I, 28? WWW

Sept. 18, 1934.
J. K. DOUGLAS
-
1,974,134
PUMP
_
Filed Jan. 24, 1931
‘12-1
‘
4 Sheets-Sheet
1
P4.
46'
74
gwuentoz
JAMES K. DDLIGLAS.
I, 28? WWW
Sept. 18, 1934.
J. K.v DOUGLAS
1,974,134
PUMP
Filed Jan.‘ 24, 1931
4 Sheets-Sheet‘ 3
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JAMES K. DOUGLAS.
Sept. 18, 1934.
1,974,134
J. K. DOLIGLAS
PUMP
Filed Jan. 24, 1931
4 Sheets-Sheet
4
55
'LJAMES K. DUUGLAS.
12,7
/.9
W%
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Patented Sept. lé, ‘1,934
1,974,134 "
umraojs'm Tris , PATENT‘- OFFICE ~_
1,914,134
rum
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James K. Douglas, Milwaukee, Wis., assigno'r to v
The Oilgear Company, Milwaukee, Wis., a cor:
poration of Wisconsin
Application January 24, 1931, Serial Nat-10,965
4 Claims.
(01. (makes) '
This invention relates to positive displacement tons reciprocated in the ‘cylinders and the cylin
der barrel rotated upon the pintle by a circular
driver which engages the outer ends of the. pistons
and has its axis of rotation eccentric to the axis
of the pintle, and the working liquid delivered. to 60
pumps which have two relatively rotatable parts
arranged one within the other and the coacting
surfaces thereof separated by a lubricating ?lm
5 which is maintained therein by the working ?uid
of the pump and subjected at all times to pump ~
pressure.
.
Such pumps are frequently employed, to per
and discharged from the cylinders through ports
and passageways formed in the pintle. A pump
of this character is fully illustrated and described
form work which requires the highest possible in Patent No. 1,753,562 issued April 8, 1930 to John P.. Ferris. '
>,
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.
.y
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65
10 degree of accuracy in the delivery rate of the.
The pump disclosed’. in the above patent has
pump during a wide’variation in certain factors ‘/been
extensively and successfully‘ used but, when
which tend to change the delivery rate, such as
variation in the viscosity of the working fluid,“ it is employed to operate the hydraulic vfeeds of
,
due to temperature changes, and variation in the certain machine tools, the variation in slip precludes the possibility of accurately and uniformly 70 _'
pressure
of
the
working
?uid
due
to
variation
in
H 91
maintaining a finely graduated feeding speed.
the resistance encountered thereby.
'
_
As'an illustration, a pump of thesize' which is
The working‘ ?uid is ordinarily a good quality
of lubricating oil which provides a satisfactory ordinarily employed to operate machine tool feeds
?lm between the coacting surfaces of the rela has a slip of about 20 cubic inches per minute at .75
moderate temperatures and pressures, but tem-'
20 tively rotatable parts but which varies in vis-, peratures and pressuresare often created which
cosity in accordance with the variation in the
temperature thereof.
\
'
. The clearance between the coacting surfaces of
the relatively rotating parts is ordinarily sum
cause the slip to increase to 30 cubic, inches per ‘
minute.
T
'
‘
'
'
'
A variation in slip of 10 cubic inches is small
80
' cientito allow a film of oil in its heaviest or most relatively to the volumetric capacity of the pump .
viscous state to be formed therein and, as this but it often happens that a delivery of only 20
?lm is subjected to pump pressure and as the cubic inches per minute is required to produce
parts rotate relatively to each other when the,‘ a desired feeding speed and then a. variation of '
'30
pump is in operation, a small volume of oil leaks
from between these parts and another small vol
ume passes from the discharge side of the pump
to the intake side thereof so that the volume of
oil delivered to an external circuit is less than
the volume of oil which passes through the pump.
The total volume of oil which is lost by leakage
and by passing from the discharge side ‘of the
pump to the intake side thereof is generally desig-.
nated as the slip of the pump, that is, the slip
10 cubic inches in slip will cause an error of 50%
in the feeding speed.
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85
In order to reduce slip~ and to maintain the
net delivery of- the pump as constant as possible,
the clearance between the pintle and the cylinder -
barrel‘ has been reduced far below that‘ ordinarily
allowed between relatively rotating parts of cor
responding diameters, and devices responsive to
cc
an increase in presure have been provided for
increasing the stroke of the pump to compensate
_
of a pump is the di?erence between. the volume for the increase in slip caused by the increase in, 95
of oil pumped by the pump and the volume ‘actu
pressure.
,
~
ally delivered thereby to an external circuit.
It has been found, however, that it is neces,
At room temperatures and under low pressures, . sary to compensate for variations in both pres- '_ i
this slip is negligible relatively to the volumetric sure and temperature in order tomaintain. the
capacity of the pump but it increases in re
net delivery of the pump constant.
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'
m0 '
- sponse to increases in pressure and temperature,
An object of the invention is to provide a pump‘
the increased pressure'forcing the 011 more rapid having a net delivery'which remains substan
ly from between the’ relatively rotating parts and tially constant throughout a wide range of varia
the increase in temperature reducing the viscosity tion in temperature and pressure. '
a
‘
’
of the oil and allowing it to ?ow more rapidly
Another object is to provide apositive displace-1 105
‘from between the relatively rotating parts at any ment pump which is self-compensated for slip. ,
given pressure.
a
‘The invention-is exempli?ed by the pump illus
For the purposeo f illustration,1 the invention trated in the accompanying drawings‘in which
has been shown embo died in a pump which has its the views are as follows: 4
'
cylinders arranged radially in _a cylinder barrel
Fig. 1 ‘is a‘ central vertical se
55, journaled upon a central shaft or pintle, its pis
ction (through a my
2
1,974,134
pump in which the invention is embodied, certain posite each ?ange 19 with an opening 29 through
parts being shown in full and other parts partly which a push pin 24 extends.
/
broken away.
Each of the cylinders 21 has a port 30 formed
Fig. 2 is a schematic drawing illustrating the in the inner end thereof to register alternately
hydraulic circuit of the pump.
‘
Fig. 3 is a transverse section on the line 3—3
of Fig. ‘1.
Fig. 4 is a transverse section on the line 4-4
of Fig. 1.
10
with a segmental intake port 31 and a segmental 80
discharge port 32 which are formed diametrically
opposite each other in the pintle 23.
“
When the driver 6 is rotated, the cylinder bar- ‘
rel 22 is rotated and, if the pintle 23 is positioned
Fig. 5 is a longitudinal section on'the line 5~5 V eccentric to the axis of the driver 6, thepistons
I
of Fig. 3.
20 upon one side ‘of the pintle 23 are drawn out
The pump chosen for illustration is of the same wardly by the ?ange 28 and‘the pistons 20 upon
type as the pump shown in Patent No. 1,753,562 the other side thereof are forced inwardly by the
referred to above, and the characteristics which
15 are common to both pumps have not been illus
trated in detail nor extensively described herein.‘
The pump mechanism is arranged within and
- supported by a casing 1 having a liquid reservoir
2 in the lower part thereof and its front closed
by a plate 3 in which the outer end of a pump
shaft 4 is journaled.
25
'
The shaft 4 is provided at its outer end with
means, such as a pulley 5, for connecting the pump
to a prime mover and has its inner end connected
to the driver 6 of a variable displacement pump.
The driver 6 is journaled in an anti-friction bear
ing 7 which is carried by a bracket 8 ‘attached
to the front plate 3, thereby rotatably supporting
the inner end of the shaft 4.
30
The bracket 8 has a gear pump chamber 9
?anges 19.
85
_
The outwardly moving pistons 20 draw liquid 90
into their cylinders 21 through the ports 30 and
31 and the inwardly moving pistons 20- expel
liquid from their cylinders 21 through the ports 30
and 32, the volume of liquid delivered by the pump
depending upon the position of the pintle 23
relative to the axis of the driver 6.
'
’ The pintle 23 is carried by a rock arm 33 having
a sleeve 34 arranged at its upper end and jour
naled upon a. tubular support 35 which is rigidly
secured at its front end in the bracket 8 and has 100
a stationary arm 36 secured in position upon its
rear endby a clamping bolt 37.
The lower part of the rock arm 33 is provided
with an intake passageway 38 and a discharge
passageway 39 which communicate with the in- 1 05:
formed therein and closed at its front by the front take port 31 and the discharge port 32, respective
plate 3 to enclose a gear pump which has its driv
ly, through two passageways 40 and 41 formed >
ing gear 10 ?xed upon the shaft 4 and its driven axially in the pintle 23.
gear 11 arranged upon a‘ stub-shaft’ 12 carried
The passageways 38 and 39 are connected, re
r
35 by the bracket 8.
spectively, through two tubes 42v and 43 to an in- 1
The gear pump, which has a larger volumetric take passageway 44 and a discharge passageway 10
capacity than the variable displacement pump, 45 formed in the upper end of the stationary
has its intake connected to the reservoir 2 by a arm 36.
.
suction pipe 13 and its outlet connected by a low
The
intake
passageway 44 has the low pres
40 pressure supply pipe 14 to the intake of the vari
able displacement pump and to a control valve 15 sure supply pipe 14 connected thereto and the 1 15
which isarranged in the front plate 3. The pres discharge passageway 45 is connected by an out
pipe 46 to the control valve 15,. as shown dia
sure of the liquid delivered by the gear pump is let
grammatically in Fig. 2.
limited by a relief valve 16 through which excess
The tubes 42 and 43 have their upper ends
45 ‘liquid is exhausted, as shown diagrammatically
rounded and ?tted in concave seats 47, which 1 201
in Fig. 2.
’
The relief valve 16 exhausts into a'chamber 17 are formed in the upper end of the stationary
which is formed in the bracket 8 and cpmmuni arm 36 in alinement with the passageways 44
cates with the chamber 9 and with the front' and 45, and their lower ends rounded and ?tted
50 bearing of the shaft 4 so that liquid delivered to in concave seats 48, which are formed in plungers
the chamber 17 may form a liquid seal around 49 ?tted in the enlarged upper ends, of the pas ha 25
the gear pump and lubricate the shaft bearing, as sageways 38 and 39.
The rounded ends of the tubes 42 and 43 are
fully disclosed in the patent referred to above.
The upper part of the chamber 17 has an over held in ?rm engagement with the seats 47 and
65 ?ow pipe 18 connected thereto through which liq 48 by the ?uid pressure against the inner ends
uid is returned to the reservoir 2.
‘
of plungers 49, and also by helical compression 1
The driver 6 has a number of segmental ?anges springs 50, one of which is arranged between
>
19 arranged around its outer periphery .for re
the lower end of each plunger 49 and a shoulder
ciprocating an equal number of hollow pistons 20 51 formed in each of the passageways 38 and 39.
C0 in their cylinders 21 which are formed in a cyl
The tubes 42 and 43 thus provide ?exible con
inder barrel 22 and arranged in radial ‘alinement nections for the ?ow of liquid between the lower 1 35
with the ?anges 19, the cylinder barrel 22 being end, of the rock arm 33 and'the upper end of the
journaled upon a pintle 23 which is arranged stationary arm 36 and allow the arm. 33 to be
eccentric to the axis of the driver 6 when the rocked upon the support 35 without affecting this
'
65 pump is delivering liquid.
)Each of the pistons 20 has a push pin 24 secured
?ow of liquid.
'
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\The gear pump draws liquid from the reservoir ‘L it,
loosely therein and provided upon its, outer end 2 through the pipe 13 and delivers it through the
I I
with a crosshead 25 which bears against an anti pipe 14, the passageway 44, the tube 42, the
i'riction bearing 26 arranged between it and a passageway 38, the passageway 40 and the intake
hardened bearing plate 27 carried by the corre port 31 to the cylinders 21. Liquid is discharged
sponding. ?ange 19.
,
v
from the cylinders 21 through the outlet port 32,
The inner face of each 'crosshead 25 bears the passageway 41, the passageway _39,,-the tube
against the flattened periphery of an annular
43, the passageway 45 and the pipe 46 to the
?ange 28 which is formed on the driver 6 con valve 15,; the pressure created by the variable
centric to its axis‘ of rotation and provided 0;) displacement pump being limited by a high pres-
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‘ 45
150
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1,974,134
'su're relief valve 52 which is connected to the;
pipe 46 and discharges into the reservoir 2.
I‘ In ‘the prior pump, the cylinder barrel is
ordinarily made of cast iron and; the pintle of
steel but, in the present invention, the pintle is
journaled thereon and provided with a‘ threaded
laterat bore 65 to receive the threaded end of a
thrust pin 66. The head 64 is bifurcated along one
side of the bore 65 and provided with a bolt 6'7 for ~
clamping the thrust pin 66 in adjusted positions.
The head of the thrust ‘pin 66 abuts the inner
made of a metal, such as brass or bronze, which end’ of a recess 68 formed in the front end of a
has a much higher coemcient of expansion‘ than plunger 69 which is provided upon its rear end
the cast iron of “which the cylinder barrel is with a guide pin '70 and arranged forreciprocation
made. Consequently, an increase in temperature in a bore '71 formed in a piston '72 and in the stem 85
will cause the pintle to have a‘ greater diametral
expansion than the cylinder barrel with the re
sultant reduction in the clearance between the
same, and this reduction in clearance corresponds
substantially to the reduction in the viscosity of
15 the oil throughout the range of ordinary operat
ing temperatures, for instance, up. to 140° vF.
In other words, the pintle expands and reduces
the clearance between itself and the cylinder
barrel in response to increases in temperature
and thereby prevents a substantially greater
120' amount of oil ‘from escaping when the pintle and
the oil are heated than can escapewhen both are
7 cold.
'73 thereof.
'
The piston '72 is ?tted» in a cylinder '74, which
is carried by the lower end or the stationary arm
36 and closed at its inner end by an integralhead
'75 and at its outer end by a cap 76, and the stem 90
'73 extends through the head '75 and is ?tted there-. v
into prevent the escape of liquid from the cylin
der '74.
Q
~
.The piston '72 is urged against the head 75 by a
helical compression spring '77 which abuts the in 95
ner face of the capg'76 and is arranged in an an
nular recess '78 formed in the piston '72.
The plunger ,69 is urged outwardly against‘the .
thrust pin 66 by a stack of Belleville spring wash
In actual practice, the pintle and the bore of ers '79 which are arranged in the bore '11 between 100v
the inner end thereof and the plunger 69.
to a close ?t, and then the cylinder barrelis
The piston '72 has a bore’80 of smaller diameter
adjusted upon the pintle to provide the closest than the bore '71 and coaxial therewith to receive
possible running ?t when the pintle and the a helical compression spring 81 which holds the
cylinder barrel are heated to the highest’tem washers '79 against movement relatively to the 105
30 perature, which may be encountered in service, plunger 69 when the piston '72 is retracted. A still
for instance 160° F., atwhich time the, oil is smaller bore 82 in the outer end of the piston '72
'~ thinnest and provides a very thin lubricating ?lm receives the end of the guide pin '10 whichv ex
“ between the cylinder barrel and'the pintle.
tends through the washers '79 and the spring 81.
‘For example, a common size pump has a 117;”
The-cylinder '74 is connected by a duct 83, which 110
35 diameter bronze pintle and a cast iron cylinder is formed in the arm 36, to a pipe 84 which is
barrel ?tted thereon‘ to provide a‘ clearance of connected to the control valve 15 as shown dia
about .0006 inches when hot. If a considerably grammatically in Fig. 2, andthe control valve 15
larger or smaller pintle is employed, materials maybe operated to direct liquid ‘from the gear
are- selected which have the correct relative pump to the cylinder‘ '74 to retract the piston '72 115
thermal characteristics.
,
against the resistance of the spring '77.
A reduction in temperature causes an increase
Retracticn of, the piston '72 allows the pump to
25 the cylinder barrel are tapered slightly and lapped
inthe clearance between the cylinder barrel and increase its stroke until a lug 85 on the rock arm
the pintle and a corresponding increase in the 33 engages a stop bolt 86, as will be described here
viscosity of the oil so that the amount of slip inafter. The bolt 86 is threaded into the station 120
remains substantially constant throughout the ary arm 36 and is adjusted to arrest further move
entire range of operating temperatures.
.
ment of the arm 33 when full stroke or a pre
As the metals which are otherwise suitable determined maximum displacement has been
for pint1e=constructionare usually too soft to
reached.
,
'
provide high resistance to the wear thereon, the
Aspreviously stated, the gear pump has a larger 125
pintle is preferably provided with a shell or cover volumetric capacitythan the‘ variable displace
ing 53 'of hard metal, such as’chromi'um; to re, ment pump and delivers liquid to the intake of the
sist the wear thereon and this covering'is genef-_ variable displacement pump so that it maintains
ally applied by plating the pintle with chromium in'the passageways 40 and 44 av pressure deter
andthen grinding and ?tting, it to the'cylinder mined by the‘ adjustment of the relief valve 16.
130
, This liquid acts upon the opposed walls of the
‘ The stroke of the pump may be changed, to passageways 40 and 44 and tends to separate
obtain accurately graduated changes in displace them, thereby tending to swing the rock arm 33
ment, by operating a control lever 54 secured upon upon the support 35 and holding the thrust pin
the front end of acontrol shaft 55 which is jour 66' in engagement with the plunger 69.
.
naled in the front plate 3 and has a locking lever
When the variable displacement pump is deliv
barrel.
,
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T
56 threaded thereon for securing it in adjusted ering liquid under pressure, the liquid in the pas
'
39 and 45 acts upon the opposed walls
The control shaft 55 extends rearwardly sageways
thereof andolikewise tends to swing the rock arm
through the‘tubular; support 35 and it is held 33 upon the support 35 and, when the pressure ‘of .1 against axial movement by a collar 5'7 and a gear the discharge liquid becomes high enough to cause
58 which are secured thereon inengagement, re,- a
. spectively, with the front and rear ends of the sup‘ an appreciable increase in the slip of the pump,
the force exerted by thedischarge liquid is suil‘l-v
positions.
port 35.
,
t
.
,
The gear~58 meshes with an idler gear 59 which cient to compress the Belleville washers and swing ~
is arranged upon a shaft 60 carried .by the rock the lower end of the arm 33 toward the piston '72
arm 33,\and the gear 59 meshes with a gear 61 to increase the stroke of the pump a correspond
‘ .journaled upon a shaft 62 which is carried by the ing amount and thereby increase the volume-of
liquid discharged from the cylinders an amount.v
1
pintle 23 at the rear end thereof.
_
,
which is substantially equab to the increase" in
the
gear
61
is
eccentric
to
the
The hub 63 of
; axis of the shaft 62 and has an eccentric head 64‘
slip.
,
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i '
4
10
15
20
25
1,974,134
As variations in temperature cause variations intake and discharge ‘passageways, a pintle car
in the diameter of the pintle with the resultant ried by said rock arm and having intake and
variations in the clearance between the pintle ‘ discharge ports and passageways communicat
and the cylinder barrel, so that the slip of the ing with the intake and discharge passageways in
pump is maintained substantially constant at any said rock arm, a cylinder barrel journaled upon
given temperature, and as the pump automati said pintle and having cylinders arranged radial 80
cally compensates for variations in slip caused by ly thereto and provided with ports for register
variations in pressure, the net discharge of the ing with said intake and discharge ports alter
pump remains substantially constant throughout nately, pistons ?tted in said cylinders, a driver
the entire range of operating pressures and tem for reciprocating said pistons, means for rotating
peratures.
said" driver, a stationary armi carried by said
The stroke'of the pump is adjusted manually support and having intake and discharge pas
by loosening the locking lever 56 and operating sageways, an expansion joint connecting each’
the control lever 54 to rotate the gears ,58, 59 and passageway in said rock arm to one of the pas
61. Rotation of the gear 61 causes its eccentric sageways in said stationary arm and spaced from
hub 63 to move the head 64 and the thrust pin the axis of said support to enable the pressure
66 toward or from the piston 72.
created by said pump to tend to rotate said rock
The hub 63 is shown in the drawings, and arm upon said support and swing its free end
particularly in Fig. 3, with its thick part toward toward the free end of said stationary arm and
the thrust pin 66 so that the pump is at zero thereby increase the stroke of said pump, and
stroke. When the hub 63 is rotated, the distance means carried by the free end of said stationary 95
between the axis of the shaft 62 and the outer arm to resist the movement of said rock arm and
end of the thrust pin 66 is shortened and the
to enable said pump pressure to in
pressure of the discharge liquid swings the lower yieldable
crease the stroke (bf said pump after said pres
end of the arm 33 toward the piston 72 and in sure has increased above a predetermined mini
100
creases the stroke of the pump," and the eccen
mum to thereby compensate for the increase in
tricity of the hub 63 is ordinarily such that the the slip of said pump caused by said increase in
pump is on full stroke when the thinnest part
of the hub 63 is toward the thrust pin 66.
30
However, the pump is adapted to operate hy
draulic mechanisms at various speeds, for in
stance, to operate the feeding mechanism of a
machine tool at both feeding and rapid traverse
35
<
"40
45
' ,
50
55
pressure.
3. A radial in?ow pump, comprising a sup
port, a rock arm carried by said support and hav
105
ing intake and discharge passageways, a pintle
carried by said rock arm and having intake and
discharge ports and passageways communicaté
speeds.
'
ing with the intake and discharge passageways
In such a case, the pump is adjusted to deliver in said rock arm, a cylinder barrel journaled upon
a volume of liquid considerably below its ca said pintle and having cylinders arranged radially 110
pacity to operate the mechanism at feeding speed thereto and provided with ports for registering
and the control valve is operated to direct liquid with said intake and discharge ports alternately,
from the gear pump into the cylinder 74 at pistons fitted in said cylinders, a driver for re
certain intervals.
ciprocating said pistons, means for rotating said
When the gear pump liquid enters the cylinder driver, a stationary arm carried by said support 115
74, it retracts the piston 72 and the pressure of and having intake and discharge passageways,
the discharge liquid swings the arm 33 to put an
expansion joint connecting each passageway
the pump on full stroke, thereby instantly in in said rock arm to one of the passageways in
creasing the delivery of the pump from a pre~ said stationary arm and spaced from the axis of
determined minimum volume to its full volu said support to enable the pressure created by 120
metric capacity or to a maximum volume which said pump to tend to rotate, said rock arm upon
determined by the adjustment of the stop bolt said support and swing its free end toward the
86. When the valve 15 is operated to disconnect free end of said stationary arm and thereby in
the cylinder '74 from the gear pump, the spring crease the stroke of said pump, a cylinder car
77 sets the pump back instantly to the predeter ried by the free end of said stationary arm, a 125
mined stroke.
piston arranged in said cylinder, a spring urging
- The invention herein se/Liorth is susceptible said piston against the head of said cylinder, a
of various modi?cations and adaptations without plunger arranged in said piston, a thrust pin
departing from the scope thereof as hereafter carried by said ‘rock arm_ and engaging said
claimed.
plunger and spring means urging said plunger 130
The invention is hereby claimed as follows: against said thrust pin and adapted to be de
1. In a pump having driving and" driven mem ?ected by said rock arm in response to a prede
bers eccentric to each other, the combination of termined increase in the pressure created by said
60 means responsive to the pressure created by said pump to increase the stroke of said pump and
pump ,for increasing the eccentricity of said thereby compensate for the increase in the slip 135
,
members to thereby increase pump displacement,v of said pump caused by said increase in pressure.
means resisting the action of said pressure re
sponsive means and yieldable under the in?u
4. A radial in?ow pump, comprising a support,
a rock arm carried by said support and having
65 ence of pressures above a predetermined mini intake and discharge passageways, a pintle car
mum to enable said pressure responsive means ried by said rock arm and having intake and dis
to increase the stroke 01’ said pump an amount charge ports and passageways communicating
sufficient to compensate for the increase in the with the intake and discharge passageways in
slip of said pump caused by the increase in said said rock arm, a cylinder barrel journaled upon
pressure, and hydraulically operated means for said pintle and having cylinders arranged radial
retracting said action resisting means to increase ly thereto and provided with ports for register 145
the stroke of said pump to a predetermined ing with said intake and discharge ports alter
maximum.
,
nately, pistons ?tted in said'cylinders, a driver
2. A radial in?ow pump, comprising a support, for reciprocating said pistons, means for rotating
a rock arm carried by said support and having said driver, a stationary arm carried by said sup
-
5
1,974,134
port and having intake and discharge passage
enable said pump pressure
increase the stroke
of said pump after said~pressure has increased
way in said rock arm to one of the passageways above a predetermined minimum and thereby
in said stationary arm and spaced from the axis compensate .for the increase in the slip of said . 80
caused by said increase in pressure, and
of said support to enable the pressure created by pump
said pump to tend to rotate said rock arm upon hydraulic means for retracting said movement re
said support and swing its free end toward the sisting means to enable said pressure to increase
free end of said stationary arm and thereby in the stroke of said pump to a predetermined maxi
ways, an expansion joint connecting each passage
crease the stroke of said pump, means carried
10 by the free end of said stationary arm to resist
JAMES K. DOUGLAS.
,
the movement of said rock arm and yieldable to
15
95
20
100
25
370
as
40
105
‘110
.115
120
125
50
130"
55
>135
.60
140
145
70

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