AN IMPROVED MACHINE FOR BORING TAPER HOLES SPECIALLY APPLICABLE TO BORING TRENAILS FOR THE CHAIRS OF PERMANENT WAY
Year: 1883

page_text: LETTERS PATENT to Robert Letherby of Barnstaple in the County of Devon
for an Invention of AN IMPROVED MACHINE FOR BORING TAPER HOLES
SPECIALLY APPLICABLE TO BORING TRENAILS FOR THE CHAIRS OF PERMANENT
WAY
PROVISIONAL SPECIFICATION left by the said Robert Letherby.at the
Office of the Commissioners of Patents on the 14th November 1883.
ROBERT LETHERBY of Barnstaple in the County of Devon, "AN IMPROVED
MACHINE FOR BORING TAPER HOLES, SPECIALLY APPLICABLE TO BORING TRENAILS
FOR THE CHAIRS OF PERMANENT WAY,"
This invention, which relates to an improved machine for boring taper holes, is
specially applicable to boring that class of trenails having a central conical hole
for the reception of a spike.
It is designed to mechanically effect the intermittent withdrawal of the boring
tools from the trenails necessary to clear away the borings, which action has
hitherto been manually performed.
Behind the rest in which are fitted the boring tools is a jaw capable of sliding
horizontally and carrying a cam having tongues or notches of different lengths
formed on its periphery. The jaw tends, either by the action of weights suspended
therefrom or by other means, to withdraw the rest backwards from the trenails,
and in the rotation of the cam the tongues or notches thereof are brought into
contact with a roller at the front end of the jaw. The rest is thus impelled
forwards to an extent governed by the lengths of the tongues or notches of the
cam, so that the boring tools, after being withdrawn, are each time again presented
at the proper position in the holes.
The machine may-be used for boring conical holes for other purposes

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Robert Letherby in the Patent Office on the 12th May 1884.
ROBERT LETHERBY of Barnstaple in the County of Devon AN IMPROVED
MACHINE FOR BORING TAPER HOLES, SPECIALLY APPLICABLE TO BORING TRENAILS
FOR THE CHAIRS OF PERMANENT WAY
My said invention, which relates to an improved machine for boring taper holes,
is specially applicable to boring that class of trenails having a central conical hole
for the reception of a spike. It is designed to mechanically effect the intermittent
withdrawal of the boring bitts or augers from the trenails necessary to clear the
holes of the borings or chips produced in process of boring. Behind the cross head
or holder, in which are fitted or secured the bitts or augers, is a jaw capable of
sliding longitudinally, and partially enclosing a cam having tongues or notches of
different lengths formed on its periphery. The jaw tends, either by the influence
of weights connected thereto or by equivalent means, to withdraw the bitts or
augers backwards from the trenails, and, in the rotation of the cam, the tongues or
notches thereof are brought to, bear against a roller situated towards the front end
of the jaw which is thereby thrust forward to an extent governed by the length of
the tongue or notch acting on the roller.
Thus the bitts or augers are, after being withdrawn, each time again présented
at the proper position in the holes.
And in order that my said invention may be properly understood, I now proceed
more particularly to describe the same with reference to the accompanying sheet of
drawings and the figures and letters marked thereon.
Fig. 1, on the accompanying sheet of drawings, represents a side elevation, and
Fig. 2. a plan, of a machine constructed in accordance with my said invention, and
as specially applicable to boring trenails for the chairs of permanent way. Fig 3
is' a horizontal section through the mandrils a, and shows the boring bitts or
augers has presented to the trenails b in position to commence boring.
Supported in the bearings c, formed on the platform d, is the jaw e partially
enclosing the cam f centred on the shaft f' and provided on its periphery with
tongues or notches of different length, as shown. In the cross-head g, connected to
the jaw e, are secured the boring bitts or augers h, partially surrounded by the
guard k. The bitts or augers h may be of the hollow or "shell". or other type
suitable for the work to be done.
Through the pinión i and rack i¹, the platform d is capable of being moved
longitudinally by actuation of the hand lever j. The trenails b having been placed
in the mandrils a carried in the headstock A, the lever ; is actuated to bring the
platform & forward.
The guard k is thus brought into contact with the trenails b which are thereby
driven firmly into position to be bored. The mandrils a are caused to rotate
through the pullies b¹. Secured to the frame of the machine, and not connected to
the movable platform d, are the bearings supporting the pulley through which
motion is imparted to the bevelled toothed or friction wheel m. Upon the cam
shaft f¹ is carried the bevelled toothed or friction wheel n which, when the
platform d is moved forward, as aforesaid, is brought into gear or contact with the
wheel m. Rotary motion being thus imparted to the cam f, the periphery of
which bears against the roller o carried towards the front end of the jaw e, the jaw
is impelled forward and the bitts or augers h are projected beyond the front of the
guard k and made to penetrate the rotating trenails 6 to the extent of the throw
off caused by the passage of the shortest tooth or notch of the cam f over the face
of the roller o.

page_text: When the said tooth or notch has cleared the roller o, the jaw e and bitts or
augers h are free to be withdrawn. The withdrawal is at once effected by means
of the counter weight p connected by the chain p¹ to the jaw e, as shown. The
weight p exerts a constant strain upon the jaw e tending to withdraw it backward.
By the withdrawal of the jaw e and the bitts or augers h, the borings or chips are
cleared from the holes in the trenails, so that when the bitts or augers are again
presented to resume boring, their action is not obstructed or impeded. Each tooth
of the cam acts in turn upon the jaw e to cause the bitts or augers h to be presented
at the point at which the boring was last arrested. The longest tongue or notch
of the cam completes the boring of the trenails which are ejected from the
mandrils a by the ejectors & after the platform d has been moved back. The
ejectors & are operated by means of the hand lever S, to which is attached the
counter weight S¹, by the influence of which, when the lever S is released, the
ejectors s are returned to their normal position. The cam f may be turned by
means of the hand wheel R to present any desired tongue or notch to the roller o,
as, for instance, the shortest tongue or notch when about to commence boring.
The machine may be employed for boring holes otherwise than in trenails
Having now described my said invention and the mode or manner in or under
which the same is or may be used, I claim as the invention secured to me by the
hereinbefore in part recited Letters Patent.
The employment of the cam f acting upon the counterbalanced jaw e and
thereby upon the boring bitts or augers h, in such manner that the said bitts or
augers are intermittently presented to and withdrawn from the articles operated
upon, to clear the holes of borings or chips, substantially as herein before, described
as for boring trenails, with reference to the accompanying sheet of drawings.
In witness whereof I the said Robert Letherby have hereunto set my hand
and seal this ninth day of May, in the year of our Lord one thousand eight
hundred and eighty four
("S"T)
ROBERT LETHERDY