PATENTS SUMMARIZED.
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Devices are not unknown for improving upon the spark given by a magneto which is revolving slowly, and these have become .known as " impulse starters." The principle is generally that of an articulated coupling between engine and magneto so devised that the half which is attached to the magneto spindle is temporarily held when the engine is revolving at a very slow speed, such as when it is being started by means of the usual starting handle. After a small angular movement this stationary portion of the coupling is re
leased, and acting under the influence of a spring rapidly makes up leeway, revolving the magneto armature at a comparatively high speed, and producing a spark in the cylinder at the correct instant of considerable ignition effect. The two most interesting patents which have been published this week concern these special devices. They are No. 121,168, by L. Johnson, and 121,181, by B. Lawrence. The fundamental difference between the two designs is that in the former that portion of the coupling which is temporarily restrained when the engine is being started is held stationary by means of a tripping gear, i which gear s rendered inoperative by centrifugal farce so soon as the engine is under way, the actual drive from engine to magneto being a positive one and between the,esseutial .components -of the couplings themselves; in the latter, the two portions of the coupling are Connected together by means of a spring or sprigs, and a tripping gear operating mainly under the influence of gravity and centrifugal force is also embodied. The trip levers, however, so soon as the engine Is under way, swing into such a position that they themselves either directly or indirectly effect the mechanical connection between the two halves of the coupling. Taking patent No. 121,168, and referring now to our drawing : that portion of the coupling which is attached to the magneto spindle is a hollow open-ended cylinder, and the wall is cut in the form of a cam and so that a deep pocket is formed in the side of the cylinder. A portion of the coupling which is attached to the engine shaft slides longitudinally and has integral with it a pin on which is a roller which engages with the surface of this cam. Normally acting under the influence of a coiled compression spring, this roller lies at the bottom of the deep pocket, and the drive is transmitted direct from engine to magneto. A couple of pivoted levers, disposed longitudinally, are so balanced that when revolving at anything more than mere starting speed they do not interfere with the normal operation of the coupling, but at starting, and when the coupling is being revolved slowly, they are then free from any 'effect of centrifugal force, and, acting under gravity, fall into such a. position that the magneto half of the coupling is temporarily held in a stationary position, the while the engine half may be revolved. In these circumstances, the roller to which we have already referred moves out of the pocket and along the surface of the cam, and when it is almost at the top of the slope of this cam, the trip levers are mechanically operated by means of a second cam on the engine half of the coupling, thus free:ng the magneto half of the coupling, and the latter revolves rapidly under the combined influence of the compression spring and the roller acting on the cam slope. In 121;181 a shallow cylindrical portion of the coupling is provided with a
tongued projection which can readily .engage withthe corresponding groove in the coupling on the engine shaft. Within the cylinder is a coiled spring, or maybe more than one, which connects this part of the coupling with the inagneto half. Connected also to the engine' half is a disc in which are secured pine on which the two trip levers are pivoted. The whole coupling is carried within a stationary case into which from the outside is projected a. stop of special form. Additionally, in , some cases the two halves of the coupling are more positively connected by means of roundnosed detents. Upon the engine being slowly revolved by hand, one of the trip levers comes into contact with the stop in the casing. It thus forcibly disengages the sprng-held detente and allows the engine coupling to advance beyond the magneto half. A little further on a portion of the engine half of the coupling releases this trip lever and the magneto armature is revolved rapidly under the influence of the connecting spring. So soon as the engine gains speed, these trip levers are sprung out of engagement with the stop owing to the effect of centrifugal force, and the drive is thereafter transmitted normally • through the coupling by means of the detente Or other similar arrangement. -
121,192. C. Andrews. An adjustable spanner to accommodate four sizes of not.
121,212, Hooton. A silencer which in principle consists of a long pipe with by passes arranged at periodic intervals, the object being to damp out the normal pulsations of the exhaust of a number of cylinders. An air-cooled sparking plug is the subject of No. 121,222. Integral with the plug itself is a small automatic air inlet valve through which a small quantity of cool air is drawn on each suction stroke of the engine; this air passes the plug points.
121,223, by J. W. White, refers to the utilization of coal dust as a fuel for internal-combustion engines, solid and liquid fuel being introduced separately and simultaneously, 121,243, F. W. Lanchester. A forcefeed lubricating arrangement for the connecting rod of an engine, the principle of which may be gathered from the illustration, Dr. A. Jackson, 121,266, has patented a special valve, which, when fitted to the bulb of a horn, prevents its use by unauthorized persons.
121,268 is a specification for the friction lining of the driven wheel of a friction drive. (A.. G. Grim).