Improvements in Valve Gear for Pumping Engines Driven by Steam or Compressed Air.
Year: 1897

page_text: Date of Application, 22nd Jan., 1897--Accepted, 1st May, 1897
COMPLETE SPECIFICATION.
Improvements in Valve Gear for Pumping Engines Driven by
Steam or Compressed Air.
1, JAMES ALFRed Towler, of 1 Cromer Road, Leeds, in the County of York,
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 valve gear for pumping engines driven by steam or
compressed air having the valves of the main cylinder actuated from a subsidiary
cylinder which has its distribution valve or valves operated from the piston of the
main cylinder.
The chief object of my invention is the application of gear hereinafter described
to the actuation of valves for the main cylinder of the Corliss kind with provision
of trip gear for rapid closing of the supply valves and an arrangement of the
exhaust valves so as to provide adequate cushion in the main cylinder.
I shall describe valve gear according to my invention referring to the accom-
panying drawings-
Fig. 1 is a side view of the main cylinder and valve gear with section of the
subsidiary and cataract cylinders.
Fig. 2 is a part longitudinal section at one end of the main cylinder.
Figs. 3 and 4 shew to an enlarged scale a front view and section of the trip gear
for the front supply valves.
Figs. 5, 6, 7 and 8 are corresponding views of a modification, Fig. 7 shewing the
trip gear for the rear supply valves.
In all the figures like parts are denoted by similar reference letters.
Referring first to Figs. 1 to 4 inclusive, A is the main cylinder, B its piston rod
which has an arm blinked to a lever C. To this lever is jointed a rod c having on
it tappets which move the distribution valve of the subsidiary cylinder D, the
piston of which is rigidly connected to the piston of the cataract cylinder E the
movement of this piston being controlled in the usual way by adjusting its by-pass
valve e.
The rod of the pistons of D and E is linked by a connecting rod d to a
crank pin on a wrist plate F which is pivotted at f to the main cylinder A or to
the engine frame at the side of the cylinder.
On the wrist plate F are four crank pins linked respectively to the arms which
work the supply and exhaust valves these are of Corliss form, the two supply
valves G on the one side of the cylinder governing ports close to the ends of the
cylinder, and the two exhaust valves H on the other side governing ports which are at
some distance from the ends of the cylinder so that the piston passes over them and
so determines cushions as it approaches the ends of its stroke. The exhaust
valves H are worked by simple crank arms h, but the supply valves G are worked
by trip action which is of the following description
Each of the links g from the two upper crank pins of the wrist plate is jointed
to an arm K which is loose on the valve spindle L, and has jointed on it a catch k
having a roller k¹ mounted on its side.
To the lever C is jointed a rod m which is jointed to an arm M also loose on the
valve spindle L, and having a cain N adjustably fixed on its side.
On the valve spindle is fixed a lever P which presents a square shoulder p to be
engaged by the hook of the catch k and which is connected by a rod s to a spring
or a piston under pressure in a casing S, this spring or piston always tending to
move the arm P in the direction of the arrow.

page_text: This gear operates in the following manner :-
The main piston in making its forward stroke, by means of one of the tappets
on the rod c, moves the valve d of the subsidiary cylinder D so that its piston
moves the wrist plate F to the position shewn in Fig. 1 by which motion the back
exhaust valve of the main cylinder is opened, the front exhaust valve is closed and,
the catch being engaged with the shoulder p of the front trip gear, the front
steam valve is opened causing the main piston to make its back stroke. The rod m
then moves back the arm M and brings the cam N round to act upon the roller k¹
so as to raise the catch and release the lever P, which urged by the spring or
pressure in S immediately closes the front steam valve, the main piston thereupon
being propelled backwards by the pressure of the steam expanding in front of it.
During the return stroke of the main piston the valve of the cylinder D is moved
so that the motion of the wrist plate is reversed and the main cylinder valves are
operated so as to exhaust from the front and supply steam behind.
In the modification. shewn in Figs. 5 to 8 inclusive the wrist plate F is dispensed
with, both the steam valves G and the exhaust valves H being situated at the lower
side of the main cylinder, the ports of the steam valves opening close to the ends
and the ports of the exhaust valves opening at some distance from the ends to
provide for cushion. The rod d worked by the piston of the subsidiary cylinder D
in this case is jointed directly to the arms h of the exhaust valve spindles which
have jointed on them the catches k engaging square pins p on the arms P which
are fixed on the spindles L of the steam valves and are connected by rods s to the
springs or pistons subject to pressure in S. In this case also in each of the trip.
gears the cam N worked by the arm M and rod m from the lever C raises the
roller and so releases the catch k allowing the steam valve to be closed by the
arm P.
In both modifications I have shewn a cataract cylinder E containing liquid to
control the movement of the subsidiary piston in D making that movement the
more slow and gradual the more the bypass by the valve e is throttled. This is
necessary only when the subsidiary cylinder D is supplied with steam or other
elastic fluid under pressure. In cases where it is supplied with water or other liquid
under pressure the cataract cylinder E is dispensed with the regulation of speed
being effected by adjustinent of the distribution valve of the cylinder D.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. In valve gear for a pumping engine the combination of a lever moved by the
main piston and working by tappets the distribution valve of a subsidiary cylinder,
the piston rod of which moves a wrist plate having crank pins linked to the arms
of the exhaust valve spindles both at the one side of the cylinder and to trip arms
which engage the arms of the supply valve spindles both at the other side of the
cylinder and are disengaged by the movement of the lever above mentioned,
substantially as described.
2. The modified valve gear in which the exhaust and supply valves are all
arranged at one side of the cylinder and have their arms and trip arms worked
directly from the piston of the subsidiary cylinder substantially as described.
3. In the trip gear referred to in the preceding claim the combination of an arm
fixed on the exhaust valve spindle moved by the subsidiary piston and carrying a
pivotted catch and roller, a cam loose on the supply valve spindle and moved by
the lever which is worked by the main piston, a lever or arm fixed on the supply
valve spindle having a pin engaged by the catch, and urged by a spring or piston
subject to fluid pressure so as to close the valve substantially as described.
Dated this 22nd January 1897.
ABEL & IMRAY,
Agents for the Applicant.