IMPROVE- MENTS IN ROCK DRILLS
Year: 1886

page_text: HENRY JAMES COLES, of 89 Sumner St. Southwark in the County of Surrey,
Mechanical Engineer do hereby declare the nature of my invention for IMPROVE-
MENTS IN ROCK DRILLS and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement:—
My invention consists in a novel combination of a circular or piston valve with
steam passages recessed in the drill piston, and exhaust ports suitably situated in the
cylinder of the machine, whereby extreme simplicity of construction and working
is secured, the arrangement and construction of which is set forth in the drawings
hereto appended.
.
Fig. 1 and 2 shew sections of the cylinder and valve casing. Fig. 3 shews a
section of the valve which is perfectly cylindrical in form.
A A represents the cylinder, B the valve casing, C C₁ the covers of the valve
chest, D the valve. E E' are the steam ports in the cylinder connected with the
ports F F¹ in the valve chest and receiving steam through the ports G G¹ in the
valve D. H is the main exhaust port which is coupled with either steam port F
by the recess J in the valve D. K K' are the coupling recesses in the piston L
which put the ports M M¹ leading from the extremities of the valve casing B into
the cylinder, in communication with the ports N N¹ leading to the main exhaust
port H. O is the outlet for exhaust. P the inlet for steam, Q Q¹ steam chambers
in ends of valve casing.
In the drawings only one exhaust port M is shewn, the other one, occupying an
exactly corresponding position on the lower half of the cylinders, is not shown,
owing to both the views being sections.
The valve D is not shewn inside the casing for clearness but its position during
the downward stroke is indicated by the dotted lines.
The action of the drill is as follows.-When the valve is in the position shewn,
steam is passing inside the valve from the inlet P and out through the ports G
into the upper part of the cylinder through the passage E and continues to do so
until the recess K descends sufficiently far to couple the port M with the port N,
and this exhausts the steam which has collected in the chamber Q and consequently
the steam in the other chamber Q₁ forces the valve D to the other end of the casing
and steam is admitted to the underside of the piston L and exhausted from the top

page_text: side until the recess K' couples the ports M¹ and N¹ when the valve D travels
instantly to the other side of the casing and the piston is again caused to descend.
Steam flows into both chambers QQ¹ through small passages and the valve D is
therefore always in equilibrium, except when the recesses K K¹ by coupling the
ports M N allow the steam to escape from one end or chamber Q and therefore the
pressure at the other end instantly causes the valve to travel to the end from which
the steam is exhausted.
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
The combination of the recesses in the piston with the exhausting ports in the
cylinder and the steam chambers in the valve casing actuating a piston valve
substantially in the manner and for the purposes herein described,