Improvements in Rotary Steam Engines.
Year: 1895

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Date of Application, 16th Apr., 1895-Accepted, 27th July. 1895
· Improvements in Rotary Steam Engines.
We, CARL ALRIK. HULT, of Flemminggatan 48, and OSCAR WALFRID HULT,
of Hummersberg, both of Stockholm, in the Kingdom, of Sweden, Engineers, 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:
Our invention relates to a rotary steam engine in which the parts actuated by the
steam do not slide but roll against the surfaces with which they are in contact
whereby friction being reduced to a minimum the resistance of the movable partsı
and the wear of the surfaces will be also reduced: The latter is: of particular,
advantage and constitutes, as is well known, one of the principal conditions for, the
successful working of rotary, steam engines in general.
In,the,accompanying drawing,
Figures 1 and 2 are vertical sections of a rotary steam engine constructed
according to our invention.
Figure 3 is an elevation of the same; and,
Figure 4 is a section illustrating a modification.
In the sides or plates B of the cylinder is journalled the main shaft Con which
is fixed a disc D concentric with the cylinder and situated: between the sides of the
same. In the steam space E formed between this disc. and the. cylinder are two,
loose rollers F, F. consisting of spring rings arranged in a suitable manner or made
of suitable elastic material and fitting, quite. tight against the plates; B of the.
cylinder as well as against the disc D and the walls of the cylinder.
One of the rollers, for example the roller F as represented in the, drawing, is
always kept near the steam inlet G by means of a suitable. locking device. and,
constitutes the end of the steam-space E, while the other roller F is driven
forwards through the steam-space by the steam admitted through.G.. The roller, F¹
thereby also receives a rotary motion owing to the resistance created, by the cylinder-
wall, and this rotary motion is transmitted, as will be well understood, to, the disc D
and main shaft C.
The said locking device consists of two pips. H adapted to be moved out of, and
into their respective cylinder-plates B; the inner conical ends, of the, said, pins
fitting into corresponding depressions in the rollers. F, F. The pins are connected
to levers I pivotted outside the cylinder-plates B, the upper ends. of the said, levers.
being provided with oblique slots K in which are located pins L.carried, by a bar M,
fixed to another bar N passing through the cylinder-wall. The said, bar, N. is.
pressed downwards by a spiral spring and its lower end: extends. into the steam-
space, and is provided with a head P, which partly projects into the steam-space.
When the roller F¹ actuated by the steam, reaches the said head P the latter is
forced by the roller into a recess Q-made in the wall of the cylinder and the bar, N
is thereby pushed outwards; the motion of the said bar is, by means of the bar M,
communicated to the levers I which are thereby caused to pull the pins H outwards,
so as to free the roller F and allow it to roll forwards. Simultaneously, the steam
is cut off at G by a plunger R traversing the steam-inlet G, the said, plunger being,

page_text: by means of an arm S, firmly connected to one of the pins H. After the steam is
cut off there is, as will be well understood, a dead point at which time the continued
motion of the rollers is maintained by a fly wheel on the shaft C. During this
time the roller F¹ keeps the head P raised and by the time the roller has passed
the head, it will bave come into position between the pulled out ends of the pins H,
which, at the moment that the bead P regains its former position and the steam-
inlet G opens, return into the depressions of the roller F¹ and retain the roller.
The roller F having at this moment arrived in front of the steam inlet is now in
turn driven forwards by the steam.
The roller which, for the time being, is locked is caused to rotate by the disc D
and instead of rubbing against the cylinder-wall and causing obstructive friction,
the roller rotates against another roller or disc U.
The outlet T for the waste-steam. is almost opposite the head P. In order that
this outlet may not be closed, when the head is pushed in, the latter can be provided
with openings.
In
When the resistance of the main shaft is very great and the friction between the
rollers and the disc D is not sufficient to drive the shaft C, the rollers as well as
the dise D and the inner surface of the cylinder A.can. be provided with teeth.
some cases we only use one roller and replace the locked roller by a pivotted
flap V as shewn in. Figure 4. In this case the locking device is of course dispensed
with the opening and closing of the, steam inlet being. effected by means of the.
said flap.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is. to be. performed, we declare that what we
claim is :-
1. A rotary steam engine, in which the steam acts upon a loose.roller in contact
with the circumference of a disc or cylinder fixed on the main, shaft as well as with
the inner side of the steam cylinder this side.. being, concentric with the said disc,
the roller as well as the disc: and the steam cylinder, being, if desired, provided
with teeth gearing one with another, in order that the, rotary motion of the roller
caused by its contact with the cylinder-wall shall by means of the disc be commu-
nicated to the main shaft.substantially as herein before described. .
2. In a rotary steam engine.of the kind claimed in the preceding claiming clause
the employment in the steam space of two rollers which are alternately locked by
means of a suitable.locking device. (so as to.constitute the end of the steam space)
and driven forwards by the steam substantially as hereinbefore. described and
illustrated in Figures 1, 2 and 3 of the accompanying drawings.
3. In a rotary steam engine the locking device referred to in. Claim 2 consisting
of two pinstadapted to be moved out and in through the cylinder covers or plates
the inner ends of which pins, which are in a line with each other, fit in corresponding
dépressions in the rollers and which pins are further by means of suitable levers
connected with a spring actuated bar arranged to be pushed out and in through the
cylinder-wall, the end of the said bar which projects into the steam space being
provided with a suitable head or, plate so that the roller when driven forwards by
the steam, and acting upon the head causes said bar to move and, by means of the
levers, to pull out the pins-so as to free, the locked roller, the pins being then
pushed in again thereby locking the roller which before was free, when the latter
has passed the. head substantially as. hereinbefore described and illustrated in
Figures 12 and 3 of. the accompanying drawings..
4. In a rotary steam engine. arranged in the manner referred to in Claims 2 and 3,
the combination with one of the pins of a plunger connected thereto and traversing
the steam-inlet which plunger leaves the inlet open, when the pins are pushed in,
but closes the same, when the pins are pulled out, substantially as bereinbefore
described and illustrated in Figures 1 2 and 3 of the accompanying drawings.
5. The modified arrangement of rotary steam-engine in which only one roller is

page_text: employed and a pivotted flap constitutes the end of the steam-space substantially
as hereinbefore described and illustrated in Figure 4 of the accompanying
drawings.
Dated the 16th day of April 1895.
G. F. REDFERN & Co.,
4, South Street, Finsbury, London, Agents for the Applicants.