THE MEN WHO LEARN VALVE-SETTING.
Most of intelligent machinists engaged on engine-work, make it an object of ambition to learn to set valves; and the operation is mastered as soon as the opportunity offers. It has been a practice in numerous shops for those who have the work of valve-setting to do, to invest the operation with fictitious mystery, to patiently disseminate the belief that valve-setting is an exceedingly difficult matter. Cases sometimes arise where the squaring of an engine’s valves is really an arduous task, requiring intimate familiarity with delicate methods of adjustment; but valve-setting, as it is usually practiced in building establishments, in repairing-shops, and in round-houses, is merely a matter of plain measurement.
A man may be a first-class engineer without knowing how to set valves, and familiar acquaintance with the operation will not increase his ability in managing his engine when merely getting a train over the road on time is the consideration; but the method of valve-setting is so closely associated with an intelligent appreciation of the valve-motion’s philosophy, that most of engineers who take an extended interest in their business, wish to acquire the knowledge of how the valves are set.
BEST WAY TO LEARN VALVE-SETTING.
The best way to learn valve-setting is by taking part in the work. Whatever can be said in books on a subject of this kind, provides but an indifferent substitute for going through the actual operations. But a man’s ambition to learn may exceed his opportunities; so, for those who can not get a gang boss to direct them into the art of valve-setting, this description will be made as plain as possible.
When an engine’s valve-motion is designed, the sizes of the different parts are arranged; and, if this business is done by a competent engineer, there will only be trifling changes necessary in valve-setting.
PRELIMINARY OPERATIONS.
Let us suppose the engine to be an ordinary eight-wheel locomotive, with cylinders 17 × 24 inches. Let us assume that the top and bottom rocker-arms are straight, of equal length, and that the eccentric-rods are connected to the link so as to be opposite the block in full gear. This will make the extreme travel of valve equal the eccentric’s throw. We will now look round to see that every thing connected with the motion is ready for valve-setting.
First, it is necessary to see that the wedges are properly set up to hold the driving-boxes in about the same position they will occupy when the engine is at work.