An Improvement in Starting Valves for Compound Engines.
Year: 1891

page_text: Date of Application, 21st Jan., 1891
Complete Specification Left, 20th Oct., 1891-Accepted, 16th Jan., 1892
PROVISIONAL SPECIFICATION.
An Improvement in Starting Valves for Compound Engines.
I, Arthur HerBERT WALLIS, of North Hants Iron Works, Basingstoke, in
the County of Hampshire, Engineer, but at present of Cape Town in the South
African Republic, do hereby declare the nature of this invention to be as
follows:-
:-
My invention relates to an automatic valve arrangement whereby, on the
occasion of starting a compound engine, steam from the boiler is supplied to the low
pressure as well as to the high pressure valve chest, thus enabling the engine to
start even when, owing to the position of the high pressure piston or of the slide
valve of the high pressure cylinder, the high pressure piston is not effective for
moving the engine. A simple form of valve arrangement for this purpose is as
follows-A valve box is made in two compartments, a lower compartiment com-
municating with the high pressure steam chest and containing a valve which rests
on stops a little above the bottom of the valve box and cam seat upward against
the lower edge of the upper compartment. This upper compartment is a cylinder
fitted with a piston which is fixed to the stem of the valve below it, and from this
upper compartment under the piston; when in its lowest position, there is a passage
to the low pressure valve chest. The piston is loaded by a weight which can be
adjusted to some predetermined pressure. When the engine is to be started, steam
from the boiler is admitted to supply the high pressure valve chest, whence it can
pass into the lower compartment of the valve box above described, past the valve
which remains in equilibrium, into the upper compartment, and thence into the
low pressure slide chest. When the pressure of the steam thus supplied to the low
pressure cylinder acting on the piston in the valve box is sufficient to overcome the
load in that piston, the piston is forced upwards and thus closes the valve, shutting
off the supply of steam from the boiler to the low pressure cylinder. When the
engine is to be stopped by shutting off supply of steam from the boiler to the high
pressure cylinder, after a revolution or two the pressure under the valve and on the
piston becomes so far reduced that the load on the piston re-opens the valve.
When the engine is provided with shut off valves simultaneously cutting off supply
of steam, not only from the boiler to the high pressure slide chest, but also from the
intermediate reservoir to the low pressure slide chest, as described in my previous
Specification No. 3031 of 1890, I make the valve box with an intermediate com-
partment between the lower containing the valve, and the upper containing the
piston, this intermediate compartment being open to the lower compartment and
having a communication to the reservoir, but being separated by a valve plug from
the upper compartment, so that the pressure acting on the piston is not that in the
reservoir but that in the low pressure slide chest, and consequently, until the latter
pressure becomes sufficient to overcome the load on the piston, the valve in the
lower compartment remains open and the reservoir continues to be supplied with
steam from the boiler. But when the shut off valve is opened, admitting this steam
to the low pressure valve chest, the pressure therein becomes such as acting on the
piston closes the valve in the lower compartment.
Dated this 21st day of January 1891.
ABEL & IMRAY,
Agents for the Applicant.

page_text: COMPLETE SPECIFICATION.
An Improvement in Starting Valves for Compound Engines.
I, ARTHUR HERBERT WALLIS, of North Hants Iron Works, Basingstoke, in
the County of Hampshire, Engineer, but at present of Cape Town, in the South
African Republic, 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 an automatic valve arrangement whereby on the
occasion of starting a compound engine, steam from the boiler is supplied to the
low pressure as well as to the high pressure valve chest, thus enabling the engine
to start even when, owing to the position of the high pressure piston or of the slide
valve of the high pressure cylinder, the high pressure piston is not effective for
moving the engine. A simple form of valve arrangement for this purpose is shewn
in section by Fig. 1 of the accompanying drawings. The valve box is made in two
compartments a lower compartment communicating with the high pressure steam
chest by passage A, and containing a valve K which rests on stops a little above
the bottom of the valve box and can seat upward against the lower edge of the
upper compartment. This upper compartment is a cylinder fitted with a piston D
which is fixed to the stem of the valve K, and from this upper compartment under
the piston when in its lowest position there is a passage C to the low pressure valve
chest. The piston is loaded by a weight E which can be adjusted to some
predetermined pressure. When the engine is to be started, steam from the boiler is
admitted to supply the high pressure valve chest whence it can pass by A into the
lower compartment of the valve box past the valve K which remains in equilibrium
into the upper compartment and thence by the pipe C into the low pressure valve
chest. When the pressure of the steam thus supplied to the low pressure cylinder
acting on the piston D is sufficient to overcome the load E, the piston is forced
upwards and this closes the valve K shutting off the supply of steam from the boiler
to the low pressure cylinder. When the engine is to be stopped by shutting off
supply of steam from the boiler to the high pressure cylinder, after a revolution or
two the pressure under the valve K and on the piston D becomes so far reduced
that the load E pushes down the piston and reopens the valve K. When the
engine is provided with shut off valves simultaneously cutting off supply of steam
not only from the boiler to the high pressure slide chest but also from the inter-
mediate reservoir to the low pressure slide chest, I make the valve box as shewn
in section by Fig. 2 with an intermediate compartment between the lower one
containing the valve K and communicating by A with the high pressure valve
chest and the upper one containing the piston D and communicating by C with the
low pressure valve chest.
The intermediate compartment is open to the lower compartment through a
passage at H and has a communication B to the reservoir but is separated by a
valve plug G from the upper compartment, so that the pressure acting on the
piston D is not that in the reservoir, but that in the low pressure valve chest, and con-
sequently until the latter pressure becomes sufficient to overcome the load E which
bears down the piston D, the valve K in the lower compartment remains open and the
reservoir continues to be supplied with steam from the boiler. But when the shut
off valve is opened, admitting this steam to the low pressure valve chest, the
pressure therein becomes such that, acting on the piston D, it closes the valve 'K in
the lower compartment, and so prevents passage of steam from the high. pressure
valve chest to the reservoir.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A starting valve for a compound engine, consisting of a valve box made in two

page_text: compartments the lower one communicating with the high pressure valve chest and
having in it a valve which when raised closes the passage between the two com-
partments, the upper one communicating with the low pressure valve chest and
being fitted with an adjustably loaded piston rigidly connected to the valve below,
substantially as described with reference to Fig. 1.
2. The modified arrangement adapted to compound engines having simultaneously
moved shut off valves for both cylinders wherein, there is an intermediate compart-
ment communicating with the reservoir between the cylinders, substantially as
described with reference to Fig. 2.
Dated this 20th doxe of October 1801
ABEL & IMRAY,
Agents for the Applicant.