US746745A - Valve-gear for fluid-compressors. - Google Patents

Description

PA'TENTED DEC. 15, 1903.

P. M. mus. I VALVE GEAR FOR FLUID GOMPRESSORS.

APPLICATION FILED MAR. 5, 1903.

4 SHEETSSHEET 1,

N0 MODEL.

% wmmmm ORNEYS No. 746,745. PATENTEIS DEC. 15, 1903.

P. M. RITESl VALVE GEAR PORTLUID GOMPRESSORS.

APPLICATION FILED MAR. 5, 1903.

4 SHEETS-SHEET 2.

HO MODEL.

' ATTORNEYS PATENTED DEC. 15, 1.9031

F. M. RITES'.

VALVE GEAR FOR FLUID'GOMPRBSSORS.

APPLIGATION FILED MAR. 5, 1903.

N0 MODEL.

KAAA Q I INVENTOR ht/3Z2 BY' 44 g 'ad. A TORNEYS PATENTED DEC. 15,1903.

F. M. RITES. VALVE GEAR FOR FLUID commzssoas.

APIPLIOATION FILED MAB. 5, 1903.

' 4 SHEETS-SHEET 4.

N0 monnn,

INVENTOH GIL Q21 no: mmms warms co Pwmumm" WASHTNOTOR, oi c.

FRAN oIs M. srrns,

Patented December 1 5, 1 903.

ATENT- OF ICE.

OF ITHACA, NEW YORK, ASSIGNOR TO RALPH BAGGALEY, PITTSBURG, PENNSYLVANIA.

VALVE-G EAR FOR-FLU-lD-COlVI PRESSORS.

SPECIFICATION forming part of Letters Patent No. 746,745, dated D mbe 15, 1903.

t nmitt filed March 5, 1503.

of the invention, such as will enable others.

skilled in the art to which it appertains to make and use the same.

My invention relates to valve-gear for fluid-compressors; and it consists in the various novel features hereinafter pointed out in the claims.

The objects of my invention are to improve and simplify the valve-gear of fluid-compressors, to control automatically the adjustment of the valve-gear,so as to discharge the comat proper pressure into the receiver, to control in a simple manner the speed of the compressor, to operate the valves positively, to enable the compressor to operate at relatively high speed, to cause the valves to open and close quickly, and to provide ample port-opening.

I will now proceed to describe my invention withreference to theaccompanyingdrawings, in which valve-gears embodying myinvention are illustrated, and will then point out the novel features in claims.

In the said drawings, Figure 1 shows a side elevation of one side of an air-compressor, the side shown being that upon which the valve-gear of the air-cylinder is located. Fig. 2 shows a central vertical section of the compressor on a plane parallel to Fig. 1. Fig. 3 shows a central vertical section of the aireompressor on a plane at right angles to Figs. 1 and 2. Fig. 4 shows an elevation of the side of the compressor opposite that shown in Fig. 1 and in particular shows the valveear of the steam or motor cylinder. Fig. 5 shows a horizontal section, looking down, on the line XX of Fig. 2. Fig. 6 shows a central longitudinal section of the Speeder 36. Fig. 7 is a view similar to Fig. 1, showing an alternative valve-gear which maybe used for operating the valves of the compression-cylinder. Fig. 8 shows a section on a plane parallel to that of Fig. 7 through the pressed fluid Serial NO: 146,363. (No model.)

valve-chambers and valves of the compression-cylinder. A Fig. 9 is a detail viewshowing a side elevation of the valvegear of Fig. 7. Fig. 10 is a diagrammatic view illustrative of theconnectiouot the fluid pressure governor to one of the dischahge valves.

blowing-engine type, and certain of its structural features form the subject-matter of another application for Letters Patent filed -March 5,1903, Serial No. 146,362.

The compressor comprises a motor-cylinder 1 and a compression-cylinder 2, both cylinders being vertically arranged, the motor-cylinder being above the compression-cylinder. The steam-chest 3 of the motor-cylinder is provided with a liner-bushin g 4, within which works a piston-valve 5, controlling the admission of steam to and its-exhaust from the motor-cylinder. The exhaust from the cylinder passes into a chamber 6, formed therein, and thence out through exhaust-pipe 7. Live steam is admitted through pipe 8. The lower portion of the motor cylinder casting forms the upper head of the air-cylinder 2 and besides containing the exhaustchamher 6 is cored out to form air-passages 9 and 10. The compressiomcylinder rests upon a pedestal 11, forming the lower head of the cylinder 2, and in this pedestal are air-passages 12 and 13, corresponding, respectively, to passages 9 and 10. The pedestal rests upon a hollow base-piece l4, constituting the crankcase of the enginef The piston 15 of the aircylinder has as an integral part of it a hollow or trunk piston-rod l6,working within aguide cylinder formed in pedestal 11. Air-cham hers 9 and 12 are connected to a passage 19, which constitutes the ad mission-passage. Airchambers 10 and 13 are connected by a si milarpassage 20, constituting the air-discharge passage. In the upper and lower heads of the compression-cylinder are valve-chambers communicating with said admission and discharge passages, and within said valve-chambers are rotary double-ported valves 21, 22, 23, and 24. I r

The valve-gear of the steam or motor cylinder 1 isoperated by a shifting-eccentric governor 26 of wellknown type mounted upon a fly wheel 25, carried by the crank- The particular compressor shown is arm shaft of the engine. From the eccentric of said governor motion is transmitted to the valve 5 through an eccentric-rod 27, rockerarms 28 and 29, and a rod 30,connecting them, a rock-shaft 31, mounted in bearings above the steam-cylinder, a second rocker-arm 32 thereon, and a valve-rod 33. Another rockerarm 34, likewise secured to rock-shaft 31, is connected to the piston-rod 35 of a speeder 36, Fig. 6, such as is covered by my Patent No. 582,233, dated May 11, 1897, for a governing device for fluid-pressure motors. As described in said patent, the speeder comprises a cylinder and piston, the latter connected to a reciprocating member of a valvegear controlled by a governor, a by-pass passage connecting the ends of the cylinder, and a valve regulating the fiow of air or other elastic fluid from one end of the cylinder to the other. When the by-pass valve 37 is closed, the alternate compression and expansion of the air in the opposite ends of the cylinder tends to balance the inertia of the reciprocating parts of the valve-gear and to overcome the tendency of such inertia to shift the governor to a position of longer cut-off. When the by-pass valve is partly open, the inertia of the reciprocating parts is less completely balanced, and therefore the cut-oif is longer and the speed of the engine higher.

One valve-gear which may be used for operating the valves of the compression-cylinder 2 is shown in Figs. 1 and 3. A crank-pin 38, carried by one of the engine fly-Wheels, and a pitman-rod 39 transmit motion to a rocker-arm 40, connected to the lower ad mission-valve 23. Another arm, 41, likewise connected to said valve, transmits motion through a link 42 and similar arm 43 to the upper admission-valve-21. Upon the pitmanrod 39 are two crank-pins 44 and 45. A rod 46 connects pin 44 to a slotted link 47, hav ing an extension 48, pivoted at 49 to a spider 50, itself pivoted at 51 to a fixed portion of the engine and connected by rod 52, arranged approximately at right angles to pitman-rod 39, to pin 45. Within the guide-slot of link 47 there is a sliding block 53, connected by a rod 54 to an arm 56, which drives the upper discharge-valve 22. Another arm, 57, like; wise connected to said valve, drives the lower discharge-valve 24 through rod 58 and arm 59. Block 53 is adjusted in position with respect to link 47 by a cylinder 60, having a piston 61, Fig. 3, and piston-rod 62, connected to one arm, 63, of a bell-crank pivoted to a stationary portion of the engine, the other arm, 64, of said bell-crank being connected by a rod 65 to the rod 54 at the point 55 thereon. Piston 61 is operated by fluid-pressure, preferably hydraulic pressure, derivedlfrom any convenient source and is adjusted in position by a slide-valve 66 of the ordinary piston type controlling admission and exhaust of the fluid which operates said piston and adapted to prevent admission to or exhaust from either end of the cylinder or to permit admission to one end of the cylinder and exhaust from the other end, accordingto its position. Said valve is adjusted in position by a diaphragm 67, located within a diaphragmchamber 68, one side of which is connected to the discharge-passage 20 by a pipe 69,

while the other side is connected by a pipe 70 to a port 71, formed in the wall of the valve-chamber within which discharge-valve 22 is located. (See Fig. 10.) Said valve is a double-ported valve, having a passage 72 through it connecting the end of cylinder 2 and a recess 73 in the side of the valve-chamber. When the valve 22 opens at edge 74, it also opens at edge 75, thereby permitting compressed air to pass through port 72 and recess 73 into the portion of the valve-chamber 22 in rear of the valve, which portion is in communication with the main portion of the valve-chamber and the passage 10 by passages, (not shown,) and at the same time valve 22 connects port 71 to the cylinder 2 by means of a recess 76, and if the pressure in said cylinder at the instant when the valve 22 opens is either less or greater thauthe pressure in the discharge passage20 then obviously the diaphragm 67 will shift valve 66, so as to admit fluid under pressure to one end of adjusting-cylinder and to permit exhaust of fluid from the other end of said cylinder, thereby moving the piston 61 and shifting the position of the block 53, so varying the point of opening of the valves 22 and 24. As soon as equilibrium between the pressure at which the air compressed by the cylinder 2 is discharged and the-pressure in the discharge-passage 20 has been established the diaphragm 67 will move valve 66 to its central position, thus preventing admission of fluid to or exhaust of fluid from either end of cylinder 60, thereby locking the piston 61. A governor operating upon substantially this principle for controlling the pressure at which a compressor discharges the fluid compressed is covered by Patent No.636,180, granted to me on October 31, 1899, for a fluid-compressor.

The operation of this valve-gear will now be described. Rotation is in'the direction of the arrow shown in Fig. 1. The piston is just beginning a downstroke, and therefore the upper discharge-valve 22 has just closed. Since crank-pin 44 is close to crank-pin 38, its motion is nearly circular. At this time the crank-pin 44 is in a portion of its arc of travel in which its motion is nearly in line with the rod 46, so that the linear motion of said rod is relatively rapid. Crank-pin 45, which moves in a path which is approximately elliptical, is at the time moving in a direction nearly at right angles to the rod 52, and therefore the motion of crank-pin 45 produces at the time relatively little movement of spider 50. During the first portion of the downstroke of the piston, therefore, link 47 moves nearly as if it were moving about-a fixed center at 49,and obviously valve 24 will open early or late in the stroke, according as the block 53 is near the center or near the end of the link. As the piston nears and passes half-stroke the motion imparted to point 49 grows more rapid with respect to the angularvelocity of cran kpin 38,and therefore the inner end of the link 47 is moved down, so that when the crank-pin 44 after passing its dead-center begins to move up again to close said valve 24 the latter will close at about the end of the downstroke of the pis ton in whatever portion of the link 47 the block 53 may be. On the upstroke of the piston the valve 22 is opened in a similar manner at a variable point in the stroke, depending upon the position of block 53 in link 47, said link first moving about point 49 as a center, while said point remains very nearly stationary, after which point 49 rises, so that valve 22 may close at or about the end of the upstroke of the piston in whatever portion of the link 47 block 53 may be.

This valve-gear gives relatively rapid portopening, and the block 53 is readily adjusted along the link by cylinder to discharge at the pressure existing in the discharge-passage. Oylinder 60 does not regulate the quantity of gas com pressed. Regulation of quantity is eifected by varying the speed of the compressor by means of the speeder 36.

It will be noted that the motion imparted by crank-pin 45 and pitman-rod 52 to the link 47 is substantially the motion that would be imparted by a crank-pin revolving with the fly-wheel and a pitman therefor so arranged that the crank-pin is substantially on a deadoenter when the piston is at the end of its stroke. Crank-pin 45is substantially on a dead-center with respect to pitman 52 when the piston is at either end of its stroke.

In Figs. 7 to 9, inclusive, I show a valvegear similar in many respects to that just described, but in which both crank-pins which operate the link revolve with the fly-wheel. One of these crank-pins is carried by the fly-wheel 81 and has a return crank-arm 82 keyed to it, carrying a second crank-pin 83. The motion of crank-pin 83 is the same as though it were carried directly by the flywheel. Grank-pin 80 has a pitman-rod 84, which for lightness and strength is of the triangular form shown and is connected to the link 85, corresponding substantially to link 47 of Fig. 1, and is also connected by a rod or link 86 to an arm 87 for operating the admission-valves, reference to which will be made hereinafter. Crank-pin 83 is connected to link by a pitman 88, which is guided at its point of connection to the link by means of an arm 89, pivoted to some stationary portion of the engine. Link 85 has a sliding block 90, connected by a rod 91 to a wrist-plate92, pivoted upon a stud 93 and connected by adjustable rods 94 and 95 to the arms 96 and 97 of the two discharge-valves. The relation of the points of connection of these rods 94 and 95 to the wrist-plate 92 and to the valve- arms 96 and 97 is such that the valves are moved with relative rapidity at the times of opening.

and closing of the valves, so as to avoid wiredrawing. The block 90 is adjusted in position on the link 85 by means of a pressure-cylinder 60, similar to that shown in Figs. 1 and 3, the piston-rod 62 of which has in it a yoke 98, spanning the hubs ot wrist-plate 92 and the other wrist-plate hereinafter referred to and connected to one arm of a bel1-crank 99, the other arm of which is connected by a rod 100 to rod 91. Motion of the piston of this cylinder 60 is controlled by a diaphragm and valve, the same as shown in Fig. 3. The admission-valves are operated from arm 87 by an arm 101, connected thereto and connected by a rod 102 to a second wrist-plate 103, mounted upon the stud 93, and connected by adjustable rods104 and 105 to arms 106 and 107 of the admission-valves. The operation of this valve-gear is as follows: In Fig. 7 the parts of the valve-gear are shown in positions occupied at the beginning of a downstroke of the piston, rotation being clockwise. Crank-pin 83 is substantially on a dead-center, while crank-pin 80 is in that portion of its arc in which it transmits motion mostrapidly to its pitman, the angles of advance of the crankpins being different. the beginning of the downstroke link 85 moves nearly as if'it were moving about a fixed center located at the point of connection of said link to arm 89, and obviously the lowerdischarge-valve will open early or late in the stroke, according as the block 90 is near the center or near the end of the link. As the piston moves downward the crankpin 83 moves arm 89 downward, at first slowly and then more rapidly, and therefore the inher end of link 85 is moved down, so that when crank-pin 80 after passing its dead-center begins to move up again to close the upper discharge-valve the latter will close at aboutthe end of the downstroke of thepiston in Whatever portion of the link 85 the block 90 may be. On the upstroke of the piston the upper discharge-valve is opened in a similar manner at a variable point in the stroke, depending upon the position of the block 90 on link 85, said link first moving about its point of connection to arm 89 nearly as if said arm were stationary, so that the upper discharge-valve will open at a variable point determined by the position of block 90, the arm'89 afterward moving more rapidly, so that atwhatever position the upper discharge-valve may open it will close at about the end of the upstroke. It will be seen that the motion imparted to the link 85 is practically the same as that imparted to the link 47 by the valve-gear shown in Fig. 1. Since, however, motion is imparted from this link .to the discharge-valve through a wrist-plate, the discharge-valves are opened and closed very rapidly, owing to the well-known action of such a wrist-plate and the rods connecting it to the valve-arms. While the dischargevalves are opened and closed in the mannerabove mentioned, the admission-valves are also opened and closed through the vibration of wrist-plate 103, said admission-valves each to remain open during substantially all ofits respective admission-stroke. It will be noted that all of the valves of the compression-cylinder are operated positively by this valve-gear. This permits a relatively high speed of rotation of the engine, such as is not possible with independent admission and discharge valves for both ends ofa cylinder operated .by nonpositive valve-gear, while at the same time valves of the Corliss type may be used, and such valves have substantially the same motion as would be imparted to them by valvegear of the Corliss type. Crank- pins 80 and 83 are substantially eccentrics, and disk eccentrics might be used in place of these crankpins.

In Fig. 8 I illustrate a form of valve which I preferably employ both for the admission and for the discharge valves of the compressioncylinder. These valves are similar, and a description of one of them will answer for them all. Eachvalveisacylinderrotativelymounted in a cylindrical valve-chamber and having a recess 108, adapted to form a port to connect a port 109, leading from the interior of the cylinder to said valve-chamber, and another port 110, connecting said chamber and the receiver-space of the engine. The valve has also a passage 111, forming a second port for the same purpose. These two ports of the valve open and close simultaneously, and thereby afford large port-opening when the valve is only partly open. The forms of recess 108 and passage 111 are such as to permit exceedingly easy flow of the air, since there are no sharp bends. The valve-chambers are provided with balancing-recesses 112 and 113, with one of which passage 11] connects when the valve is closed, while with the other a passage 114 in the valve connects. The purpose of these recesses is to partly balance the pressure upon the valve, so as to reduce friction.

The blowing engine above described is intended to operate at a relatively high rotative speednamely, twohundred revolutions per minute and over. Because of its relatively high rotative speed, rendered possible by its general compactness of design and by the positive operation of all of the air-valves, a relativelysmall compressor is able to do the work heretofore done by machines of much larger size.

It is obvious that the invention'herein described is capable of many variations and modifications, and I do not limit myself to the particular details of construction and arrangement herein shown and described.

What I claim is 1. In a fluid-compressor, the combination with a discharge-valve, alink, a sliding block thereon and means connected to said block for operating said valve, of a movable guide for said link pivotally connected to it, means for oscillating said link about its guide, other means for moving said guide during the oscillation of the link, and automatic fluid-pressure-governing means, actuated by variation in relation of pressure reached in the compressor to pressure in the receiver, for ad justing the position of the block on the link.

2. In a fluid-compressor, the combination with a discharge-valve, a link, a sliding block thereon and means connected to said block for operating said valve, of a movable guide for the link pivotally connected thereto, means for vibrating said guide arranged to move such pivotal point relatively slowly during the early portion of each stroke,means for oscillating said link about said guide during such early portion of the stroke, and automatic means for adjusting the position of the block upon the link.

3. In a fluid-compressor, the combination with a discharge-valve, a link, a sliding block thereon and means connected to said block for operating said valve, of a movable guide for the link pivotally connected thereto, a crank pin and a pitman therefor connected to said guide and arranged to vibrate the same, said crank-pin being in proximity to a dead-center during the early portion of each stroke, a second crank-pin or equivalent device and a pitman therefor connected to said link and adapted to vibrate the same about said guide, said second crank-pin arranged to move said link with relative rapidity during the early portion of each stroke, and automatic means for adjusting the position of the block upon the link.

at. In a fluid-compressor, the combination with a discharge-valve, a link, a sliding block thereon, and means connected to said block for operating said valve, of means for movably supporting and operating said link, comprising two crank -pins and pitmen arranged to transmit motion therefrom to said link,

.said crank-pins arranged to arrive at their respective dead-centers with respect to their pitmen at different times, and automatic means for adjusting the position of said block upon said link.

5. In a fluid-compressor, the combination with a discharge-valve, a link, a sliding block thereon, means for communicating motion from said block to said valve and a swinging arm for guiding said link pivotally connected thereto, of two crank-pins for giving motion to said link, and pitmen therefor, one of said pitmen connected to said arm, the other connected to said link, and automatic fluid-pressure-governing means, actuated by variation in relation of pressure reached in the compressor to pressure in the receiver, for adjusting the position of the block upon the link.

6. In a fluid-compressor, the combination with a discharge-valve, a link, a sliding block thereon and means connected to said block for operating said valve, of a movable guide for said link pivotally connected to it, means for oscillating said link about its guide, other means for moving said guide during the oscillation of the link, and automatic governor mechanism for adjusting the position of the block upon the link comprising a fluid-pressure cylinder, a piston therefor, a valve, and a fluid'pressure-actuated device, connected to the receiver and to the compression-cylinder for adjusting the position of the valve.

7. In a fluid-com pressor, the combination with a discharge-valve, a link, a sliding block thereon and means connected to said block for operating said valve, of a movable guide for the link pivotally connected thereto, means for vibrating said guide arranged to move such pivotal point relatively slowly during the early portion of each stroke, means for oscillating said link about said guide during such early portion of the stroke, and automatic governor mechanism for adjusting the position of the block upon the link comprising a fluid-pressure cylinder, a piston therefor, a valve, and means operated by fluid-pressure for adjusting the position of the valve.

-8. In a fluid-compressor, the combination with a discharge-valve, a link, a sliding block thereon and means connected to said block for operating said valve, of a movable guide for the link pivotally connected thereto, a crank-pin and a pitman therefor connected to said guide and arranged to vibrate the same, said crank-pin being in proximity to a dead-center during the early portion of each stroke, a second crank-pin or equivalent device and a pitman therefor connected to said link and adapted to vibrate the same about'said guide, said second crank-pin arranged to move said link with relative rapids ity during the early portion of each stroke, and automatic governor mechanism for adjusting the position of the block upon the link comprising a fluid-pressupe cylinder, a piston therefor, a valve, and means operated by fluid-pressure for adjusting the position of the valve. I

9. In a fluid-compressor, the combination with a discharge-valve, a link, a sliding block thereon, and means connected to said block for operating saidvalve, of means for movably guiding and operating said link, comprising two crank-pins and pitmen arranged to transmit motion therefrom to said link, said crank-pin arranged to arrive at their respective dead-centers with respect to their pitmen at different times, and automatic governor mechanism for adjusting the position of the block upon the link comprising a fluidpressure cylinder, a piston therefor, a valve,

and means operated byfluid-pressure for adjusting the position of the valve.

10. In a fluid-compressor, the combination with ad mission and discharge valves,a crankpin and a pitman, of a link, a block thereon, means connected to said block for operating said discharge-valve, means i l 1 i the position of the block on the link, a guide, for the link, means for vibrating said link comprising a connection to said pitman other means for vibrating said guide during the oscillation of the link, and means independent of the link, but operated by said pitman, for operating the admission-valve.

11. In a fluid-compressor, the combination with a discharge-valve, a valve-arm therefor, a wrist-plate, and a rod connecting said valvearm with said wrist-plate at a point which moves in a direction approximating a right angle to the line of the rod in closed positions of the valve and in a direction approximating parallelism with said rod in open positions of the valve, of means for vibrating said wrist plate, comprising adjustable means for varying the time of opening of the valve.

12. In a fluid-compressor, the combination with a discharge-valve, a valve-arm therefor, a wrist-plate, and a rod connecting said val vearm with said wrist-plate at a point which moves in a direction approximating a right angle to the line of the rod in closed positions of the valve and in a direction approximating parallelism with said rod in open positions of the valve, of means for vibrating said wristplate, comprising adjustable means for varying the time of opening of the valve, and automatic governing means for afiecting the adjustment.

13. In a fluid-compressor, the combination with a discharge-valve, a valve-arm therefor, a wrist-plate, and a rod connecting said valvearm with said wrist-plate at a point which moves in a direction approximating a right angle to the line of the rod in closed positions of the valve and in a direction approximating parallelism with said rodin open positions of the valve, of means for vibrating said wristplate, comprising adjusting said block along said link, and means for vibrating said link.

14. In a fluid-compressor, the combination with a discharge-valve, a valve-arm therefor, a wrist-plate, and a rod connecting said val vearm with said wrist-plate at a point which moves in a direction approximating a right angle to the line of the rod in closed positions of the valve and in a direction approximating parallelism with said rod in open positions of the valve, of means for vibrating said wristplate, comprising a link, a block, means for adjusting said block along said link, and means for vibrating said link comprising two crank-pins having difierent angles of advance and .pitmen therefor connected to said link.

15. In a fluid-compressor, the combination with a discharge-valve, a wrist-plate, and means for driving said valve from said wristplate, of means for vibrating said wrist-plate, comprising a link, a block, means for adjusting said block along said link, and means for vibrating said link comprising two crank-pins for adjusting l or equivalentdevices and pitmen therefor cona link, a block, means for .llO

nected to the link, one crank-pin substantially on dead-center at the beginning of each stroke, the other crank-pin in advance of its dead-center position at the beginning of each stroke.

16. In a fluid-compressor, the combination with separate admission and discharge valves, separate wrist-plates for said admission and discharge valves, and means for driving said valves from their respective wrist-plates, the means for driving the discharge-valves comprising valve-arms, and rods connecting said arms to points on the discharge-valve wristplate Which move in directions approximating right angles with respect to their respective rods, during closed positions of the corresponding valves, and in directions approxi-' mating parallelism with respect to their respective rods, in open positions of the corresponding valves, of means for driving the admission-valve Wrist-plate, and means for driving the discharge-valve wrist-plate comprising adjusting means for varying the time of discharge.

17. In a fluid-compressor,- the combination with separate admission and discharge valves, separate wrist-plates for said admission and discharge valves, and means for driving said valves from their respective Wrist-plates, the means for driving the discharge-valves comprising valve-arms, and rods connecting said arms to points on the discharge-valve wristplate which move in directions approximating right angles with respect to their respective rods, during closed positions of the corresponding valves, and in directions approximating parallelism with respect to their respective rods, in open positions of the corresponding valves, of-means for driving said admission wrist-plate, and means for driving said discharge wrist-plate comprising a link, a block and means for adjusting said block along said link to vary the time of discharge.

18. In a fluid-compressor, the combination with separate admission and discharge valves, separate wrist-plates for said admission and discharge valves, and means for driving said valves from their respective wrist-plates, the means for driving the discharge-valves com prising valve-arms, and rods connecting said arms to points on the discharge-valve wristplate which move in directions approximating right angles with respect to their respective rods, during closed positions of the corresponding valves, and in directions approximating parallelism with respect to their re spective rods, in open positions of the corresponding valves, of mechanism for driving said wrist-plates comprising a crank-pin, a pitman therefor, and means connecting said pitman to each of said Wrist-plates.

19. In a fluid-compressor, the combination with separate admission and discharge valves, separate wrist-plates for said admission and discharge valves, and means for driving said valves from their respective Wrist-plates, of two crank-pins having difierent angles of ad- Vance, a swinging arm and means connected therewith for operating the admission wristplate, a second swinging arm, a link pivotally connected thereto, a block on said link, and means connecting said block to the discharge Wrist-plate, a pitman connecting one of said crank-pins to said first-mentioned swinging arm and to said link, and another pitman connecting the other crank-pin to said second swinging arm.

In testimony whereof I affix my signature in the presence of two witnesses.

FRANCIS M. RITES. Witnesses:

C. F. CARRINGTON,

MINERVA POPE.

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