Improvements in and connected with Coal Cutting and like Machines.
Year: 1892

page_text: Date of Application, 4th Aug., 1892
Complete Specification Left, 4th May, 1893-Accepted, 4th Sept., 1893
PROVISIONAL SPECIFICATION.
Improvements in and connected with Coal Cutting and like
Machines..
1, FREDERICK HURD of Manygates Park, Wakefield, Yorkshire and of
11 Grittleton Road, St. Peters Park in the County of Middlesex Engineer, do
hereby declare the nature of the said invention to be as follows :-
My invention relates to machinery or apparatus for sinking, tunnelling, under-
cutting, nicking on end, and other operations in connection with the excavating of
coal or other minerals. By means of this invention mines can be worked with less
expense and greater output than can be attained by the methods at present in use.
At the same time the safety, confidence and comfort of the workmen are secured,
by relieving them of the most dangerous and laborious part of their duties.
My invention consists, in the cutting and drilling mechanisms and their relative
arrangements to the motor or generator and in the apparatus required with the
machines to enable them, the generator or motor and machine, to better carry out
the various operations necessary for the excavating of coal or other minerals.
In applying my invention for undercutting I actuate by the motor a combined
forged or cast steel cutter bar drill with separate chilled steel or chilled iron
cutters fixed on its end and along its fluted or twisted periphery; the cutter bar
drill is caused to revolve and reciprocate in a twisted or rifled sleeve having a key
cast in it which fits the fluted or twisted cutter bar drill; the sleeve forms the
wheel boss by which it is driven through suitable gearing from the motor shaft ;
the driving wheel may be cast or keyed on the sleeve or wheel boss.
The cutters are fixed to the cutter bar drill in the following manner.
I form a
number of dovetail recesses at intervals along one edge of the twisted groove and
I drill holes from such recesses transversely through the bar, the cutters are
formed to fit the recesses and they are retained in position by a split locking shank
which may be separate from or attached to the cutter; the head of the split
locking shank, when this latter and the cutter are made in one piece, springs into a
countersink formed at the outer end of the transverse hole.
The cutters may be fitted into a dovetail recess extending the full depth or
nearly so of the twisted groove, and in such case a transverse hole is formed
through the bar at right angles to the cutter, when a split locking shank is passed
through a hole in the cutter and into such transverse hole or vice versa, so that the
split spring head can spring into a recess in the cutter or in the cutter bar.
end cutter is of angur form slightly modified.
The
In using this machine the operations are as follows:-When the machine is
brought up to the face of the coal or mineral to be operated upon, the cutter bar
drill is set in motion and while revolving it is fed into the face by an automatic or
hand feed motion, in which latter case a circular or screw rack is cast or cut on the
cutter bar, or otherwise, combined therewith, a pinion being arranged to gear into
such rack.
When the cutter has entered to the depth required it is locked by the recipro-
cating motion gear and all strain taken off the feed gear; the reciprocating motion
is obtained preferably by forming on the sleeve a worm thread into which gears a
worm wheel carrying on its gudgeon two crank pins which actuate two rocking
levers. Fitting round the sleeve between two or more shoulders is a thrust block
in halves, each half being coupled by a right and left hand screw; these divided
thrust blocks are connected to connecting rods operated by the rocking levers
which impart the reciprocating motion of the latter to the cutter bar drill when
the thrust block and drill are connected.

page_text: The machine is traversed forward along the face of the mineral by means of a
snatch block and a hauling drum, chain wheel or connecting cranks and rods
mounted on the axis of a switch, the casing of which latter is fitted to the front
trunk of an electric motor, and the hauling drum or chain wheel and connecting
cranks and rods is or are driven from the motor shaft by means of worm gearing
and friction cones described in my Specification 1036 of the year 1872.
The cutter bar drill at the same time revolves, thus cutting away the coal in
front of it, while its reciprocating motion assists in breaking up the coal and
dislodging any lumps of pyrites that may be met with.
In order that the coal or mineral may be nicked on end to expedite the breaking
down of the mineral when undercut, the cutter bar drill with its sleeve and feed
gear are carried by a separate casting carrying the bearing for the motor shaft,
and which is so arranged as to make a whole or partial revolution round the
motor shaft.
By this arrangement also the machine is enabled cut either right or left hand,
thus dispensing with a costly left hand cutting arrangement as required in other
machines now in use.
In this class of machine the vibration when at work is very great and I reduce
this greatly by fixing or constructing the journal to carry the cutter bar drill at an
angle of about 80° with the rails in the direction in which the machine is moving,
thereby causing the machine to hold itself well up to its work.
I also provide the machine with rail slide blocks in addition to the usual wheels
and when at work these blocks are let down on to the rails and, by their large
bearing surface, give the machine more stability and greater steadiness. The
wheels and blocks are provided with screws similar to those patented by ine on
April 8th 1872 No. 1036 for raising and lowering same and so varying the height
or angle of the cut. One set or pair of wheels or blocks and their respective
raising screws are attached to a separate casting made free to revolve, or partly so,
round the outer portion of the leading trunk of the motor and are thus capable of
adapting themselves to any unevenness of the rails on which the machine works;
another set or pair of wheels or blocks with their screws are fixed or coupled to
the back trunk of the motor.
To take out the cuttings made by the cutter bar drill I use a cleaning bar,
preferably Ū shaped in section, set at an acute angle to, and behind, the cutter bar
drill and fixed to the machine by suitable means when at work. The cuttings are
caused, by the forward motion of the machine, to slide along the face of
this cleaning bar and be deposited between or at the side of the rails as the
machine proceeds.
I remove irregularities from the face of the mineral and from the bottom by
means of a fixed cutter attached to the journal casting of the cutter bar drill,
the said fixed cutter forming at the same time a cover for the thrust block gear.
This fixed cutter has a cutting edge to clear the bottom and an inclined cutting
edge to remove projections on the face of the mineral sufficiently high to clear the
cutter bar bearing.
The fixed cutter is also formed with an inclined groove so arranged as to
carry the cuttings back over the cutter bar front journal to the rear of the
machine. By this means the machine is enabled to proceed with its work without
stoppages.
In applying my invention to a machine for tunnelling or sinking, a slight
modification of the machine before described is necessary; in this case the cutter
bar drill with or without its reciprocating motion is fitted to the end of a telescopic
arm carried by a centre casting which is free to revolve around the end trunk of
the motor in a plane at right or other angles to the motor shaft, as patented by me
in 1869 No. 906.
The cutter bar drill is tapered down from its driven to its working end; it is
driven by shaft and bevel gearing from the motor shaft and is fixed to the
telescopic arm at such an angle that the tips of the cutters are located slightly

page_text: heyond the plane of the driving wheel and make a cut parallel to motor shaft; by
this means clearance is obtained between the bevel pinion on the cutter bar drill
and the sides of the shaft or tunnel.
By the centre piece which carries the telescopic arm is also carried an externally
rifled tubular drill similar to one patented by me, August 27, 1880, No. 3474, this
drill is driven from the shaft driving the cutter bar drill. The mode of operation
with this machine is as follows: the machine is brought up to the face of the
mineral and the centre drill and cutter bar drill set in motion. The two drills are
then fed into the face by the entire machine being worked forward by means of
hauling and snatch block or connecting rod gear hereinbefore referred to, to the
full depth required.
The centre drill is then stopped from rotating and the centre casting carrying the
telescopic arm is then caused to revolve by means of worm gearing driven by hand
or from the motor shaft; thus the cutter bar drill is caused to cut a deep circular,
oval or square groove in the face of the mineral; this groove may be made of any
desired shape by fixing a suitable template or cam on the trunk of the machine by
which the length of the telescopic arm may be varied and thus enable it to cut a
square, oval, rectangular or other shaped groove.
The centre drill being allowed to remain in at full depth serves to steady the
machine.
When a complete revolution has been made by the telescopic arm carrying the
cutter bar drill, the drills are withdrawn from the mineral by the machine being
moved backwards away from the face of the mineral, which is then broken up to
the depth of the cut, the centre hole greatly facilitating this operation.
When the material is removed the machine is brought up to the face of the
mineral again and the operation repeated.
In sinking operations the centre piece carrying cutter bar drill, centre externally
rifled tubular drill and mechanism before described and the motor for driving
the same, are mounted in a cage similar to the one patented by me on March 25,
1869 No. 906, the mode of operation being the same as described for the preceding
machine.
COMPLETE SPECIFICATION.
Improvements in and connected with Coal Cutting and like
Machines.
I, FREDERICK HURD of Manygates Park, Wakefield, Yorkshire, and of
11 Grittleton Road, St. Peter's Park, in the County of Middlesex, Engineer, do
hereby declare the nature of this invention and in what manner the same is to
be performed to be particularly described and ascertained in and by the following
statement:-
My invention relates to machinery or apparatus for, sinking, tunnelling, under-
cutting, nicking on end, and other operations in connection with the excavating of
coal or other minerals.
By means of this invention mines can be worked with less expense and greater
output than can be attained by the methods at present in use.
At the same time
the safety confidence and comfort of the workmen are secured, by relieving them of
the most dangerous and laborious part of their duties.
My invention consists in the cutting and drilling mechanisms and their relative
arrangements to the motor and in the apparatus required with the machines to

page_text: enable them, the motor and cutting and drilling mechanisms to better carry out the
various operations 'necessary for the excavating of coal or other minerals.
My invention is represented in the accompanying drawings in which
Figure 1 is a plan of a coal cutting or like machine with most of the cutting and
drilling mechanism broken away;
Figure 1 is a plan mainly in section of the cutting and drilling mechanism which
completes the view shown at Figure 1.
Figure 2 is a side elevation partly an section and Figure 3 is an end view of the
same with parts removed.
Figure 4 is an end view of parts shown at Figure 1^ looking at the drilling end
of the cutter bar.
Figure 5 is an internal view of the cover carrying the bearings of the recipro-
cating motion worm wheel and shaft.
Figures 6 and 6 represent the cutter 'bar'drill which is drawn in three parts for
convenience in drawing.
Figure 7 is an end or face view of the auger or drilling cutter.
Figure 8 is a cross section of the cutter bar drill and,
Figure 9 is a plan showing one form of cutter and method of fixing the same in
the cutter bar and
Figure 10 is a face view of the cutter separately.
Other forms of cutters and methods of fixing the same are shown at Figures 11
to 20. A modified form of cutter bar drill is shown at Figure 21.
Figure 22 is a plan of parts of a coal cutting or like machine similar to that
shown at Figures 1 to 3 but slightly modified in parts.
Figure 23 is a sectional plan of parts showing the cutter bar drill provided with
a screw feed.
Figure 24 is a sectional plan of parts showing the cutter bar drill without feed
motion and in combination with a cleaning bar, and
Figure 25 is a sectional elevation of drilling and cutting mechanism for a
tunnelling or sinking machine.
Figure 26 is a perspective view of my cutting machine showing it performing the
work of undercutting, and
Figure 27 is a perspective view representing my improved cutting machine as
applied to heading or tunnelling.
In all the figures like parts are indicated by similar letters of reference.
In applying my invention for undercutting I actuate, by a motor A constructed
according to the Specification filed in pursuance of my application No. 14124 of the
year 1892, a combined cutter bar drill a formed of forged or cast steel or other
suitable metal or alloy and 'having separate or detachable chilled steel or chilled
iron cutters a' fixed along its fluted or twisted periphery, and an auger cutter a³ at
its outer end; the cutter bar drill a is caused to revolve and reciprocate in a twisted
or rifled sleeve having rifled grooves * for the passage of the cutters on the bar
and a key b' cast in it, which fits the twisted groove a' of the cutter bar drill a ;
the sleeve forms the boss of the wheel 2 by which it is rotated by a bevel pinion c¹
fixed on the motor shaft c. I preferably use double helical teeth for the wheel
and pinion, but other suitable gearing may be employed; the wheel
may be
keyed or otherwise fixed on the sleeve b instead of being cast thereon. The rear
end of the cutter bar up to the first cutter is bored out so as to give a free outlet
to the cuttings when nicking on end or otherwise.
The cutters a may be fixed to the cutter bar drill a according to any of the
methods shown at Figures 6 to 21.
According to the method shown at Figures 8, 9, 10, I form a number of
dovetail recesses a³ at intervals along one edge, of the twisted groove at. I form
the shanks a of the cutters to fit the recesses and they are retained in position by
a split pin a fitting in a hole bored partly in the side of the shank a' and partly in
the side of the dovetail recess a³.

page_text: According to the method shown at Figures 11 and 12, the cutter shank extends
into a hole drilled in the cutter bar down to a little below the bottom of the twisted
groove a', and in such case the upper part of the shank a' fits in a dovetailed or
other recess a formed in the upper edge of the twisted groove. In this case the
cutter is held in position by a split pin a passing through an angular hole drilled
through the cutter shank a and the bar a and springing into a countersink. If
desired the lower end of the shank a' may also be formed with an eccentric stud or
prolongation a to enter a corresponding hole in the cutter bar a to assist in holding
the cutter from rotation in its recess.
According to the method shown at Figures 13, 14, 15, the shank a of the cutter
fits into a hole bored in the cutter bar as described with respect to Figures 11
and 12, but it is held in position and free from rotation by a split pin or spring
shank a passing into an eccentric hole in the bar a, one side of said split shank
being hooked to catch under the bottom of one side of the eccentric hole a³.
desired the cutter may be formed as shown by dotted lines in Figure 13 and full
lines in Figure 14 with a backward extension a to give strength to the working
part thereof.
If
According to the method shown at Figures 16 and 17, the cutter a' has the
shank a fitting an angular or circular recess formed in the bar a, the eccentric stud
or prolongation a' fits a corresponding hole and it has a split pin or shank a
extending from its bottom end and passing through a hole formed for it in the bar a
as described with respect to Figures 13, 14, 15.
The method shown at Figures 18, 19 and 20 is similar to that described with respect
to Figures 11 and 12, except that the eccentric stud or prolongation a' is dispensed
with and the cutter is held from rotation by the rear part of the cutter head
entering a recess in the cutter bar and such cutter is held in position either by an
angular split pin a or by a split pin or shank a extending from the bottom of the
cutter shank and springing into a countersink and if desired the said split shank a
may be eccentric to the cutter shank a*.
Figure 21 represents a cutter bar drill a provided with two twisted grooves a
and fitted with cutters a¹ of the forms shown, but which may be of any of the
forms previously described so far as such are suitable to the said doubly grooved
bar. The auger cutter a' is formed as shown with a central cutter and with two
forward and two backward acting cutters so that the said auger shall cut both in
its forward and backward motions.
In using this machine the operations are as follows: When the machine is
brought up to the face of the coal or mineral to be operated upon the cutter bar
drill a is set in motion and while revolving it is fed into the face of the mineral by
an automatic or hand feed motion which latter is shown in the drawings at
Figures 1 and 23 and consists of a circular rack a⁰ as shown at Figures 1 and 6
or a screw rack a as shown at Figure 23 which may be either cast or cut on the
cutter bar a or otherwise combined therewith, a pinion & being arranged to gear
into such rack.
As shown at Figure 1 the said piuion d has its axis d' formed square to receive
a lever handle by which it can be rotated but if desired it may be fitted with a
ratchet wheel and driving pawl. The said pinion d is carried by a casting d²
pivotted at d³ to the cutter bar bearing and such casting is fixed in working
position by a bolt d' passing through a segmental slot so that by loosening said
bolt the casting d can be turned on its pivot and the pinion d removed out of
gear with the rack a¹.
When the cutter bar drill a has entered to the depth required it is locked by the
blocks e of the reciprocating motion gear and all strain or action taken off the feed
gear by removing the pinion d out of gear with the rack a; the reciprocating
motion is obtained preferably by forming on the sleeve a worm thread into
which gears a worm wheel f carrying on its gudgeon two crank pins fitting
into blocks which actuate two rocking levers Fitting round the circular
rack a and embracing several rings of said rack is the thrust block e which is in

page_text: halves, each half being coupled by a right and left hand screw e¹; these divided
thrust blocks e are connected to connecting rods e operated by the rocking levers f**
which impart the reciprocating motion of the latter to the cutter bar drill a when
the thrust block e and drill a are connected.
Instead of the divided thrust block e as above described acting in connection
with the rack a¹0 it may as described in my Provisional Specification act between
two or more shoulders on the sleeve and give motion to the cutter bar drill through
the intervention of the sleeve b; the sleeve in such case being capable of sliding
through the bevelled wheel ³.
The machine is traversed forward along the face of the mineral by means of a
snatch block and a hauling drum 9 mounted on an axis g¹ passing through the
axis of the switch h, the rope being wound on to the drum and passing around a
snatch block and then to a fixture on the machine or such rope may pass direct
from the hauling drum to any fixture. Instead of using the hauling drum a
chain wheel and chain may be employed but when working down hill or on a level
cranks g fixed on the axis g' are used and connecting rods g³ connect such cranks
with the driving wheels . The casing of the switch is fitted to the front
trunk A' of the motor A and the hauling drum g or chain wheel and cranks g'
and rods are driven from the motor shaft c by means of worm and spur gearing
and friction cones as shown in Figure 22 and described in my Specification No. 1036
of the year 1872. The cutter bar drill at the same time revolves, thus cutting
away the coal in front of it while its reciprocating motion assists in breaking up
the coal and dislodging any lumps of pyrites that may be met with.
In order that the coal or mineral may be nicked on end to expedite the
breaking down of the mineral when undercut, the cutter bar drill a with its sleeve b
and feed gear are carried by a separate casting B carrying the bearing B' for the
motor shaft c and which is so arranged as to make a hole or partial revolution
round the motor shaft. by means of worm i and worm wheel see Figures 1,
1ª, 2, 22, 23, 24 and 25.
By this arrangement also the machine is enabled to cut either right or left
hand thus dispensing with a costly left hand cutting arrangement as required in other
machines now in use.
In this class of machine, the vibration when at work is very great and I reduce
this greatly by fixing or constructing the journals to carry the cutter bar drill a
at an angle of about 80° with the rails in the direction in which the machine is
moving as represented at Figures 14, 23 and 24, thereby causing the machine to
hold itself well up to its work.
I also provide the machine with rail slide blocks x see Figure 3 in addition
to the usual wheels g which blocks when at work are let down on to the
rails and, by their large bearing surface give the machine more stability and
greater steadiness.
The wheels and blocks are provided with screws 9³ similar to those patented
by me on April 3rd 1872 No. 1036 for raising and lowering same and so varying
the height or angle of the cut, except that the screws are right and left threaded
so that when acting to lower the blocks, they shall raise the wheels and vice versa,
separate screws however may be employed.
One set or pair of wheels g' and blocks and their respective raising screws g
are attached to a separate casting C, see Figures 1, 22, made free to revolve, or
partly so, round the outer portion of the leading trunk A¹ of the motor A and
are thus capable of adapting themselves to any unevenness of the rails on which
the machine works; another set or pair of wheels g and blocks with their
respective screws g' are fixed or coupled to the back truuk A' of the motor A, see
Figures 23, 24.
To take out the cuttings made by the cutter bar drill I use a cleaning bar ; see
Figure 24, preferably U shaped in section, set at an acute angle to and behind
the cutter bar drill a and fixed to the machine by suitable means when at work.
The cuttings are caused, by the forward motion of the machine to slide along the

page_text: lace of this cleaning bar and to be deposited between or at the side of the rails as
the machine proceeds.
I remove irregularities from the face of the mineral and from the bottom
by means of a fixed cutter k, shown at Figure 1 and by dotted lines at
Figure 4 and at Figure 26, attached to the front journal casting B of the cutter
bar drill a, the said fixed cutter k at the same time forming a cover for the thrust
block gear.
This fixed cutter k has a cutting edge ¹ to clear the bottom and an inclined
cutting edge k to remove projections on the face of the mineral sufficiently high to
clear the cutter bar bearing.
The fixed cutter k is also formed with an inclined grooved conductor so
arranged as to carry the cuttings back over the cutter bar front journal to the rear
of the machine. By this means the machine is enabled to proceed with its work
without stoppages.
In applying my invention to a machine for tunnelling or sinking a slight
modification of the machine before described is necessary and which is illustrated
at Figures 25 and 27, in this case the cutter bar drill a with or without its recipro-
cating motion, (in the drawing it is shown without,) is fitted to the end of a tele-
scopic arm carried by the centre casting B which is free to revolve around the end
trunk A of the motor in a plane at right or other angles to the motor shaft as
patented by me in 1869, No. 906.
The cutter bar drill a is tapered down from its driven to its working end; it is
driven by shaft m and bevel gearing m³ m² from the motor shaft through the
sleeve band gearing 6 c', and is fixed to the telescopic arm l, which also forms a
casing for the gearing, at such an angle that the tips of the cutters are located
slightly beyond the plane of the casing of the wheel m³ and make a cut parallel
to motor shaft e; by this means clearance is obtained between the casing of the
bevel pinion m³ on the cutter bar drill a and the sides of the shaft or tunnel. By
the centre piece B which carries the telescopic arm is also carried an externally
rifled tubular drili n, similar to one patented by me August 27, 1880, No. 3474;
this drill n is driven from the sleeve b by bevel gearing n¹ n. The mode of operation
with this machine is as follows: the machine is brought up to the face of the
mineral and the centre, drill n and cutter bar drill a set in motion The two drills
are then fed into the face by the entire machine being worked forward by means
of hauling and snatch block or connecting rod gear herein before referred to, to the
full depth required. The centre drill n is then stopped from rotating and the centre *
casting B carrying the telescopic arm is then caused to revolve by means of worm
gearing driven by hand or from the motor shaft, thus the cutter bar drill a
is caused to cut a deep circular, oval or square groove in the face of the mineral,
this groove may be made of any desired shape by fixing one or two suitable tem-
plates or cams o on the trunk A2 of the machine by which the length of the
telescopic arm may be varied as the centre, casting B revolves and thus enable it
to cut a square, oval, rectangular or other shaped groove. Motion is given to the
telescopic arm by studs fixed therein and provided with rollers working, in the
grooved cams o.
1
The centre drill n being allowed to remain in at full depth serves to steady the
machine.
When a complete revolution has been made by the telescopic arm / carrying the
cutter bar drill a, the drills are withdrawn from the mineral by the machine being
moved backwards away from the face of the mineral which is then broken up to the
depth of the cut, the centre hole greatly facilitating this operation.
When the material is removed, the machine is brought up to the face of the
mineral again and the operation repeated.
In sinking operations the centre piece, carrying cutter bar drill a, centre
externally rifled tubular drill n and mechanism before described and the motor for
driving the same are mounted in a cage similar to the one patented by me on

page_text: March 25 1869 No. 906, the mode of operation being the same as described for the
preceding machine.
It will be evident that the cutting mechanism herein described may be con-
nected with and driven by a motor of different construction to that hereinbefore.
referred to.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed I declare that what I
claim is :-
1. The improved constructions and arrangements of coal cutting and like
machinery substantially as herein shown and described.
2. In coal cutting and like machinery the improved construction of cutter bar
drill and the methods of fixing the cutters therein substantially as herein; shown
and described.
3. In coal cutting and like machinery the combination with a suitable motor
and driving gear, of a rotating and reciprocating cutter bar drill having cutters
on its length and an end cutter or auger substantially as herein shown and
described.
. 4. In coal cutting and like machinery the combination with a driving shaft of a
casting carrying the cutting mechanism and capable of being rotated around the
said driving shaft by suitable gearing substantially as herein. shown and described
and for the purposes stated.
5. In coal cutting and like machinery the combination of a cutter bar drill, a
rifled driving sleeve to permit of the cutter bar drill with its side and end cutters
being fed through the sleeve and mechanism for giving endwise motion to the cutter
bar drill substantially as herein shown and described.
6. In coal cutting and like machinery the combination with suitable cutter or
cutters of a cleaning bar arranged at an acute angle therewith and acting to clean
out the debris from the groove cut in the coal or other mineral substantially as
berein shown and described.
7. In coal cutting and like machinery the combination with suitable cutting and
driving arrangements of a fixed cutter and inclined conductor for cutting the face
and bottom of the mineral and for lifting or conveying the debris backward. and
over the cutter bar journal substantially as herein shown and described.
8. In coal cutting and like machinery the combination of a driving shaft, a
casting capable of being rotated around said driving shaft, a telescopic arm carried
by said casting, a cutter bar drill carried by said telescopic arm, a central cutter
or drill carried by the rotatable casting and driving mechanism for rotating the
cutter bar drill and central drill, substantially as herein shown and described.
9. In coal cutting and like machinery for tunnelling or sinking, the combination
with a telescopic arm carrying a drill or cutter, of a cam or cams acting to give a
to and fro motion to the telescopic arm to control the shape of the groove cut in
the coal or mineral, substantially as herein shown and described.
Dated May 4th 1893.
Dated May 4th 1893.
FRED. HURD,
By Harris & Mills,
23, Southampton Buildings, London, W.C., Agents.