Year: 1898

page_text: A communication from NIELS ANTON CHRISTENSEN, of Milwaukee, in the United
States of America, Mechanical Engineer.
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention to be as
follows:-
The main object of this invention is to provide a combined compressor and
motor of small compass or compact form and of simple and durable construction,
that will not be affected by exposure to the weather and outside influences, that
will be convenient and economical in operation and that will require the least
possible care.
It consists of certain novel features of construction and combinations of parts,
as hereinafter described.
The machine herein described is designed particularly for use in connection
with air brakes for railway cars on which the compressor and motor are usually
exposed to dust, dirt, mud, rain, ice and snow, and the working parts, if unpro-
tected, require constant care or frequent attention and soon become worn, and
inoperative or defective.
The main or compressor frame or case, is preferably made of cast iron and
is formed with a well or chamber to enclose and protect the working parts and
driving connections of the compressor and to contain oil for their continuous and
thorough lubrication. This frame or case is formed or provided with boxes which
open at their ends into the oil chamber.
A shaft is supported in said boxes and formed or provided between them with
cranks or eccentrics.
Compressor cylinders are formed with or attached at one end to the frame
and opening into the oil chamber.
Pistons fitted to work in said cylinders are connected by pitmen with the
cranks. The bottom of the oil chamber or well is preferably located at or near
the level of the lower sides of said cylinders, so that when said chamber is partially
filled the oil will flow therefrom into the cylinders and thoroughly lubricate the
pistons. Upon the frame or case is mounted an electric motor, comprising a
base which is bolted to the top of said frame and serves as a cover or closure for
the oil chamber. The working parts and driving connections of the compressor
are thus completely enclosed and protected from dust and dirt.
The motor base is formed or provided on its upper side in a line parallel with
the crank shaft with housings for the armature bearings. The upper halves or
caps of these housings are made detachable for the purpose of removing the
armature and affording easy access to its bearings.
The field frame or armature housing, which is mounted upon the motor base
between the armature bearings is provided on the inside with the field magnets.
This frame or housing is preferably left open at the ends to allow free access of
air to the armature and thus afford ample ventilation and prevent heating of the

page_text: armature coils. If desired, covers may be provided to protect the commutator
and otherwise exposed ends of the armature; but under ordinary conditions these
are not necessary.
The armature and armature shaft are supported parallel with the crank shaft
in boxes or bushings which are fitted and held in the housings.
At one end of the machine the oil chamber opens through the side of the case
and at that end the armature and crank-shafts are extended and provided re-
spectively with a pinion and gear which mesh with each other.
A case or cover, the larger part of which is bolted or otherwise attached to
the frame or case over the gear encloses said gear and forms a receptacle for
holding oil or other lubricant. The upper smaller portion of the gear case
covering the pinion is formed with or attached to the cap or cover of the adjacent
housing and is removable therewith for the purpose of removing or of obtaining
access to the armature shaft and pinion.
The housings are formed around and below the bushings, with chambers and
wells, and oil is continuously supplied therefrom to the journals of the armature-
shaft, when the motor is running, by the usual rings which hang loosely over
them in transverse grooves or slots formed through the upper sides of said bush-
ings, and dip on their lower sides into the oil contained in said wells. At their
inner ends said housings are also formed or provided with chambers which have
openings into the oil wells. The armature shaft is provided in these chambers
with rings by which the surplus oil, working through the inner ends of the
bushings, is thrown off by centrifugal force into said chambers and thus
prevented from following the armature-shaft to the armature windings or. coils
and to the commutator. To ensure the protection of the armature coils from any
oil that might possibly escape from the chamber past the ring the armature-shaft
may be provided with a shield or guard.
The housing is formed below the oil well with a chamber which has an overflow
opening into the gear-case. A tube or passage opening out of the oil well at
the level at which the oil is to be maintained therein, extends into the chamber
below its overflow opening, so that the lower end of said tube or passage will
be sealed by the oil contained in said chamber and thus prevent oil vapour escap-
ing from the compressor and gear-case through the chambers to and injuring
or affecting the coils of the armature. The opening from the chamber into the oil
well is preferably placed at or slightly above the level at which the oil is to be
maintained in said well so that the oil will not needlessly flow from said well
into said chamber in case the oil level in the latter should be below that in the
former.
The housing is formed at its outer end with a chamber which has a drain
opening into the oil well. The bushing is formed inside near its outer end with
an annular groove which opens on the lower side into the oil well, so that sur-
plus oil working outwardly through said bushing from the oiling ring or inwardly
from the gear-case will be caught in said groove and discharged therefrom into
the oil well. When the surplus oil caught in the chamber rises therein above
the opening it will flow through said opening into the well from which the surplus
oil flows through the passage into the chamber below the overflow opening. From
this chamber the surplus flows through an opening into the gear-case. The well
will be replenished to a certain extent by the oil carried up by the gear to the
pinion and working therefrom along the armature-shaft into an intercepting
groove in the bushing. The deficiency is supplied from time to time through a
filling opening or passage which is provided with a removable cap or plug. This
filling opening or passage is located, so as to gauge the supply of oil to the well
or chamber. The surplus working through the inner end of the bushing is
thrown off by the ring into a chamber and drains therefrom back into the well,
and the oil working through the outer end of said bushing is thrown from the
end of the armature shaft into a chamber from which it drains back into said
well.

page_text: In practice the oil chamber and the gear-case are partially filled with oil so
that the compressor pistons, the cranks or eccentrics with which they are con-
nected and the gear are constantly and thoroughly lubricated, thus dispensing
with much of the care and attention that would otherwise be required to keep
the machine in proper working order.
The cylinder heads are each formed transversely to the axes of the cylinders
with cylindrical valve chambers arranged side by side in a vertical position.
These chambers are provided at their upper ends with caps which afford ready
access to the valves. Each of the suction valve chambers communicates above
the valve seat with the interior of its cylinder through a port and below the
valve seat with a suction or inlet passage formed in the cylinder head. The
discharge valve chambers communicate above the valve seats with a common
discharge passage or chamber formed in the cylinder heads between the suction
passages and below the valve seats said valve chambers communicate with the
interior of their respective cylinders through suitable ports. The suction pas-
sages are provided at their lower ends with strainers or screens by which dirt
and impurities are prevented from being carried into the compressor.
A discharge pipe leads out of the discharge chamber or passage. Suction and
discharge valves are provided. For the sake of lightness each valve is made of
thin tubing or sheet metal drawn into cylindrical form with one closed end which
forms the working face of the valve, and to reduce the clearance space of the
compressor as much as possible the suction valves are closed at their upper ends
by caps and are made imperforate and air-tight. They are loosely fitted in and
nearly fill the valve chambers. The discharge valves are preferably made like
valves for convenience and for the sake
the suction
of uniformity,
so that if the valves are removed and accidentally interchanged, the discharge
valves being placed in the suction valve chambers, the clearance space will not
be increased and the operation of the compressor will not be affected.
It is obvious that a compressor with a single cylinder may be constructed on
the plan herein shown and described and that various other modifications in the
details of construction and arrangement of parts may be made without departure
from the spirit and intended scope of the invention.
Under certain conditions, compressors encased and constructed as described
may be advantageously employed without the special motor directly mounted
The com-
thereon and it is not intended to limit the invention to such a motor.
pressor cylinders being so set and arranged with respect to the oil chamber that
a portion of them at least will be below the normal level of the oil in said cham-
ber, the oil will serve by its contact with the metallic walls of said chamber, as
well as with the cylinders and pistons, to distribute the heat produced by the
operation of the compressor and thereby prevent overheating of the cylinders
without using cooling jackets.
Lubricants of different kinds, may if desired, be used, one for the gears and
another for the cylinders, pistons and cranks, and to keep them separate the open-
ing in the end of the motor frame or case between the chamber and the gear-
case may be closed.
The end of the crank-shaft upon which the gear is mounted terminates within
the gear-case which thus completely encloses and protects the driving connection
of the compressor and dispenses with the stuffing box which is indispensable in
that class of machines where the crank-shaft projects through the casing and
has a driving connection outside thereof. Such a stuffing box is objectionable
in a machine of this kind because if it is kept sufficiently tight to prevent the
escape of oil it is liable to bind and cause the crank-shaft to heat and run hard
and in any case requires constant care.
Dated this 19th day of September 1898.
BOULT & WADE,
Agents for the Applicant.

page_text: A communication from NIELS ANTON CHRISTENSEN, of Milwaukee, in the United
States of America, Mechanical Engineer
I, ALFRED JULIUS BOULT, of 111, Hatton Garden, in the County of Middlesex,
Chartered Patent Agent, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer
tained in and by the following statement:-
The main object of this invention is to provide a combined compressor and
motor of small compass or compact form and of simple and durable construction,
that will not be affected by exposure to the weather and outside influences, that
will be convenient and economical in operation and that will require the least
possible care.
It consists of certain novel features of construction and combinations of parts,
as hereinafter particularly described and pointed out in the claims.
In the accompanying drawings like letters designate the same parts in the
several figures.
Fig. 1 is a vertical section, cutting one of the compressor cylinders longi-|
tudinally, as indicated by the broken line 1, 1, Fig. 2, of a combined compressor
and motor embodying the invention; Fig. 2 is a vertical section, cutting the
machine lengthwise of the crank-shaft, as indicated by the broken line 2, 2,
Fig. 1; Fig. 3 is an end elevation on an enlarged scale of the compresser cylin-
ders, as viewed from the right with reference to Fig. 1, showing the valve cases
and suction and discharge connections of one cylinder in section, as indicated by
the line 3 3, Fig. 4; Fig. 4 is a horizontal section indicated by the line 4, 4,
Fig. 3; Fig. 5 is a vertical section on the line 5 5, Fig. 6, and Fig. 6 is a vertical
section on the line 6 6, Fig. 5, showing a modification of the arrangement of oil
chambers and passages in connection with one of the armature bearings.
The machine shown and described is designed particularly for use in connection
with air brakes for railway cars on which the compressor and motor are usually
exposed to dust, dirt, mud, rain, ice and snow, and the working parts, if unpro-
tected, require constant care or frequent attention and soon become worn and
inoperative or defective.
Referring to Figs. 1 and 2 of the drawings, A designates the main or com-
pressor frame or case, which is preferably made of cast iron and is formed with a
well or chamber a to enclose and protect the working parts and driving con-
nections of the compressor and to contain oil for their continuous and thorough
lubrication. This frame or case is formed or provided with boxes a¹ a¹ which
open at their ends into the chamber a.
B is a shaft supported in said boxes and formed or provided between them
with cranks or eccentrics b b.
EE are compressor cylinders formed with or attached at one end to the
frame A and opening into the chamber a.
CC are pistons fitted to work in said cylinders and connected by pitmen D D
with the cranks bb. The bottom of the oil chamber or well a is preferably located
at or near the level of the lower sides of said cylinders, so that when said chamber
is partially filled the oil will flow therefrom into the cylinders and thoroughly
lubricate the pistons. Upon the frame or case A is mounted an electric motor,
comprising a base which is bolted to the top of said frame and serves as a
cover or closure for the oil chamber a. The working parts and driving con-

page_text: nections of the compressor are thus completely enclosed and protected from dust
and dirt.
The motor base F is formed or provided on its upper side in a line parallel with
the crank-shaft B with housings G G for the armature bearings. The upper
halves or caps g g of these housings are made detachable for the purpose of
removing the armature and affording easy access to its bearings.
J is the field frame or armature housing, which is mounted upon the motor
base E between the armature bearings, and is provided on the inside with the
field magnets j j. This frame or housing is preferably left open at the ends
to allow free access of air to the armature and thus afford ample ventilation and
prevent heating of the armature coils. If desired, covers may be provided to
protect the commutator and otherwise exposed ends of the armature; but under
ordinary conditions these are not necessary.
I designates the armature and H the armature-shaft supported parallel with
the crank-shaft B in boxes or bushings 2 and g³ which are fitted and held in.
the housings G G¹, as shown in Fig. 2.
At one end of the machine the chamber a opens through the end of the case
and at that end the armature and crank-shafts are extended and provided re-
spectively with a pinion M and gear L which mesh with each other.
N is a case or cover, the larger part of which is bolted or otherwise attached
to the frame or case A over the gear L, thus enclosing said gear and forming a recep-
tacle for holding oil or other lubricant. The upper smaller portion of the gear
case covering the pinion M is formed with or attached to the cap or cover 9 of
the adjacent housing and is removable therewith for the purpose of removing
or of obtaining access to the armature-shaft H and the pinion M.
The housings G and G¹ are formed around and below the bushings and g³
with chambers and wells () and (1, and oil is continuously supplied therefrom to
the journals of the armature-shaft, when the motor is running, by the usual
rings oo which hang loosely over them in transverse grooves or slots formed
through the upper sides of said bushings, and dip on their lower sides into the
oil contained in said wells. At their inner ends said housings are also formed
or provided with chambers P P which have openings into the oil wells
and 0 The armature-shaft is provided in these chambers with rings and
by which the surplus oil, working through the inner ends of the bushings
and g, is thrown off by centrifugal force into said chambers and thus prevented
from following the armature-shaft to the armature windings or coils and to the
commutator. To insure the protection of the armature coils from any oil that
might possibly escape from the chamber P past the ring h, the armature-shaft
may be provided, as shown in Fig. 2, with a shield or guard ².
The housing G is formed below the oil well with a chamber Q which has
an overflow opening y into the gear-case N. A tube or passage ',
opening out of the oil well ( ) at the level at which the oil 1S
to be maintained therein, extends into the chamber Q below its overflow
opening g, so that the lower end of said tube or passage will be sealed by the oil
contained in said chamber and thus prevent oil vapor escaping from the com-
pressor and gear-case through the chambers Q, O and P and coming into contact
with and injuring or affecting the coils of the armature. The passage also
prevents the oil from rising in the oil well 0 above the desired level and over-
Howing the adjacent armature bearing.
The housing G' is formed at its outer end with a chamber R which has a
drain opening into the oil well 01. Surplus oil working through the outer end
of the bushing is thrown from the end of the armature shaft into said chamber
and flows therefrom back into said well. The bushing is formed inside near
its outer end with an annular groove which opens on the lower side into the
oil well, so that surplus oil working outwardly through said bush-
ing from the oiling ring o or inwardly from the gear-case will be

page_text: caught in said groove and discharged therefrom into the oil well 0. When the
surplus oil caught in the chamber l' rises therein above the opening it will
flow through said opening into the well from which the surplus oil flows
through the passage into chamber Q. From the latter, the surplus flows
through the opening into the gear-case. The well will be replenished to a
certain extent by the oil carried up by the gear L to the pinion M. and working
therefrom along the armature-shaft into the intercepting groove h³ in the bush-
ing . The deficiency is supplied from time to time through the filling opening
or passage o which is provided with a removable cap or plug, as shown in Fig. 1.
This filling opening or passage is located, as shown, so as to gauge the supply
of oil to chamber O.
In practice the chamber a and the gear-case N are partially filled with oil so
that the compressor pistons, the cranks or eccentrics with which they are con-
nected and the gear L are constantly and thoroughly lubricated, thus dispensing
with much of the care and attention that would otherwise be required to keep
the machine in proper working order.
Referring to Figs. 3 and 4, showing in connection with Fig. 1 the valves and
suction and discharge connections of the compressor, e e designate the cylinder
heads which are each formed transversely to the axes of the cylinders with cylindri-
cal valve chambers S and T, arranged side by side in a vertical position. These
chambers are provided at their upper ends with caps s and t which afford ready
access to the valves. Each of the suction valve chambers S communicates above
the valve seat with the interior of its cylinder through a port s and below the
valve seat with a suction or inlet passage S₁ formed in the cylinder head. The
discharge valve chambers T communicate above the valve seats with a common
discharge passage or chamber T formed in the cylinder heads between the suction
passages S, and below the valve seats said valve chambers communicate with
the interior of their respective cylinders through ports t¹. The suction pas-
sages S are provided at their lower ends with strainers or screens S2 by which
dirt and impurities are prevented from being carried into the compressor.
T2 is the discharge pipe leading out of the chamber or passage T. U and V
designate the suction and discharge valves respectively. For the sake of light-
ness each valve is made of thin tubing or sheet metal drawn into cylindrical form
with one closed end which forms the working face of the valve, and to reduce the
clearance space of the compressor as much as possible the suction valves l'are
closed at their upper ends by caps and are made imperforate and air-tight. They
are loosely fitted in and nearly fill the chambers S. The discharge valves Vare
preferably made like the suction valves for convenience and for the sake of
uniformity, so that if the valves are removed and accidentally interchanged, the
discharge valves being placed in the suction valve chambers, the clearance space
will not be increased and the operation of the compressor will not be affected.
It is obvious that a compressor with a single cylinder may be constructed on
the plan herein shown and described and that various other modifications in the
details of construction and arrangement of parts may be made without departure
from the spirit and intended scope of the invention.
Under certain conditions, compressors encased and constructed as shown in the
accompanying drawings may be advantageously employed without the special
motor directly mounted thereon and it is not intended to limit the invention to
such a motor except as to those claims in which it is expressly included. The
compressor cylinders being so set and arranged with respect to the oil chamber a
that a portion of them at least will be below the normal level of the oil in said
chamber, the oil will serve by its contact with the metallic walls of said chamber,
as well as with the cylinders and pistons, to distribute the heat produced by the
operation of the compressor and thereby prevent over-heating of the cylinders
without using cooling jackets.
Lubricants of different kinds may, if desired, be used, one for the gears and
another for the cylinders, pistons and cranks, and to keep them separate the open-

page_text: ing in the end of the motor frame or case A between the chamber a and the gear-
case N may be closed.
The end of the crank-shaft B upon which the gear L is mounted terminates with-
in the gear-case N which thus completely encloses and protects the driving connec-
tion of the compressor and dispenses with the stuffing-box which is indispensable
in that class of machines where the crank-shaft projects through the casing and
has a driving connection outside thereof. Such a stuffing box is objectionable in
a machine of this kind because if it is kept sufficiently tight to prevent the
escape of oil it is liable to bind and cause the crank-shaft to heat and run hard
and in any case requires constant care.
Referring to Figs. 5 and 6, illustrating a modification of the arrangement of
oil chambers and passages in connection with one of the motor bearings, the
lower chamber Q is omitted and the passage q' opens into the chamber a, or it
may be made to open into the gear case N. Any oil vapor that might in this case
find its way from chamber a or gear case N through the passage q' into the well O
would be prevented from escaping therefrom through the adjacent bearing by
the film of oil, which constantly fills the space between the bushing g² and the
journal of shaft H, particularly when the machine is in operation. The escape
of vapor from the well into the chamber P and thence to the armature may be
prevented by locating the opening ? below the upper end of the passage q¹, as
shown. In other respects the oil chambers and passages are substantially like
those shown in Figs. 1 and 2 in construction and arrangement, and serve to
prevent an over-supply of oil in the well O, and the escape of oil vapor to the
armature through the adjacent bearing.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that when I claim is :-
1. In a combined air pump and electric motor the combination of the frame
having a chamber adapted to contain oil, a shaft provided with a crank or
eccentric enclosed in said chamber, a cylinder formed with or attached to said
frame and opening at one end into said chamber, a piston fitted to work in said
cylinder and connected with said crank or eccentric, a motor base attached to said
frame and forming a cover for said oil chamber, an armature supported upon
said base and connected by gears with said crank shaft, and a gear case attached
to said frame and motor base and forming therewith an enclosure for said gears
and a receptacle for holding oil, said frame, gear case and motor base completely
enclosing and protecting the driving connection of the pump and the crank
shaft terminating within said gear case, whereby a stuffing box therefor is dis-
pensed with, substantially as and for the purposes set forth.
2. In a pump the combination with a frame or case formed or provided with
a closed chamber adapted to exclude dirt and to contain oil, a shaft having bear-
ings in said frame or case and provided with a crank or eccentric within said
chamber, a cylinder formed with or attached to said frame or case, a piston
fitted to work in said cylinder and connected with said crank or eccentric, a shaft
mounted on said frame or case and connected by gearing with said crank shaft,
and a gear case forming an oil-tight closure over said gearing and the end of
the crank shaft with which the driving connection of the pump is made, whereby
a stuffing box for said crank shaft is dispensed with, substantially as and for the
purposes set forth.
3. The combination of a frame provided with boxes and formed with an oil
chamber or well between said boxes, a shaft supported in said boxes and pro-
vided between them with a crank or eccentric, a cylinder attached to said frame
and opening at one end into the oil chamber or well therein, a piston fitted in
said cylinder and connected with said crank or eccentric, a motor base mounted
upon said frame and forming a closure for said chamber, an armature shaft
supported in bearings upon said base parallel with said crank shaft, and pro-

page_text: vided at one end with a pinion which meshes with a gear on the crank shaft, and
a case enclosing said pinion and gear forming a receptacle for holding oil, a
part of said case over said pinion being detachable, substantially as and for the
purposes set forth.
4. The combination of a frame formed with an oil well or chamber and pro-
vided with boxes in communication with said chamber, a shaft supported in
said boxes and provided with a crank or eccentric, a cylinder attached to said
frame and opening at one end into said oil chamber, a piston fitted in said
cylinder and connected with said crank or eccentric, an electric motor mounted
upon said frame and comprising a base which covers said oil chamber and is
provided on the upper side with oil wells and box housings, having detachable
caps and with an armature housing and yoke having also a detachable cap, an
armature and its shaft supported in said housings parallel with the crank shaft
and provided at one end with a pinion which meshes with a gear on said crank
shaft, and a gear case forming an oil receptacle and composed of two parts, one
attached to the frame and motor base, and the other to and removable with the
cap of the adjacent box housing, substantially as and for the purposes set forth.
5. The combination with a bearing of a lubricating device comprising an oil
well, means for conveying oil from said well to said bearing, means for replenish-
ing said well with oil, and an overflow passage leading out of said well above the
bottom thereof at a level above which it is desired that the oil shall not rise
therein, substantially as and for the purposes set forth.
6. The combination with a bearing of an oil well provided with a filling opening
at a level above which it is desired the oil shall not rise therein, means for con-
veying oil from said well to said bearing, means for replenishing said well with
oil, and an overflow passage leading out of said well at a level above which it
is desired the oil shall not rise therein, substantially as and for the purposes set
forth.
7. The combination with a bearing, of a lubricating device comprising an oil
well from which oil is supplied to said bearing, and a chamber below said well
having an overflow opening and a passage leading out of said well at the level
at which the oil is to be maintained therein and extending into said chamber
below its overflow opening, substantially as and for the purposes set forth.
8. The combination with a bearing, of an oil well provided with a filling open-
ing at about the level at which oil is to be held therein, means for conveying
oil from said well to said bearing, a chamber below said well having an over-
flow opening, and a passage leading out of said well above its bottom and extend-
ing into said chamber below its overflow opening, substantially as and for the
purposes set forth.
9. The combination with a shaft and a bearing therefor, of an oil well below
said bearing, means for raising oil therefrom to said bearing, a chamber sur-
rounding said shaft at the inner end of said bearing and communicating below
it with said well, an oil intercepting ring on the armature shaft within said
chamber, a chamber below said well having an overflow opening and a passage
leading out of said well above the bottom thereof, and extending into said last
mentioned chamber below its overflow opening, substantially as and for the
purposes set forth.
10. The combination with the armature shaft of an electric motor, encased
power-transmitting gearing and a bearing for said shaft between said gearing
and the armature, of an oil well below said bearing, means for conveying oil
from said well to said bearing, a chamber surrounding said shaft at the inner
end of said bearing and communicating below it with said well, a ring on said
shaft within said chamber, a chamber below said well having an overflow open-
ing above its bottom into the gear case, and a passage leading out of said well
above its bottom and extending into the last mentioned chamber above its over-i
flow opening, ubstantially as and for the purposes set forth.
11. The combination with a cylindrical valve chamber of a hollow imper-

page_text: forate cylindrical suction valve closed at both ends and nearly filling said cham-
ber, substantially as and for the purposes set forth.
12. The combination with a cylinder having a cylindrical valve chamber com-
municating through a port above the valve seat with the interior of the cylinder
and below said seat with an inlet passage or opening, of a hollow imperforate
cylindrical suction valve closed at both ends and loosely fitting and nearly filling
said chamber, substantially as and for the purposes set forth.
13. The combination of a cylinder provided with valve chambers and inter-
changeable hollow imperforate suction and discharge valves closed at both ends,
the suction valve chamber being nearly filled by the valve contained therein,
substantially as and for the purposes set forth.
Dated this 8th day of June 1899.
BOULT & WADE,
Agents for the Applicant.