U.S. patent number 3,834,837 [Application Number 05/336,299] was granted by the patent office on 1974-09-10 for air compressor with governor.
This patent grant is currently assigned to Adam Pianga, Manuel Pinko, Winfred D. Weldon. Invention is credited to Claude H. Nickell.
United States Patent |
3,834,837 |
Nickell |
September 10, 1974 |
AIR COMPRESSOR WITH GOVERNOR
Abstract
An air compressor apparatus for maintaining the air pressure in
a reservoir within predetermined upper and lower limits. The air
compressor is driven continuously but the compressing of air is
intermittently cycled on and off automatically in response to
pressure in the reservoir by means of a governor which is directly
attached to the compressor. The governor includes apparatus for
unloading the suction side of the compressor in direct response to
fluid pressure in the pressure side of the compressor.
Inventors: |
Nickell; Claude H. (Dearborn,
MI) |
Assignee: |
Weldon; Winfred D. (Detroit,
MI)
Pinko; Manuel (Dearborn, MI)
Pianga; Adam (Dearborn, MI)
|
Family
ID: |
23315462 |
Appl.
No.: |
05/336,299 |
Filed: |
February 27, 1973 |
Current U.S.
Class: |
417/298;
137/102 |
Current CPC
Class: |
F04B
39/125 (20130101); F04B 49/243 (20130101); Y10T
137/2544 (20150401) |
Current International
Class: |
F04B
49/24 (20060101); F04B 49/22 (20060101); F04B
39/12 (20060101); F04b 049/08 () |
Field of
Search: |
;137/102 ;417/298 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
1,340,965 |
|
Sep 1962 |
|
FR |
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595,612 |
|
Sep 1958 |
|
IT |
|
Primary Examiner: Freeh; William L.
Assistant Examiner: Sher; Richard
Attorney, Agent or Firm: Dowell & Dowell
Claims
I claim:
1. In a governor for controlling the operation of an air compressor
having an inlet valve and including a body having a first axial
bore closed at one end, a cap closing the other end of said body, a
hollow post mounted on the cap and extending into the first bore, a
piston slidably mounted within the first bore, the piston having a
second axial bore for slidably receiving one end of the post and
having a generally concentric counterbore, resilient means urging
said piston toward said one end of the body, a valve member located
within said counterbore and normally closing the bore of the
piston, and means for introducing fluid under pressure into the
counterbore of the piston, the improvement comprising an internal
groove in said piston communicating with the second bore in
predetermined spaced relationship with said counterbore, said
groove communicating with the inlet valve of the compressor, said
post having an annular recess spaced from said one end and being of
a length greater than the distance between the internal groove of
the piston and the counterbore thereof, and said post having a
diameter slightly less than the diameter of the piston bore between
said one end and said annular recess, whereby fluid under pressure
within the counterbore of the piston leaks past said one end of
said post to the internal groove of said piston when the valve
member is initially opened so that a buildup of pressure occurs at
the inlet valve of the compressor and continued movement of the
piston against the tension of the resilient means causes the
annular recess of said post to extend into the counterbore of the
piston to permit free flow of fluid under pressue to the inlet
valve of the compressor.
2. The combination of an air compressor and a governor for
automatically controlling the operation of the air compressor, said
air compressor comprising a body having at least one cavity
defining a cylinder, a first piston reciprocably mounted within
said cylinder, a cylinder head mounted on said body at one end of
said cylinder, said head including an inlet bore and an outlet bore
communicating with said cylinder, inlet valve means removably
mounted in said inlet bore, outlet valve means removably mounted in
said outlet bore, said inlet valve means including a body having an
axial bore with a valve seat at one end, a first valve member
normally engaging said inlet valve seat, a second piston slidably
mounted within the bore of said inlet valve body, said second
piston being selectively movable into engagement with said first
valve member to unseat the same, means for introducing fluid under
atmospheric pressure into said inlet valve bore, said outlet bore
having a valve seat, a second valve member normally engaging the
valve seat of said outlet bore, resilient means carried by said
outlet valve means and normally urging said second valve member
against the valve seat in said outlet bore, an outlet manifold
communicating with said outlet bore, said governor including a body
mounted on said cylinder head and having an axial bore closed at
one end, cap means closing the other end of said body, post means
mounted at one end on said cap means and extending into the axial
bore of said governor body, a third piston slidably mounted within
said governor body, said third piston having an axial bore with a
generally concentric counterbore extending inwardly from one end,
the bore of said third piston slidably receiving the other end of
said post means, said counterbore being in communication with the
outlet manifold of said cylinder head, a third valve member
normally closing the bore of said third piston, said third piston
having an internal groove communicating with the axial bore in
predetermined spaced relationship with said counterbore, said
groove communicating with one end of said second piston, said post
means having an annular recess spaced from said other end and being
of a length greater than the distance between the internal groove
of the third piston and the counterbore thereof, and said post
means having a diameter slightly less than the diameter of the bore
of the third piston between said other end and said annular recess,
whereby fluid under atmospheric pressure is introduced through said
inlet valve means into said cylinder during the suction stroke of
said first piston and is compressed and discharged through said
outlet valve means and said outlet manifold during the pressure
stroke of said first piston and fluid under pressure from said
outlet manifold is introduced into the counterbore of said third
piston and leaks past the other end of said post means to the
internal groove of said third piston when the third valve member is
initially opened so that a buildup of pressure occurs at said
second piston and continued movement of the third piston causes the
annular recess of said post to extend into the counterbore of said
third piston and permit free flow of fluid under pressure to the
second piston to move said second piston and open said first valve
member.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to the compressing of fluids and
relates specifically to air compressors which are operated
itermittently to maintain the pressure in a reservoir between
predetermined limits.
2. Description of the Prior Art
Heretofore many efforts have been made to provide air compressors
with a control mechanism for controlling the operation of the
compressor so that the compressor introduces air under pressure
into a reservoir on demand. In many instances, the control
mechanism is located in a position remote from the compressor and
is operated to cause the compressor to be selectively energized so
that it operates only when the fluid in the reservoir falls to a
predetermined pressure. Some efforts have been made to provide a
compressor control for use with compressors which are constantly
driven and are provided with control means or governors for
maintaining the compressor in an unloaded condition so that no air
or other fluid is compressed until the pressure within a reservoir
falls to a predetermined level at which time the compressor is
relieved of its unloaded condition so that the compressor
compresses air or other fluid and introduces the same into the
reservoir. Most of these control devices are located at a position
remote from the compressor and connected thereto by hoses or
tubing. The hoses or tubing are not satisfactory since they are
subject to rupture which produces an additional hazard,
particularly when the compressor provides air under pressure to a
reservoir of a truck or other motor vehicle which utilizes air
brakes. Some examples of this type of structure are the patents to
Fishwood et al. U.S. Pat. No. 2,804,878 and Glass et al. U.S. Pat.
No. 3,043,496.
Some efforts have been made to eliminate the hoses or tubing
connecting the control mechanism to the compressor by mounting the
governor directly on or adjacent to the cylinder head of the
compressor. The governor includes means for unloading the suction
valve of the compressor so that the compressor performs no useful
work until the pressure within the reservoir falls to a
predetermined lower limit. Some examples of this type of structure
are the patents to McCune et al. U.S. Pat. No. 2,033,437 and
Valentine U.S. Pat. No. 2,792,169.
SUMMARY OF THE INVENTION
The present invention is an air compressor of the reciprocating
type for supplying fluid under pressure to a reservoir and having a
governor mounted directly on the cylinder head and such governor is
adapted to a cycle a compressor "On" and "Off" intermittently and
automatically in response to demand from a remote reservoir. The
governor is operated by fluid under pressure from the high pressure
side of the air compressor and is adapted to unload the suction
side of the compressor when a predetermined pressure has been
obtained.
It is an object of the invention to provide an air compressor
having a governor mounted directly thereon. Such governor is
directly responsive to the high pressure fluid being discharged
from the compressor into a reservoir and such governor is adapted
to move the suction valves of the compressor to an unloaded
position when the outlet pressure reaches a predetermined upper
level and permit the suction valves to move to a closed position
when the pressure within the reservoir falls to a predetermined
lower limit.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of an air compressor having a governor or
control mechanism mounted thereon.
FIG. 2 is an end elevation thereof.
FIG. 3 is an enlarged section on the line 3--3 of FIG. 1.
FIG. 4 is an enlarged vertical section on the line 4--4 of FIG.
1.
FIG. 5 is a section on the line 5--5 of FIG. 4.
FIG. 6 is a section on the line 6--6 of FIG. 4.
FIG. 7 is a fragmentary vertical section illustrating one of the
suction valves of the compressor in unloaded condition.
FIG. 8 is an enlarged section of the governor taken on the line
8--8 of FIG. 3 and illustrating the condition of the governor when
air is being compressed by the compressor.
FIG. 9 is a section on the line 9--9 of FIG. 8 and illustrating the
condition of the governor when the suction valve of the compressor
is unloaded.
FIG. 10 is a section on the line 10--10 of FIG. 8.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With continued reference to the drawings, an air compressor 15 is
provided having a body or jacket 16 with a plurality of cylinders
17. As illustrated, the compressor 15 includes a pair of cylinders
17 each of which has a reciprocating piston 18 connected by a wrist
pin 19 to one end of a connecting rod 20. The opposite end of each
connecting rod is rotatably mounted on an offset lobe of a
conventional crankshaft (not shown). Normally the crankshaft is
driven continuously from a power plant such as the gasoline or
diesel engine of a truck or motor vehicle. When the power plant is
operated, the crankshaft alternately raises and lowers each of the
pistons 18 in such a manner that when one of the pistons is fully
raised, the other piston normally is at its lowermost position.
A head 21 is mounted on the upper end of the body 16 and is secured
thereto in any desired manner, as by a plurality of head bolts 22
(FIGS. 1 & 2), and preferably a head gasket 23 is located
between the body 16 and the head 21 to prevent leakage of air under
pressure.
The head 21 is provided with a pair of spaced vertically disposed
inner bores 24 located generally centrally along the longitudinal
axis of the head 21 and a pair of outer bores 25 located along the
longitudinal axis of the head and disposed outwardly of and in
alignment with the bores 24. The inner bores 24 communicate with
the cylinders 17 and are provided with suction operated valves 26
to introduce air under atmospheric pressure into the cylinders 17
when the pistons 18 are being retracted. The outer bores 25
communicate with the cylinders 17 and are provided with pressure
operated valves 27 which are adapted to open when a predetermined
pressure has been attained within the cylinders 17 during the
compression stroke of the pistons 18.
In order to introduce atmospheric air into the cylinders, each of
the inner bores 24 is in communication with an enlarged well or
recess 28 and such well in turn is in communication with a
passageway 29 which is open to atmosphere. If desired, a horn 30
(FIG. 2) could be provided for directing atmospheric air into the
passageway 29, and preferably such horn includes a screen (not
shown) to exclude foreign material from the passageway.
Each of the suction operated valves 26 includes an elongated
generally cylindrical body 33 having a cap 34 at one end with an
outwardly extending flange 35. The end of the body 33 adjacent to
the flange 35 is threadedly received within the inner bores 24. A
fluid tight gasket 36 is disposed beneath the flange 35 to form an
airtight seal between the suction operated valve 26 and the head
21. An axial bore 37 extends upwardly from the end of the body 33
remote from the cap 34. Such bore extends most of the length of the
body 33 and a counterbore 38 extends inwardly from the lower end of
the body 33 generally concentrically of the bore 37. As illustrated
in FIGS. 4, 5 and 7, the wall structure of the body 33 surrounding
the counterbore 38 has a plurality of openings 39 providing
communication between the counterbore 38 and the well 28 so that
atmospheric air can enter the counterbore.
Within the bore 37, a piston 40 is slidably mounted and such piston
includes a reduced upwardly extending stop 41 adapted to engage the
upper end of the bore 37 and define an annular chamber 42 at the
upper end of the piston 40. The stop 41 normally is urged against
the end of the bore 37 by a spring or other resilient member 43 the
upper end of which engages a shoulder of the piston 40 and the
lower end of such spring bears against a stop plate 44 held in
position by a spring retainer 45. The lower end of the piston 40 is
provided with a reduced elongated finger or prong 46 which extends
downwardly through an opening in the stop plate 44 and terminates
slightly above the lower end of the valve body 33 when the stop 41
is against the upper end of the bore 37.
The lower end of the valve body 33 forms a seat for a valve member
47, which normally is urged into intimate contact with the valve
seat at the end of the body 33 by a spring or other resilient
member 38. Adjacent to the flange 35, the valve body 33 is provided
with an annular recess or groove 49 which communicates with the
annular chamber 42 at the top of the piston 40 by means of a
plurality of orifices 50 for a purpose which will be described
later.
Each of the pressure operated valves 27 includes an elongated
generally cylindrical body 55 having a cap 56 at one end with an
outwardly extending annular flange 57. The end of the pressure
valve body adjacent to the flange 57 is threadedly received within
the outer bores 25 of the head 21 and a gasket 36 is disposed below
the flange 57 to provide an airtight connection between the valve
body 55 and such head. An axial bore 58 extends upwardly from the
end of the body 55 remote from the cap 56. A compression spring or
other resilient member 59 is mounted within the bore 58 and such
spring is adapted to bear against a valve 60 and normally force
such valve into intimate engagement with a valve seat 61 mounted
within each of the outer bores 25. An opening 62 provides
communication between the cylinders 17 and the bores 25 so that
fluid being compressed on the compression stroke of the pistons 18
overcomes the tension of the spring 59 and unseats the valve 60 so
that fluid under pressure can be discharged from the cylinders.
As illustrated best in FIG. 5, each of the outer bores 25 is
provided with an enlarged pocket 63 and such pockets communicate
with a passageway or outlet manifold 64 extending through the body
16 to an outlet port 65. A pressure line 66 (FIG. 1) has one end
connected to the outlet port 65 and the opposite end of such
pressure line is connected to a high pressure fluid reservoir (not
shown) of conventional construction. Fluid under pressure within
the bore 25 passes through the pockets 63, manifold 64, and
pressure line 66 into the fluid reservoir.
In order to move the inlet or suction valves 47 to an open unloaded
position when the pressure within the reservoir reaches a
predetermined value, a governor 70 is provided and such governor
includes a body 71 mounted on the head 21 in any desired manner, as
by cap screws 72 or the like. The body 71 includes an axial bore 73
which extends substantially through the body, as illustrated best
in FIGS. 8 and 9. A cap or plug 74 is connected by screws or other
fasteners 75 to the body 71 in a manner to seal the open end of the
bore 73. A piston 76 is slidably mounted within the bore 73. The
piston 76 has an axial bore 77 extending entirely through the same
and a counterbore 78 extends inwardly from one end of the piston in
concentric relationship with the bore 77. The shoulder between the
bore 77 and the counterbore 78 defines a valve seat 79 which is
engaged by a valve 80. A spring or other resilient member 81 is
mounted within the counterbore 78 and normally maintains the valve
80 in intimate engagement with the valve seat 79.
The piston 76 has an annular groove or recess 82 intermediate its
ends and such groove is in communication with an internal groove 83
by means of a plurality of orifices 84. The internal groove 83
communicates with the axial bore 77 of the piston in spaced
relation to the valve seat 79. A calibrated spring 85 is located
within the bore 73 of the body 71 and such spring urges the piston
76 against the end of the bore 73 under a predetermined force. One
end of the spring 85 engages the end of the piston 76 and the
opposite end of such spring normally bears against one or more
shims 86 carried by the cap 74. The predetermined force of the
spring 85 can be adjusted by adding or removing one or more shims
86.
A post 87 is connected at one end to the cap 74 and the axial bore
77 of the piston 76 is slidably mounted on the opposite end of such
post. As illustrated in FIG. 8, the post 87 normally extends
through the piston 76 substantially to the internal groove 83 for a
purpose which will be described later. The end of the post 87
located within the axial bore 77 of the piston 76 is provided with
an annular recess 88 spaced from the end of the post. If desired,
the post 87 may have a plurality of annular grooves forming a
labyrinth seal which creates a pressure drop between one groove and
the next adjacent groove to retard leakage along the axial bore 77
of the piston. The post 87 is provided with an axial bore 89
extending downwardly along most of the length of the post and such
bore is in communication with the bore 73 of the body 71 exteriorly
of the post by means of one or more orifices 90.
With particular reference to FIG. 9, the end of the body 71 remote
from the cap 74 is provided with an enlargement 93 having an
orifice 94 extending inwardly from the exterior of the enlargement
and providing communication with the bore 73. A second enlargement
or boss 95 is connected to the body 71 in spaced relation to the
enlargement 93 and such enlargement 95 has an axial orifice 96
providing communication between the exterior of such enlargement 95
and the bore 73 of the body 71 in the area of the annular groove 82
of the piston. Adjacent to the opposite end of the body 71, an
orifice 97 provides communication between the bore 73 and
atmosphere.
With particular reference to FIGS. 3 and 4, the compressor body or
block 16 is provided with a bore 98 extending inwardly from one
side thereof and counterbore 99 arranged generally concentrically
of the bore 98. A plug 100 is force fitted into the counterbore 99
to divide the bore and counterbore into two separate airtight
compartments. The outer end of the counterbore 99 is closed by a
threaded plug 101.
The governor 70 is mounted on the top of the body 16 in such a
manner that a downwardly extending orifice 102 in the body 16
provides communication between the bore 98 and the orifice 96 of
the enlargement 95. A pair of orifices 103 extend outwardly from
the bore 98 to the inner bores 24 and provide communication between
the bore 98 and the annular recess or groove 49 in each of the
suction valve bodies 33. An orifice 104 in the body 16 extends
through the counterbore 99 and such orifice provides communication
between the orifice 94 of the enlargement 93 and a chamber 105
within the compressor body 16. The chamber 105 communicates with
the high pressure passageway 64 of the body 16.
In order to protect the pressurized system, a safety relief valve
106 (FIG. 3) communicates with the chamber 105 and is provided with
an exhaust to atmosphere so that excessive pressures within the
system will open the safety relief valve and exhaust excess
pressures to atmosphere.
In operation of the device, the crankshaft of the air compressor 15
normally is driven substantially continuously as long as the power
plant of the vehicle is in operation. When the crankshaft is being
rotated, the connecting rods 20 cause the pistons 18 to be
reciprocated within the cylinders 17. A fluid reservoir (not shown)
is associated with the air compressor 15 and is in communication
therewith through the pressure line 65 to permit air or other fluid
being compressed by the air compressor 15 to be discharged into the
reservoir so that a supply of air or fluid under pressure is
available for use by the brakes and other apparatus of the vehicle.
When a portion of the compressed fluid within the reservoir has
been utilized, it is necessary to replenish the supply
automatically so that the fluid pressure operated devices can
continue to function.
With particular reference to FIGS. 3-6, the supply of fluid under
pressure within the reservoir has been depleted to the point where
the air compressor is cycled "On". In this position, atmospheric
air enters the passageway 29 in the head 21 and passes into the
well 28. From the well 28 air passes through the openings 39 in the
wall structure of each of the inlet valve bodies 33 into the
counterbore 38. During the suction stroke of the piston 18 (as
illustrated on the right in FIG. 4) a negative pressure is created
within the cylinder 17 and the pressure differential between the
counterbore 28 and the cylinder 17 causes the valve member 47 to
overcome the tension of the spring 48 and unseat the valve member.
This permits air under atmospheric pressure to flow around the
valve member 47 and into the cylinder 17. As the connecting rod 20
approaches bottom dead center of the crankshaft lobe on which it is
mounted, the pressure differential on opposite sides of the valve
47 is substantially equalized so that the spring 48 urges the valve
member to closed or seated position.
During the compression stroke of the piston 18 (as illustrated on
the left of FIG. 4) initial upward movement of the piston begins to
compress the air within the cylinder and forces the inlet valve
member 47 against the seat at the bottom of the suction valve body
33. As the piston continues its upward movement, the fluid within
the cylinder is compressed until it is sufficient to overcome the
tension of the spring 59 at which time the valve 60 is unseated so
that the fluid under pressure flows through the opening 62 and the
outer bore 25 of the head 21 into the pocket 63. From the pocket
63, the fluid under pressure flows into the passageway 64 and
through the pressure line 66 to the fluid reservoir. The
compressing of the fluid within the cylinders continues until the
pressure within the reservoir approaches its designed upper
limit.
In order to automatically interrupt the introduction of fluid under
pressure into the reservoir after a predetermined pressure has been
attained, a governor 70 is mounted on the head 21 in such a manner
that the orifice 94 communicates with the passageway 64 through the
orifice 104 and chamber 105. When the pressure within the
passageway 64 increases, fluid under pressure is introduced into
the counterbore 78 of the piston 76 and urges such piston away from
the end of the bore 73 in the governor body. As the pressure within
the passageway 64 approaches the designed limit of the reservoir,
the pressure is sufficient to move the piston 76 against the
tension of the calibrated spring 85. Initial movement of the piston
76 causes the valve 80 to engage the end of the post 87 and seal
the axial bore 89 of such post. During continued movement of the
piston 76, the post 87 moves the valve 80 away from the valve seat
79 so that fluid under pressure leaks past the post 87 into the
internal groove 83 and then through the orifices 84 into the
annular groove 82 around the exterior of the piston 76. From the
annular groove 82, fluid under pressure passes through the orifice
96 into the bore 98 within the body 16 of the compressor and from
the bore 98 fluid under pressure passes through orifices 103 into
the annular recesses 49 of the suction valve body 33 and then
through the orifices 50 into the annular chamber 42 at the upper
end of each of the inlet pistons 40 and begins a buildup of
pressure against the springs 43.
Continued movement of the governor piston 76, as pressure within
the upper end of the bore 73 continues to rise, causes the annular
recess 88 of the post 87 to communicate with the counterbore 78 and
permits free passage of fluid under pressure from the counterbore
78 into the annular chambers 42 within the suction valve bodies 33.
When full pressure is applied to the annular chambers, such
pressure overcomes the tension of the springs 43 and moves the
pistons 40 downwardly into engagement with the stop plate 44.
Downward movement of the pistons causes the fingers or probes 46 to
engage the valve members 47 and move such valve members to open or
unloaded position, as illustrated in FIG. 7. As long as the valve
members 47 remain open, fluid within the cylinders 17 cannot be
compressed since the air drawn into the cylinders during the
suction stroke is merely forced back through the inlet valves
during the pressure stroke. In this manner, the compressor is
automatically cycled to the "Off" position so that no compression
can occur.
As fluid within the reservoir is used, the pressure begins to drop
and the calibrated spring 85 begins to force the piston 76 back
toward the end of the bore 73 in the governor body 71. As more and
more fluid under pressure is removed from the supply within the
reservoir, the piston 76 is forced back until the valve 80 engages
the valve seat 79 and removes the valve from the end of the post
87. As soon as the valve 80 is removed from the post, air under
pressure within the bore 37 of the suction valve body passes
through the orifices 50 and annular recesses 49 into and through
the orifices 103 and bore 98 back through the orifices 102 and 96,
annular groove 82, orifies 84, internal groove 83 to the bore 89 of
the post. The annular bore 89 permits fluid to flow through the
orifices 90 into the bore 73 of the governor body and from the bore
73 air under pressure is exhausted to atmosphere through the
orifice 97. Since the annular chamber 42 is thus opened to
atmosphere, the spring 43 quickly moves the piston 40 until the
stop 41 engages the end of the bore 37 and permits the valve member
47 to seat against the end of the valve body 33 to cycle the
compressor to the "On" position.
The gradual buildup of pressure in the annular chamber 42
substantially reduces or prevents vibration and chatter when the
inlet valve are moved to unload position.
When the device is to be used with a truck or other vehicle, it is
contemplated that the compressor 15 will be cycled "On" when the
pressure within the air supply reservoir reaches approximately 90
p.s.i. and will be cycled "Off" when the pressure reaches 110
p.s.i. Since the reservoir normally is located in a position remote
from the compressor, it is recognized that there may be a pressure
drop in the pressure line 66 so that a pressure differential
between the reservoir and the outlet manifold 64 may exist. This
differential can be overcome by adjusting the governor 70 by adding
or removing shims 86 so that the compressor is cycled "On" and
"Off" at desired pressures within the outlet manifold. For example,
the governor may close the compressor inlet valve when the pressure
within the outlet manifold is approximately 100 p.s.i. and may move
the inlet valve to open or unloaded condition when the pressure
within the manifold is approximately 120 p.s.i.
* * * * *