Improvements in Apparatus for Drilling Boiler Rings and Objects of Cylindrical or other Formation.
Year: 1894

page_text: Date of Application, 4th Jan., 1894
Complete Specification Left, 4th Oct., 1894-Accepted, 10th Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Drilling Boiler Rings and Objects
of Cylindrical or other Formation.
1 SAMUEL DIXON of the Firm of Kendall & Gent of the Victoria Works,
Springfield Lane, Salford, in the County of Lancaster, Machine Tool Makers, do
hereby declare the nature of this invention to be as follows:-
My invention relates to machines adapted to be used principally in the drilling
of holes in boiler rings or in cylinders or parts of cylinders. In such machines the
work is secured upon a revoluble table and the drill spindles are adjustably mounted
upon standards which can be adjusted in distance from the axis of such table. It
has been usual to apply more than one drill spindle so that two or more holes could
be drilled simultaneously. There has been a tendency for the work to yield to
some extent to the pressure of the drills especially when operating at a comparatively
great height above the table.
To support the work against the drill pressure I provide an adjustable abutment
to bear against the inside of the cylinder.
The table is made of an annular form and a pillar or standard to carry the
abutment projects through the hole in the table to the required height the table
being mounted to revolve around this pillar the latter being carried by a bed or
foundation so as not to revolve with the table. By preference the pillar is mounted
to slide upon a bed toward and from the drill spindle and is operated by means of
a screw or rack and pinion or by other suitable means the hand wheel whereby the
pillar is moved being in a position convenient to the operator. The abutment is
adjustable vertically and may be of a crutch form or of a suitable form and by
preference would be hinged to a part projecting from the pillar so that both ends
would bear equally. The pillar might be fixed and the abutment piece be mounted
to slide in and out and be operated by screws connected by means of vertical and
horizontal shafts and gearing with a hand wheel.
In practice there would be an abutment piece to correspond with each drill
standard. In some cases I provide a set of drills arranged upon a vertical line and
preferably opposed to a set arranged upon a horizontal line. The drill spindle
mountings would be adjustable upon a vertically sliding carriage and would receive
motion from a vertical shaft. One feed motion would be connected by means
of a vertical shaft and worm or suitable gearing with the nut wheels of all
the spindles.
The spindles would preferably be actuated to have the quick return movement in
accordance with the Specification of a former invention for which Letters Patent
Number 10936 of the year 1887 have been granted to me. The mountings of the
horizontally arranged spindles would be adjustable so as to align with radials from
the work, as in my said former invention and would by preference be secured upon
a cross slide fitted to slide vertically upon two adjustable standards so as to furnish
a firmer resistance to the end thrust of the spindles. The cross slide would be
raised and lowered by connected screws which might be actuated by power.
I may apply one feed motion to serve for all the spindles as in the case of the
vertically arranged spindles but to provide for the radiating adjustment of the
spindle mountings I mount the connecting feed shaft above the spindles and connect
it with wheels having axes in line with the axes of the pivots of the spindle
mountings such wheels being connected by shafts and gearing with the nut wheels
upon the screws.

page_text: I provide the annular table with dividing apparatus and with apparatus for
chucking or centering and holding the work. In a machine of my improved con-
struction I can arrange a comparatively large number-as for example six or more-
spindles upon each slide.
I provide two speed driving gear for the spindles and arrange the changing
levers and starting and reversing levers in position to be ready to the hand of the
attendant.
Dated this 3rd day of January 1901
E. K. DUTTON & Co.,
5, John Dalton Street, Manchester, Agents.
COMPLETE SPECIFICATION.
Improvements in Apparatus for Drilling Boiler Rings and Objects
of Cylindrical or other Formation.
I SAMUEL DIXON of the Firm of Kendall & Gent of the Victoria Works,
Springfield Lane, Salford, in the County of Lancaster, Machine Tool Makers, 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 and accompanying drawings :-
―
My invention relates to machines adapted to be used principally in the drilling
of holes in boiler rings or in cylinders or parts of cylinders. In such machines the
work is secured upon a revolvable table and the drill spindles are adjustably mounted
upon standards which can be adjusted in distance from the axis of such table. It
has been usual to apply more than one drill spindle so that two or more holes could
be drilled simultaneously. There has been a tendency for the work to yield to
some extent to the pressure of the drills especially when operating at a comparatively
great height above the table.
To support the work against the drill pressure 1 provide an adjustable abutment
to bear against the inside of the cylinder.
The table is made of an annular form and a pillar or standard to carry the
abutment projects through the hole in the table to the required height, the table
being mounted to revolve around this pillar, the latter being carried by a bed or
foundation so as not to revolve with the table. By preference the pillar is mounted
to slide upon a bed toward and from the drill spindles and is operated by means of
a screw or rack and pinion or by other suitable means, the hand wheel whereby the
pillar is moved being in a position convenient to the operator. The abutment is
adjustable vertically and may be of a crutch form or of a suitable form and by
preference would be hinged to a part projecting from the pillar so that both ends
would bear equally. The pillar might be fixed and the abutment piece be mounted
to slide in and out and be operated by screws connected by means of vertical and
horizontal shafts and gearing with a hand wheel.
In practice there would be an abutment piece to correspond with each drill
standard. In some cases I provide a set of drills arranged in a vertical plane and
preferably opposite to a set arranged in a horizontal plane. The drill spindle
mountings would be adjustable upon a vertically sliding carriage and would receive
motion from a vertical shaft. One feed motion would be connected by means
of a vertical shaft and worm or suitable gearing with the nut wheels of all
the spindles.
The spindles would preferably be actuated to have the quick return movement in
accordance with the Specification of a former invention for which Letters Patent
Number 10936 of the year 1887 have been granted to me.
The mountings of the spindles arranged in a horizontal plauc would be adjustable
so as to align with radials from the work, as in my said former invention and would
by preference be secured upon a cross slide fitted to slide vertically upon two

page_text: adjustable standards so as to furnish a firmer resistance to the end thrust of the
spindles. The cross slide would be raised and lowered by connected screws which
might be actuated by power.
may apply one feed motion to serve for all the spindles as in the case of the
vertically arranged spindles but to provide for the radiating adjustment of the
spindle mountings I mount the connecting feed shaft above the spindles and connect
it with wheels having axes in line with the axes of the pivots of the spindle
mountings, such wheels being connected by shafts and gearing with the nut wheels
upon the screws.
I provide the annular table with dividing apparatus and with apparatus for
chucking or centering and holding the work. In such a machine of my improved
construction I can arrange a comparatively large number-as for example six or
more spindles upon each slide.
I provide two-speed driving gear for the spindles and arrange the changing levers
and starting and reversing levers in position to be ready to the hand of the attendant.
In order that my invention may be more clearly understood I have annexed
hereunto four sheets of illustrative drawings which I will now describe upon the
lines of the foregoing preliminary Specification.
On Sheet 1 of the drawings, Fig. 1 is a side elevation of the improved boiler
ring drilling apparatus.
Ön Sheet 2 Fig. 2 is a plan of Fig. 1.
On Sheet 3 Fig. 3 is a side view on an enlarged scale of one of the arrangements
for driving, feeding forward and returning the drills in the horizontal plane.
Fig. 4 is a view of the same at right angles to Fig. 3. Figs. 5, 6, 7 and 8 are
further detail views of the clutches and other means for effecting the advance and
withdrawal of the drills.
On Sheet 4 Figs. 9, 10, 11 and 12 illustrate the means for driving, advancing
and retracting the drills where a hollow screw is employed.
Similar letters in the respective figures identify similar parts.
The standards carrying the drills lying in the horizontal plane and used to drill
the circumferential rivet holes in the boiler are marked A. The opposite standard
which carries the vertically arranged drills for boring the longitudinal rivet holes
is marked B. These standards rest on slides on the bed C and they can be adjusted
on the bed to any desired position.
Between the standards is situated a table D which is of an annular or ring shape.
This table has a flange D₁ which rests upon anti-friction rollers D2 carried by the
intermediate portion C₁ of the bed C. The outer circumference of the flange D' is
furnished with teeth so as to form a circular worm rack, and a worm E (see Fig. 2)
gears with this worm rack, so that by turning the shaft E' which carries the worm E,
the table D can be turned and adjusted to any position. Vertically arranged
anti-friction rollers D³ (which appear in Fig. 2) bear upon the inner circumference
of the flange D' and keep the table in its true concentric position. For convenience
we connect the shaft E¹ by mitre wheels E2 with an upright shaft E³, which is in
its turn connected by mitre wheels E' with the spindle of a change wheel E' which
gears with a wheel E which is operated by a handle E7. An index or indicator of
any suitable nature is operated by the spindle of the handle E' and the change
wheels E and E are so arranged that one turn of the handle E' will give a fixed
and certain amount of revolution to the table D. Thus the operator standing on
the platform F and having charge of the machine can revolve the table to a fixed
extent without leaving the platform and without requiring to check the work, the
indicator rendering the movement certain. While on the platform F it may be
noted that the attendant has at his hand and under his direct control the three
governing handles which manipulate the machine viz. the handle E' for revolving
the table; the handle G for adjusting the abutments, as will be hereinafter shown;
and the lever H for shifting the belt forks, for reversing and altering the speeds of
the drills. The adjustable abutments which form essential features of my invention

page_text: are marked respectively I and J. The abutment I is for the purpose of keeping
he boiler rings (indicated by dotted lines X) against the pressure of the drills K
in the horizontal plane; while the abutment is for the purpose of keeping the
boiler rings up against the pressure of the drills L in the vertical plane. The
abutment is carried on a bracket I which is bolted to the planed face of a pillar M
which projects upward through the hole in the centre of the annular table D.
The abutment J is bolted to the opposite side of the same pillar. The abutment I
is formed of a crutch shape as clearly shown in Fig. 2 and is pivotted to
the bracket I so as to accommodate itself to obstructions and irregularities of the
boiler rings. The pillar M rests in slides on the intermediate portion C¹ of the
bed C, and is moved in either direction by means of a screw M¹ which is formed on
a spindle M which extends nearly the whole length of the machine, and is rotated
either by the handle G from the platform through the mitre wheels G¹ or by the
hand wheel G2 at the other end of the spindle M2 as clearly appears from Figs. 1 and 2.
Thus either the crutch shaped abutment I may be brought up against the interior
of the boiler ring so as to oppose the thrust of the horizontally arranged drills K
or the abutment J may be moved in the opposite direction against the other side of
the boiler ring interior so as to oppose the thrust of the vertically arranged drills L.
The boiler ring X is supported and held by sliding dogs N of which a suitable
number (in the example five) are arranged to slide in the annular table D. The
dogs N engage with screws N¹ the inner ends of the said screws being furnished
with bevel pinions N2 which gear into a central bevel rack O applied so as to be
capable of being rotated in the centre of the table D. All five of the bevel
pinions N2 gear with the circular bevel rack O and as the outer end of each screw
spindle N' has a squared head which enables the screw to be turned by a box key,
the consequence is that when one of the screws N' is rotated, it drives the circular
rack and thus the whole of the screws N₁ are simultaneously rotated. This has
the effect of sliding the whole five dogs N simultaneously inward or outward
according to the direction of revolution, so that when employed to bind the boiler
ring in position, the dogs N do so in a position absolutely concentric with the centre
of the table. Thus the boiler ring X is chucked and held with absolute precision.
The drills K for boring the holes to receive the rivets of the circumferential
joints of the boiler, are carried in drill spindles P revolving in sleeve brackets Q
and having screws cut on their rear ends. These sleeve brackets are carried on a
cross slide R which can be moved up and down in slides on the planed faces of
the standards A, by means of side screws S which are rotated by mitre gear from
a cross shaft T. A chain wheel U or other means on the end of the cross shaft T
facilitates the working of the screws. The side screws S, cross shaft T and chain
wheel U only appear in Fig. 1 of the drawings. By their means the height of the
horizontal plane of the drills is adjusted. The drill spindles are revolved and
advanced and retracted by the following means. I will deal in the first place with
the drills K lying in the horizontal plane and used for drilling the rivet holes for the
circular seams in the boiler, and will afterwards where necessary refer to the
vertically arranged drills L. The motion is obtained from a side shaft V which is
driven from an overhead shaft by means of crossed and straight belts running on
the fast and loose pullies V and V. The shaft V imparts motion by means of
mitre wheels W to an upright spindle Y, and this spindle Y gears by means of
bevel wheels Y (see Figs. 5 and 6) with the cross shaft Z which lies beneath the
sleeve brackets Q. Short upright connections a (see Fig. 3) and mitre gearing,
furnish driving communication between the cross shaft Z and each of the drill
spindles P which are thereby revolved at a rapid speed. The sleeve a¹ is
connected by a slip feather and groove to the drill spindle so that the spindle
while driven by the sleeve a¹ can slide to and fro therein. A spur wheel b on the
shaft Z and at the back of the bevel wheel Y₁ imparts motion through the gear
wheels &¹², to the clutch half e which revolves on but is not keyed to the reduced
neck d' of the worm screw d. On the same neck but keyed thereto by a slip

page_text: feather and groove so as to slide on the neck, I place another clutch half c', which
is held up against the clutch half c by a spring f. When the clutch half c is
revolved in the direction of the arrow, then it drives the half c' and rotates the
worm screw d. On the contrary when the motion of the clutch half c is reversed,.
the half clicks back at each revolution without being driven, and the worm
screw is at a standstill. The worm screw d is connected to the feeding nut j of
each drill spindle P see Fig. 3 by means of the worm wheel, mitre wheels y,
spindle h, and gear wheels i, . The connecting gear wheels from the upright
spindle Y are so proportioned that the spindle h runs at the same speed as the drill
spindles, consequently if the gear wheels i were equal the nuts; would run at
exactly the same speed as the screws P¹ on the drill spindles P, and no advance of
the drill spindles would take place. But to give the required feed I make the
wheels with say one tooth less than the wheels so that the wheels and nuts j
hang back to the extent of one tooth at each revolution.
This under-speeding of the nuts on the screws P₁ advances the drills slowly
during the boring operation since the nuts j are confined, as clearly shown in the
drawing, and cannot alter their position longitudinally. Since the nuts j revolving
more slowly than the screws, cause the drills to advance slowly, it will be evident
that a stoppage of the revolution of the nuts and a reversal of the revolution of the
screws, would cause the screws and drill spindles to be very expeditiously
retracted. This stoppage of the nuts is brought about by the reversal of the
machine which is done by throwing the crossed belt working on the pullies V¹
upon the fast pulley. On the consequent reversal of the upright shaft Y see
Figs. 5 and 6 the clutch half c is also reversed and ceases to drive the opposite
clutch half e' as already clearly explained. The worm screw d is therefore stopped
and consequently the nuts j remain at rest. At the same time the reversal of the
revolution of the screws, runs the drill spindles quickly back to their original
starting point. The attendant now revolves the table by means of the handle E'
so as to present a fresh portion of the boiler ring X to the drills, and then causes
the drills once more to advance. In order not to lose time, by the slow advance
of the drills before they actually touch the work, I arrange for the crossed belt on
the pullies V (Fig. 2) to be shifted from the loose to the fast pulley, and this
being of smaller diameter than the fast pulley of the pullies V1, while the driving
drum is of the same or of a larger size, I obtain increased speed, and this increased
speed of feed I maintain until the angular noses of the drills have actually entered
the boiler plate X. At this point the attendant throws the belt of the pullies V2,
again upon the loose pulley, while the open belt of the pullies V₁ is thrown upon
the fast pulley thereby reducing the speed of the shaft V so that the drilling proceeds
at a reduced speed of feed.
This successive changing of the belts on the pullies carried by the shaft V is
brought about by manipulating the same lever H on the platform F. This lever
is connected to a rock shaft k and the rock shaft k by a rod i to a cam m which
governs the belt fork rods n in such a manner that they are pushed forward or
withdrawn in accordance with the movements of the lever. The cam arrangement
for governing the belt fork rods has been used by me for similar purposes for some
time, and forms no part of my present invention, so that it is unnecessary to describe
the same in detail.
Before leaving the drill driving and feeding arrangements I may point out that
these may be modified. For example Figs. 7 and 8 on Sheet 3 illustrate a substitute
for the slip clutch c c' in those cases where the drills can be withdrawn without
reversing the machine as already described. In such non-reversible arrangement
I cut the screws P' with a left hand instead of a right hand screw thread, and make
the nuts over-run the screw to the extent of say one tooth per revolution instead
of under speeding the same as in the former arrangement. The result of this
over-running of the nuts on the left hand screws is that the drills are advanced as
before. When it is desired to withdraw the drills all that is necessary is to stop
the revolution of the nuts and this is done by the simple clutch arrangement shown

page_text: in Figs. 7 and 8. The upright spindle Y drives the worm screw d through an
arrangement of gearing similar to that shown in Figs. 5 and 6, and to stop the
screw and therefore the nuts j I provide the clutch composed of the parts c, c', c².
The part c runs constantly on the neck d' of the screw. The intermediate part c¹
is keyed to the neck by a slip feather and groove. The part is simply a stop and
is fixed to the brackets. When it is desired to run the screw the handle t is moved
to throw the part c¹ into gear with the running part c. When it is desired to stop
the screw the part c¹ is moved out of gear with the part e and into gear with the
clutch stop ². The stoppage of the nuts; by the described means has this result
that the left hand screws P' continuing to revolve in the same direction run
themselves rapidly back and are again advanced by the throwing of the nuts j
and screw d once more into action. The use of the stop c² is not absolutely
necessary, but is advisable lest the friction of the revolving part cand
sleeve should tend to move the worm screw d to some degree when it should
remain at rest.
The handle t or the clutch lever may be connected to a lever operated from the
platform.
In the foregoing arrangements the screw P¹ is cut on the drill spindle P, but it
might be cut on a sleeve and slipped over a reduced portion of the drill spindle.
This is shown in Fig. 9 Sheet 4 of the drawings. The rear end of the drill
spindle P is reduced for a sufficient length and the threaded sleeve P¹ slipped
thereon and maintained in position by the jamb nuts u.
The boss does not as in the foregoing instances when it is marked j constitute
a nut, but is simply a plain sleeve through which the screw P¹ passes loosely. The
fixed gland is the nut with which the screw engages and it is by turning the
screw P' in this nut that the drill spindle is advanced. To effect this turning of
the screw the boss 2 is connected to the screw by a slip feather and groove so that
when the boss is turned the screw is advanced or retracted according to the direction
of revolution. It will be seen that this necessitates the reversal of the worm screw a
from which the boss is driven. The reversal of the worm screw is obtained
through the clutches shown in Figs. 11 and 12. The worm screw d is not driven
from the upright shaft Y as in the previous figs. This shaft is merely utilised to
rotate the shaft Z which revolves the drill spindles.
The screw d is driven from a pulley w. A worm on the spindle of this pulley
drives the worm wheel x. A toothed wheel y on the opposite end of the spindle
gears with a similar toothed wheel z and on the spindle of the wheel z there is a skew
wheel which drives an equal skew wheel 7. The worm wheel r has formed on it a
clutch portion c.
The skew wheel 7 has formed on it a clutch portion c². Between
them is an intermediate clutch c¹. The clutch portions c and c with their wheels
both run loosely on the neck d' of the screw d. The clutch is connected to the
neck d' by a slip feather and groove so that it can be slid in or out of gear with
either the clutch portion c or c². The worm and worm wheel r give a slow
motion. The skew wheels give a much quicker motion but in the opposite
direction. It will therefore be plain that if I throw the clutch into gear with
the portion the screw d is slowly revolved and a slow forward feed of the drill
spindles and drills takes place, whereas if I throw the same clutch into gear with
the portion I obtain a quick reversal of the screw d and a quick withdrawal of
the drills. The direction of rotation of the drills remains of course unaltered.
I might on the spindle of the pulley w have driving arrangements to quicken the
first forward feed of the drills to the moment of touching the work, so as to save
time in advancing the drills.
It will be noted that in all cases where employed to drill the holes for the
circular seams the drills are set radially on the cross slide R or they may be set
to any desired angle, the swivelling pivot being the spindle of the mitre wheels a,
so that no matter at what angle the sleeve brackets Q are set, the driving mitre
wheels remain in driving contact. As the centre of the wheels a is also the centre
of the worm wheels with which the worm screw d engages, it is obvious that the

page_text: driving contact of the said worm screw with the worm wheels remains also
unaltered, so that although the worm screw d imparts motion simultaneously
and all along the line to the whole of the feed worms, nevertheless the sleeve
brackets may be swivelled on their pivots a without affecting in the least the
contact of either the driving or the feeding gear.
After the foregoing exhaustive description of the driving and feeding mechanism
of the horizontally arranged drills, it will scarcely be necessary to do more than
give a cursory glance at the arrangement for similarly operating the vertically
arranged drills L carried by the standard B. The sleeve brackets Q' are carrie
on a cross slide R' sliding on the planed face of the bracket B. A screw S is used
to adjust the height of the cross slide R'. A shaft Z' drives the drill spindles P
by means of mitre gearing as in the arrangements already described. This shaft Z
derives its motion from the driving shaft V through the geared counter
shafts V3 V4. The shaft Z' also communicates motion through the gear
wheels b, b1, b2 to the clutch half which runs loosely on the shaft a', the said
shaft operating the nuts which feed forward and retract the screws P₁ by means
of the clutch c and clutch half c¹ which operate to revolve and stop the shaft d¹
and the worms or other mechanism which engage with the nuts and revolve them
just as in the case of Figs. 5 and 6 already described. The shaft E' for revolving
the turn table D so as to present a fresh portion of the work to the drills, can be
turned by the handle E' from the platform or it may be worked by a handle at the
other end of the shaft E'.
The standard B may be moved and adjusted on the bed C by a handle on the
shaft 2 carrying a pinion which gears with a rack 4.
The working of the mechanism as a whole will be so apparent from the foregoing
description that to describe the modus operandi would be only to recapitulate what
has already been said. The triple thickness of boiler ring shown by the
dotted lines X in Fig. 1 represents the butt straps which are laid over each
longitudinal joint.
The two sets of drills are not operated simultaneously.
In mere matters of detail my improved apparatus is capable of and may be
modified without departing from the spirit of my invention.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is.―
1. In apparatus of the indicated nature for drilling cylindrical and other bodies
such as boiler rings, the employment of an annular supporting turn table such as D
cut out in the centre so as to allow a separate and independent pillar, standard or
support such as M to project upward through the aperture in the annular table,
the said pillar or support carrying adjustable abutments which can be brought to
bear upon the inner circumference of the boiler ring or circular or other shaped
body being drilled, substantially as described and as illustrated.
2. In apparatus of the indicated description for drilling cylindrical and other
bodies such as boiler rings and the like, the annular supporting turn table D
mounted upon and maintained in position by anti-friction bowls so as to be easily
capable of adjustment, and formed with an aperture in the centre to allow of the
passage of an independent and separately placed standard, pillar or support M
capable of adjustment upon the bed of the apparatus, and carrying adjustable
abutments intended to bear against the inner circumference of the boiler ring or
other body being drilled, substantially as described and illustrated.
3. The annular table D having an aperture in the centre for the purposes and
substantially as described and shown.
4. Mounting and carrying the abutments which bear upon the internal circum-
ference of the boiler ring or other body, upon a standard or pillar such as M, the
said standard or pillar being separate from and independent of the annular table
supporting the work, and projecting upward through the centre of the table, which

page_text: is cut out to admit of the upward projection of the standard or pillar, substantially
as described and as illustrated.
5. As means for supporting the abutments which bear upon the internal circum-
ference of the boiler ring or other body, the standard or pillar M sliding on and
carried by the bed of the machine, and projecting upward through a hole or
aperture in the revolvable annular table D from which it is separate and
independent, substantially as herein before described and as shown.
6. In apparatus of the indicated nature for drilling cylindrical bodies such as
boiler rings and the like, the means for advancing and retracting simultaneously
the drill spindles and drills, the said means consisting mainly of a worm screw
such as d, engaging with all of the feed motions of each set of drills and operated
by the various mechanisms and forms of clutches set forth so as to advance the
drills slowly and withdraw them quickly, substantially as described and as
illustrated in the drawings.
7. The arrangement and combination of the pivotted radial drills, the worm
screw for feeding the same, the threaded prolongations or sleeves of the drill
spindles and the over or under-speeded nuts engaging with the said threaded
prolongations or sleeves substantially as described and shown.
8. The general arrangement construction and combination of parts constituting
my improved apparatus for drilling cylindrical and other bodies such as boiler
rings and the like substantially as hereinbefore described and as illustrated in the
annexed four sheets of drawings.
Dated this 3rd day of October 1894.
E. K. DUTTON & Co.,
5, John Dalton Street, Manchester, Agents.