STALLING

Rotorua Morning Post, Volume 1, Issue 146, 12 February 1932, Page 7

STALLING

EXCESSIVE AND IMPROPER 4 USE OF CHOKE, BIG FACTOR. NON-STALLING DEVICE. Present-day driving conditions are so exacting that the accidental stopping of a car's engine is often a matter not only of deep annoyance to its driver but also the cause of interference to traffic. Sometimes the stalling of an engine may involve serious danger. The recent announeement tha^ certain new ftiodels are being hrought out with engines which start automatically upon the switehing on of their ignition and are automatically prevented from stallirrg gives this subject special interest. The non-stallable motor-car engine is not a new invention, for early in the history of the industry there were certain makes of cars provided with an engine-coupled dynamo, "floating" on the line with the battery which was powerful enough to act as a startermotor whenever engine speed fell so low that dynamo voltage dropped below battery voltage. For many years past, there has been upon the max'ket an anti-stall device capable of f estarting the engine as soon as its speed is lowered too far towards the stalling point. 1 Principle Involved. The principle involved in the nonstalling device is as follows: Turning on the ignition also closes the starter circuit, through a relay aetuated by battery current, energising the starter-motor and cranlcing the engine. After the engine starts, the dynamo begins to furnish current, which, flowing through another coil on the relay magnet, overpowers the effeet of the battery current upon it and breaks the starter circuit, shutting down the starter-motor and disengaging its drive. A Cold Engine. In starting a cold engine, the choke should be applied gradually until firing occurs. In most instances it will have to be fully applied, but as soon as explosions begin, choking should gradually he reduced, until the engine begins to miss and slow down, when it will have to be increased just enough to prevent stalling. The eharacteristic rhythmic variation of engine speed, known as rolling, should be the signal for immediate reduction of the degree of choking, and slowing down from irregular firing should be -the cue for instant moderate increase of the choking effeet.

When the car is first started, one shonld keep hold of the choke, ready to reduce its effeet so long as the engine runs normally and to increase it if backfires occur or the engine falters. In a car having a choke of the butterfly-valve type, tightly closing off the carhuretter air, the throttle never should be opened widely while the choke is fully in action, for by so doing, the eylinders will be flooded with petrol. Always be sure to put the choke entirely out of action just as soon as the engine can he made to run satisfa'ctorily without it. Running long distances with a carhuretter even partially choked may result in serious engine damage. If at any time engine speed falls dangerously close to the stalling point, the dynamo immediately ceases to deliver the effeet of the battery current acting on the magnet windings of the relay, and the battery current closes the relay cantaets, throwing the starter-motor into action and cranking the engine to a speed at which it begins to run again. Current from the dynamo is obviously taken direct from its armature terminal so as to exclude the reverse current cut-out from any part in the operation. Excessive or improper use of the carhuretter choke is a cause of1 stalling. It seems almost unfortunate that the carhuretter of every car is fitted with a choking device to give the

over-rich mixture .required at starting. The choke is often very careleSsly used and when this happens, ■all kind§ of trouble result. The rule for- handling the choke is to use it as slightly and as briefly as possible. and still - keep the engine running. Choking the carhuretter too eompletely or for too long a time, floods the engine with unburned petrol, which runs down the cylinder walls into the oil, thinning it and making it unfit as a lubricant, and the "wet" mixture fouls sparking-plugs and forms carbon. More than any one other thing, it is the excessive choking which engines are subjected to in cold weather which leads manufacturers to llecommend more frequent oil changes in winter.