Improvements in Reversing Valve Gear for Winding and other Engines required to be Started at any Portion of their Stroke, or occasionally to go extremely slowly for Inspection Purposes.
Year: 1894

page_text: Date of Application, 27th June. 1894-Accepted, 28th July, 1894
COMPLETE SPECIFICATION.
Improvements in Reversing Valve Gear for Winding and other
Engines required to be Started at any Portion of their Stroke,
or occasionally to go extremely slowly for Inspection Purposes.
We, ROBERT THORNEWILL and ALFRED DAVIES, both of Iron Works,
Burton-on-Trent, in the County of Stafford, 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 :-
This invention has for its object an arrangement of link motion or valve gear
applicable for winding engines so as to enable one to get all the advantages of lap
and lead on the valve while at the same time setting the eccentrics without any.
By this means in a winding engine the engine.can be stopped and started at any
point or made to go as slowly as possible without any fear of reversing or stoppage
such as would take place if there were a considerable lap and lead, and yet when
the engine is travelling quickly can have practically any required amount of
lead.
The invention is best described by aid of the accompanying drawings, in which,
Figure 1 is an elevation, and
Figure 2 a plan of an engine made in accordance with our invention;
Figure 3 is a detail view on rather larger scale, showing a plan of our new link
and its appurtenances.
In these,
A A are the ordinary eccentric rods, B the usual eccentric link; C, connecting
rod supported on its terminal C' by a radius rod C2 vibrating on the fixed centre Ď
and attached at the other end to the usual slide block actuated from the reversing
apparatus by the rod C³. E, Figure 3, is a saddle attached by bolt F to the link G
hereinafter described. To this saddle the connecting rod C is pivoted on the pin H
to which also the radius rod C is attached. I is a washer and J a set screw for
holding the radius rod securely in its bearing on the pin H. K is a shank forged
to the link G and supported at the other end by the eccentric rod L worked by
eccentric M. This eccentric is fixed on a countershaft M' driven off the engine
shaft by bevel wheels and shafting or otherwise. N is a radius rod connected with
the slide block in link G and the other end to rock arm V actuating rock shaft W
on which are keyed the arms lifting valve spindles: the steam valves having a
cut off apparatus, which we prefer being that set forth in our Specification
No. 17833% This radius rod N is supported and shifted and connected with the
governor O by means of links P, Q, R, S, T and U. By this means the rod N is
raised and lowered automatically by the governor, so that, as the speed of the
governor increases, the block is moved in the link and thus an effect is produced
almost precisely the same as if, while the engine is going at this speed, there is lap
on the valve, in fact this link performs the same purpose as would be effected by
changing temporarily the angular position of the eccentrics on the rod so as to
cause an increase of lead. The efficiency of the steam in the cylinder while the
engine is running is greatly increased, while at the same time the setting of the link
motion is not interfered with, and thus easy starting from any position of the crank
is secured.

page_text: 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. The combination between the valve or the cut off apparatus of winding
engines and the link motion of a secondary link slide block and radius rod, the
latter actuated by the governor, substantially as described.
2. The arrangement of reversing valve gear for winding engines in which the
eccentrics are set so as to give little or no lap or lead at starting but in which there
is a secondary apparatus beyond the link motion brought into action by the
governor which shall give the required amount of lead when the engine is in
full action.
3. In combination with our automatic cut off apparatus substantially as set forth
in No. 17833, a variable lead gear of the nature set forth herein.
4. The variable lead gear taken as a whole substantially as described and
illustrated in the accompanying drawings.
Dated this 26th day of June 1894
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Birmingham, Nottingham, and London,
Patent Agents.