjusters in the third group could be coded by having three bands or stripes of the same or differing colors applied to the body 44. In this regard, the lash adjuster 42, as shown in FIGURE 3, has two such bands or stripes, as indicated at 90, applied to its body 44.
In conclusion, my improved method of rebuilding valve bridges, as disclosed herein, provides a practical solution to a problem which the llZZ790 industry has long faced. As noted above, after a valve bridge has been used for an extended period, ~ two to three years, the inner diameter dimension of the lash adjuster sockets in the valve bridge generally become worn to such an extent that a standard lash adjuster can no longer be press-fit within the worn socket. Over the years, there have been a number of proposals as to how to resize the inner diameter dimension of the worn lash adjuster sockets. None of these proposed solutions, as a practical matter, have received wide spread acceptance in the industry, primarily because of costs involved. Hence, prior to my 10 invention, it was still the general industry practice to discard or scrap used valve bridges found to have the worn oversized lash adjuster sockets and to replace these worn valve bridges with new valve bridges even though a new valve bridge presently costs over $30. 00 and even though the worn valve bridges were structurally sound and capable of further usage except for the oversize sockets. With over millions of valve bridges in use in the industry, the cost to the industry of discarding or scrapping these used valve bridges was and is significant.
One of the principle advantages of the improved method of my present invention is that it materially extends the productive life of such 20 used valve bridges without appreciably increasing the cost of rebuilding the valve bridges. In other words, used valve bridges having worn oversized lash adjuster sockets can be rebuilt, using my improved method, for substan-tially the same cost as rebuilding valve bridges which do not have over-sized lash adjuster sockets, and a person employing my method thus realizes a significant saving equal to the cost of a new valve bridge.
Since my invention, as disclosed herein, may be embodied in other specific forms without departing from the spirit or central characteristics ~;~Z790 thereof, the preferred embodiment described herein is there~ore to be considered in all respects as illustrative and not restrictive, the scope of my invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
The present invention relates to an improved method for rebuilding valve bridges, and more particularly, to an improved, novel method for rebuilding or salvaging a valve bridge wherein one or both of the lash adjuster sockets therein have been worn oversized during usage.
In larger, internal combustion engines, such as, for example, diesel engines used in locomotives, a valve bridge comprises a part of the mechanism utilized to actuate the two exhaust valves that are associated with an engine cylinder. Each such valve bridge includes a main body 10 portion and a cross arm portion whose outer, distal ends cooperate with the valve stems of the two associated exhaust valves. The rocker arm assembly of the engine periodically causes the valve bridge, and thus the exhaust valves, to be moved in a direction parallel to the longitudinal axes of the exhaust valves so as to open the valves.
Lash adjusters have long been used with valve bridges to improve the operation of the exhaust valves and thus, the overall operation of the engine. More particularly, a lash adjuster socket is formed in each of the outer, distal ends of the cross-arm portion of a valve bridge, and a lash adjuster is press-fit within each of these sockets. The lash adjusters 20 are positioned so that they are in direct contact with the upper ends of the valve stems. The use of lash adjusters minimizes clearance problems in the exhaust valve actuating mechanism and compensates for thermal expan-sion and wear in this mechanism. The lash adjusters also serve to auto-matically adjust the exhaust valve actuating mechanism for smooth efficient operation and to reduce maintenance of the associated parts of that mechanism.
It has long been an accepted practice in the industry to rebuild the valve bridges in an engine as a part of a regular engine maintenance ,~
-1- ' q~
Z7~
program. The rebuilding or maintenance of a valve bridge generally includes the replacement of the lash adjusters carried by the valve bridge with either new or "remanufactured" lash adjusters. However, after a valve bridge has been rebuilt two or three times, it has frequently been found that one or both of the lash adjuster sockets have become so oversized, out of round, etc. due to wear that standard size new or re-manufactured lash adjusters can no longer be press-fit within the sockets.
Insofar as the industry has been concerned, valve bridges that have such worn lash adjuster sockets are no longer considered as being usable, and it has been the general practice in the industry to discard or scrap such worn valve bridges.
There are approximately eighteen million valve bridges presently in use at the present time. I am aware of one major company in the industry that has discarded over two hundred thousand worn valve bridges in the last several years and of another company that has over one hundred and fifty thousand worn valve bridges now awaiting scrapping. Since thè cost of a new valve bridge is presently over thirty dollars, the industry practice of discarding or scrapping worn valve bridges is of one consider-able economic significance.
Accordingly, the industry has for years been attempting to solve the problem of how to avoid having to discard or scrap these worn valve bridges when, in effect, most of these worn valve bridges still have a long, useful life, aside from the fact that their lash adjuster sockets have been worn - oversize. In this regard, some persons have been rebuilding or repairing worn valve bridges by "filling" the worn lash adjuster socket with a weld-ment and then reaming or grinding out the socket to its original, inner dian--eter dimension. While this method of rebuilding worn valve bridges does generally produce satisfactory results, it is a tinle consuming ll;~Z790 procedure and thus is relatively expensive.
Others have proposed, as a solution to this long-standing problem, that the outer distal ends of the cross-arm portion of the valve bridges be swedged, through the use of a press, so as to reduce the inner diameter dimension of a worn lash adjuster socket and thereby to enable a standard sized lash adjuster to again be press-fit within the socket. The difficulty with this proposal is that there is a tendency for the cross-arm portions of the worn valve bridges to crack as a result of this swedging action. In addition, it has been found to be difficult to ascertain the amount of swedging 10 force needed to porperly resize the lash adjuster sockets without cracking the cross-arm portion of the valve bridge.
Still others in the industry have proposed, as a solution to this long-standing problem, to dip worn valve bridges in chrome plating solutions so as to plate the valve bridges, including the inside of the lash adjuster sockets. The sockets are then reground to their original inner dimension so that standard size new or remanufactured lash adjusters can be press-fitted therein. However, this proposal has not been widely adopted by the industry because frequently particles o the plating "flake off" and get into the hydraulic oil used with the lash adjusters thereby tending to cause the 20 lash adjusters to "freeze". It has also been suggested that the inside surfaces of a worn lash adjuster socket be knurled so that the socket will be thereby sized so as to again accept a standard size new or ret~lanufactured lash adjuster, This knurling suggestion has also not found acceptance in the industry because of the expense involved and because it did not really provide a satisfactory rebuilt valve bridge.
In summary then, the industry has, for many years, followed the practice of discarding or scrapping used valve bridges which were zz790 structurally sound except that one or both of their lash adjuster sockets were oversized, out of round, etc. This practice has prevailed even though the industry has long recognized that this practice presents a serious economic problem with respect to minimizing the cost of maintaining and repairing internal combustion engines. Although a variety of solutions to this longstanding problem have been proposed, none of the proposed solutions has received widespread acceptance in the industry, and consequently, large numbers of worn valve bridges are still being discarded or scrapped each year, even though as noted these valve bridges were perfectly capable of continued usage in engines but for the fact that one or both of their lash adjuster sockets therein had been worn oversized.
My improved method of rebuilding worn valve bridges provides a novel, inexpensive, and practical solution to this problem which has faced the industry for many years.
According to the present invention there is provided an improved method of rebuilding a used valve bridge that is utilized in a diesel locomotive engine to actuate the exhaust valves associated with an engine cylinder in the diesel locomotive engine and that includes a cross-arm portion having lash adjuster sockets formed therein, adjacent to each of its distal ends, with the lash adjuster sockets being adapted to have a lash adjuster press-fitted therein for providing smooth efficient operation of the exhaust valves and with at least one of the lash adjuster sockets having an oversized inner diameter dimension due to wear so that a standard size lash adjuster can no longer be properly press-fitted therein, the improved method consisting essentially of the steps of: maintaining a stock of oversized lash adjusters which each include an outer cylindrical wall having a radially outwardly extending rib formed thereon that is adapted to be in surface to surface contact with the inner surface of the lash adjuster sockets and that has an outer diameter dimension machined so as to be larger, in diameter, than the outer diameter dimension of the corresponding rib on 1.~, . i ~lZZ790 a standard size lash adjuster and which each have indicia on their outer bodies for indicating the size of their outer diameter dimension so as to facilitate selection of an oversized lash adjuster having a particular over-sized outer diameter dimension; disassembling the used valve bridge, includ-ing removing the used lash adjusters from each of the lash adjuster sockets;
cleaning the valve bridge, including the lash adjuster sockets formed therein, without machining the lash adjuster sockets in the valve bridge; measuring the inner diameter of each of the oversized lash adjuster sockets in the valve bridge; selecting an oversized lash adjuster from said stock of over-sized lash adjusters having an outer diameter dimension comparable to the measured inner diameter dimension of each of the oversized lash adjuster sockets; and reassembling the valve bridge including press-fitting the selected oversized lash adjuster into the measured oversized lash adjuster socket so that the radially outwardly extending rib formed thereon is in surface to surface contact with the inner surface of the measured oversized lash adjuster socket.
The performance of my improved method can be expeditiously accomplished by having available groups of oversized lash adjusters, with the adjusters in each of the groups being oversized by a specific, predeter-mined amount. For example, one group would be oversized by fifteen thousandths of an inch, the second by thirty thousandths of an inch and the third by forty-five thousandths of an - 4a -inch over the standard diameter of a lash adjuster. Thus, a person rebuilding worn valve bridges need only measure the inner diameter dimension of a worn lash adjuster socket and then readily select an over-sized lash adjuster from the group of lash adjusters having an oversized dimension comparable to the measured inner diameter dimension of the worn socket. To enable a person using my improved method to quickly select the comparable oversized lash adjuster, color coding can be applied to the oversized lash adjusters, which color coding will indicate the amount that a particular la~adjuster is oversized with respect to the dimension 10 of the standard size lash adjuster.
Although from a superficial viewpoint, it might appear that the basic concept underlying the improved method of my present invention should have been obvious to a person having ordinary skill in this industry, the fact remains that the industry has been aware of the problem for which my method provides such a ready and practical solution for over twenty years and yet prior to my invention, no one had developed a satisfactory solution to this problem, much less developed a method similar to my improved method as described and claimed herein. In this regard, literally millions of used valve bridges have been discarded or scrapped by 20 those in the industry over the years even though but for the fact that their lash adjuster sockets were oversized, these used valve bridges were structurally sound and capable of many more years of satisfactory perform-ance in internal combustion engines. In addition, there certainly was an incentive to those in the industry to develop a solution to this longstanding problem since a new valve bridge costs over $30. 00; whereas, a new lash adjuster costs under $2. 00 and a remanufactured lash adjuster costs even less. Furthermore, even though my improved method has only been ~2Z790 available to the industry for only a few months, it has already been accepted by and recognized by persons in the industry as being a practical answer to this longstanding problern and one that is significantly superior to the methods which have heretofore been proposed to overcome this proble m.
Accordingly, it is a primary object of my present invention to provide an improved method of rebuilding a valve bridge wherein one or both of the lash adjuster sockets therein have become oversized, out of round, etc. due to wear. Another object of my present invention is to 10 provide an improved method of rebuilding or repairing a valve bridge of the type described wherein the improved method includes the steps of removing the old, used lash adjusters from the lash adjuster sockets in the valve bridge, cleaning the valve bridge, measuring the inner diameter dimension of each of the worn lash adjuster sockets, selecting a new or remanufactured oversized lash adjuster having outer diameter dimension comparable to the inner diameter dimensions of the measured lash adjuster sockets, and then reassemblying the valve bridge by press-fitting the oversiæed lash adjusters into the measured lash adjuster sockets. A
still further object of my present invention is to provide an improved 20 method as described wherein each oversized lash adjuster includes an indicia on its body indicating the size of its outer diameter dimension so as to facilitate the selection of the oversized lash adjuster having an outer diarneter dimension comparable to the inner diameter or dimension of an oversized lash adjuster socket.
These and other objects and advantages of my present invention will become apparent from the following description of the preferred embodiment of this invention, described in connection with the accompanying drawings.
DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a partial, perspective view of a portion of an internal combustion engine showing a part of the mechanism utilized to actuate the two exhaust valves associated with one of the cylinders in the engine.
FIGURE 2 is a side, plan view of a valve bridge wherein one lash adjuster is sho~,vn press-fit within one of the lash adjuster sockets of the valve bridge and wherein a second lash adjuster, with its component parts shown in an exploded position, is disposed adjacent to the other lash adjuster socket of the valve bridge.
FIGURE 3 is a side, plan view of an oversized lash adjuster made for use in connection with the improved method of my present invention.
FIGURE 4 is a vertical cross-section view taken along the line 4-4 in FIGURE 3.
FIGURE 5 is a partial vertical cross-section view taken along the line 5-5 in FIGURE 2 and illustrates the difficulties which may occur when a standard size lash adjuster is disposed within an oversi~ed lash adjuster socket.
FIGURE 6 is a cross-sectional view similar to that shown in FIGURE 5 and illustrates the fit between oversized lash adjuster socket 20 and an oversized lash adjuster selected so that its outer diameter dimension is comparable to the inner diameter dimension of the lash adjuster socket.
Throughout the various figures of the drawings, the sarne reference nurrlerals will be used to designate the same parts or components.
Moreover, when the terms "right", "left", "upper", "lower", "up", and "down" are used herein, it is to be understood that these terms have reference to the structure shown in the drawings as it would appear to a person viewing the drawing.
~Z279 DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIGURE 1 of tl~e drawings, a portion of a conven-tional internal conlbustion engine is indicated generally at 10. The engine 10 may, for example, be a large diesel engine of the type utilized in locomotives and includes a cylinder 12 which has two exhaust valves 14 and 16 associated therewith. The mechanism utilized to actuate the exhaust valves 14 and 16 includes a cam shaft, not shown, a rocker arm assembly, shown generally at 18 and a valve bridge assembly shown generally at 20. Except as hereinafter noted, the valves 14 and 16, cam shaft, rocker arm assembly 18 and valve bridge assembly 20 are of conventional design and construction, and they all function in a conventional manne r.
During the operation of the engine 10, rotation of the cam shaft causes the rocker arm assembly 18 to depress the valve bridge 20 so as to, in turn, cause the exhaust valves 14 and 16 to be moved away from their seats 22 and 24 in the cylinder lZ. During normal engine operation the exhaust valves 14 and 16 are opened and closed in the range of 800-900 times per minute depending on the R.P.M. of the engine 10, and proper exhaust valve action is a critical factor in efficient engine operation.
As best shown in FIGURE 2, the valve bridge assembly 20 includes a valve bridge 26 comprising a transverse cross-arm portion 28 and a longitudinal main body portion 30. Lash adjuster sockets 32 and 34 are forrned in the outer, distal ends 36 and 38, respectively, of the cross-arm portion 28. The sockets 32 and 34 open downwardly tov.~ard the exhaust valves 14 and 16, respectively, and the central longitudinal axes of the sockets 32 and 34 are parallel with the central longitudinal axis of n~ain body portion 30 of the valve bridge 26.
~lZZ790 To facilitate the action of the exhaust valves 14 and 16, lash adjusters 40 and 42 are press-fit in the sockets 32 and 34, respectively, in the distal ends 36 and 38 of the cross-arm portion Z8 of the valve bridge Z6 and are disposed between the distal ends 36 and 38 and the upper ends of the valve stems of the exhaust valves 14 and 16. The use of the lash adjusters 40 and 4Z minimizes any clearance in the valve actuating mechanism and compensates for thermal expansion and wear in this mechanism. In addition, tha lash adjusters 40 and 4Z automatically adjust the exhaust valve actuating mechanism so as to provide smooth efficient operation of the exhaust valves and reduce the maintenance of the associated parts of the mechanism.
The valve bridge 26, as shown in FIGURE Z, has been used for a substantial period of time, and as a result, the inner diameter dimension of the sockets 32 and 34 have become enlarged due to wear. However, when the valve seat 22 was initially manufactured, the inner dimensions of the sockets 32 and 34 were machined so that standard size lash adjusters could be press-fit therein and so that the lash adjusters would remain properly positioned within the sockets during normal operation of the engine 10. In this regard, the standard outer diameter dimension of conventional lash adjusters has for years been 0. 8755 inches.
The lash adjusters 40 and 42 are structurally and functionally identical except as explained hereinbelow, the outer diameter of these adjusters 40 and 42 may be different since in accordance with the principles of my invention, the outer dimension of these lash adjusters are selected so as to be comparable with the inner diameter dimensions of the worn, over-sized sockets 32 and 34 in which they are press-fit. In view of the structural identity of the lash adjusters 40 and 42, only the adjuster 42, as shown in FIGUI?ES 2-4, is described in detail.
The lash adjuster 42 includes a generally cylindrical outer body 44 having a radially outwardly extending flange 46 formed at its lower end 48.
The outer diameter of the flange 46 is greater than the inner diameter dimension of the socket 34 so that the inner radial surface 50 of the flange 46 abuts against the annular portion 51 of the cross-arm portion 28 immediately surrounding the socket. The upper end 52 of the body 44 has a generally frustoconical shape and has a relatively small diameter, oil 10 inlet passage 54 disposed therein such that the central longitudinal axis of the passage 54 is coaxial with the central longitudinal axis of the body 44 of the lash adjuster 42, The passage 54 is adapted to be connected with a source of oil or hydraulic fluid, not shown.
The body 44 has a bore 56 and a smaller diameter counter-bore 58 formed therein. The bore 56 communicates the exterior of the body 44, adjacent to the lower end 48 and with the counterbore 58 which, in turn, communicates with the passage 54. The bore 56 and counterbore 58 are forrned in the body 44 such that their central longitudinal axes are coaxial with each other and with the central longitudinal axis of the body 44.
A cylindrical plunger 60 is disposed in the bore 56 so that relative, sliding movement may occur between the plunger 60 and the body 44. The plunger 60 includes a cylindrical recess 62 which faces the upper end 52 of the body 44, when the plunger 60 is positioned within the body 44, and whose central longitudinal axis is coaxial with the central longitudinal axis of the body 44.
A cylindrical, stepped dialneter retainer 64 is press-fit within the counterbore 58 and extends from the counterbore 58 to~ard the lower end llZZ~O
48 of the body 44 so that its smaller diameter, lower projecting end 66 is disposed within the recess 62 of the plunger 60. A relatively small, cylindrical recess 68 is formed in the upper, larger diameter end 70 of the retainer 64 and is in direct fluid communication with the passage 54. A passage 72 is formed in the upper end 70 of the retainer 64 and extends between the recess 68 and the interior of the bore 56. The central longitudinal axes of the retainer 64, its ends 66 and 70, and the recess 68 therein, are coaxial with the central longitudinal axes of the body 44 while the longitudinal axis of the passage 72 is disposed at an acute angle with respect to the central longitudinal axis of the body 44.
A ball 74 is positioned within the recess 68 of the retainer 64. The diameter of the ball 74 is larger than the diameter of the passage S4 so that when the ball 74 is adjacent to the passage 54, the ball blocks flow through the passage 54. The diameter of the ball 74, however, is less than the diameter of the recess 68.
A coil compression spring 76 is disposed within the recess 62 of the plunger 60 and extends between the lower end 78 of the plunger 60 and the shoulder 80 formed on the retainer 64 between the lower and upper ends 66 and 70 thereof. The spring 76 urges the plunger 60 downwardly in the bore 56, away from the retainer 64. A snap ring 82 is positioned within a groove 84 formed in the bore 56, adjacent to the upper end 48 of the body 44, and serves to retain the plunger 60 within the bore 56.
During operation of the engine 10, oil or other hydraulic fluid is present within the passage 54, the recess 68, the passage 72, the recess 62 and that portion of the bore 56 between the upper end 52 of the body 44 and the lower end 78 of the plunger 60. As the cam shaft of l:he engine 10 rotates, the rocker arm assembly 18 forces the valve bridge assembly 20 11;~2790 to move downwardly toward the exhaust valves 14 and 16. During this downward movement, the plunger 60 tends to move inwardly against the force of the spring 76. The oil trapped in the body 44 forces the ball 74 to close the oil inlet passage 54. The continued downward movement of the valve bridge assembly 20 causes the exhaust valves 14 and 16 to move away from their seats 22 and 24. Some of the oil trapped in the body 44 leaks down through the clearance between the plunger 60 and the bore 56 during this relative mcv ement between the plunger 60 and the bore 56.
Continued cam shaft rotation allows the valve bridge assembly 20 to move 10 upwardly. When the valves 14 and 16 are again seated on their seats 22 and 24, respectively, the pressure on the lash adjuster plunger 60 is ~lo~n ~1 rdJ~
relieved. The lash adjuster spring 76 then moves the plunger 60 u~ard~, relative to the bore 56, and this permits the ball 74 to move away from the passage 54 so that oil is again permitted to enter the recess 68, through the passage 54, and from there, flow through the passage 72 into the interior of the lash adjuster body 44 so as to replenish any oil leakage that occured during the downward stroke of the valve bridge assembly 20. This cycle of operation is repeated each time the cam shaft actuates the rocker arm assembly 18.
As shown in FIGURE 3, the outer cylindrical wall of the body 44 has a raised rib 86 formed thereon adjacent to the flange 46. The outer diameter dimension, indicated by the letter "A" in FIGURE 3, of the rib 86 is less than the outer diarr~eter of the flange 46 and is machined so as to be comparable, in diameter, to the inner diameter dimension of the socket 34, in which the lash adjuster is to be press-fit. More specifically, the rib 86 includes an annular radially outwardly facing surface 88 whose central longitudinal axis is coaxial to the longitudinal axis of the body 44 ~Z;~790 and which is adapted to be in surface to surface contact with the inter surface of the socket 34. The diametrical dimension "A" of this surface 88 is selected so that when the lash adjuster 42 is positioned within a lash adjuster socket 34, a press-fit will exist between the lash adjuster and the lash adjuster socket such as shown in FIGURE 6.
In accordance with my present invention, when it is desired to rebuild a valve bridge such as the valve bridge 26, the bridge is removed from the engine 10. Initially, the used lash adjusters are removed from the lash adjuster sockets 32 and 34 in the bridge. The bridge, including the sockets 10 32 and 34, is then cleaned, and the inner diameter dimensions of the sockets 32 and 34 are measured by any conventional means. Oversized lash adjuster 40 and 42 are then selected, with reference to their diameter dimensions "A", so that their dimensions "A" match the measured inner diameter dimensions of the oversized sockets 32 and 34. Thereafter, the selected adjusters 40 and 42 are press-fit within the sockets 32 and 34, respectively, and the rebuilt valve bridge 26 is again ready for use in the engine 10.
FIGURE 5 illustrates the relationship which would occur between a lash adjuster and a lash adjuster socket if a person attempted to use a standard 20 size lash adjuster in an oversized, worn lash adjuster socket such as the socket 34. However, when a properly selected oversized lash adjuster, such as the adjuster 42, is press-fit within an enlarged lash adjuster socket 34, in accordance with the principles of my invention, the relation-ship between the adjuster and socket is as illustrated in FIGURE 6 and is similar to the relationship which exists between a standard size lash adjuster and a standard sized socket in a newly manufactured valve bridge. Further-more, a valve bridge assembly which has been rebuilt, pursuant to my ll~Z7~0 improved method, will function in the same manner as a new valve bridge assembly; whereas, if a person attempts to use a standard size lash adjuster with an oversized worn socket, such as shown in FIGURE 5, the valve bridge assembly will not function properly.
In accordance with the basic principle underlying my invention, the diameter dimension "A" of the surface 88 of the lash adjuster 42 is machined so that it has an outer diameter dimension greater than the standard 0. 8755 inch dimension. To facilitate the selection of the proper oversize lash adjuster to be used with a particular oversized worn lash 10 adjuster socket, groups of lash adjusters can be machined to different oversize dimensions. For example, a frist group of oversized lash adjusters can be made having a diameter dimension "A" of 0. ~G0 (+ ~ 000, - . 0005); a second group of oversized lash adjusters can be made ~ ~57~
having a dimension "A" of :~ (+ . 000, - . 0005); while still a third group can be made having a diameter dimension "A" of 0. 88000 (+ . 000, - . 0005). In this regard, and to enable a workman to distinguish between the first, second and third groups, the first group might be coded with indicia consisting of a single colored band or stripe being applied around the outer surface of its body 44 between the rib 86 and the upper end 52.
20 Similarly, the oversize lash adjusters in the second group could be coded by having two bands or stripes of the same or differing colors being applied around the body 44 while the oversize lash adjusters in the third group could be coded by having three bands or stripes of the same or differing colors applied to the body 44. In this regard, the lash adjuster 42, as shown in FIGURE 3, has two such bands or stripes, as indicated at 90, applied to its body 44.
In conclusion, my improved method of rebuilding valve bridges, as disclosed herein, provides a practical solution to a problem which the llZZ790 industry has long faced. As noted above, after a valve bridge has been used for an extended period, ~ two to three years, the inner diameter dimension of the lash adjuster sockets in the valve bridge generally become worn to such an extent that a standard lash adjuster can no longer be press-fit within the worn socket. Over the years, there have been a number of proposals as to how to resize the inner diameter dimension of the worn lash adjuster sockets. None of these proposed solutions, as a practical matter, have received wide spread acceptance in the industry, primarily because of costs involved. Hence, prior to my 10 invention, it was still the general industry practice to discard or scrap used valve bridges found to have the worn oversized lash adjuster sockets and to replace these worn valve bridges with new valve bridges even though a new valve bridge presently costs over $30. 00 and even though the worn valve bridges were structurally sound and capable of further usage except for the oversize sockets. With over millions of valve bridges in use in the industry, the cost to the industry of discarding or scrapping these used valve bridges was and is significant.
One of the principle advantages of the improved method of my present invention is that it materially extends the productive life of such 20 used valve bridges without appreciably increasing the cost of rebuilding the valve bridges. In other words, used valve bridges having worn oversized lash adjuster sockets can be rebuilt, using my improved method, for substan-tially the same cost as rebuilding valve bridges which do not have over-sized lash adjuster sockets, and a person employing my method thus realizes a significant saving equal to the cost of a new valve bridge.
Since my invention, as disclosed herein, may be embodied in other specific forms without departing from the spirit or central characteristics ~;~Z790 thereof, the preferred embodiment described herein is there~ore to be considered in all respects as illustrative and not restrictive, the scope of my invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. An improved method of rebuilding a used valve bridge that is utilized in a diesel locomotive engine to actuate the exhaust valves associa-ted with an engine cylinder in the diesel locomotive engine and that includes a cross-arm portion having lash adjuster sockets formed therein, adjacent to each of its distal ends, with the lash adjuster sockets being adapted to have a lash adjuster press-fitted therein for providing smooth efficient operation of the exhaust valves and with at least one of the lash adjuster sockets having an oversized inner diameter dimension due to wear so that a standard size lash adjuster can no longer be properly press-fitted therein, the improved method consisting essentially of the steps of: maintaining a stock of oversized lash adjusters which each include an outer cylindrical wall having a radially outwardly extending rib formed thereon that is adapted to be in surface to surface contact with the inner surface of the lash adjuster sockets and that has an outer diameter dimension machined so as to be larger, in diameter, than the outer diameter dimension of the corresponding rib on a standard size lash adjuster and which each have indicia on their outer bodies for indicating the size of their outer diameter dimension so as to facilitate selection of an oversized lash adjuster having a particular over-sized outer diameter dimension; disassembling the used valve bridge, includ-ing removing the used lash adjusters from each of the lash adjuster sockets;
cleaning the valve bridge, including the lash adjuster sockets formed therein, without machining the lash adjuster sockets in the valve bridge; measuring the inner diameter of each of the oversized lash adjuster sockets in the valve bridge; selecting an oversized lash adjuster from said stock of oversized lash adjusters having an outer diameter dimension comparable to the measured inner diameter dimension of each of the oversized lash adjuster sockets; and reassembling the valve bridge including press-fitting the selected oversized lash adjuster into the measured oversized lash adjuster socket so that the radially outwardly extending rib formed thereon is in surface to surface con-tact with the inner surface of the measured oversized lash adjuster socket.
cleaning the valve bridge, including the lash adjuster sockets formed therein, without machining the lash adjuster sockets in the valve bridge; measuring the inner diameter of each of the oversized lash adjuster sockets in the valve bridge; selecting an oversized lash adjuster from said stock of oversized lash adjusters having an outer diameter dimension comparable to the measured inner diameter dimension of each of the oversized lash adjuster sockets; and reassembling the valve bridge including press-fitting the selected oversized lash adjuster into the measured oversized lash adjuster socket so that the radially outwardly extending rib formed thereon is in surface to surface con-tact with the inner surface of the measured oversized lash adjuster socket.
2. The improved method described in claim 1 wherein the selected oversized lash adjuster is a new lash adjuster.
3. The improved method described in claim 1 wherein the indicia includes at least one colored band marked on the outer tubular side wall of the body of the oversized lash adjuster.
4. The improved method described in claim 3 wherein the selected over-sized lash adjuster is a new lash adjuster.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US72180376A | 1976-09-08 | 1976-09-08 | |
| US721,803 | 1976-09-08 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1122790A true CA1122790A (en) | 1982-05-04 |
Family
ID=24899362
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA263,915A Expired CA1122790A (en) | 1976-09-08 | 1976-10-22 | Method of rebuilding valve bridges |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1122790A (en) |
-
1976
- 1976-10-22 CA CA263,915A patent/CA1122790A/en not_active Expired
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