US1649298A - Compressor - Google Patents

Description

Nov. l5, 1927.

F. A. HALLECK COMPRESSOR 2 SheetsSheet 1 Original Filed AuiLll. 1922 Nov. 15, 192 7.

F. A. HALLECK COMPRESSOR Original Filed Aug. ll. 1922 2 Sheets-Sheet 2 Patented Nov. l5, 1927.

UNITED STATES PATENT OFFICE.

FRANK A. HALLECK, 0F CHICAGO, ILLINOIS, ASSIGNOR TO SULLIVAN MACHINERY COMPANY, A CORPORATION 0F MASSACHUSETTS.

COMPRESSOR.

Application filed August 11, 1922, Serial No. 581,216. Renewed November 18, 1924.

My invention relates to compressors. and more particularly to compressor systems provided with means for effecting a progressive unloading thereof whereby with a constant speed drive it may be possible for the compressor output to be varied in such manner as to maintain the discharge line pressure within certain desired limits.

An object of my invention is to provide an improved compressor mechanism. Another object of my invention is to provide an improved compressor mechanism having improved partial or step by step unloading means. A further object of my invention is to provide an improved compressor system having improved means for effecting a step by step unloading of the entire system in which less of complication is involved than in such systems of other types. Other objects and advantages of my invention will hereinafter more fully appeal'.

In the accompanying drawings I have shown .t'or purposes of illustration one form f which my invention may assume in practice.

In these drawings,-

Fig. 1 is a diagrammatic view of a compressor system provided with the illustrative form of my invention.

Fig. 2 is a view in central vertical section through the intake unloading,T means provided foruse on the low pressure cylinders of the compressor units, certain parts being shown in elevation.

Fig. 3 is a central vertical section through the pilot mechanism controlling the operation of my improved system.

Fig. 4 is an elevation of thc same viewed from a dilierent angle.

Fig.y 5 is a transverse section on the line 5-5 of Fig. 3.

Fig. 6 is a detail sectional view through the unloading means for one end of one of vthe high pressure cylinders.

In the form of my invention shown for purposes of illustration in the accompanying drawings I have shown it embodied in a twin angle compound compressor system which comprises a pair of angle compound compressors 1 and 2. each having low pressure cylinders 3 and high pressure cylinders 4, the low pressure cylindersbeing supplied with air from intake lines 5 and discharging through intercoolcrs 6 to the high pressure cylinders 4 which, in turn, discharge by Way of a discharge line 7 to a receiver or other point of storage or use.

In the customary construction the compres sors 1 and 2 are driven from a common crank shaft 7', but in order to permit the more intelligible disclosure of the piping system employed, I have shown the compressor units 1 and 2 set one behind the other instead ot' in their customary relation. As each of the units is the same in its general details and as it is by of the piping connections with the pilot mechanism that the progressive or step by step unloading of the system is accomplished, it will suffice if I describe the unloading mechanism for one compressor and then describe the control connections and pilot valve for both units.

Accordingly, considering the compressor unit 1 and noting particularly Fig. 2, it will be observed that the intake line 5 communicates with a casing 8 transversely of which there extend partition members 9 and 10, the partition members 9 and 10 being connected at about the longitudinal center of the casing 8 by a vertical partition 11 so that separate chambers 12 and 13 are formed and these chambers 12 and 13 communicate respectively with the inlet valve for the front and rear ends of the low pressure cylinder 3. Above the partition 10 is a chamber 14 which is connected with the chamber below the partition 9 in a manner which will shortly be made apparent.` The partitions 9 and l0 at opposite sides ot' the partition 11 ersed by circular ports 15 and 16, which ports are surrounded by valve seats 17 and 18, the ports being identical at each side of the partition 11, and the upper portsbeing somewhat larger than the lower-to permit the insertion of the valve mechanism. Slidable through the openings 15 and 16 are valve members which for purposes of convenience will be designated 2O 'for the rear end of the cylinder and 21 for the front end thereof, these valve members each comprising a pair of circular valve seat portions 22 and 23 which are respectively adapted to seat upon the seats 17 and 18 and from each of the valve seating portions 22 and 23 there depend supported by suitable ribs 24 and 25 guiding portions 26 and 27 which serve to maintain the valves 20 and 21 properly centered within their seats during reciprocation thereof. The valves are hollow throughthe particular nature' are trav- IUS charge line 7.

upon the suction out their length as indicated at 28, thereby permitting the connection of the chamber 14 with the chamber below the partition 9. Extending centrally through the valve members are valve stems 3() which are connected as at 31 to cross arms 32, these latter being in turn connected by springs 33 with cross arms 34 arranged at the top of operating cylinders 35 which are mounted as indicated at 36 upon heads 37 closing the top of the casing 8. Within the cylinders 35 there are pistons 38 reciprocable, these pistons engaging stems 39 connected with the stems 30 and being operative to force the` valves 2O or 21, as the case may be, closed on admission of air to their cylinders 35. Suitable stops 42 limit the upward travel of the pistons 3S.

For the purpose of greater convenience 1n subsequent reference to the unloading system as a whole, thennloading mechanism for the front end of the low pressure cylinder of unit No. 1 will be designated generally 43, that for the rear end thereof 44, that for the front end of the lorsr pressure cylinder of the unit No. 2, 45, and that for its rear end 46.

JIt will be obvious that any suitable type of inlet or discharge valves may be employed upon the low pressure cylinders, the mode of operation of my mechanism being absolutely inde ndent of the nature of the valves used. On t e high pressure cylinders I prefer for reasons which will shortly be apparent to employ a type of combined inlet and discharge mechanism which is disclosed in my co-pending application, Serial No. 532,7 41, filed Jan. 30, 1922, this mechanism comprising a pair of spaced valve seat elements 51 and 52 coaxially arranged with respect to each other and disposed at opposite sides of a port 53communicating with the end of the cylinder bore whereby an annular chamber 54 communicating with the cylinder bore of the high pressure cylinder is formed betweenthe valve seat members 5,1 and 52. Suitable annular valves 55 normally held closed by transversely flexed springs 56, which are supported by guards 57, close the ports 58 through the valve seat member 52 and so control the discharge of pressure to a passage 59 which communicateswith the dis- Suitable valves 60 normally held closed by transversely flexed springs 61 supported by a guard member 62, normally.

communicating with of the high pressure that duropcration of the compressor, strokes of the high pressure maintain paages 63 the intake chambers 64 ing the normal piston, the valves tercooler pressure during the suction strokes,

Iand that during the discharge' strokes the valves 55 will be unseated by the pressure within the cylinder. One or more of these valve 1n may be used at each end of the type 60 will be unseated by iny the high pressure cylinders of both the units 1 and 2.

At onel end of the high pressure cylinders 4, herein at the rovided means for forcing open the inlet valves 60 which means, it will be observed, when in operation will cause a discontinuation of the compressive action in one end o the high pressure cylinder. This means takes the form of a cylinder member 71 supported upon a closure member 72 held in position over an opening 73 in the top of the cylinder head, the cylinder 71 being coaxial with the valve mechanism. lVithin the cylinder member 71 is formed a bore 74 in which a piston normally being held in raised position by the combined action of a spring 76 housed in a bore 77 in the lower end thereof and resting upon the top of a stud 78 which holds the valve mechanism in position, and by the further effect of intercooler pressure which acts upon the lower end of the piston. Carried by the piston at its lower end is a spider 79 having depending therefrom valve operating stems 80 which pass through the ports 63 in the valve seat member 51 and are engageable with the upper surface of the valve member 60 and on downward movement of the piston 7 5 force the latter open and so maintain it. Pressure may be admitted through a port 81 communicating With the upper end of the cylinder bore 'i' 4 from the receiver and this pressure will be sufficient to overcome intercooler pressureQ and the actionof the spring 7 6 and the pressure of the spring 61, and will hold the inlet valves of the high pressure cylinder open. lt will be clear since similar mechanisms are provided at one end, herein the upper ends of the high pressure cylinders 4 of each of the units 1 and 2, that when pressure is supplied through the ports 8l of the mechanism located on either cylinder the discharge of fluid from the high pressure cylinder to the line will be cut in half for that unit.

For the purpose of easieisubsequeut reference, I shall designate the high lpressure cylinder unloading mechanism just described which is employed with the unit 1 as 82 and that used with the unit 2 as 83.

`With each of the ders I employ a relief valve mechanism of disclosed in the patent to H. C. Johansen 1,404,176, J an. 17, 1922, which automatically permits the discharge direct to atmosphere of the small quantity of leakage air that might be compressed in the lower ends of the high pressure cylinders with both low pressure intake closure valves closed, this mechanism being generally desi gnated 85 and not further illustrated as its construction and mode of operation are fully described in the patent.

For the purpose of controlling the lseveral upper ends thereof, there is 75 is reciprocable, this piston ilu 4high pressure cylinl unloading means 43, 44, 45, 46, 82 and 83 I employ a pilot means which is the invention of one Alexander D. Ferguson. This pilot valve mechanism is generally designated and comprises a series of valve members which are annular in construction and which are designated respectively 101, 102, 103 and 104, which valve members are controlled by means which I shall now more specifically describe. The valve members 101 to 104 respectively' are arranged to cooperate with seats 105, 106, 107 and 108, the several seats being plane and each containingV an annular groove 100, the several annular grooves 109 communicating respectively by passages respectively numbered 110, 111, 112, and 113 with pipes 114, 115, 116, and 117, which pipes l will hereafter refer to again. Each of the seats to 108 inclusive is traversed by a central passageway, these passageways being of uniform diameter and being indicated at 118. Extending longitudinally through the several passageways mentioned isa stem formed at its top with a. plunger or piston 121 upon which a spring 122 housed in the casing 123 and adjustable by `means of a follower 124 coacts. Formed upon the stem 120 is a collar 125 which is adapted to engage, after a predetermined movementffrom a given lower position which will be more fully described later, the valve member 101 and lift it from its seat 105. Resting upon the top of the valve member 101 is a sleeve 126 which is of slightly less length than the distance between the valve member 101 and the valve member 102 when both are seated. This sleeve is adapted to be raised on upward movement of the valve 101 and after sufficient upward movement to engage and lift the valve member 102.y A simila r sleeve cooperating with the valve 103 in a similar manner and designated 127 is superimposed on the valve 102 and a further similar sleeve 128 is arranged to be lifted by the valve member 103 to raise the valve member 104. The piston 121 is slidable in a cylinder 129 formed in the casing 123 and fluid pressure from a suitable source is conducted by a passage 130 to chambers 131, 132, 133 and 134 in which the valve members 101 to "104 respectively are located. This pressure normally tends, of course, to maintain the several valve members seated and as it will be observed that each of the valve members is raised successively alone from its seat and as it will be observed that the valve members are all of substantially equal diameter with the piston 121, it will be apparent that the pressure of air acting beneath the piston 121 is such as to practically neutralize the work necessary in raising one of the valve members oil its seat. The stem 120 passes through a suitable bore 136 downward into a space formed between a pair of support members 137 formed integral with a support 138. Secured to the support 138 is an expansible diaphragm chamber 139 to whose interior 140 fluid may be conducted by a passage 141 and a series of grooves 142 formed in a member 143which threadedly engages the lower head 144 of the diaphragm chamber and holds it fixedly in position on the member 138. The member 143 is traversed by a passage 145 through which a, plunger 146, alined with the stem 120 and having suitable sealing grooves 147 snugly extends, the plunger 146 engaging at 148 the upper head 149 of the diaphragm chamber. The plunger 146 is provided at its lower end with a handle 150 and is traversed by a series of four parallel transverse passageways 151, 152, 153, and 154. rlhe member 143 is provided with a depending sleeve in which a series of holes 156, 157, 158 and 159 are formed, these holes being so spaced relative to each other and to the holes 151 to 154 that the hole 151 will register with t-he hole 159 with a very slight upward movement of the stein 146, while progressively further upward movements of the stem 146 will successively cause registration of the holes 152 and 158, 153 and 157, and 154 and 156.

lVhen the first of these pairs of holes register, valve 101 is unseated; and as each successive pair ot' holes is brought into register an additional valve is opened. The function ot' this mechanism will 'shortly be explained.

Leading from a receiver to which the compressors discharge, or from their common discharge line, is a passage or connection controlled by a stop valve 161 and provided with a strainer 162 to prevent the passage of impurities or solid matter to the valve mechanism. Beyond the strainer 162 is a T 163 from which a connection 164 leads to the passageway 130 previously described. From the other end of the T a connection 165 leads to the pop valve 166, which pop valve works on the principle of the ordinary safety valve, that is, it opens whena desired pressure is reached in the line 160 and permits a pressure equal to the excess above the desired pressure inline 160 to pass through the valve before it again closes. The chamber above the valve in the pop valve 166 communicates with the passage 141 so that a pressure equal to the excess above the seating of the pop valve will be transmitted to the diaphragm chamber 140. Upon the top of the pop valve 166 is a safety valve 167 loaded to prevent building up of more than a desired pressure in the diaphragm chamber 140. A suitable pin hole leak or adjustable leak as may be desired is arranged at any suitable point between the pop valve 166 and the limits of the diaphragm chamber whereby the pressure in the chamber 140 will promptly fall on closure of the pop valve 166. Leakage may also be permitted around the plunger 146, a shoulder 168 lfi thereon thus cooperating with the top of the member 143 in preventing leakage when the diaphragm is collapsed to its smallest size.

The several pipes 114, 115, 116, and 117, described above, serve to conduct operating fluid to cause the proper sequential operation of the several unloading means 43, 44, 45, 46, 82 and 83. The pipe 114 leads by branched connections 170 and 171, respectively, to the unloading means 44 for the rear end of unit No. 1 and to the unloading means 82 for the head end of the high pressure cylinder 4 of that unit. The pipe 115 leads to the unloading means 4?, for the crank end of the low pressure cylinder 3 of unit No. 1. The passage 116 leads by suitable branches 172 and 17B, respectively, to the unloading means 46 and 83, while the pipe 117 leads to the unloading means 45.

From the foregoing description the mode of operation of this mechanism will already be clearly apparent. To recapitulate, however, it may be briefly described as follows: The compressor may be run when desired to have a certain substantially definite maximum output with progressively less production of air as may be desired. lf the demand for air falls olf from full load, the compressor ma also be caused to give three-quarters, hal quarter, or no output, being entirely sluit down as far as the delivery of compressed air is concerned, although the engine speed may remain con stant. Let it be assumed that the maximum demand for air in a given plant is equal to the full output of both the units 1 and 2. During such demand, the receiver pressure or pressure in the compressor discharge lines will be approximately equal to what is desired and will not exceed the setting ot' the pop valve 166. Should the demand for air i'all oil' in part, the compressor, continuing to deliver the same amount of air, will build up an increased pressure in its discharge line or receiver and the pop valve 166 will open and pressure will pass into the diaphragm chamber 140. This chamber will accordingly increase somewhat in volume in proportion to the pressure that is transmitted past the pop valve 166 and as its top moves upward it Will cause the plunger or stem 120 to rise and the collar 125 will lift the valve 101 and fluid pressure will be transmitted through the pipe 114 to thc rear end unloading means 44 of the low pressure cylinder of unit No. 1 and to the unloading means 82 for the head end of the high pressure cylinder 4 of that unit. As a result. the delivery of air by the compressor plant will be cut down to three-quarters of what was previously being delivered, the unit No.

1 then simply operating as a compound compressor having a pair of single acting plstons, the crank ends of the low pressure cylinder and o the high pressure cylinder alone operatin to compress air. If the demand for air lias fallen off in such manner as to result in the continued rise of pres sure in the discharge line, despite the reduced output of the compressor, a. higher pressure will be transmitted through the pop valve 166 and the stem 120 will be forced upward, further causing the valve 101 to raise the sleeve 118 and lift the valve 102 whereby pressure passes through the line 115 to the unloading means 43 and no further air is thereafter admitted to the low pressure cylinder of unit No. 1. As a result, unit No. 1 is completely unloaded and supplies no more :fir to the discharge line. In the event of any leakage past the intake closure valves 20 and 21, the mechanism 185 will permit the discharge ol' such air as might be compressed in the crank end of the high pressure cylinder directly to atmoshere. It will be understood that in the event that the demand for air is such that the single operating unit 2 can supply more pressure fluid than is needed, the unit 2 will be progressively unloaded, the supply of fluid through t e pipe 116 taking place on opening of the valve 103 and resulting in the unloading of the head ends of the high and low pressure cylinders of unit No. 2, while, il' the demand for air entirely ceases o1` the pressure in the discharge line gets high enough, the further rise in pressure in the receiver or discharge lines of the compressor will cause the valve 104 to be unseated with a discharge of air to the line 117 to completely unload the unit No. 2 by the supply of air to the mechanism 45. Thereafter the compreor plant will simply operate idly, no air being discharged by the Compressor to its discharge lines. As the demand for air increases, 1t will be understood that the discharge pressure Will fall and' in proportion as the pressure falls the valves 104, 103, 102 and 101 will successively close and there will occur a reloading of the units 1 and 2, beginning with the opening ot' the valve 21 in unit No. 2 followed by a complete ieloading of unit No. 2. 'lhe next step will be the opening of valve 21 of unit No. 1 and finally unit No. 1 will be fully loaded. The pistons 38 are not absolutel ti bt tits for their cylinders and accor ingly when no Inore air is supplied through the pipes` 114, 115, 116, and 117, the air under pressure in. these pipes will rapid] leak out and reloading will take place ue to raising of the unloader pistons by their respective springs. As explained above, if desired, by the use of the plunger 146 and a suitable pin which may be inserted through the holes 154 and 156, 153 and 157, 152 and 158, or 151 and 159, the compressor may be so set as to be incapable of producing more than a fraction of its full output. Any possibility of damage due to excessive pressures in the chamber 140 will be avoided by the use of safety valve 167.

While I have in this a plication specifically described one embo iment which my invention may assume in practice, it will be understood that this form,of the same is shown for purposes of illustration, and that the invention may be modified and embodied in various other forms Without departing from its spirit or the scope of the appended claims.

lVhat I claim as new and desire cure by Letters Patent is:

1. In combination, a compressor having piston and cylinder mechanism constituting a double acting compressor, and unloading mechanism therefor adapted first to unload one end and then to effect complete unloading comprising separate means, thc one operative to effect an unloading operation While How of fluid to the cylinder mechanism is maintained, to effect partial unloading, and the other operative to effect an unloading operation by preventing How of Huid to the cylinder mechanism, thereby to effect a complete unloading.

2. In combination, a compound compressor having suitably valved high and low pressure cylinders cooperating to supply air to a common line, unloading mechanism therefor whereby said compressor may be caused to be operated continuously with reduced output, or totally unloaded, comprisin means for closing the intake valve mechanism for the low pressure cylinder and means for opening the intake valve mechanism for one end of the high pressure cylinder, and a common pilot valve for controlling each of said unloading mechanisms.

3. In combination, a pair of compound compressors having suitably valved high and low pressure cylinders and cooperating to supply air to a common line, and unloading mechanism therefor comprising means for separately closing the intake to each end of the low Vpressure cylinders thereof and means for opening the inlet valve mechanisms of one end of the high pressure' cylinders thereof.

4. In combination, a pair of compound compressors having suitably valved high and low pressure cylinders and cooperating to supply air to a common line, and unloading mechanism therefor comprising means for separately closing the intake to each end of the low pressure cylinders thereof, means for opening the inlet valve mechanisms of one end of the high pressure cylinders thereof, and common pilot valve means for controlling said several means.

5. In combination, a pair of compound compressors having suitably valved high and low pressure cylinders and cooperating to supply air to a common line, and unloading mechanism including intake closure to semeans for one end of one of said low pressure cylinders and inlet valve opening means for one end of the high pressure cylinder of the same compressor, intake closure means for the other end of the lo7 pressure cylinder of said compressor, similar unloading mechanism for the other compressor, and means causing said mechanism to partially and then totally unload one of said compressors and then the other.

6. In combination, a pair of compound compressors having suitably valved high and low pressure cylinders and cooperating to supply air to a common line, and unloading mechanism including intake closure means for one end of one of said low pressure cylinders and inlet valve opening means for one end of the high pressure cylinder of the same compressor, intake closure means for the other end of the low pressure cylinder of said compressor, similar unloading mechanism for the other compressor, and means operated by variations in line pressure for causing said mechanism to partially and then totally unload one of said compressors and then the other.

7. In combination, a pair of compound compressors having suitably valved high and low pressure cylinders and cooperating to supply air to a common line, and unloading mechanism therefor comprising means for separately closing the intake to each end of the low pressure cylinders thereof,

lmeans for opening the inlet valve mechanisms of one end of the high pressure cylinders thereof, common pilot valve means for controlling said several means, and automatic relief valve means for said high pressure cylinder.

B. In combination, a compound compres sor comprising double acting high and low pressure cylinders, and means for unloading the same in two stages comprising means for interrupting the intake to one end of the low pressure cylinder and opening and so maintaining the inlet to one end of the high pressure cylinder to halve the output of the compressor, and means for closing the intake to the other end of the low pressure cylinder lto completely unload the compressor.

9. In combination, a compound compressor comprising double acting high and low pressure cylinders. and means for unloadl ing the same in two stages comprising means for interrupting the intake to one end of the low pressure cylinder and opening and sn maintaining the inlet to one end of the high pressure cylinder to halve the output of the compressor, means for closing the intake to the other end of the low pressure cylinder to completely unload the compressor, and means for preventing excessive temperatures in the end of the high pressure cylinder whose inlet valve is not opened.

10. In combination, a single valve sup- [lll porting stem, combined inlet and discharge valve mechanism comprising annular coaxial valves mounted on sald stem, and means for opening and so maintaining one of said valves.

11. In combination, a single valve supporting stem. combined inlet and discharge valve mechanism comprising annular coaxial valves mounted on said stem, and means coaxial with said valves for opening and so maintaining one of said valves.

12. In combination` a single valve supporting stem` combined inlet and discharge valve mechanism comprising annular coaxial valves mounted on said stem, and means for opening and so maintaining said inlet valve.

13. In combination, combined inlet and discharge valve mechanism comprising annular coaxial valves, and means coaxial with said valves for opening and so maintaining said inlet valve.

14. In a pump, in combination, coaxially arranged inlet and discharge valve seats, c-

a fiange covering said opening and seated on i said support adjacent;v said opening, a pist0n movable therein, and means operated by said piston to open one of said valves.

15. In combination, combined inlet and discharge mechanism comprising coaxial ported valve seat elements and annular valves cooperating' with said seat elements, means for maintaining said valve seat elements in rigid relation extending axially thereof, and means for opening one of said valves and so maintaining it movable in a path parallel to but offset from the axis of said seat elements and through the port controlled by said valve to engage the latter and unseat it.

In testimony whereof I alix my signature.

FRANK A. HALLECK.

porting stem, combined inlet and discharge valve mechanism comprising annular coaxial valves mounted on Said stem, and means for opening and so maintaining one of said valves.

11. In combination, a single valve supporting stem. combined inlet and discharge valve mechanism comprising annular coaxial valves mounted on said stem, and means coaxial with said valves for opening and so maintaining one of said valves.

1Q. In combination` a single valve supporting stem combined inlet and discharge valve mechanism comprising annular coaxial valves mounted on said stem, and means :for opening and so maintaining said inlet valve.

l). In combination, combined inlet and discharge valve mechanism comprising annular coaxial valves, and means coaxial with said valves for opening and so maintaining said inlet valve.

14. In a pump, in combination, ooaxially arranged inlet and discharge valve seats, co-

axially arranged valves cooperating ,therewith, a hollow support having an opening therein, a coaxially disposed cylinder projecting into said hollow portion and having a flange covering said opening and seated on said support adjacent said opening, a piston movable therein, and means operated by said piston to open one of said valves.

15. In combination, combined inlet and discharge mechanism comprisingr coaxial ported valve seat elements and annular valves cooperating with said seat elements, means for maintaining said valve seat elements in rigid relation extending axially thereof, and means for opening one of said valves and so maintaining it movable in a path parallel to but ofset from the axis of said seat elements and through the port controlled by said valve to engage the latter and unseat it.

In testimony whereof I aix my signature.

FRANK A. HALLECK.

CERTIFICATE OF CORRECTION.

Patent No. l, 649, 298.

Granted November 15, 1927, to

FRANK A. HALLECK.

lt is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 6, line 17, claim 13, before theword "combined" insert the words and comma "a single valve supporting stem,", and line 19I after the word "valves" insert the words "mounted on said stem"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 17th day of January, A. D. 1928.

Seal.

M. J. Moore, Acting Commissioner of Patents.

CERTIFICATE 0F CORRECTION.

Patent No. 1,649,298. Granted November l5, i927, to

FRANK A. HALLECK.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 6, linel7, claim 13, before theword J'combined" insert the words and comma "a single valve supporting stem, and line 19, after the word "valves" insert the words "mounted on said stem"; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 17th day of January, A. D. 1928.

M. J. Moore, Seal. Acting Commissioner of Patents.

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